OHSU

Research & Publications

The microbiology laboratory in the Department of Endodontology was directed for 18 years by Dr. J. Craig Baumgartner until his retirement in 2009. Under his directorship the laboratory was fortunate to have Dr. Kwang-Shik Bae, an associate professor from Seoul National University, Seoul, Korea for two years; and Dr. Tian Xia an associate professor, Department of Oral and Maxillofacial Surgery, West China University of Medical Sciences, Chengdu, Sichuan, PR China for two years. In addition, Bev Watkins, a microbiologist and Dr. Larry David, a biochemist at OHSU School of Dentistry, made significant contributions. The studies progressed from basic cultivation of microorganisms associated with endodontic infections to the use of molecular methods to detect the presence of specific strains of bacteria and specific virulence factors.

Since 2010 the microbiology laboratory in the Department of Endodontology has been under the directorship of Dr. Christine Sedgley whose research interests encompass microorganisms associated with infections of endodontic origin. Under her directorship the laboratory has been fortunate to have the following visiting scholars from Brazil: Dr. Fernanda Signoretti, Dr. Rogerio de Castilho Jacinto and Dr. Tiago Pereria da Rosa.

EFFECT OF THREE NITI-FILES ON TRANSPORTATION OF THE APICAL FORAMEN

William Hu DMD, Brian Whitten DDS, Christine Sedgley MDS, MDSc, PhD, Timothy Svec DDS, MS. Int Endod J 2014 Jan 16. doi: 10.1111/iej.12249. [Epub ahead of print]

Aim  To compare landed and non-landed rotary file overinstrumentation on transportation of the apical foramen in the curved canals of extracted teeth.

Methodology  Severely curved molar root canals (n=45) were distributed into three equal groups (n=15) according to angle (mean 54°) and radius of curvature (mean 5 mm).  Canals were overinstrumented 0.5 mm beyond the foramen to a size 35 master apical file using landed (ProFile ISO), non-landed (ProFile Vortex), or non-landed, reduced shape memory (Vortex Blue) files.  Post-instrumentation images of the apical foramen were compared to pre-instrumentation control images for differences in area, circularity, and ratio of Feret’s diameters.  Groups were compared by using ANOVA or Kruskal-Wallis tests with significance of P<0.05.

Results  There were no differences between pre-treatment groups in the parameters tested.  All groups demonstrated alterations in the geometry of the apical foramen.  There were no significant differences between ProFile ISO, ProFile Vortex, or Vortex Blue in area, circularity, and ratio of Feret’s diameters.

Conclusions  Landed, non-landed, and non-landed reduced shape memory files all produced transportation of the apical foramen when overinstrumented by 0.5 mm in severely curved canals.  There was no difference between these file systems with regard to the degree of this effect.

CURRENT TRENDS IN ENDODONTIC TREATMENT BY GENERAL DENTAL PRACTITIONERS: REPORT OF A UNITED STATES NATIONAL SURVEY

Gina Savani DDS, Wael Sabbah BDS, DDPH, MSc, PhD, Christine Sedgley MDS, MDSc, PhD, Brian Whitten DDS. J Endod In press

Introduction: In the United States (US) almost 70% of root canal treatment (RCT) is performed by general dentists (GPs), yet little is known about their treatment protocols.

Methods: A paper survey was mailed to 2,000 US GPs with questions about the types of endodontic cases treated, routine treatment protocols, utilization of newer technologies, and endodontic continuing education (CE).

Results: Completed surveys were returned by 479 (24%) respondents. GPs that perform RCT (84%) reported providing anterior (99%), bicuspid (95%) and molar (62%) RCT, and retreatment (18%). Rubber dam was used always (60%), usually (16%), sometimes (13%) and never (11%). Newer technologies employed by GPs included digital radiography (72%), magnification (80%), electronic apex locator (70%), and NiTi rotary instrumentation (74%). Compared to GPs with >20 years experience, those in practice for ≤10 years were more likely to use rubber dam (p<0.05), NiTi rotary instrumentation (p<0.001), apex locators (p<0.001) and magnification (p<0.01); in contradistinction, GPs in practice >20 years were more likely to perform retreatments (p<0.05). Females were less likely to perform retreatment or molar RCT (both p<0.05). GPs with >5 hours of CE were more likely to use rotary instrumentation (p<0.001), irrigant activation devices (p<0.01) and apex locators (p< 0.001), and perform molar RCT (p<0.001) and retreatment (p<0.05), but no more likely to use rubber dam.

Conclusions: Recent GP graduates (≤10 years) were more likely to adopt new technologies and use rubber dam than those who practiced for >20 years. More experienced GPs were more likely to take on complicated cases than those with fewer years of practice. There was no association between hours of CE and compliance with rubber dam usage.

DENTAL STEM CELLS AND THEIR SOURCES

Christine Sedgley MDS, MDSc, PhD, Tatiana Botero DDS, MS. Dent Clin North Am 2012 Jul;56:549-61.

The search for more accessible mesenchymal stem cells than those found in bone marrow has propelled interest in dental tissues. Human dental stem/progenitor cells (collectively termed dental stem cells [DSCs]) that have been isolated and characterized include dental pulp stem cells, stem cells from exfoliated deciduous teeth, stem cells from apical papilla, periodontal ligament stem cells, and dental follicle progenitor cells. Common characteristics of these cell populations are the capacity for self-renewal and the ability to differentiate into multiple lineages. In vitro and animal studies have shown that DSCs can differentiate into osseous, odontogenic, adipose, endothelial, and neural-like tissues.

CRISPR-CAS, A PROKARYOTIC ADAPTIVE IMMUNE SYSTEM, IN ENDODONTIC, ORAL AND MULTIDRUG-RESISTANT HOSPITAL-ACQUIRED ENTEROCOCCUS FAECALIS

Katie M. Burley BSDH, DMD, Christine M. Sedgley MDS, MDSc, PhD J Endod 2012 Nov;38:1511-5.

Introduction: Microorganisms are vulnerable to invasion by mobile genetic elements such as viruses, plasmids and transposons. The recently discovered CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-associated system, or CRISPR-Cas, is an adaptive immunity system found in most archaea and many bacteria that targets and inactivates invading foreign genetic elements. Cells with CRISPR-cas are more likely to resist the invasion and uptake of foreign DNA such as viruses, plasmids and transposons. The aims of this study were to: (1) compare the occurrence of CRISPR-cas in collections of endodontic (n=34), oral (n=21), and multidrug-resistant hospital-acquired strains of E. faecalis (n=23); and (2) evaluate the distribution of antibiotic resistance and virulence traits amongst strains without CRISPR-cas.

Methods: E. faecalis strains were screened for CRISPR1-cas and CRISPR3-cas by using PCR, and products were verified by DNA sequencing. Associations were investigated between the occurrence of CRISPR-cas and the expression of phenotypic traits (antibiotic resistance, gelatinase activity, bacteriocin production, hemolysin activity, and clumping response to pheromone).

Results: CRISPR-cas determinants were present in proportionally more endodontic (25 of 34) and oral (15 of 21) strains than hospital-acquired (9 of 23) strains (P=0.01 and 0.04,respectively).Significant associations were found between the absence of CRISPR-cas and the presence of antibiotic resistance in strains overall (P=0.04) and bacteriocin activity in endodontic strains (P=0.01).

Conclusions: Evidence for the presence of CRISPR-cas in the majority of endodontic and oral E. faecalis strains raises intriguing questions as to how prokaryotic immune systems might modulate interactions within the polymicrobial endodontic biofilm environment.

COMPARISON OF THE SELF-ADJUSTING FILE (SAF) WITH ROTARY AND HAND INSTRUMENTATION IN LONG-OVAL SHAPED ROOT CANALS

Jim E. Ruckman DMD, Brian Whitten DDS, Christine M. Sedgley MDS, MDSc, PhD, Timothy Svec DDS, MS. J Endod 2013 Jan;39:92-5.

Introduction: The aim of this study was to compare the root canal debridement ability of the self-adjusting file (SAF) with ProFile rotary (PF) and hand filing (HF) instrumentation in long-oval shaped canals.

Methods: Extracted human teeth (n=30) were selected based on a root canal ratio of ≥ 2.5:1 measured 5 mm from the root apex. Each group (n=10) was matched with regards to the average root canal ratio.Canals were filled with a radiopaque contrast medium (Vitapex), and instrumented by using SAF, PF, or HF with 20 mL of saline irrigation. Teeth receiving irrigation alone served as controls. Preoperative and postoperative radiographs were taken, submitted to digital subtraction, and the percentage reduction of contrast medium was quantified at 0-5 mm and >5-10 mm from the apex. Values were compared using one-way analysis of variance and unpaired t-tests.

Results: In the 0-5 mm segment, the SAF, PF and HF removed 80.6% (±14.1%), 84.2% (±7.7%), and 76.5% (±10.2%) of the contrast medium, respectively (P > 0.05). In the >5-10 mm segment, the SAF, PF, and HF removed 75.5% (±10.8%), 72.3% (±12.0%), and 60.9% (±11.3%) of the contrast medium, respectively, with significantly more material removed by SAF compared to HF (P < 0.05). There was significantly more contrast media removed by using combined instrumentation and irrigation compared to irrigation alone (P < 0.01).

Conclusions: All three techniques removed contrast medium equally well from the 0-5 mm segment of long-oval shaped canals. The SAF performed significantly better than hand filing in the >5-10 mm canal segment.

COMPARISON OF A CONTINUOUS ULTRASONIC IRRIGATION DEVICE AND CONVENTIONAL NEEDLE IRRIGATION IN THE REMOVAL OF ROOT CANAL DEBRIS

Tyson Curtis DDS, Christine M. Sedgley MDS, MDSc, PhD. J Endod 2012;38:1261-4.

Introduction: The purpose of this in vitro study was to compare a continuous ultrasonic irrigation device [VProTM StreamCleanTM System, Vista Dental Products (VSS)] with conventional needle irrigation when used as a final irrigation procedure to debride the apical region of the root canal; the null hypothesis was tested that there is no difference.

Methods: Root canals of matched-pairs (n=20) of extracted human teeth were prepared to an apical size 36/.04 using Profile series 29/.04 rotary files with 6% NaOCl irrigation. One tooth of each pair was randomly assigned to receive final irrigation with either VSS or conventional needle irrigation; needle gauge (#30), irrigation cycles (5 mL NaOCl, 5 mL 15% EDTA, 5 mL NaOCl), irrigant flow rate (5 mL per minute) and needle depth placement [1 mm from working length (WL)] were experimental constants. Serial sections were obtained at 1 mm and 3 mm from WL, stained with hematoxylin and eosin, and viewed at X100 magnification for the presence of debris. The percentage of debris in the canal lumen after VSS or conventional needle irrigation were compared by using the Wilcoxon matched pairs test.

Results: There was significantly less debris in the VSS groups compared with the conventional needle irrigation groups at the 1 mm level [1.50% (VSS) versus 9.90% (conventional needle irrigation)(p=0.0001)], and at the 3 mm level [0.45% (VSS) versus 5.16% (conventional needle irrigation)(p=0.0014)]. The null hypothesis was rejected.

Conclusions: Final irrigation with the VProTM StreamCleanTM System compared with conventional needle irrigation delivery resulted in significantly less debris present in root canals at 1 mm and 3 mm from working length.

EFFECTS OF BONE GRAFT MATERIALS ON THE MICROHARDNESS OF MINERAL TRIOXIDE AGGREGATE

Erick Sato DDS, Timothy Svec, DDS, MS, Brian Whitten, DDS, Christine M. Sedgley MDS, MDSc, PhD. J Endod 2012 May;38:700-3.

Introduction: Large through-and-through lesions have been reported to heal faster and better when filled with bone graft material at the time of an apicoectomy. It is unknown what effect these have on retrograde filling materials such as white mineral trioxide aggregate (WMTA). In this study, the null hypothesis was tested that the presence of bone graft materials does not affect the microhardness of WMTA.

Methods: Freshly mixed WMTA was condensed into acrylic cylinders and preincubated aerobically at 37°C for 1 hour. Cylinders were immersed in simulated body fluid in close proximity to graft materials: xenograft (Bio-Oss, n = 60), freeze-dried bone allograft (MinerOss, n = 60), demineralized freeze-dried bone allograft (OraGraft, n = 40), and allograft (Puros, n = 60). Knoop microhardness of half the samples in each group was evaluated after 2 weeks of incubation and the remainder at 4 weeks. The values for each group were then compared with 2-way analysis of variance and Bonferroni post hoc tests.

Results: WMTA microhardness values for Bio-Oss, MinerOss, and Puros groups were lower than those for OraGraft and control groups regardless of incubation period (P < .001); values for the OraGraft group were higher than those for the control group at 2 weeks (P < .001), with no difference at 4 weeks. Microhardness values were higher at 4 weeks compared with 2 weeks for MinerOss (P < .05), OraGraft (P < .01), and control (P < .001), with no differences for Bio-Oss and Puros groups. The null hypothesis was rejected.

Conclusions: Demineralized and mineralized graft materials appear to have a differential effect on the microhardness of WMTA.

ROLE OF (p)ppGpp IN BIOFILM FORMATION BY ENTEROCOCCUS FAECALIS

Chavez de Paz LE, Lemos JA, Wickstrom C, Sedgley CM. Appl Environ Microbiol 2012 Mar;78:1627-30.

Enterococcus faecalis strain OG1RF and its (p)ppGpp-deficient ΔrelA, ΔrelQ, and ΔrelA ΔrelQ mutants were grown in biofilms and evaluated for growth profiles, biofilm morphology, cell viability, and proteolytic activity. E. faecalis lacking (p)ppGpp had a diminished capacity to sustain biofilm formation over an extended period of time and expressed abundant proteolytic activity.

ANTIBACTERIAL ACTIVITY OF ENDOSEQUENCE ROOT REPAIR MATERIAL AND PROROOT MTA AGAINST CLINICAL ISOLATES OF ENTEROCOCCUS FAECALIS

Karen F. Lovato DDS, Christine M. Sedgley MDS, MDSc, PhD.J Endod 2011 Nov;37:1542-6.

Introduction: Endodontic repair materials such as mineral trioxide aggregate (MTA) are utilized for various endodontic procedures.An alternative material to MTA with purportedly improved handling properties is EndoSequence Root Repair Material which is available as a premixed putty (ESP) or syringeable paste (ESS), and is described as possessing antibacterial activity during its setting reaction due to its highly alkaline pH. The aim of this in vitro study was to determine whether ESP and ESS possesses antibacterial properties against a collection of Enterococcus faecalis strains recovered from root canal infections. The hypotheses tested were that: 1) ESP and ESS possess antibacterial activity during their setting reaction, 2) there is no difference between ESP, ESS and MTA in antibacterial activity, and 3) E. faecalis strains isolated from root canals differ in susceptibility to the materials.

Methods: The direct contact test was used. ESP, ESS and white MTA were preincubated at 37°C in >95% humidity for 30 minutes and 24 hours prior to a one hour direct contact exposure to E. faecalis strains (n=10). Absence of antibacterial carryover effect from the materials to the bacterial cultures was confirmed. Log10 viable counts were compared using ANOVA with significance level at p≤0.05.

Results: Combining data for all strains, the mean (± standard deviation) log10 viable counts for ESP (4.55±0.85), ESS (4.5±0.95), and MTA (4.12±1.26) were significantly lower than for untreated controls (7.40±0.33) (p < 0.0001). The reduction in viable counts ranged 1.86 (±0.24) to 4.78 (±0.42), with no statistically significant differences between the materials or preincubation periods in reduction in viable counts. One strain was significantly more susceptible than four other strains.

Conclusions: ESP, ESS and MTA had similar antibacterial efficacy against clinical strains of E. faecalis. Clinical strains varied in their susceptibility to the root repair materials.

APICAL EXTRUSION OF SODIUM HYPOCHLORITE USING DIFFERENT ROOT CANAL IRRIGATION SYSTEMS

Ross P. Mitchell, BS, DMD, J Craig Baumgartner, DDS, PhD, and Christine M. Sedgley, MDS, MDSc, PhD. J Endod 2011 Dec;37:1677-81.

Introduction: Root canal irrigation carries a risk of extrusion of irrigant into the periapical tissues. The objective of this study was to compare different irrigation systems in matched pairs of teeth prepared to an apical size of 35.06 and 50.06 by measuring the frequency and extent of apical extrusion of NaOCl into a simulated periapical environment. The null hypothesis was tested that there is no difference between systems.

Methods: Bilaterally matched pairs (n=10) of single canal extracted human anterior teeth were instrumented to an apical size of either 35.06 or 50.06. Teeth were embedded in a gel containing the pH-sensitive dye M-Cresol purple that changes from yellow at pH 7.4 to purple at pH 9. Root canals were irrigated with 6% NaOCl (pH 11) using EndoActivator (EA), EndoVac (EV), Rispisonic/MicroMega 1500 (MM), passive ultrasonic irrigation (PUI), and syringe irrigation with a slot-tipped needle (SN) so that each tooth underwent all irrigation procedures in a randomized cross-over design. Apical extrusion was evaluated by image analyses.

Results: The frequency of extrusion was less in teeth with apical preparation size 35.06 (36%) compared to 50.06 (60%) (p=0.014), and was dependent on the irrigation system in 35.06 (p=0.039) but not 50.06 groups. In the 35.06 group the frequency of extrusion was less for EV than for MM and SN (both p=0.029). The extent of extrusion was less for MM compared to PUI (p=0.024) and SN (p=0.046) in the 35.06 group, and greater for SN compared to all other systems in the 50.06 group (p<0.05). The null hypothesis was rejected.

Conclusions: The frequency of apical extrusion of NaOCl was dependent on the type of root canal irrigation system and apical preparation size. The extent of extrusion depended on the irrigation system, with syringe and slotted needle irrigation resulting in the greatest extent of extrusion.

PRECIPITATE FORMATION OF INACTIVATED SODIUM HYPOCHLORITE PRIOR TO CHLORHEXIDINE IRRIGATION.

David V. Christianson, DDS and Christine M. Sedgley, MDS, MDSc, PhD

Introduction: Root canal irrigation is an important step during endodontic therapy. Sodium hypochlorite (NaOCl) and chlorhexidine (CHX) used in combination may reduce postoperative positive cultures. However, SEM has shown that NaOCl/CHX precipitate can block dentin tubules. Sodium thiosulfate (Na2S2O3) is known to inactivate NaOCl. The null hypothesis tested was that precipitate formation observed on root canal walls after root canal irrigation with NaOCl followed by CHX can be reduced by irrigation with Na2S2O3 prior to using CHX.

Methods: Seventy-eight extracted single-rooted human teeth were divided into 6 groups of 13 teeth. Instrumented root canals in each group was subjected to one of 6 different irrigation procedures [two experimental (NaOCl/ Na2S2O3/CHX and NaOCl/CHX), one positive control and three negative controls]. Roots were split. Samples were randomized and blinded for subsequent imaging using environmental SEM. Images were obtained at 3 randomly selected fields of view at a level 3 mm from the anatomical apex. Images were analyzed for remaining debris and precipitate, and patent dentinal tubules on root canal walls based on Bui et al (2008). Groups were compared by using Kruskall-Wallis tests with significance level at p ≤ 0.05.

Results: There were no significant differences between any groups, including controls. The null hypotheseis could not be confirmed or rejected.

Conclusions: Evidence to support the use of sodium thiosulfate to avoid formation of precipitation was not shown.

BACTERIOCIN-RELATED SIBLICIDE IN CLINICAL ISOLATES OF ENTEROCOCCI

Yun-Chan Hwang DDS, PhD, Susan E. Flannagan MA, Don B. Clewell PhD, Christine M. Sedgley MDS, MDSc, FRACDS, MRACDS(ENDO), PhD. Probiotics and Antimicrobial Proteins. Probiotics and Antimicrobial Proteins 2011 Mar;3:57-61.

Siblicide is a phenomenon defined in the present context as an Enterococcus strain that, while growing as a colony on solid media, exhibits an inhibitory effect on a lawn composed of the identical strain. It was shown to occur in seven clinical isolates of enterococci (one E. faecalis and six E. faecium). Four involve inhibitory anti-listerial activities consistent with class II bacteriocins, two of which appear to be up-regulated by extracellular autoinducers.

COMPARISON OF INTRACANAL ENDOSEQUENCE® ROOT REPAIR MATERIAL AND PROROOT® MTA TO INDUCE PH CHANGES IN SIMULATED ROOT RESORPTION DEFECTS OVER 4 WEEKS IN MATCHED PAIRS OF HUMAN TEETH

Stephen W. Hansen DMD, J. Gordon Marshall DMD, Christine M. Sedgley MDS, MDSc, FRACDS, MRACDS(ENDO), PhD. J Endod. J Endod 2011 April;37:502-6.

Introduction: Intracanal mineral trioxide aggregate (MTA) may provide an alternative to calcium hydroxide in the treatment of external inflammatory root resorption. This in vitro study using human matched pairs of teeth compared white ProRoot® MTA (WMTA) and an alternative material with purportedly improved handling properties, EndoSequence® Root Repair Material (ES), by measuring pH in simulated root surface resorptive defects after intracanal placement. The null hypothesis was tested that there is no differencebetween WMTA and ES.  Methods: Bilaterally matched pairs (n=24) of extracted, human, single-rooted teeth were instrumented to apical size 50/.06, and root surface cavities were prepared at 5mm and 2mm from the apex. Root canals of experimental matched pairs (n=20) were filled with WMTA or ES; control pairs (n=4) were filled with calcium hydroxide (POS) or saline (NEG).  Teeth were sealed coronally and apically, and immersed in saline. The pH in root surface cavities was measured at 20min, 3h, 24h, 1wk, 2wk, 3wk and 4wk.  Results: The pH at 5mm when compared with the 2mm level was significantly higher for WMTA, ES and POS groups (p<0.05, paired t-tests), therefore each level was analyzed separately. Intragroup effects: At both the 2mm and 5mm levels significant pH changes occurred over time in groups WMTA, ES (both p<0.0001, RM-ANOVA) and POS (p<0.0001, Friedman's test) and not in NEG (mean pH 7.32±0.04, p>0.05). Intergroup effects: There were no differences between WMTA and ES at 20min and 3h at both levels, or at 24h at 5mm. The pH of WMTA was higher than ES by 24h at the 2mm level (8.79 versus 8.56, p<0.05, paired t-test), and after 1wk at the 5mm level (8.91 versus 8.05, p<0.0001) and was thereafter always significantly higher in WMTA compared to ES (p<0.0001). The null-hypothesis was rejected. Conclusions: In matched pairs of teeth, intracanal placement of WMTA compared to ES resulted in a higher pH in simulated root resorption defects that was time- and root-level-dependent.

THE EFFECTS OF INTRACANAL MTA AND CALCIUM HYDROXIDE OVER 4 WEEKS ON PH CHANGES IN SIMULATED ROOT SURFACE RESORPTION DEFECTS: AN IN VITRO STUDY USING MATCHED PAIRS OF HUMAN TEETH

Sarah Heward DMD and Christine M. Sedgley MDS, MDSc, FRACDS, MRACDS(ENDO), PhD. J Endod January 2011;37:40-44.

Introduction. Diffusion of hydroxyl ions from intracanal calcium hydroxide (CH) through dentin is utilized to arrest external inflammatory root resorption. However, long-term and short-term CH placement has been associated with an increased risk of root fracture. Intracanal mineral trioxide aggregate (MTA) might provide an alternative to CH as a source of hydroxyl ions. This in vitro study compared the effects of intracanal MTA and CH on hydroxyl ion diffusion through dentin by measuring pH changes over time in simulated root surface resorption defects prepared in matched pairs of teeth; the null hypothesis tested was that there is no difference.  Methods. Root surface cavities were prepared 5 mm from the apex in extracted human permanent anterior teeth (21 matched pairs) and seven additional teeth (controls). Root canals were instrumented to size 50/.04 and filled with either tooth-colored formula MTA (ProRoot) or CH (UltraCal XS); control teeth were filled with saline. The pH in root surface cavities was measured at 3 hr, 24 hr, 1 wk, 2 wk, 3 wk and 4 wk.  Results. Controls: pH readings did not differ significantly over the 4wk experimental period (p > 0.05, repeated measures ANOVA. Experimental intragroup effects: significant pH changes occurred over time in the MTA group (p=0.005, repeated measures ANOVA), and the CH group (p<0.0001). Experimental intergroup effects: the overall mean pH was higher in the MTA group [8.66 (SE 0.07)] compared to the CH group [8.46 (SE 0.07)] (p=0.014, paired t-test).  At 4 wk pH was higher in the MTA group [8.30 (SE 0.16)] compared to the CH group [7.90 (SE 0.11)] (p=0.011); at all other time points intergroup differences were insignificant. The null hypothesis was rejected. Conclusions. Intracanal MTA and CH groups differed in their overall effect on pH measured in simulated root surface resorption defects. At 4 wk, intracanal placement of MTA compared to CH resulted in a small but significantly higher pH.

A COMPARISON OF THE DEBRIDEMENT EFFICACY OF THE ENDOVAC IRRIGATION SYSTEM AND CONVENTIONAL NEEDLE ROOT CANAL IRRIGATION IN VIVO

Chris Siu BSc, DDS and J. Craig Baumgartner DDS, PhD. J Endod November 2010;36:1782-1785.

INTRODUCTION: The purpose of this study was to compare the debridement efficacy of EndoVac irrigation versus conventional needle irrigation in vivo.

METHODS: Seven adult patients with a total of 22 matched pairs of single-canaled vital teeth with fully formed apices were recruited. Canals were instrumented to a master apical file size #40/.04 taper. One tooth from each matched pair was irrigated by using the EndoVac system. The other tooth was irrigated by conventional needle irrigation. Five additional teeth were used as positive controls. A #10 K-file was inserted into the control canals to determine working length (WL), with no other instrumentation or irrigation performed to confirm the presence of debris. The teeth were extracted, fixed, and decalcified. Six histologic slides each 6 μm thick were made from sections at 1 and 3 mm from WL and stained. The slide with the most debris was photographed at each level for each tooth. A Wilcoxon signed rank test was used to compare the percentage of debris remaining in the canals between the 2 irrigation techniques.

RESULTS: The median amount of debris remaining at 1 mm was 0.05% for the EndoVac group and 0.12% for the conventional irrigation group (P < .05). The median amount of debris remaining at 3 mm was 0.09% for the EndoVac group and 0.07% for the conventional needle irrigation group (P > .05).

CONCLUSIONS: EndoVac irrigation resulted in significantly less debris at 1 mm from WL compared with conventional needle irrigation. There was no significant difference at the 3-mm level.

ANTIMICROBIAL EFFICACY OF THE ENDOVAC COMPARED TO NEEDLE IRRIGATION

Todd Miller, DDS, J. Craig Baumgartner, DDS, PhD. J Endod March, 2010; 36:509-511.

The purpose of this investigation was to compare the antimicrobial efficacy of irrigation with the EndoVac® versus needle irrigation in the apical 5mm of roots infected with Enterococcus faecalis. Bilaterally matched, extracted human teeth were sterilized and inoculated with E. faecalis. Specimens from Group A were irrigated using the EndoVac system, while those in Group B were irrigated with a 30 gauge side vented needle. Following chemomechanical preparation, the root ends were resected and pulverized in liquid nitrogen to expose E. faecalis in dentinal tubules or other recesses away from the main root canal system. The number of colony forming units (cfu) of E. faecalis per mg was determined from the pulverized root ends. Irrigation with EndoVac (Group A) had a mean of 31.6 cfu/mg and needle irrigation (Group B) had a mean of 157 cfu/mg. This represents a bacterial reduction of 99.7% in Group A and 98.8% in Group B when compared to positive controls. Although there was no statistically significant difference between Group A and Group B, there was a trend towards fewer cfu/mg when using the EndoVac®.

COMPARISON OF PUSH-OUT BOND STRENGTHS OF RESILON WITH 3 DIFFERENT SEALERS

Danielle Stiegemeier, DDS, J. Craig Baumgartner, DDS, PhD Jack Ferracane, PhD. J Endod February, 2010; 36:318-321.

The purpose of this study was to evaluate the push-out bond strengths of different obturating materials.  40 single rooted human extracted teeth were used in this study.  Teeth were cleaned and shaped using 5.25% NaOCl, 15% EDTA and sterile water as irrigants.  The teeth were then filled with Resilon and RealSeal, Resilon and RealSeal SE, Resilon and MetaSeal, or gutta-perch and Kerr EWT sealer.  The roots were then sectioned into 1mm thick slices and subjected to compressive loading to displace the obturating material toward the coronal side of the slice.  The bond strength was then calculated and subjected to statistical analysis.  Slices were examined under stereomicroscope at 10x power to determine mode of failure.  The push-out bond strengths of MetaSeal and gutta-percha with Kerr EWT were statistically significantly higher than either RealSeal or RealSeal SE.  MetaSeal and gutta-percha with Kerr EWT did not differ significantly.

TOOTH PULP INFLAMMATION INCREASES BRAIN-DERIVED NEUROTROPIC FACTOR EXPRESSION IN RODENT TRIGEMINAL GANGLION NEURONS.

Leila Tarsa, E Balkoviec-Iskra, FJ Kratochvil III, V K Jenkins, A McLean, AL Brown, JA Smith, J C Baumgartner and A Balkowiec. Nueroscience 2010;167:1205-1215.

Nociceptive pathways with first-order neurons located in the trigeminal ganglion (TG) provide sensory innervation to the head, and are responsible for a number of common chronic pain conditions, including migraines, temporomandibular disorders and trigeminal neuralgias. Many of those conditions are associated with inflammation. Yet, the mechanisms of chronic inflammatory pain remain poorly understood. Our previous studies show that the neurotrophin brain-derived neurotrophic factor (BDNF) is expressed by adult rat TG neurons, and released from cultured newborn rat TG neurons by electrical stimulation and calcitonin gene-related peptide (CGRP), a well-established mediator of trigeminal inflammatory pain. These data suggest that BDNF plays a role in activity-dependent plasticity at first-order trigeminal synapses, including functional changes that take place in trigeminal nociceptive pathways during chronic inflammation. The present study was designed to determine the effects of peripheral inflammation, using tooth pulp inflammation as a model, on regulation of BDNF expression in TG neurons of juvenile rats and mice. Cavities were prepared in right-side maxillary first and second molars of 4-week-old animals, and left open to oral microflora. BDNF expression in right TG was compared with contralateral TG of the same animal, and with right TG of sham-operated controls, 7 and 28 days after cavity preparation. Our ELISA data indicate that exposing the tooth pulp for 28 days, with confirmed inflammation, leads to a significant upregulation of BDNF in the TG ipsilateral to the affected teeth. Double-immunohistochemistry with antibodies against BDNF combined with one of nociceptor markers, CGRP or transient receptor potential vanilloid type 1 (TRPV1), revealed that BDNF is significantly upregulated in TRPV1-immunoreactive (IR) neurons in both rats and mice, and CGRP-IR neurons in mice, but not rats. Overall, the inflammation-induced upregulation of BDNF is stronger in mice compared to rats. Thus, mouse TG provides a suitable model to study molecular mechanisms of inflammation-dependent regulation of BDNF expression in vivo.

Supported by NIH, HL-076113 grant to A.B.

COMPARISON OF APICAL EXTRUSION OF NAOCl USING THE ENDOVAC OR NEEDLE IRRIGATION OF ROOT CANALS

Ross Paton Mitchell, DMD, Sung-Eun Yang, DDS, PhD, and J. Craig Baumgartner, DDS, PhD. J Endod February, 2010; 36:338-341.

Introduction: The purpose of this study is to compare extrusion of irrigants delivered with a 27-G needle or the EndoVac system (Discus Dental, Culver City, CA) during instrumentation and final irrigation of teeth. Methods: Matched paired single canal teeth were divided into four sample groups and controls. The experimental groups were needle irrigation International Standards Organization (ISO) size #40 (N40) and #60 (N60) and EndoVac ISO size #40 (E40) and #60 (E60). Teeth were secured and embedded in 0.2% agarose gel (ph = 7.3-7.4) containing 1 mL 0.1% m-cresol purple, which changes color at a pH of 9.0. Teeth received NaOCl and EDTA irrigation with the 27-G slot needle or the EndoVac system. The amount of irrigation was controlled for each sample. Standardized digital photographs were taken 20  minutes after the first irrigant was used. Photographs were analyzed by using Adobe Photoshop 7 (Adobe, San Jose, CA) to determine the amount of extrusion expressed as percent of total pixels. Results: Data from sample groups show the following: N40 with 50% extrusion (6/12), E40 with 8.33% extrusion (1/12), N60 with 58.33% (7/12), and E60 with 8.33% (1/12). The overall extrusion frequency, regardless of apical preparation size, was 54.17% (13/24) for needle and 8.33% (2/24) for EndoVac. Analysis of N40 and E40 revealed p < 0.03. Analysis of N60 and E60 revealed p < 0.01. Comparison of needle irrigation versus EndoVac showed a significant p value of 0.0007. Conclusions: This study showed significantly less extrusion risk using the EndoVac system compared with needle irrigation.

A GENETIC DETERMINANT IN STREPTOCOCCUS gordonii CHALLIS ENCODES A PEPTIDE WITH ACTIVITY SIMILAR TO THAT OF ENTERCOCCAL SEX PHEROMONE cAM373, WHICH FACILITATES INTERGENERIC DNA TRANSFER

Vickerman MM, Flannagan SE, Jesionowski AM, Brossard KA, Clewell DB, Sedgley CM. J Bacteriol. 2010 May;192(10):2535-45.  

Enterococcus faecalis strains secrete multiple peptides representing different sex pheromones that induce mating responses by bacteria carrying specific conjugative plasmids. The pheromone cAM373, which induces a response by the enterococcal plasmid pAM373, has been of interest because a similar activity is also secreted by Streptococcus gordonii and Staphylococcus aureus. The potential to facilitate intergeneric DNA transfer from E. faecalis is of concern because of extensive multiple antibiotic resistance, including vancomycin resistance, that has emerged among enterococci in recent years. Here, we characterize the related pheromone determinant in S. gordonii and show that the peptide it encodes, gordonii-cAM373, does indeed induce transfer of plasmid DNA from E. faecalis into S. gordonii. The streptococcal determinant camG encodes a lipoprotein with a leader sequence, the last 7 residues of which represent the gordonii-cAM373 heptapeptide SVFILAA. Synthetic forms of the peptide had activity similar to that of the enterococcal cAM373 AIFILAS. The lipoprotein moiety bore no resemblance to the lipoprotein encoded by E. faecalis. We also identified determinants in S. gordonii encoding a signal peptidase and an Eep-like zinc metalloprotease (lspA and eep, respectively) similar to those involved in processing certain pheromone precursors in E. faecalis. Mutations generated in camG, lspA, and eep each resulted in the ablation of gordonii-cAM373 activity in culture supernatants. This is the first genetic analysis of a potential sex pheromone system in a commensal oral streptococcal species, which may have implications for intergeneric gene acquisition in oral biofilms.

IDENTIFY AND DEFINE ALL DIAGNOSTIC TERMS FOR PERIAPICAL/PERIRADICULAR HEALTH AND DISEASE STATES

James L. Gutmann, DDS,J. Craig Baumgartner, DDS, MS, PhD,Alan H. Gluskin, DDS,Gary R. Hartwell, DDS, MS,and Richard E. Walton, DMD, MS. J Endod December, 2009; 35:1658-1674.

Introduction: The purpose of this in-depth investigation was to identify, clarify, and substantiate clinical terminology relative to apical/periapical/periradicular diagnostic states, which is used routinely in the provision of endodontic care. Furthermore, the information gleaned fromthis investigation was used to link diagnostic categories to symptoms, pathogenesis, treatment, and prognosis wherever possible, along with establishing the basis for the metrics used in this diagnostic process. Materials and Methods: Diagnostic terminologies and their relevance to clinical situations were procured from extensive historic and electronic searches and correlated with contemporary concepts in disease processes, clinical assessments, histologic findings (if appropriate), and standardized definitions that have been promulgated and promoted for use in the last 25 years in educational programs and test constructions and for third-party concerns. Results: In general, clinical terminology that is used routinely in the practice of endodontics is not based on the findings of scientific investigations. The diagnostic terms are based on assumptions by correlating certain signs, symptoms, and radiographic findings with what is presumed (not proven) to be the underlying disease process of a given clinical state. There were no studies that specifically tried to assess the accuracy of the metrics used contemporarily for the classification of clinical disease states. Conclusion: A succinct diagnostic scheme that could be described thoroughly, agreed on unanimously, coded succinctly for easy electronic input, and ultimately used for follow-up analysis would not only drive treatment modalities more accurately, but would also allow for future outcomes assessment and validation.

An In Vivo Comparison of the Root ZX II, the Apex NRG XFR, and Mini Apex Locator by Using Rotary Nickel-Titanium Files

Chris Siu, DDS, BSc, J. Gordon Marshall, DMD, and J. Craig Baumgartner, DDS, PhD. J Endod July, 2009;35:962–965.

Introduction: The purpose of this study was to compare the accuracy of working length (WL) measurements by using the Root ZX II, Apex NRG XFR, and Mini Apex Locator with rotary nickel-titanium (NiTi) instruments. Methods: Twenty-eight teeth had their WLs determined with each electronic apex locator (EAL) by using 0.04 taper ProFiles sizes 40–20 in a crown-down technique until WL was reached. Four control teeth had their WL determined by using stainless steel hand files. The files were cemented at WL, and the teeth were extracted. The apical 4 mm of each root was shaved to the apical constriction, exposing the file. Photographs were taken under 15_ and 30_ magnification and projected at 360_ and 720_ for evaluation. Results: The accuracy of the Root ZX II, Apex NRG XFR, and Mini Apex Locator in locating the minor diameter within _0.5 mm was 50%, 46.43%, and 39.29%, respectively. There was no statistically significant difference between the EALs in locating the minor diameter. The determination of WL by using hand files in the control teeth was more accurate. Conclusions: The Root ZX II, Apex NRG XFR, and Mini Apex Locator used with rotary NiTi files were able to locate the apical constriction within _0.5 mm only 50% or less of the time.

Herpesviruses in Abscesses and Cellulitis of Endodontic Origin

Vicky Chen, BS, Yanwen Chen, PhD, Hong Li, DDS, MSc, PhD, Karla Kent, PhD, J. Craig Baumgartner, DDS, PhD, and Curtis A. Machida, PhD J Endod  February, 2009;35:182–188.

Acute apical abscesses and cellulitis are severe endodontic diseases caused by opportunistic bacteria with possible coinfection with latent herpesviruses. The objectives of this study are to identify herpesviruses, including human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), herpes simplex virus-1 (HSV-1), and Varicella zoster virus (VZV) in patients (n _ 31) presenting with acute apical abscesses and cellulitis of endodontic origin. Primary and nested polymerase chain reaction (PCR) was conducted using virus-specific primers and DNA isolated from cell-free abscess fluid. From patients exhibiting concurrent spontaneous pain (n _ 28), nine abscesses contained HCMV, two abscesses contained EBV, one abscess contained HSV-1, and no abscesses contained VZV. Control PCR using genomic or recombinant templates showed detection limits to a single genomic copy of HCMV, 100 genomic copies for EBV, and 1 to 10 copies for HSV-1 with no cross-amplification between herpesviral DNA targets. Nested PCR was required for detection of herpesviral DNA in the abscess specimens, indicating that these viruses were present in low copy number. Filtration of abscess specimens and virus transfer experiments using human fibroblastic MRC-5 cells confirmed the presence of HCMV particles in several abscess specimens. We conclude that herpesviruses are present but not required for the development of acute apical abscesses and cellulitis of endodontic origin.

Herpesviruses in Endodontic Pathoses: Association of Epstein-Barr Virus with Irreversible Pulpitis and Apical Periodontitis

Hong Li, DDS, MSc, PhD*, Vicky Chen, BS,  Yanwan Chen, PhD, J. Craig Baumgartner, DDS, MSc, PhD, and Curtis A. Machida, PhD. J Endodon 35:23. January, 2009

Irreversible pulpitis and apical periodontitis are inflammatory diseases caused by opportunistic bacteria with possible co-infection with latent herpesviruses.  The objectives of this study are to identify herpesviruses, including human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV-1) and Varicella zoster virus (VZV), in patients presenting with irreversible pulpitits (n=29) or apical periodontitis, either primary (n=30) or previously treated (n=23).   EBV DNA and RNA were present in endodontic pathoses in significantly higher percentages (36.6% and 20.8%, respectively) compared to healthy pulp controls (0%).  HCMV DNA and RNA were found in measurable numbers in both endodontic patients (20.8% and 25.7%, respectively) and in healthy pulp controls (42.2% and 10.5%, respectively).  HSV-1 DNA was found in low percentages in endodontic patients (11.9%), and only one patient, exhibiting symptomatic irreversible pulpitis, demonstrated presence of VZV. We conclude that EBV may be associated with irreversible pulpitis and apical periodontitis.

Evaluation of the Interaction between Sodium Hypochlorite and Chlorhexidine Gluconate and its Effect on Root Dentin

Tung B. Bui, DDS *1, J. Craig Baumgartner, DDS, PhD , John C. Mitchell, PhD. J Endodon 34:181. February, 2008.

The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) forms a precipitate. The aim of this study was to evaluate the effect of irrigating root canals with a combination of NaOCl and CHX on root dentin and dentinal tubules by using the environmental scanning electron microscope (ESEM) and a computer program (Photoshop CS2). Forty-four extracted single-rooted human teeth were instrumented and irrigated with both NaOCl and CHX to produce a precipitate. Root canal surfaces were analyzed with the ESEM. The amount of remaining debris and number of patent tubules were determined. There were no significant differences in remaining debris between the negative control group and the experimental groups. There were significantly fewer patent tubules in the experimental groups when compared with the negative control group. The NaOCl/CHX precipitate tends to occlude the dentinal tubules. Until this precipitate is studied further, caution should be exercised when irrigating with NaOCl and CHX.

Effect of Electropolishing ProFile Nickel –Titanium Rotary Instruments on Cyclic Fatigue Resistance, Torsional Resistance, and Cutting Efficiency

Tung B. Bui, DDS, John C. Mitchell, PhD, J. Craig Baumgartner, DDS, PhD. J Endodon 34:190. February, 2008.

This study investigated the effect of electropolishing ProFile nickel titanium rotary instruments on torque resistance, fatigue resistance, and cutting efficiency. Size 25/.04 ProFile files (Dentsply Maillefer, Switzerland) that were nonpolished for the control group (n = 15) and electropolished for the experimental group (n = 15) were used for each experiment. Cyclical fatigue was determined by counting rotations until breakage with an applied 30°, 45°, and 60° curve with a 5-mm radius. Torque and angle at failure were measured by rotating clamped files at 2 rpm until breakage. Cutting efficiency was determined by measuring the velocity of file advancement into plastic blocks with 100-g constant force for 5 seconds. Data were analyzed by either an unpaired t test or analysis of variance followed by a Fisher probable least-square difference test. Electropolishing significantly reduced resistance to cyclic fatigue but did not affect torsional resistance. However, electropolishing reduced the angle at failure and amount of unwinding. Electropolishing did not significantly affect cutting efficiency.

Nerve Growth Factor Regulates Synaptophysin Expression In Developing Trigeminal Ganglion Neurons In Vitro

L. Tarsa, D.D.S., M.S. and A. Balkowiec, M.D., Ph.D. Neuropeptides 43:47-52. 2009.

The role of neuronal growth factors in synaptic maturation of sensory neurons, including trigeminal ganglion (TG) neurons, remains poorly understood. Here, we show that nerve growth factor (NGF) regulates the intracellular distribution of the synaptic vesicle protein synaptophysin (Syp) in newborn rat TG neurons in vitro. While reducing the number of Syp-positive cell bodies, NGF dramatically increases Syp immunoreactivity in both proximal and distal segments of the neurite. Intriguingly, the increase in Syp immunoreactivity occurs only in neuron-enriched cultures, in which the number of non-neuronal cells is significantly reduced. Together, our data indicate that NGF is a candidate molecule involved in early postnatal maturation of TG neurons, including control of presynaptic assembly, and thereby formation of synaptic connections.

An Evaluation of GuttaFlow and Gutta-Percha in the Filling of Lateral Grooves and Depressions

Tracie M. Zielinski, DDS, J. Craig Baumgartner, DDS, PhD, J. Gordon Marshall, DMD. J Endodon 34:295. March, 2008.

The purpose of this study was to compare the flow of GuttaFlow (Coltène/Whaledent Inc, Cuyahoga Falls, OH) and gutta-percha into lateral grooves and depressions in the apical 7 mm of the root canal system. A maxillary canine was used to fabricate a split-tooth model with depressions and lateral grooves placed in the canal walls at 1 mm, 3 mm, 5 mm, and 7 mm from the working length. The model was obturated with GuttaFlow or gutta-percha and Roth’s 801 sealer (Roth International, Chicago, IL). Obturations with gutta-percha were performed by using warm vertical compaction with the System B plugger (Analytic Endodontics, Orange, CA) advanced to 5 mm, 4 mm, or 3 mm from the working length. All obturations with GuttaFlow showed extrusion of material beyond the apex. GuttaFlow completely obturated the grooves and depressions at all levels from the working length, and, at the 1-mm level, GuttaFlow flowed significantly better into grooves. GuttaFlow flowed better than gutta-percha into depressions at the 1-mm level when the System B plugger was inserted to 5 mm and 4 mm from the working length, but no significant differences were seen when the System B plugger was inserted to 3 mm from the working length. Gutta-percha flowed significantly better into grooves and depressions at the 1-mm level when the System B plugger was inserted 3 mm from the working length compared with 5 mm and 4 mm from working length.

Comparison of the EndoVac system to needle irrigation of root canals

Benjamin A. Nielsen, DMD, J. Craig Baumgartner, DDS, PhD. J Endodon 33:611. May, 2007.

Past studies have shown that current irrigation methods are effective at cleaning root canals coronally but less effective apically. To be effective, endodontic irrigants should ideally be delivered near working length. The purpose of this study was to compare the efficacy of the EndoVac irrigation system and needle irrigation to debride root canals at 1 and 3 mm from working length. One tooth of each matched pair was instrumented and irrigated by using the EndoVac, which uses negative pressure to deliver irrigating solutions to working length. The other tooth of the matched pair was instrumented and irrigated with a 30-gauge ProRinse irrigating needle. All teeth were irrigated with sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) for a predetermined amount of time, and total volume of irrigant used was recorded. After instrumentation and irrigation, the teeth were fixed, decalcified, and sectioned at 1 mm and 3 mm from working length. Serial sections were made and digitally photographed. The amount of remaining debris was determined as a percentage of the area of the canal lumen. Remaining debris and total irrigant were analyzed by using the Wilcoxon signed rank test at the 5% confidence level. At the 1-mm level, significantly less debris was found in the EndoVac group (p = 0.0347). At the 3-mm level, there was no significant difference between groups. Significantly more irrigant was delivered with the EndoVac (p < 0001). This study showed significantly better debridement at 1 mm from working length by using the EndoVac compared with needle irrigation.

A comparison of gutta-percha and Resilon in the obturation of lateral grooves and depressions.

Nicole Karr-Slaughter DMD Craig Baumgartner, DDS, PhD J Gordon Marshall, DMD. J Endodon 33:749. June, 2007. The purpose of this study was to compare the flow of gutta-percha and Resilon into lateral grooves and depressions in the apical 7 mm of a root canal using warm vertical compaction. A split-tooth model was constructed with lateral grooves and depressions prepared at 1, 3, 5, and 7 mm from working length (WL). Groups A, B, and C were obturated with gutta-percha with a System B  plugger placed 5 mm, 4 mm, or 3 mm from WL. Groups D, E, and F were obturated with Resilon with a System B  plugger placed 5 mm, 4 mm, or 3 mm from WL. Gutta-percha and Resilon demonstrated similar movement into lateral grooves and dentin depressions, with a significant difference found only with increased flow of gutta-percha into depressions at the 1 mm level when the System B plugger was placed 3 mm or 4 mm from WL (p ≤ .05).

Bacterial community profiles of endodontic abscesses from Brazilian and USA subjects as compared by denaturing gradient gel electrophoresis analysis

J. C. Machado de Oliveira, J. F. Siqueira Jr, I. N. Rôças, J. C. Baumgartner, T. Xia, R. S. Peixoto, A. S. Rosado. Oral Microbio Immuno 22:14-18. February, 2007.

This study compared the bacterial community profiles of the microbiota associated with acute apical abscesses from Brazilian and USA patients using denaturing gradient gel electrophoresis (DGGE). DNA was extracted from purulent exudate aspirates and part of the 16S rRNA gene was amplified by polymerase chain reaction and separated by DGGE. The resulting banding patterns, which were representative of the bacterial community structures in samples from the two locations, were then compared. Distinct DGGE banding patterns were observed from different samples. Ninety-nine bands with distinct positions in the gels were detected, of which 27 were found only in the USA samples and 13 were exclusive to Brazilian samples. Four of the 59 shared bands showed very discrepant findings with regard to prevalence in the two locations. Cluster analysis of DGGE banding profiles showed a great variability in the bacterial populations associated with teeth with abscesses regardless of the geographical location. Two big clusters, one for each location, were observed. Other clusters contained a mixture of samples from the two locations. The results of the present study demonstrated a great variability in the bacterial community profiles among samples. This indicates that the bacterial communities of abscesses are unique for each individual in terms of diversity. The composition of the microbiota in some samples showed a geography-related pattern. Furthermore, several bands were exclusive for each location and others were shared by the two locations and showed great differences in prevalence.

Comparison of the antimicrobial efficacy of 1.3% NaOCl/BioPure MTAD to 5.25% NaOCl/15% EDTA for root canal irrigation.

Johal S, Baumgartner JC, Marshall JG. J Endodon 33:48-51. January, 2007.

The purpose of this study was to compare the antimicrobial efficacy of 1.3% NaOCl/BioPure MTAD to 5.25% NaOCl/15% EDTA for root canal irrigation. Twenty-six bilaterally matched pairs of human teeth were collected. The teeth were incubated with Enterococcus faecalis for 4 weeks. The teeth were divided into two experimental groups and one positive control group. The canals were instrumented and irrigated with either 5.25% NaOCl/15% EDTA or 1.3% NaOCl/BioPure MTAD. Bacterial samples were collected after instrumentation/irrigation and after additional canal enlargement. Statistical analysis of the data using the Wilcoxon Signed Rank test showed significant differences between the experimental groups. The first bacterial samples revealed growth in 0 of 20 samples with 5.25% NaOCl/15% EDTA irrigation and in 8 of 20 samples with 1.3% NaOCl/BioPure MTAD irrigation. Samples taken after additional canal enlargement revealed growth in 0 of 20 samples in 5.25% NaOCl/15% EDTA and in 10 of 20 samples in 1.3% NaOCl/BioPure MTAD group. This investigation showed consistent disinfection of infected root canals with 5.25% NaOCl/15% EDTA. The combination of 1.3% NaOCl/BioPure MTAD left nearly 50% of the canals contaminated with E. faecalis

The antimicrobial effect of chloroform on Enterococcus Faecalis following gutta-percha removal.

Edgar SW, Baumgartner JC, Marshall JG.  J Endodon 32:1185-1187. December,2006.

The purpose of this in vitro study was to evaluate the antimicrobial effectiveness of chloroform on Enterococcus faecalis when used as a gutta-percha solvent during endodontic retreatment.  Bilaterally matched human teeth were instrumented, infected with E. faecalis, and obturated.  The gutta-percha was then removed using either chloroform or saline.  Bacterial samples were collected after gutta-percha removal and following additional apical enlargement.  A significant difference was seen (p < 0.05) between the number of colony forming units (CFU) of E. faecalis for teeth retreated using chloroform (mean 21+56 CFU/ml) versus saline (mean 280+480 CFU/ml).  Negative cultures were obtained in 11/17 chloroform samples and none of the saline samples.  Samples taken following apical enlargement two sizes larger than the original master apical file showed a significant difference (p<0.05) between teeth retreated using chloroform versus saline.  Negative cultures were seen in 9/17 chloroform samples and 1/17 saline samples.  This study demonstrated that the use of chloroform during endodontic retreatment significantly reduced intracanal levels of cultivable E. faecalis.

Prevalence of selected bacterial named species and uncultivated phylotypes in endodontic abcesses from geographic locations.

Rôças IN, Baumgartner JC, Xia, T, Siqueira, Jr, JF. J Endodon 32:1135-1138. December, 2006.

Evidence is mounting that the prevalence of some putative endodontic pathogens can significantly vary according to the geographic location in which samples were taken. This study aimed to provide additional knowledge on this subject by comparing the frequencies of 10 selected candidate endodontic pathogens in samples of acute apical abscesses obtained from two distinct geographic locations; Portland, OR, and Rio de Janeiro, Brazil. DNA was extracted from aspirates and used as template in nested PCR assays using 16S rRNA gene taxon-specific oligonucleotide primers. Of the target species/phylotypes, Treponema denticola (73% of the cases), Porphyromonas endodontalis (70%), and Tannerella forsythia (57%) were the most prevalent taxa found in Brazilian samples. Dialister invisus (70% of the cases), P. endodontalis (63%) and Dialister pneumosintes (55%) were the most frequent taxa in the Portland, OR samples. Data analysis revealed that T. denticola and T. forsythia were significantly more detected in Brazilian samples than in the Portland, OR samples. Although D. invisus, Filifactor alocis, and Synergistes oral clone W090 were detected in many more samples from the Portland, OR patients, differences were not found to be statistically significant. These findings confirmed that some bacterial taxa can markedly differ in the frequencies they occur in samples from different locations. It remains to be clarified whether this observation translates into relevant therapeutic implications.

Comparison of root canal debridement using either Er,Cr:YSGG laser HKS or rotary instrumentation.

Radatti DA, Baumgartner JC, Marshall JG. J Am Dent Assoc 137:1261-1266, September, 2006.

Background: The authors evaluated the efficacy of the Er, Cr: YSGG laser powered hydrokinetic system (HKS) (Biolase technology, Inc. San Clemente, CA) in comparison to rotary instrumentation for root canal debridement. Methods:  Four uninstrumented controls and two experimental groups of 18 matched pairs were studied.  Teeth from each pair differed in instrumentation technique, but received identical irrigation solutions.  The instrumentation protocol consisted of either rotary instrumentation or the Er,Cr:YSGG laser.  The irrigation groups consisted of 0.5 ml of distilled water or 5.25% NaOCl between instruments.  The amount of debris remaining at 2 and 4 mm from the apex was measured as a percentage of total lumen area. Results: Lased canals had significantly more debris than rotary instrumentation canals (Wilcoxon signed-rank test, p<0.001).  With distilled water irrigation the debris remaining in lased canals at both the 2 and 4 mm levels was not statistically different than uninstrumented controls.  When using rotary instrumentation, significantly less debris remained compared to laser instrumentation (Wilcoxon signed-rank test , p<.001). With 5.25% NaOCl irrigation, there was no difference in remaining debris between the HKS group and the rotary instrumentation group (Wilcoxon signed-rank test , p<.001).   The lased groups received a significantly greater volume of irrigant than the rotary group (Wilcoxon rank sum test, p<.001).   Conclusions:  This study indicates the HKS used with distilled water irrigation is unacceptable as a debridement technique.  With 5.25% NaOCl irrigation, the debridement efficacy of HKS is similar to rotary instrumentation.  Clinical Implications:  Traditional chemomechanical instrumentation with files and irrigation is a more predictable method to debride canal systems than HKS.   With HKS, root canal debridement was only effective when using NaOCl irrigation.

Safety of Electronic Apex Locators and Pulp Testers in Patients with Implanted Cardiac Pacemankers or Cardioverters/Defibrillators.

Wilson, B., Baumgartner, Broberg, C., JC, Kron, J.  J Endodon 32:847-852, September, 2006.

The purpose of this study was to determine if electronic apex locators (EAL) or electric pulp testers (EPT) interfere with the function of implanted cardiac pacemakers (ICP) or cardioverter/defibrillators (ICD).  Twenty-seven patients with ICPs or ICDs had continuous electrocardiogram monitoring and device interrogation to detect interferences during the use of two types of EALs and one EPT.  No interferences were detected by any ICP or ICD.  In six patients, with intermittent pacing, a significant increase in pacing was observed during EAL/EPT stimulation (p < 0.05).  Examination of RR intervals (a measure of intrinsic heart rate) demonstrated significantly longer RR intervals (slower intrinsic heart rate) during EAL/EPT stimulation (p < 0.05).  Evaluation of the electrocardiograms for each patient failed to show any abnormalities in pacing during testing.  These findings led us to conclude that the increased pacing frequency observed was related to a slower intrinsic heart rate and not electrical interference with the cardiac devices.  In conclusion, the two EALs and one EPT used in this study did not interfere with the functioning of any of the cardiac devices tested.

Antibiotics and the Treatment of Endodontic Infections

Baumgartner, JC.. Collegues for Excellence, American Association of Endodontists. Summer, 2006.

Endodontic infections range from being asymptomatic to life threatening. They are polymicrobial infections characterized by mostly anaerobic bacteria and some facultative bacteria (1). A tooth with an infected necrotic pulp becomes a reservoir of infection isolated from the patient’s immune response. Eventually bacteria and bacterial by-products will produce a periradicular inflammatory response. With microbial invasion of periradicular tissues an abscess and cellulitis may develop. The spread of infection and the inflammatory response will continue until the source of the irritation is removed. The inflammatory response may give rise to both protective and immunopathogenic effects. The inflammatory response may be destructive to surrounding tissue and contribute to adverse signs and symptoms. Severe infections may develop depending on the pathogenicity of the microorganisms involved and the resistance of the host (Figure 1). Normal flora may prevent pathogenic organisms from invading the tissues and causing disease. However, normal flora may become opportunistic pathogens if they gain access to tissues not previously colonized. Such is the case when normal oral flora gain access to the pulp cavity and periradicular tissues. Microbes associated with endodontic disease include bacteria, fungi, and viruses (1). Clinical signs and symptoms of an infection are the result of damage to the tissues caused by the microbe and the inflammatory response produced by the host. Patient evaluation and the appropriate diagnosis/treatment of the source of an infection are of utmost importance.

Comparison of the antimicrobial efficacy of 1.3% NaOCl/BioPure MTAD to 5.25% NaOCl/15% EDTA for root canal irrigation.

Kho, T. and Baumgartner JC. J Endodon 32:652-655, July, 2006.   The purpose of this investigation was to compare the antimicrobial efficacy of irrigating with 1.3% NaOCl/Biopure MTADTM versus irrigation with 5.25% NaOCl/15% EDTA in the apical 5 mm of roots infected with Enterococcus faecalis.  Twenty-five bilaterally matched pairs of human teeth were collected and sterilized.  Two pairs were maintained as negative controls while the remaining teeth were inoculated with E. faecalis, incubated for four weeks, and then divided into two experimental groups and a positive control group.  The canals were instrumented and irrigated with either 1.3% NaOCl/Biopure MTAD, 5.25% NaOCl/15% EDTA or saline.  Following chemomechanical root canal preparation, the root-ends were resected and pulverized in liquid nitrogen to expose E. faecalis in dentinal tubules or other recesses away from the main root canal system.  Each pulverized root-end was weighed, serially diluted and cultured onto brain heart infusion agar.  Following 48 hours of incubation the number of colony forming units (CFU) of E. faecalis per mg was determined. Statistical analysis of the data using repeated measures t test showed no significant differences (t = 0.70, df =18, p = 0.495) between the number of colony forming units of E. faecalis for teeth irrigated with 5.25% NaOCl/15% EDTA (mean 131 + 291 CFU/mg) versus those teeth irrigated with 1.3% NaOCl/Biopure MTAD (mean 187 + 237 CFU/mg).  This study demonstrated that there is no difference in antimicrobial efficacy for irrigation with 5.25% NaOCl/15% EDTA versus irrigation with 1.3% NaOCl/Biopure MTAD in the apical 5 mm of roots infected with E. faecalis.

Autoaggregation and Coaggregation of Bacteria Associated with Acute Endodontic Infections.

Khemaleelakul, S, Baumgartener, JC, Pruksakon, S. J Endod 32:312-318, April, 2006.

Biofilms and microbial aggregates are a common mechanism for the survival of bacteria in nature. Microbial aggregates have been associated with intraradicular and extraradicular endodontic disease. One objective of this study was to assess bacteria isolated from acute endodontic infections for autoaggregation and coaggregation. Another objective was to use both a conventional visual assay and a novel fluorescent dye-staining technique to study bacterial aggregation. Sixty-two strains of bacteria were isolated from 10 clinical samples of endodontic abscesses or cellulitis. Autoaggregation was detected in 35/62 (56.45%) of the bacteria using the visual assay. Coaggregation of bacteria from each of the samples was demonstrated for 29/183 (15.85%) bacterial pairs using the visual assay and 148/183 (80.87%) using the dye-staining assay. Coaggregation was observed for each of the 15 genera assayed, especially Prevotella, Streptococcus, and Fusobacterium. The dye-staining assay using a confocal microscope was a highly sensitive method to detect aggregation of bacteria.

Setting times of Resilon and other sealers in aerobic and anaerobic environments.

Nielsen, B.A., Beeler, W. Vy, C., and Baumgartner, JC. J Endod 32:130-132. February, 2006.

Eleven sealers, including Resilon sealer, were mixed according to manufacturer’s instructions. Setting times were determined in both aerobic and anaerobic environments. Two samples of each sealer were mixed and placed in the following conditions: (a) uncovered in an aerobic incubator; (b) covered with a glass cover-slip in the aerobic incubator; (c) covered with phosphate buffered saline in an aerobic incubator; (d) uncovered in an anaerobic incubator; (e) light cured and then placed in the aerobic incubator (Resilon only). All samples were tested for setting times with a Gillmore needle at 15, 30, and 60 minutes, then hourly up to 8 hours, then at 24, 48, and 72 hours, and then weekly up to 3 weeks. Ketac Endo and Kerr Tubliseal, were the fastest sealers to set in aerobic environments. Ketac Endo and Resilon were the fastest sealers to set in anaerobic environments. Roth 801 and Roth 811 were the slowest sealers to set, taking over 3 weeks to set in either anaerobic or aerobic environments. Resilon sealer set in 30 minutes in both anaerobic environments. However, in the presence of air, Resilon took a week to set and when placed in PBS, an uncured layer remained on the surface.

Spreader penetration during lateral compaction of Resilon and gutta-percha

Nielsen, B.A. and Baumgartner, JC.. J Endod 32:52-54. January, 2006.

Resilon, a thermoplastic, polyester polymer–based filling material, is a new material used for sealing root canals after chemomechanical preparation. The purpose of this in vitro study was to compare nickel-titanium (NiTi) spreader penetration in root canals having a .04 taper preparation using .02 and .04 tapered master gutta-percha cones and .02 and .04 tapered master Resilon cones. Twenty canals, from extracted human teeth, were cleaned and shaped to a standardized 40/.04 size. Master cones of .02 or .04 tapered gutta-percha and .02 or .04 tapered Resilon were placed in each canal. A fine-fine NiTi spreader was then placed next to the master cone with a 1.5-kg force. The penetration depth was measured, subtracted from working length, and recorded. A significant difference in penetration depth (p < 0.01) was found for both taper of the cone and material used. The depth of spreader penetration from greatest to least was .02 tapered Resilon, .02 tapered gutta-percha, .04 tapered Resilon, and .04 tapered gutta-percha.

GUTTA-PERCHA OBTURATION OF LATERAL GROVES AND DEPRESSIONS USING WARM VERTICAL COMPACTION, THERMAFIL® PLUS OBTURATORS, AND GT® OBTURATORS

Ryan M. Lavene, DDS, J. Craig Baumgartner, DDS, PhD &  J. Gordon Marshall DMD

The purpose of the study was to compare the flow of gutta-percha using warm vertical compaction, Thermafil® Plus Obturators, and GT® Obturators into lateral grooves and depressions in the apical 7 mm of the root canal system.  A split-tooth model was used with a maxillary canine with artificial lateral grooves and depressions prepared in the canal at 1, 3, 5, and 7 mm from working length.  Obturations were performed by warm vertical compaction of gutta-percha and Roth 801 sealer using the Elements Obturation Unit (Sybron Endo, Orange, CA) or the DownPak (Hu-Friedy, Chicago, IL) inserting the plugger tip 3, 4, or 5 mm from working length.  Thermafil® Plus (Dentsply, Tulsa, OK) and GT® Obturators (Dentsply, Tulsa, OK) with ThermaSeal® Plus sealer were also evaluated as obturating techniques.  The Elements Obturation Unit and the DownPak resulted in similar movement of gutta-percha into lateral grooves and depressions except at the 1 mm level where the Elements Obturation Unit performed significantly better than the DownPak when the plugger was inserted 3 mm from working length.  Thermafil and GT Obturators showed excellent flow of gutta-percha into lateral grooves and depressions but extended past the root-end 60% and 30% of the time, respectively. 

 

ANTIMICROBIAL EFFICACY OF IRRIGATION WITH THE ENDOACTIVATOR

Michael Wheatley DDS, J. Craig Baumgartner, DDS, PhD

The purpose of this investigation was to compare the antimicrobial efficacy of irrigation with the EndoActivator versus no irrigant activation in the apical 5mm of roots infected with Enterococcus faecalis. Bilaterally matched human teeth were sterilized and inoculated with E. faecalis. Following chemomechanical root canal preparation, the root-ends were resected and pulverized in liquid nitrogen to expose E. faecalis in dentinal tubules or other recesses away from the main root canal system. The number of colony forming units (CFU) of E. faecalis per mg was determined from the pulverized root-ends. Group A had a mean of 1.74 X 103 cfu/gm and Group B had a mean of 9.37 X 102 cfu/gm. This represents a bacterial reduction of 98.7% in Group A and 99.3% in Group B when compared to positive controls. There was no statistically significant difference between Group A and Group B but the difference was significant between Group A and control and Group B and control. The trend was towards fewer cfu/gm when using the EndoActivator but the difference was not significant. 

 

MICROBIAL LEAKAGE OF ROOTS FILLED WITH RESILON

David Wilson, DDS Craig Baumgartner, DDS, PhD J Gordon Marshall, DMD.

Resilon has been introduced as a promising root canal filling material. The purpose of this in vitro study was to evaluate bacterial leakage in teeth obturated with either Resilon or gutta-percha/Kerr EWT using warm vertical compaction.  Twenty-three bilaterally matched pairs of single-rooted human teeth were instrumented to an ISO #40/.04 taper and obturated with either Resilon or gutta-percha.  Teeth were placed into a split chamber model, subjected to polymicrobial leakage, and observed for turbidity in the lower chamber for 112 days.  The failure rate of each material was statistically evaluated using a two-tailed t test for differences between proportions (p<0.05).  Twelve out of 23 (52%) of the Resilon and 19 out of the 23  (83%) of the gutta-percha groups demonstrated bacterial leakage over the 112-day period.  Differences between gutta-percha and Resilon were statistically different with a P value of 0.028.  

 

COMPARISON OF THE ENDOVAC IRRIGATION SYSTEM AND NEEDLE ROOT CANAL IRRIGATION

John Johnson, DDS & J. Craig Baumgartner, DDS, PhD

Rotary instruments have shown success in enlarging canal space while maintaining original canal shape, and sodium hypochlorite has been shown to dissolve pulp tissues and disinfect the canal space.  However, several studies have demonstrated that significant amounts of debris and bacteria can remain in the apical third of the canal system, which may contribute to treatment failure.  The EndoVac system is a new product designed to deliver irrigants safely and effectively throughout the root canal system, including the apical third. The purpose of this in vivo study is to compare the EndoVac system and conventional irrigation techniques to effectively debride the apical third of the root canal. Eleven matched pairs of anterior teeth were studied, half irrigated with the EndoVac system, and half with needle root canal irrigation.  Results indicated there was no difference in remaining debris between the two techniques at 1 and 3 mm from the apex. The EndoVac system appears to be able to provide cleaning similar to conventional irrigation syringes, while minimizing the potential of NaOCl accidents.

An Evaluation of Root ZX and Elements Diagnostics Apex Locators

Marat Tselnik, DDS, J. Craig Baumgartner, DDS, PhD, J. Gordon Marshall, DMD. J Endodon 31:507. July, 2005.

The purpose of this study was to compare the accuracy of the Root ZX and Elements Diagnostic electronic apex locators under clinical conditions. Thirty-six teeth planned for extraction were used. Each tooth was decoronated, coronally flared with Orifice Shapers, and irrigated with 2.6% sodium hypochlorite. Working lengths were measured with K-files using both electronic apex locators. The files were cemented at the last measured working length and the teeth were extracted. The apical 4 mm of each canal were exposed and photographed under 15X and 30X magnification. Images of each apex were projected and the distance from the file tip to the minor diameter was determined. The mean distances from the file tip to the minor diameter were 0.346 mm for the Elements Diagnostic and 0.410 mm for the Root ZX beyond the minor constriction. In locating the minor constriction the Root ZX was accurate 75% of the time to ±0.5 mm, 83.3% ±0.75 mm, and 88.9% to ±1 mm. The Elements Diagnostic was accurate 75% of the time to ±0.5 mm, 88.9% to ±0.75 mm, and 91.7% to ±1 mm. There was no statistically significant difference between the accuracy of the two EALs in locating the minor diameter (p < 0.05).

Bacterial Leakage with Mineral Trioxide Aggregate or a Resin-Modified Glass Ionomer Used as a Coronal Barrier

Marat Tselnik, DDS, J. Craig Baumgartner, DDS, PhD, J. Gordon Marshall, DMD. J Endodon 30:782. November, 2004.

The purpose of this study was to evaluate gray MTA, white MTA and Fuji II LC cement as coronal barriers to bacterial leakage. Seventy-eight matched human teeth were obturated with gutta-percha. In group I, eighteen pairs received a 3mm barrier of either gray or white MTA. In group II, eighteen pairs received a 3mm barrier of either gray MTA or Fuji cement. Three pairs were used as positive (obturated without barrier) and negative (covered with epoxy resin) controls. A dual-chamber leakage model utilizing salivary microbes was used for the evaluation. Leakage was recorded when turbidity was observed. All controls behaved as expected. In group I, three gray MTA and three white MTA samples leaked. In group II, one gray MTA and three Fuji samples leaked. There was no statistically significant difference in leakage between gray and white MTA or gray MTA and Fuji at 30, 60 or 90 days. Gray and white MTA or Fuji II can be recommended as a coronal barrier for up to 3 months.

Microbiologic Aspects of Endodontic Infections

J. Craig Baumgartner DDS, PhD. CDAJ 32:459. June, 2004.

Our understanding of endodontic infections and treatment of endodontic disease has increased significantly over the last decade. This article is an update of those findings. Aspects that are reviewed include: portal of entry for microorganisms, virulence and pathogenicity of organisms, descriptions of primary and recurrent endodontic infections, and treatment of endodontic infections. In summary, this article reviewed the microbiologic aspects of endodontic infections with an emphasis on removal of the cause of the infection. In addition, recommendations for appropriate adjunctive use of antibiotics was presented. These recommendations are based on recent antibiotic susceptibility tests. Finally, the issue of metastatic endodontic infections versus the “theory of focal infection” was presented.

Microbiological and molecular analysis of endodontic infections.

J. Craig Baumgartner DDS, PhD. Endo Topics 7:35. March, 2004.

This article reviews microbiological and molecular methods used to study the microorganisms associated with endodontic infections. Over 500 species of bacteria have been cultivated from the oral cavity. Endodontic infections are polymicrobial with usually from 3-12 species cultivable from either infected root canals or periradicular abscesses. Molecular methods are able to detect and identify many additional species of bacteria associated with endodontic infections. Molecular methods provide precise identification of the microbes at the DNA level and detection of microbes that are not cultivable. Future research will detect and identify other as yet unknown species of bacteria, viruses, and fungi involved in endodontic infections. Which microorganisms produce virulence factors associated with serious endodontic infections will also be better defined using molecular methods. An increase in knowledge and understanding of the organisms associated with endodontic infections will improve our ability to clinically manage endodontic infections

Cardiovascular effects and efficacy of hemostatic agent in periradicular surgery

Christina Hong Vy, DMD, J Craig Baumgartner, DDS, PhD, J Gordon Marshall, DMD. J Endodon 30:379. June, 2004.

The purpose of this study was to evaluate the hemostatic efficacy and cardiovascular effects of CollaCote (Integra LifeSciences Corporation, Plainsboro, NJ) collagen sponges saturated with 2.25% racemic epinephrine during endodontic surgery. The patients were assigned to one of two groups. In group 1 (control), patients received CollaCote saturated with saline. In group 2 (experimental), patients received CollaCote saturated with ten drops of 2.25% racemic epinephrine (Nephron Pharmaceutical Corp., Orlando FL). Blood pressure and pulse rate were recorded before and after administration of the local anesthetic, after the application of the test solutions, and prior to the patient’s dismissal. The adequacy of hemostasis was determined by the surgical operator using the following scores: 0= No hemorrhage control, 1= Slight but apparent intermittent bleeding and 2= Complete hemorrhage control. Six patients received CollaCote-saline as controls and the remaining 42 patients received CollaCote-epinephrine. Based upon an analysis of variance, there was no significant difference in blood pressure or pulse rate at any time period between the experimental and control groups. In the control group, five out of six cases failed to achieve hemorrhage control. In the experimental group, one out of 42 cases had no hemorrhage control. Two patients had slight but apparent intermittent bleeding that persisted after the application of the CollaCote-epinephrine sponges. Complete hemostasis was achieved in 39 out of 42 cases. In conclusion, the results suggest that CollaCote sponges saturated with 2.25% racemic epinephrine provides excellent hemostasis with no evident changes in blood pressure or pulse rate.

Perforation repair comparing two types of Mineral Trioxide Aggregate

Douglas J Ferris, DMD and J Craig Baumgartner, DDS, PhD. J Endodon 30:422. June, 2004.

The purpose of this study was to evaluate the ability of two types of mineral trioxide aggregate (MTA) to seal furcal perforations in extracted human molars using an anaerobic bacterial leakage model. Forty human maxillary and mandibular molars were randomly divided into two experimental groups of 18, with two teeth used as positive controls and two teeth without perforations used as negative controls. Experimental group 1 was repaired with the gray colored MTA and group 2 with the off-white colored MTA. A dual chamber anaerobic bacterial leakage model was assembled. Brain heart infusion broth with yeast extract, hemin, and menadione was used as the culture broth for Fusobacterium nucleatum. Two of the 18 gray colored MTA samples leaked and three of the off-white colored MTA samples leaked. There was no significant difference between the two types of MTA in preventing leakage of F. nucleatum past furcal perforation repairs.

Evaluation of apical debris removal using various sizes and tapers of Profile GT files

Lynn J Albrecht, DDS, J Craig Baumgartner, DDS, PhD, J Gordon Marshall, DMD. J Endodon 30:425. June, 2004.

The purpose of this study was to evaluate the effect of preparation taper using size 20 or size 40 GT files on the ability to remove debris from root canals. Forty-eight bilaterally matched pairs of extracted teeth were instrumented using .04-, .06-, .08-, and .10-tapered files with one tooth of each pair enlarged to size 20 and the other to size 40. Canals were irrigated with 5.25% NaOCl during instrumentation with a final rinse consisting of 2 ml 15% EDTA followed by 2 ml 5.25% NaOCl. The teeth were sectioned horizontally at 1mm and 3mm from the apex, and the amount of remaining debris was calculated using the NIH Image V1.56 software program. The following variables were evaluated: apical preparation size, preparation taper, root length, total volume of irrigation, irrigation needle penetration, and number of instrument changes needed to reach working length. At the 1mm level, a significantly greater percentage of debris was observed in the size 20 preparations compared to size 40 with tapers of .04, .06, and .08. There were no significant differences between the pairs prepared with a .10 taper (p = .982). At the 3mm level, there were no statistically significant differences in remaining debris. A linear regression model revealed a significant relationship between percentage of remaining debris at the 1mm level and the two variables of apical size and taper (p < .001). At the 3mm level, only the needle to apex variable was significant (p = .026). No other variables were found to be significantly related to remaining debris at either level.

Identification of Spirochetes (Treponemes) in Endodontic Infections

J. Craig Baumgartner, DDS, PhD, Saeng-usa Khemaleelakul, DDS, Tian Xia, DDS. J Endodon 29:794-797. December, 2003.

The purpose of this study was to determine the prevalence of spirochetes in asymptomatic infected root canals and in endodontic abscesses/cellulitis. Aseptic clinical samples were collected using paper points from 54 infected root canals and from aspirates of 84 abscesses/cellulitis. Oligonucleotide primers were produced for PCR identification of Treponema vincentii, T. pectinovorum, T. medium, T. amylovorum, T. denticola, T. maltophilum, and T. socranskii. PCR detected spirochetes in 51/84 (60.7%) of the samples from abscesses/cellulitis and in 20/54 (37.0%) of the samples from asymptomatic infected root canals. T. socranskii was the most frequently detected (44.9%), followed by T. maltophilum (29.7%), T. denticola (28.9%), T. pectinovorum (13.7%) and T. vincentii (5.1%). The number of treponema species detected ranged from 1 to 5 species per sample. The mean numbers of species detected were 2.3 in abscesses/cellulitis and 2.6 in infected root canals. Significance association among species were found between T. maltophilum and T. socranskii, as well as between T. maltophilum and T. denticola by determining the odds ratio ( > 2.0).

Geographical Differences in Bacteria Detected in Endodontic Infections Using Polymerase Chain Reaction.

J. C. Baumgartner, DDS, PhD, J. F. Siqueira, Jr., DDS, PhD, T. Xia DDS, I. N. Rôças, DDS. J Endodon 30:141-144. March, 2004.

The polymerase chain reaction (PCR) is an innovative nucleic acid based assay that has the highest sensitivity of any microbiological technique for the detection of bacteria. The purpose of this study was to use PCR to detect the presence of specific species of bacteria in samples collected from two different geographical locations. Microbial samples from abscesses of endodontic origin were collected from patients in Portland, OR and Rio de Janeiro, Brazil. PCR using species specific oligonucleotide primers for the 16S ribosomal RNA gene were used for detection of the bacteria following DNA extraction from each clinical sample. Statistical analysis revealed that there was a significant difference in detection of the bacteria between the two geographical locations for Prevotella intermedia, Prevotella nigrescens, Prevotella tannerae, Fusobacterium nucleatum, and Porphyromonas gingivalis but not for Porphyromonas endodontalis, Fusobacterium necrophorum, and Enterococcus faecalis. These results demonstrated that differences in bacteria detected/cultured in studies might be associated with geographical location.

Consideration of steroid for endodontic pain.

Marshall JG. Endodontic Topics 3:41-51. November, 2002.

This review article considers the use of steroids specifically glucocorticoids in the management of endodontic pain. It includes the pharmacology, pharmacodynamics and purported mechanisms of actions of steroids as well as their indications for endodontics, contraindications, dosages and side effects. The history of steroid use in endodontics is covered as well as a critical evaluation of the research done to date on the effects of glucocorticoids on endodontic post-treatment pain.

Comparison of Spreader Penetration During Lateral Compaction of .04 and .02 Tapered Gutta-Percha

Brian Wilson, DMD, J. Craig Baumgartner, DDS, PhD. Endodon December 2003.

The purpose of this study was to compare the initial penetration depth of fine-fine nickel-titanium (NiTi) and fine-fine stainless-steel (SS) spreaders during lateral compaction of .02 or .04 tapered master gutta-percha cones and to evaluate the effect of increasing canal curvature on penetration depth. Fifty-one root canals were instrumented to a standardized size and grouped by degree of curvature for comparison. Our results showed that NiTi spreaders penetrated to a significantly greater depth than SS spreaders using .02 tapered gutta-percha in canal curvatures > 20 degrees and when using .04 tapered gutta-percha regardless of canal curvature. No significant difference occurred between NiTi and SS spreader penetration using .02 tapered gutta-percha in canal curvatures of 0-20 degrees (p > 0.05). Both NiTi and SS spreaders penetrated to a greater depth as canal curvatures increased to above 20 degrees (p < 0.05). Both NiTi and SS spreaders penetrated to a shallower depth with .04 tapered gutta-percha as compared to .02 tapered gutta-percha (p < 0.0001)

Influence of Instrument Size on Root Canal Debridement

Najia Usman, DDS, J. Craig Baumgartner, DDS, PhD, J. Gordon Marshall, DMD. J Endodon February 2004. Files of Greater Taper consist of rotary nickel-titanium files of three tapers (0.06, 0.08, 0.10) with file tips of sizes 20, 30, and 40. The purpose of this study was to compare in an in situ model the efficacy of root canal debridement in the apical three millimeters when instrumenting to a GT size 20 or a GT size 40 at working length. Twenty matched human cadaver teeth with thirty-two canals were decoronated at the CEJ and instrumented with rotary Files of Greater Taper (GT) to either GT size 20 or GT size 40. NaOCl, EDTA and RC Prep were chemical aids for debridement. The teeth were extracted, decalcified, sectioned at .5mm, 1.5mm and 2.5mm from the apex and prepared for histological examination and quantification of remaining debris. No differences were found between each level within each apex size group however the GT size 20 group left significantly more debris in the apical third compared to the GT size 40 group. A regression analysis showed that the apical third cleanliness could be predicted mainly by instrument size and to a lesser extent by the canal length. Irrigant volume, number of instrument changes and depth of penetration of irrigation needle were not likely to explain differences in debridement.

An in vivo comparison of two frequency based electronic apex locators

Aaron Welk, J.G. Marshall, J. C. Baumgartner. J Endodon August 2003.

The purpose of this study was to compare the accuracy of a two frequency (Root ZX) and a five frequency (Endo Analyzer Model 8005) electronic apex locator (EAL) under clinical conditions. Thirty-two teeth planned for extraction were used. The coronal portion of each canal was flared using Gates-Glidden and Orifice Shapers. The canals were irrigated with 2.6% sodium hypochlorite. A K-type file was used to determine a separate working length in each canal using the EALs. The teeth were extracted and the apical 4 mm of each root canal was exposed along the long axis of the tooth. Photographic slides of each canal were projected and the file position in relation to the minor diameter was determined by two investigators. The mean distance between EAL and minor diameter was 1.03 mm for the Endo Analyzer and 0.19 mm for the Root ZX. A paired samples t-test showed the Endo Analyzer had significantly longer readings beyond the minor diameter than the Root ZX (p < 0.001). The ability to locate the minor diameter (± 0.5 mm) was 90.7% for the Root ZX and 34.4% for the Endo Analyzer Model 8005.

Occurrence of Actinomyces israelii, Actinomyces naeslundii and Actinomyces viscosus in Infections of endodontic origin.

Tian Xia, J. C. Baumgartner. J Endodon September 2003.

Periapical actinomycosis has been repeatedly identified in cases of failed endodontic therapy often resistant to clinical treatment. Actinomyces are found in 11% infected root canals, which are the primary port of entry for Actinomyces organisms into the periapical tissue. Specie-specific primers and a pair of universal primer for Actinomycetales order were designed to evaluate the contents of infected root canals and aspirates of cellulites/abscesses of endodontic origin for the presence of Actinomyces israelii, Actinomyces naeslundii, Actinomyces viscosus and microorganisms in Actinomycetales order using polymerase chain reaction (PCR). PCR reactions were run with the DNA extracted from 131 clinical samples. The results show that Actinomyces israelii was found in 23.7% (31/131) of clinical samples. Of those 25.6% (11/43) were from abscesses, 16.7% (6/36) were associated with cellulites, and 26.9% (14/52) were from infected root canals. Actinomyces naeslundii was found in 8.5% (11/129) of clinical samples. Of those 4.2% (2/48) were from abscesses, 6.7% (2/30) were associated with cellulites, and 13.7% (7/51) were from infected root canals. Actinomyces viscosus was found in 32.1% (42/131) of clinical samples. Of those 14% (6/43) were from abscesses, 13.9% (5/36) were associated with cellulites, and 59.6% (31/52) were from infected root canals. Microorganisms of Actinomycetales order was found in 55.8% (72/129) of clinical samples. Of those 45.8% (22/48) were from abscesses, 30% (9/30) were associated with cellulites, and 80.4% (41/51) were from infected root canals.

Antibiotic Susceptibility of Bacteria Associated with Endodontic Abscesses

J. Craig Baumgartner, DDS, PhD, Tian Xia, DDS. J Endodon 29:44-47. January 2003. Antibiotics to treat endodontic infections are routinely prescribed based on previously published susceptibility tests. There is increased concern that bacteria have increased resistance to the currently recommended antibiotics. The purpose of this investigation was to perform antibiotic susceptibility tests on a panel of bacteria recently isolated from endodontic infections. The bacteria in this study were aseptically aspirated with a needle from endodontic abscesses, cultivated, and identified at the species level. Each of the 98 species of bacteria was tested for antibiotic susceptibility to a panel of six antibiotics using the Etest. The antibiotics were penicillin V, amoxicillin, amoxicillin + clavulanic acid, clindamycin, metronidazole, and clarithromycin. The percentages of susceptibility for the 98 species were penicillin V ­ 83/98 (85%), amoxicillin ­ (89/98) 91%, amoxicillin + clavulanic acid (98/98) 100%, clindamycin ­ 94/98 (96%), metronidazole ­ 44/98 (45%). Metronidazole had the greatest amount of bacterial resistance, however, if it is used in combination with penicillin V or amoxicillin, susceptibility of the combination with penicillin V or amoxicillin increased to 93% and 99% respectively. Clarithromycin appears to have efficacy but it is still considered an antibiotic under investigation because the minimum inhibitory concentration has not been established.

Antibiotic Susceptibility of Bacteria Associated with Endodontic Abscesses

J. Craig Baumgartner, DDS, PhD, Tian Xia, DDS. J Endodon 29:44-47. January 2003.

Antibiotics to treat endodontic infections are routinely prescribed based on previously published susceptibility tests. There is increased concern that bacteria have increased resistance to the currently recommended antibiotics. The purpose of this investigation was to perform antibiotic susceptibility tests on a panel of bacteria recently isolated from endodontic infections. The bacteria in this study were aseptically aspirated with a needle from endodontic abscesses, cultivated, and identified at the species level. Each of the 98 species of bacteria was tested for antibiotic susceptibility to a panel of six antibiotics using the Etest. The antibiotics were penicillin V, amoxicillin, amoxicillin + clavulanic acid, clindamycin, metronidazole, and clarithromycin. The percentages of susceptibility for the 98 species were penicillin V ­ 83/98 (85%), amoxicillin ­ (89/98) 91%, amoxicillin + clavulanic acid (98/98) 100%, clindamycin ­ 94/98 (96%), metronidazole ­ 44/98 (45%). Metronidazole had the greatest amount of bacterial resistance, however, if it is used in combination with penicillin V or amoxicillin, susceptibility of the combination with penicillin V or amoxicillin increased to 93% and 99% respectively. Clarithromycin appears to have efficacy but it is still considered an antibiotic under investigation because the minimum inhibitory concentration has not been established.

Identification of bacteria in acute endodontic infections and their antimicrobial susceptibility.

Saengusa Khemaleelakul, J. C. Baumgartner, Sumalee Pruksakorn. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 94:746-755. December 2002.

Purpose: To identify the bacterial composition of the microbiota from acute endodontic abscesses/cellulitis and their antimicrobial susceptibilities. Study design: Purulence from 17 patients with acute endodontic abscesses/cellulitis was obtained by needle aspiration and processed under anaerobic conditions. Bacteria were isolated and identified by biochemical or molecular methods. The antimicrobial susceptibility of isolated bacteria was determined by using the Etest. Results: All 17 aspirates contained a mix of microorganisms. The mean number of strains per sample was 7.6 (range 3-13). The average number of viable bacteria was 6.37 x 107 (range 104-108) CFU/ml. Strict anaerobes and microaerophillics were the dominant bacteria in 82.35% (14/17). The genera of bacteria most frequently encountered were Prevotella and Streptococcus. The combination of Prevotella and Streptococcus was found in 52.94% (9/17). The previously reported "uncultured Prevotella clone PUS 9.180" was frequently identified. The percentage of bacteria susceptible/intermediate for each antibiotic in this study was penicillin V: 79.84% (99/124), metronidazole: 41.94% (52/124), amoxicillin: 84.68% (105/124), amoxicillin+clavulanic acid: 100% (124/124), and clindamycin: 88.71% (110/124). Conclusion: The present results confirm the existence of mixed infection with the predominance of anaerobic bacteria in acute endodontic abscesses/cellulitis. The frequency of "uncultured Prevotella clone PUS 9.180" suggests the possible key role of this Prevotella species in acute endodontic infections. Penicillin V still possesses antimicrobial activity against the majority of bacteria isolated from acute endodontic infections. However, if penicillin V therapy has failed to be effective, the combination of penicillin V with metronidazole or amoxicillin with clavulanic acid is recommended. Switching to clindamycin is another good alternative.

Proliferative Periostitis of Garré: Report of a Case

H.L. Jay Jacobson, J. C.Baumgartner, J. G. Marshall, W. J. Beeler. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 94:111-114. July, 2002.

Proliferative periostitis of Garré is described as a productive and proliferative inflammatory response of periosteum to infection or other irritation. This can be odontogenic or non-odontogenic in nature. This is a case report of an odontogenic periostitis resulting from periapical inflammation of endodontic origin. It was treated by nonsurgical endodontics. Antibiotic therapy was not used during the treatment of this patient.

Effect of early coronal flaring on working length change in curved canals using rotary nickel-titanium versus stainless steel instruments

R.D. Davis, J.G. Marshall, J.C. Baumgartner. J Endodon. 28:438-442. June, 2002

This in vitro investigation examined pre- and post-instrumentation working length (WL) measurements in curved root canals, comparing (1) early coronal flaring (flaring completed prior to WL determination) versus late coronal flaring (flaring completed after WL determination), and (2) stainless steel hand files (SS) + Gates Glidden drills versus nickel-titanium rotary files (Ni-Ti). Coronal flaring was accomplished for group 1 (SS file group) using Gates-Glidden drills, and for group 2 (Ni-Ti file group) using rotary Ni-Ti files (n=15/group). WL was determined prior to coronal flaring, immediately after coronal flaring and again after canal preparation had been completed. Results indicated that WL decreased for all canals as a result of canal preparation. The decrease in WL was significantly greater for group 1(-0.48 mm ± 0.32), than for group 2 (-0.22 mm ±0.26). There was negligible WL change in both groups when initial working length was determined after coronal flaring (Gp 1: -0.12 mm ±0.13, Gp 2: -0.15 mm ±0.25).

Efficacy of calcium hydroxide - chlorhexidine paste as an intracanal medicament in bovine dentin

Matt Evans, J. C. Baumgartner, Saeng-usa Khemaleelakul, Tian Xia. J Endodon. 29:338-339. May, 2003.

The purpose of this study was to evaluate the antibacterial efficacy of an intracanal medicament composed of calcium hydroxide with 2% chlorhexidine. Dentin from twenty-four bovine incisors was used. The incisors were made into standardized cylindrical segments of dentin and infected with Enterococcus faecalis. They were then treated with either an intracanal paste composed of calcium hydroxide and sterile water or an intracanal paste composed of calcium hydroxide and 2% chlorhexidine for one week. Dentin shavings were collected, suspended in solution, and spread on brain-heart infusion agar. Following incubation, colony-forming units were enumerated. The amount of bacteria per mg of dentin was determined. The calcium hydroxide paste with 2% chlorhexidine was significantly more effective at killing E. faecalis in the dentinal tubules than calcium hydroxide with water.

Efficacy of Irrigation with Rotary Instrumentation

Matt Walters, J. C. Baumgartner, J. G. Marshall. J Endodon 28:837-839. December, 2002.

The purpose of this study was to evaluate the efficacy of a handpiece-mounted irrigation device, and compare it to irrigation with a syringe and needle in the apical 5mm of the root canal system. Twenty matched pairs of extracted teeth were used. The only variable within each matched pair was the method of irrigation. A syringe and needle was used in Group A and the handpiece-mounted system in Group B. Sections 1, 3 and 5mm from the working length were examined microscopically, and images of the slides were digitized. The percentage of canal space occupied by pulpal and dentinal debris was calculated to be 6±12.7% in group A, versus 3.8 ±7% in group B (p=0.264). The percentages at each level were as follows: 1mm from the working length, 14.1 ±19% for group A and 5±7.5% for group B, 3mm from working length, 1.8 ±5.4% in Group A and 3.9 ±6.9% in Group B, and at 5mm from working length, 3.1 ±7.7% and 2.6 ±7.3% in groups A and B respectively. In Group A, there was significantly more debris in the 1mm section than in the 3 or 5mm sections. In Group B the differences between levels were not significant. There was no significant difference in the amount of debris remaining in the apical 5mm of canals when comparing the handpiece-mounted irrigation device to irrigation with a syringe and needle. The average times for instrumentation in Group A (needle irrigation) and Group B (Quantec-E irrigation system) were 8.7 ±2.7 and 6.5 ± 1.9 minutes respectively. Group B was associated with statistically significant shorter instrumentation time (p<0.0005). An average of 12.5 ±4.9 ml of irrigant was used in group A and 17.3 ±4.8 ml in group B. The difference was statistically significant (p<0.0005).

Microscopic Removal of Dens Invaginatus: Case Report

W.J. Girsch, T. V. McClammy J. Endodon 28:336-339. April, 2002.

Endodontic treatment for teeth which exhibit the dental anomaly dens invaginatus can be difficult due to the bizarre anatomy and relative inaccessibility of the diseased pulp tissue. Surgical intervention or extraction are common approaches to dealing with this condition. This article reports the treatment of an extreme form of dens invaginatus employing the dental operating microscope and the ultrasonic instrument. Removal of the entire anomalous structure and pulp tissue was possible, and conventional orthograde obturation was accomplished. Two and four year follow up radiographs show that healing has occurred. The article demonstrates that the anomalous structure of dens invaginatus is a separate entity from the rest of the tooth. This implies that in many instances it may be entirely removed to afford conventional endodontic therapy.

Hemostatic Efficacy and Cardiovascular Effects of Agents Used During Endodontic Surgery

F. J. Vickers, J. C. Baumgartner, J.G. Marshall. J Endodon 28:322. April, 2002.

The hemostatic efficacy as well as the cardiovascular effects of two hemostatic agents currently used during endodontic surgery were examined. The hemostatic agents used were epinephrine pellets (Racellets) or 20% ferric sulfate (Viscostat). Patients were assigned to one of two experimental groups. Blood pressure and pulse rate were recorded pre- and post-operatively, and at three additional times during the surgery (root-end resection, root-end preparation, and filling). Adequacy of hemostasis was rated by the surgical operator. Results indicated that there is no significant change in cardiovascular effects when using either of these hemostatic agents. Except in one case where ferric sulfate was the agent, both agents produced surgical hemostasis that allowed for a dry field for root-end filling.

Microbial Leakage Evaluation of the "Continuous Wave of Condensation"

H.L. Jay Jacobson, T. Xia, J. C. Baumgartner, J. G. Marshall, W.J. Beeler. J Endodon 28:269. April, 2002.

Coronal leakage has been recognized as an etiologic agent for pulpal and periradicular disease. Although cleaning and shaping of the root canal system is considered paramount, obturation of the system is an important step in endodontic success. The purpose of this study was to evaluate coronal bacterial leakage in teeth obturated with the "continuous wave of condensation" technique followed by an Obtura II backfill versus teeth obturated using the lateral condensation technique. Sixty single rooted bilaterally matched teeth were evaluated in this study. An anaerobic bacteria leakage model was utilized. Results indicate that microbial coronal leakage occurs more quickly using lateral condensation when compared to the "continuous wave of condensation" with an Obtura backfill. This difference was statistically significant (p<0.05).

Gutta-percha Obturation of Lateral Grooves and Depressions

C. J. Bowman, J. C. Baumgartner. J Endodon 28:220. March, 2002.

The purpose of this study was to evaluate movement of gutta-percha into lateral grooves and depressions in the apical 7 mm of a root canal using the System B Heat Source for the "Continuous Wave of Condensation" and the Obtura II for the backfill. A split tooth model was constructed with lateral grooves and dentin depressions prepared at 1, 3, 5, and 7 mm from working length. The study included three experimental groups with 10 obturations in each group. Group A - System B Fine heat plugger used at 5 mm from working length; group B - System B Fine heat plugger used at 4 mm from working length; and group C - System B Fine heat plugger used at 3 mm from working length. Group C had statistically better movement of gutta-percha into the 1 mm dentin depression than either Group A (p=.0005) or Group B (p=.0025) and better movement of gutta-percha into the 3 mm dentin depression than Group A. A significant difference in gutta-percha flow into the lateral grooves was seen at 3 mm from working length with Group C (p<.0001). Group C demonstrated gutta-percha in the grooves while both Group A and Group B had no gutta-percha in the grooves.

Zepbra Hunt I & II Herpes Zoster Infection

A.J. Rauckhorst and J.C. Baumgartner J Endodon 26:421&469-471. July and August 2000.

A clinical comparison of pain perception to the Wand and a traditional syringe

F.S. Saloum, J. C. Baumgartner, J. G. Marshall, J. Tinkle Oral Surg. Oral Med. Oral Pathol. 85:691-695. June, 2000.

This study compared the pain response of a group of 40 volunteers to the Wand with the response to syringe injections. Of 240 total injections given, 120 were with the Wand system and 120 were with the traditional aspirating syringe. Three injections were evaluated: injections to the middle superior alveolar (MSA) of the maxillary right first premolar and the maxillary left first premolar; palatal injections of the maxillary right first premaolar and the maxillary left first premolar; and inferior alveolar nerve injections (IAN) of both the right and left side. Each volunteer received 6injections, 3 on one side using the Wand and 3 on the opposite side with the syringe (control). All injections were given by the primary investigator without the use of a topical anesthetic. Pain perception levels were recorded with a 4-point visual analog scale: no pain, mild pain, moderate pain, and severe pain. The results were evaluated statistically by using an unpaired t-test. The results showed injections with the syringe were statistically more painful than injections with the Wand in 4 of 18 evaluations: MSA of the maxillary left first premolar, female volunteers responses to MSA of the maxillary left first premolar, IAN left side injections, and male responses to IAN left injections (P=0.01, P=0.05, P=0.05, and P=0.05, respectively). The Wand generally seemed to provide less painful injections; however, the maean ratings of pain were mostly mild pain for both injections. Therefore the clinical significance of the results should be interpreted with caution. The operator technique and tactile skill in syringe injection and site of injection (right or left) could be important factors that were not evaluated in this study.

Isolation and identification of Prevoteela tanerae from endodontic infections

T. Xia, J.C. Baumgartner, L.L. David Oral Microbiol Immunol 15:273-275. 2000.

Black-pigmented bacteria are ofton isolated from endodontic infections. Five strains of black-pigmented bacteria isolated from endodontic infections could not be identified in our laboratory. The purpose of this study was to sequence the 16S rRNA gene of the five unknown isolates and identify the organisms. The 16S rRNA genes from the unknown organism were cloned, sequenced, and determined to be Prevoteela tannarae. In addition, samples from endodntic infections were surveyed for athe presence of the organism. When 118 samples from endodontic infections were examined using polymerase chain reaction with specific primers for P. tannerae, 60% of the samples were positive for the presence of the organism. This suggests tha P. tannerae is commonly present in endodontic infections and could be a potential pathogen.

Radicular temperature associated with thermoplasticized gutta-percha

T.L. Sweatman, J.C. Baumgartner, R.L. Sakaguchi J. Endodon 27:512-515. August, 2001.

Thermoplasticized gutta-percha has been used to obturate root canals. The continuous wave of condensation technique utilizes the System B Heat Source with the choice of different sized pluggers. The purpose of this study was to measure the temperature within the root canal and on the root surface at different radicular levels while using the System B Heat Source. Fine (F), Fine-Medium (FM) and Medium (M) pluggers at temperature settings of 200 °C, 250 °C, and 300 °C were evaluated. In addition, an Obtura II and ultrasonically thermoplastized gutta-percha were used for comparative purposes. At no time did the System B, the Obtura II, or the ultrasonic delivery of warm gutta-percha exceed an increase of 10 °C at any thermocouple level on the external surface. The highest mean temperature change on the external root surface was 9.12 °C at the 6 mm thermocouple with the FM plugger set at 300 °C. At working length, the lowest mean temperature change on the external root surface was 1.88 °C with the FM plugger at 250 °C. With the Obtura II, the lowest mean internal temperature change was 5.22 °C at the working length while the highest mean internal temperature change was 23.63 °C at the 6 mm level. With ultrasonic lateral compaction, the lowest mean internal temperature change was 5.01 °C at the working length while the highest mean internal temperature change was 28.95 °C at the 6 mm level.

Occurrence of Candida albicans in infections of endontic origin

J. C. Baumgartner, C.M. Watts, T. Xia J. Endodon 26:695-696. December, 2000.

Microorganisms are recognized as the etiologic agent for the majority of pulpal and periradicular disease. Although bacteria have been the most studied, fungi have also been associated with infected root canals. The purpose of this study was to evaluate the contents of infected root canals and aspirates of cellulitis/abscesses of endodontic origin for the presence of Candida albicans using polymerase chain reaction (PCR). PCR primers specific for the 16S ribosomal RNA gene of Candida albicans were used to survey 24 samples taken from infected root canals and 19 aspirates from periradicular infections of endodontic origins. The results of the survey detected the presence of Candida albicans in five of twenty-four (21%) samples taken from root canals, but none were detected in the periradicular aspirates. The results indicate that PCR is an extremely sensitive molecular method that may be used to identify Candida albicans directly in samples from infections of endodontic origin.

A comparative study of the smear layer removal using different salts of EDTA

M.S. O'Connell, L.A. Morgan ,W.J. Beeler, J. C. Baumgartner J. Endodon 26:739-743. December 2000.

Three solutions of ethylenediamine tetraacetic acid (EDTA), a 15% concentration made from both the alkaline and acid salts and a 25% concentration made from the alkaline salt, were evaluated for smear layer removal in root canal systems. All were adjusted to pH=7.1 using either sodium hydroxide (NaOH) or hydrochloric acid (HCl). When the EDTA solutions were alternately irrigated with sodium hypochlorite (NaOCl) they completely removed the smear layer in the middle and coronal thirds of canal preparations, but were less effective in the apical third. None of the EDTA solutions themselves were effective at completely removing the smear layer at any levels.

A scanning electron microscopic study of in vivo ultrasonic root-end preparations

L.A. Morgan, J.G. Marshall J. Endodon. 25:567-570. August, 1999.

The purpose of this in vivo study was to evaluate root-ends for cracks after root resection and again after ultrasonic root-end preparation on patients undergoing endodontic surgery. Endodontic surgery was performed on 25 roots from 20 patients. Vinyl polysiloxane impressions were made after root resection and again after ultrasonic root-end preparations. Epoxy resin casts were made from the impressions and SEM examination of the root-end replicas was performed. There was no evidence of cracks after root resection. One incomplete canal crack was evident after ultrasonic root-end preparation.

Detection of a collagenase gene in P. gingivalis and P. endodontalis from endodontic infections.

L.J. Odell, J.C. Baumgartner, T. Xia, L.L. David J. Endodon. 25:555-558. August, 1999.

Collagenase is a potential virulence factor shown to be expressed by Porphyromonas gingivalis associated with periodontal disease. The purpose of this study was to use the polymerase chain reaction (PCR) to detect the presence of the collagenase gene (prtC) in 22 strains of Porphyromonas species isolated from endodontic infections. Type strains for P. gingivalis (ATCC 33277) and P. endodontalis (ATCC 35406) were used as controls. When PCR primers specific for the 16S ribosomal RNA gene of P. gingivalis or P. endodontalis were used, 17 of the strains were identified as gingivalis and five strains identified as endodontalis. The presence of the prtC gene for collagenase was detected using PCR. Amplicons were analyzed by agarose gel electrophoresis, with an 815 bp amplicon representing the presence of the collagenase gene. Of the 17 strains of P. gingivalis, 16 produced the collagenase gene amplicon. Of the five strains of P. endodontalis, one had the collagenase gene amplicon. These results indicate that P. gingivalis isolated from endodontic infections possess the gene for collagenase. In addition, P. endodontalis may be capable of possessing the gene for collagenase. The virulence of these organisms may be related to their production of collagenase.

Association of black-pigmented bacteria with endodontic infections

J.C. Baumgartner, B.J. Watkins, K.S. Bae, J. Endodon. 25: 413-415. June, 1999.

Black-pigmented bacteria (BPB) have been associated with endodontic infections. The purpose of this study was to further evaluate the presence of BPB with the clinical signs and symptoms associated with endodontic infections. Microbial samples were collected from the root canals of 40 intact teeth with necrotic pulps and apical periodontitis. Conventional laboratory methods were used for identification of the strains of BPB isolated in pure culture. In addition, the polymerase chain reaction and specific primers for 16S r-RNA genes were used to differentiate Prevotella nigrescens from P. intermedia. Twenty-two (55 percent) samples were positive for the growth of BPB. Of those 11/22 (50 percent) were identified as P. nigrescens, 8/22 (36 percent) were P. intermedia, 2/22 (9 percent) were Porphyromonas gingivalis, and 1/22 (5 percent) was P. melaninogenica. Sixteen of the 22 root canals positive for the growth of BPB were associated with purulent drainage either from the root canal or associated sinus tract. Statistical analysis did not show a significant relationship for the presence of BPB with clinical signs and symptoms.

Evaluation of diamond coated ultrasonic instruments for root-end preparation

P.D. Brent, L.A. Morgan, J.G. Marshall, J.C. Baumgartner J. Endodon. 25:672-676. September, 1999.

Ultrasonic instrumentation has been associated with cracking of the dentin in the area of the root-end preparation. The purpose of this study was to evaluate root-end preparations for cracking and to describe cavo-surface morphology following the use of diamond coated instruments. Forty teeth were inspected for intradentin cracks, incomplete canal cracks and complete canal cracks before and after preparation with a stainless steel CT-5 ultrasonic instrument and again after root-end preparation with an S12D/90 diamond coated instrument. Six teeth had polyvinylsiloxane impressions taken of the root ends after preparation with the CT-5 and again following preparation with the diamond coated instrument. Replicas were made, split, sputter-coated and inspected using the SEM. This study indicates that use of the diamond coated instrument for root-end preparation does not result in significant root-end cracking and that it can remove cracks created by a prior instrument use. The use of the diamond-coated instrument resulted in a heavily abraded, debris-covered cavosurface which may affect the apical seal.

An analysis of canal centering using mechanical intrumentation techniques

D.A. Kosa, G. Marshall, J.C. Baumgartner J. Endodon.25:441-445 June, 1999.

The purpose of this study was to compare canal transportation in moderate canal curvatures using mechanical instrumentation systems. Mesial roots of mandibular first or second molars were mounted in resin using a modified Bramante muffle system and divided into four groups. The roots were cross-sectioned 2 mm from the working length and at the height of root curvature. Tracings of the canal were made from pre-instrumentation slides of the cross sections. The canals were prepared using ProFile Series 29 rotary instruments, Quantec 2000 rotary instruments, Flex-R files in the Endo Gripper contra-angle hand piece, and Safety Hedstrom files in the M4 contra-angle hand piece. Tracings of the prepared canals were made onto the originals from post-instrumentation slides. A canal centering ratio was calculated along the line of maximum transportation. Quantec 2000 rotary instruments yielded significantly greater transportation at the apical level when compared to the Profile Series 29 system. There were no other significant differences in transportation at either level. There were no differences in the direction of canal transportation between instrument systems, and the direction of canal transportation was not related to the direction of canal curvature. Canal preparation time was shortest with Profile Series 29 system followed by Flex-R files in the Endo Gripper, Quantec 2000 and Shaping Hedstrom flies in the M4.

SDS-PAGE and PCR for Differentiation of Prevotella intermedia and P. nigrescens

J.C. Baumgartner, K.S. Bae, T. Xia, J. Whitt, L.L. David J. Endodon.25:324-328 May,1999.

Isolates previously thought to be Prevotella intermedia have been shown to be a closely related species now known as P. nigrescens. The purpose of this study was to determine the efficacy of SDS-PAGE and PCR to differentiate endodontic isolates of P. nigrescens from P. intermedia. Fifty-six strains of black-pigmented bacteria isolated from endodontic infections and conventionally identified as P. intermedia were used in this study. Using SDS-PAGE, novel polypeptide bands were used to differentiate P. nigrescens from P. intermedia. PCR was accomplished with specific primers for the 16S ribosomal RNA gene of both strains. Of 56 endodontic isolates, 41 (73 percent) strains were identified by SDS-PAGE as P. nigrescens and 15 (27 percent) strains as P. intermedia. Of the 41 strains of P. nigrescens identified by SDS-PAGE, PCR identified 37 strains as P. nigrescens. Restriction endonuclease digestion of amplified 16S ribosomal RNA genes indicated that the remaining four strains originally identified by SDS-PAGE as P. nigrescens were actually strains of Prevotella distinct from P. nigrescens and P. intermedia. Of 15 strains of P. intermedia identified by SDS-PAGE, PCR identified 14 strains as P. intermedia, but one strain was identified as P. nigrescens. The results indicated that PCR was a more precise method then SDS-PAGE to differentiate P. intermedia from P. nigrescens. This study confirms that P. nigrescens is more commonly isolated in pure culture from endodontic infections than P. intermedia.

The effect of calcium hydroxide and four irrigation regimens on instrumented and uninstrumented canal wall topography

C.T. Tatsuta, L.A. Morgan, J.C. Baumgartner, J.D. Adey J. Endodon. 1999;5:93-98

The topography of instrumented and uninstrumented canal walls exposed to calcium hydroxide and four different irrigation regimens was observed by scanning electron microscopy. Following chemomechanical debridement, one tooth in each matched pair was medicated with calcium hydroxide. One week later the teeth were irrigated and split longitudinally for evaluation. When no calcium hydroxide was used, predentin and pulpal debris covered the dentinal tubules of the uninstrumented surfaces in specimens irrigated with water or EDTA, but was absent in specimens irrigated with NaOCl or NaOCl and EDTA. A typical smear layer was absent in specimens irrigated with NaOCl and EDTA, but covered the dentinal tubules of the instrumented surfaces of the EDTA irrigated specimens (partially) and the water or NaOCl irrigated specimens (completely). Calcospherites or their remnants were seen on the uninstrumented canal walls of specimens irrigated with NaOCl or NaOCl and EDTA, respectively. Calcium hydroxide use did not alter the surface topography in specimens irrigated with water, EDTA or NaOCl, but seemed to erode the intertubular dentin in specimens irrigated with NaOCl and EDTA. All irrigants seemed to effectively remove most of the calcium hydroxide.

The topography of root ends resected with fissure burs and refined with two types of finishing burs

L.A. Morgan, J.G. Marshall Oral Surg. Oral Med. Oral Pathol. Oral Radiol Endod. 1998;85:585-591

This study compared the surface topography of roots resected with #57, Lindeman and Multi-purpose burs. Further comparisons were made after refinements with either a multifluted carbide or an ultrafine diamond finishing bur. Three groups of single-rooted human teeth were resected with each resection bur, and resin replicas of the root ends were made. Root ends from each resection bur group were finished with either a multifluted carbide or an ultrafine diamond finishing bur, and the root ends were replicated. All replicas were evaluated at a magnification of x20 for smoothness and surface irregularities. Data analysis was done with the Wilcoxon-signed rank test and the chi-squared test at a significance level of p<0.05. The Multi-purpose bur produced a smoother and more uniplanar surface than the #57 bur and caused less damage to the root than either the #57 or the Lindeman bur. The Multifluted carbide finishing bur tended to improve the smoothness of the root end, while the ultrafine diamond tended to roughen the surface. The Multi-purpose bur produced the smoothest and most uniplanar resected root-end surface with the least shattering. The multifluted carbide finishing bur produced a smoother surface than the ultrafine diamond bur.

Longitudinal study of the microleakage of two root-end filling materials using a fluid conductive system

J.D. Yatsushiro, J.C. Baumgartner, J.S. Tinkle J. Endodon 1998;24:720-726

A comparison of the microleakage of Mineral Trioxide Aggregate (MTA) and a high copper admix amalgam (Valiant PhD) in root-end preparations was made using a fluid conductive device. Thirty-three bilaterally matched pairs of extracted, single-rooted teeth were prepared and obturated using lateral compaction of gutta-percha. The root-ends were resected and 3mm deep class I cavity preparations were made. The root-end preparations were filled with either amalgam or MTA. Gutta-percha coronal to the root-end fillings was removed, leaving only the amalgam or MTA present as a barrier to fluid movement. In the fluid conductive device the root canals were filled with a phosphate buffered saline solution at a pressure of 10 psi. The flow of fluid was measured and compared at 1, 2, 3, 4, 8, 12, 16, 20 and 24 weeks. The results showed amalgam to have significantly higher microleakage after four weeks and higher variability compared to the MTA group.

Black-pigmented bacteria in coronal and apical segments of infected root canals

W.J. Dougherty, K.S. Bae, J.C. Baumgartner J. Endodon 1998;24:356-358

Black-pigmented bacteria (BPB) have been associated with infections of endodontic origin. The purpose of this study was to culture, identify and enumerate BPB from the apical and coronal segments of infected root canals to better understand their ecological relationships. Teeth with a periapical radiolucency (3-7mm) were extracted and immediately placed in reduced transport fluid for transport to an anaerobic chamber containing an atmosphere of 85 percent nitrogen, 10 percent hydrogen, and 5 percent carbon dioxide. The root surface was curretted, disinfected and sectioned 7mm from the apex. Sterile endodontic files were used to collect samples from the apical and coronal fragments. A series of 10-fold dilutions of each of these two samples were plated on non-selective Rabbit Columbia Blood agar with hemin (10 mg/L) and menadione (5 mg/L). The samples were incubated at 37C for 2-3 weeks but examinations for growth were performed every 3-4 days. Of 18 sampled roots, 12 were positive for the growth of BPB. Eight of the 12 roots with BPB had a carious exposure of the pulp chamber. Eight roots had Prevotella nigrescens in both the apical and the coronal segments. Seven of these eight teeth had carious exposures of the pulp chamber. Of the 12 roots infected with BPB, seven roots had two different species of BPB. P. intermedia was cultivated from one apical segment. P. melaninogenica was cultivated from three coronal sections and two apical segments of the roots. Porphyromonas gingivalis was isolated in the coronal section of one root which had P. nigrescens both coronally and apically. Of two patients with severe pain, one tooth had an exposed pulp chamber and the other was intact.

Development of an anaerobic bacterial leakage model

K.S. Bae, J.C. Baumgartner, T.T. Nakata J. Endodon. 1998;24:233-238

The majority of bacteria associated with infections of endodontic origin are strict anaerobes. The purpose of this study was to develop an endodontic microleakage model using strict anaerobic bacteria in a two-chamber system. Nine species of anaerobic bacteria were tested for viability and detection by either turbidity or color change of the broth. A survey of pH chromogenic substrates revealed that bromcresol purple (pH 5.2-yellow, pH 6.8-purple) could be used as a chromogenic indicator to detect the growth of anaerobic bacteria. Peptone-yeast extract-glucose broth (PYG) and brain heart infusion broth (BHI) were each used alone and with bromcresol purple (bpPYG, bpBHI) in this study. Fusobacterium nucleatum and F. necrophorum were viable in all four media for more than two weeks and produced both turbidity and a color change after only one day of incubation. Veillonella parvula in either bpBHI or BHI and Peptostreptococcus anaerobius in either bpPYG or BHI were viable for more than two weeks, and showed a color change or turbidity after one or two days.

Perforation repair comparing mineral trioxide aggregate and amalgam using an anaerobic bacterial leakage model

T.T. Nakata, K.S. Bae, J.C. Baumgartner J. Endodon 1998;24:184-187

The purpose of this study was to evaluate the ability of Mineral Trioxide Aggregate (MTA) and amalgam for sealing furcal perforations in extracted human molars using an anaerobic bacterial leakage model. Furcal perforations were made in 39 maxillary and mandibular human molars with a high-speed bur. These were randomly divided into two experimental groups of 18 with the remaining three teeth used as positive controls. Experimental Group 1 was repaired with MTA and Group 2 with amalgam. Three teeth without perforations served as negative controls. A dual chamber anaerobic bacterial leakage model was assembled. Brain heart infusion broth with yeast extract, hemin, menadione and the chromogenic indicator bromcresol purple (bpBHI) was used as the culture broth for Fusobacterium nucleatum. During this time period, eight out of 18 amalgam samples leaked, while none of the 18 MTA samples leaked. MTA was significantly better than amalgam in preventing leakage of F. nucleatum past furcal perforation repairs.

Comparison of dentinal crack incidence and removal time resulting from post removal by ultrasonic or mechanical force

J.H. Altshul, G. Marshall, L.A. Morgan, J.C. Baumgartner J. Endodon 1997;23:683-686

The purpose of this study was to compare the frequency of canal and intra-dentin cracks after intraradicular post removal using ultrasonic instrumentation or the Gonan post removal system. Sixty cadaver teeth were divided into four groups of 15 teeth each. Group 1 (Ultrasonic removal), Group 2 (Gonan post removal system), Group 3 (cemented posts not removed) and Group 4 (no posts). Groups 1 and 2 were contra-lateral matched pairs. Para posts were placed in groups 1, 2, and 3 to 7mm apical to the cemento-enamel junction and luted with ZnPO4 cement. The time required for post removal in groups 1 and 2 was recorded. The teeth were extracted, sectioned, and examined. Canal and intra-dentin cracks were mapped and their frequency recorded at each level. There were statistically more cracks present in the Ultrasonic Group than the No-Post Group. It took significantly longer for post removal using the ultrasonic tip versus the Gonan System.

Occurrence of Prevotella nigrescens and Prevotella intermedia of endodontic origin

K.S.Bae , J.C. Baumgartner, T.R. Shearer, L.L. David J. Endodon 1997;23:620-623

The occurrence of Prevotella intermedia and Prevotella nigrescens in endodontic infections was studied using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of whole cell protein to distinguish between the species. Previous studies have shown an association between black-pigmented bacteria (BPB) and endodontic infections. Prevotella intermedia (previously known as Bacteroides intermedius) was the most commonly isolated BPB. Recently, P. intermedia was shown to comprise a closely related species now known as P. nigrescens. Fifty-six strains of BPB isolated from endodontic infections and previously identified as P. intermedia were used in this study. Following SDS-PAGE, P. nigrescens showed a unique 18.6 kDa band that was used to differentiate P. nigrescens from P. intermedia. Of the 56 strains of BPB, 41 (73.2 percent) of the strains were identified as P. nigrescens and 15 (26.8 percent) as P. intermedia. This study confirms that P. nigrescens, and not P. intermedia, is the BPB most often isolated from infections of endodontic origin.

A comparison of canal centering ability of four instrumentation techniques

J.A. Short, L.A. Morgan, J.C. Baumgartner J. Endodon. 1997;23:503-507

The purpose of this study was to compare three engine-driven NiTi instrument systems with hand files for their effect on canal transportation. Mesial roots of mature lower first molars with separate canals were paired on the basis of curvature and morphology. Canal lengths were standardized to 11mm from orifice to apical foramen. Profile, Lightspeed, McXIM and Flex-R hand filing techniques respectively were randomly assigned to one of the four canals of each tooth pair. The roots were mounted and sectioned at 1-mm, 3 mm, and 5 mm from working length using a modified Bramante technique. All sections were video imaged preoperatively, after instrumentation to size #30, and after final instrumentation to size #40. The images were computer analyzed for changes in canal area and centering at each stage of instrumentation. Preparation time was also recorded. Data were analyzed using ANOVA. The NiTi systems remained better centered in the canal than stainless steel hand files. There were no significant differences among the NiTi systems at any level. The difference between hand filing and the NiTi techniques was more pronounced at size #40 than at size #30. The NiTi systems were all significantly faster than hand filing. No significant differences in preparation were found between the NiTi systems when canals were instrumented to the size nearest #40.

Comparison of ultrasonic and high-speed bur root-end preparations using bilaterally matched teeth

D.S. Mehlhaff, J.G. Marshall, J.C. Baumgartner J. Endodon. 1997;23:448-452

The purpose of this study was to compare ultrasonic and high-speed bur root-end preparations. Seventy-six roots from 29 bilaterally matched pairs of human teeth in cadavers were used in this study. In group 1, ultrasonic preparations were made in 38 roots and filled with amalgam. In group 2, high-speed bur preparations were made in 38 roots and filled with amalgam. The size of the bony crypt was measured and the teeth were extracted and radiographed mesial-distally and buccal-lingually. None of the root-end preparations resulted in root perforation. The mean mesial-distal minimum depth of ultrasonic and high-speed bur preparations were 2.11 mm and 1.39 mm, respectively. The mean buccal-lingual minimum depth of preparation was 2.51 mm for the ultrasonic and 2.05 mm for the high-speed bur preparations. The depth of the ultrasonic preparations were significantly greater for both measurements. A significantly greater bevel angle was associated with the bur preparations, 35.1 versus 16.0 for the ultrasonic preparations. The incidence of ultrasonic root-end preparations deviating from the uninstrumented canal spaces was found to be 2.6 percent. All bur root-end preparations were at an acute angle to the long axis of the root. The bony crypt size for bur preparations was significantly greater than that for ultrasonic preparations.

Evaluation for cracks associated with ultrasonic root-end preparation of gutta-percha filled canals

K.L. Beling, J.G. Marshall, L.A. Morgan, J.C. Baumgartner J. Endodon. 1997;23:323-326

Many clinicians use ultrasonics for root-end preparations. The purpose of this study was to evaluate resected root-end surfaces of bilaterally matched human teeth for cracks before and after ultrasonic root-end preparation. Twenty matched pairs of extracted single rooted teeth were divided into two experimental groups. In group 1, root-end resection was performed on uninstrumented teeth. In group 2, root-end resection was performed after the canals were instrumented and filled with gutta-percha. All teeth in both groups received root-end preparations using ultrasonic instrumentation at low power. Two examiners evaluated the root-ends after root-end resection and again after root-end preparation using zoom magnification of 20X to 63X. The number, types, and location of cracks were mapped. There were no significant differences when gutta-percha filled roots were compared to uninstrumented roots with regard to the number or type of cracks after root-end resection or root-end preparation. In addition, there were no significant differences in the number or type of cracks following root resection and ultrasonic root-end preparation when compared to teeth with root resection alone.

Demineralization of resected root-ends with methylene blue dye

L.A. Morgan, J.C. Baumgartner Oral Surg. Oral Med. Oral Path. Oral Radiol. Endod. 1997;84:74-78

Resected root-ends were treated with either 2 percent methylene blue dye for intervals of 5-11 minutes or 1 percent methylene blue for 7-9 minutes and examined with SEM for smear layer removal. Two minute applications of saline and 50 percent citric acid served as controls. All methylene blue solutions were found to be ineffective in removing the smear layer at all time intervals tested, and they are unsuitable for this purpose clinically. An experimental solution of 1 percent methylene blue in 50 percent citric acid was found to predictably remove the smear layer during a 2-minute application and retained all the favorable staining characteristics of the dye. Fifty percent citric acid solutions applied for 3 minutes appeared to over demineralize the root-end and gave poorer results than 2 minute applications.

Evaluation of cracks associated with ultrasonic root-end preparation

C.A. Layton, J.G. Marshall, L.A. Morgan, J.C. Baumgartner J. Endodon. 1996;22:157-160

The purpose of this study was to evaluate resected root-end surfaces of bilaterally matched human teeth after using ultrasonic tips at low or high frequencies for root-end preparation. Thirty-four bilaterally matched pairs of single rooted human teeth had root-end resections using a low-speed diamond saw. Thirty matched pairs of teeth were divided into two experimental groups with one member of each pair being placed in each group. They were stored in vials containing 0.004 percent methylene blue dye in distilled water. In Group 1, root-end preparations were made with an ultrasonic tip on the lowest frequency setting, while the preparations in Group 2 were done on the highest power setting. Two examiners blindly examined the resected root-ends using a stereomicroscope at 20X to 63X recording the numbers, types and location of the cracks. Three types of cracks were observed: canal cracks, intradentin cracks and cemental cracks. All types of cracks were observed both after root-end resection and after ultrasonic root-end preparation. There were significantly more root-ends with cracks after ultrasonic root-end preparation than after root-end resection. Using the ultrasonic tip on the high frequency setting for root-end preparation resulted in significantly more canal cracks per root than when the ultrasonic tip was used on the low power setting.

Evaluation of dentin thickness in curved canals after flaring with M-series canal openers and Gates-Glidden burs

T.L. Isom, J.G. Marshall, J.C. Baumgartner J. Endodon. 1995;21:368-371

A study was done comparing the dentin thickness in the mesial canals of lower first and second molars before and after flaring. Using a muffle system, Gates-Glidden burs or M-Series Canal Openers were used with either a straight up and down motion or with an anti curvature motion in the mesial canals of human mandibular molars. Dentin thickness was measured before and after instrumentation. It was found that Gates-Glidden burs used straight up and down removed statistically more dentin than Canal Openers used straight up-and-down or in an anti-curvature fashion. Gates-Glidden burs used in an anti curvature fashion removed statistically more dentin at a level two mm apical to the furcation than any other method tested.

Practical application of infection control in endodontics

G.J.Reams , J.C. Baumgartner, J.C.Kulild J. Endodon. 1995;21:281-284

The transmission of infections in an endodontic practice is a significant concern for both patients and dental health care providers. This article offers a review and practical application of infection control methods in the practice of endodontics.

A comparison of instrumentation techniques on apical canal transportation

D.J. Luiten, L.A. Morgan, J.C. Baumgartner, J.G. Marshall J. Endodon. 1995;21:26-32

The ability of four instrumentation techniques to enlarge and maintain the central axis of 51 curved canals were compared radiographically. Curved canals in extracted human teeth were instrumented using either a step-back preparation with K-files, crown-down preparation with K-files, sonic instrumentation with Shaper-Sonic files or using the NiTiMatic preparation system. Coronal flaring was performed on all canals and each was instrumented to a #35 file to within one mm of the anatomical foramen. Radiographs were taken with mercury filling the canal system using a specially designed model that allowed for the pre- and post-instrumentation canal to be viewed on the same radiograph. At several points along the canal, the amount of transportation resulting from the various instrumentation techniques was evaluated and compared using computer analysis. The results of the study indicate that although the average canal curvatures were greater in the NiTi group, no statistically significant differences were seen comparing the four instrumentation techniques for canal transportation. Sonic instrumentation provided significantly more coronal flaring than did the other techniques. The use of the crown-down and sonic techniques produced more ledges than did the NiTi or step-back techniques. Elbow formation was associated with all instrumentation techniques. The model system developed for this study provided an accurate method of assessing the preparation techniques and the instrument effects on the canal walls.

The effects of a carbon dioxide laser on human root dentin

R.P. Read, J.C. Baumgartner, S.M. Clar J. Endodon. 1995;21:4-8

The use of lasers has been suggested to seal dentin during surgical endodontic procedures. The effects of the Luxar LX-20 CO2 dental laser on resected apical root dentin were examined using stereomicroscopy and scanning electron microscopy. The use of the stereo-microscope allowed evaluation of the specimen prior to sputter coating under vacuum which has been thought to cause artifactual cracking of dentin. The surface of two mm thick sections of dentin from freshly extracted human teeth were exposed to CO2 laser radiation. A prototype curved laser tip was used and compared to a standard straight tip. The curved tip would facilitate access to a resected root end during endodontic surgery. Fluences used ranged from 2.1 to 625.0 J/cm2. The effects of the laser energy on the dentin ranged from no visible effects, to charring, cracking, cratering and glazing. The most dramatic effect was cracking. Cracking was evident on all specimens having any visible modification of the dentin. The curved tip did not deliver laser energy to the dentin as efficiently as a straight tip. CO2 laser radiation did not consistently obliterate dentin tubules. Lased dentin had more open dentinal tubules and cracking that would render the dentin more permeable to fluids and bacteria. This study was supported in part by the Research and Education Foundation of the AAE.

Factors associated with endodontic posttreatment pain

J.G. Marshall, A. Liesinger J. Endodon. 1993:19:573-575

One hundred six patients with pretreatment pain presenting for endodontic treatment participated in a controlled double blind study. Endodontic therapy was performed and various patient and treatment factors were evaluated for their effects on endodontic posttreatment pain. Patients with no radiographic periapical lesions had significantly more pain at 8,24,48 and 72 hours posttreatment than patients with periapical lesions. No other patient or treatment factors correlated with posttreatment pain. Patients who received a placebo reported an 81 percent incidence of post-treatment pain, 73 percent of the placebo group required post-treatment pain medications. By 72 hours post-treatment the incidence and severity of pain was minimal.

Intramuscular injection of dexamethasone: Effect of variable doses of steroid on post-treatment endodontic pain

A. Liesinger, F.J. Marshall,J.G. Marshall J. Endodon. 1993;19:35-39

One hundred six patients with pre-treatment pain presenting for endodontic treatment participated in a controlled double blind study. The results showed that when compared to a placebo, injection of dexamethasone (2, 4, 6, and 8 mg taken as a group) significantly reduced the severity of patient pain at four and eight hours posttreatment. Patients who received dexamethasone took significantly fewer post-treatment pain medications than those who received a placebo. Patients who received 0.07-0.09 mg/kg of dexamethasone had significantly less severe pain than patients who received a placebo at eight hours post-treatment. Patients who received 0.07-0.09 mg/kg of dexamethasone took significantly fewer post-treatment pain medications than those who received a placebo. There was no significant difference in the incidence of post-treatment pain between patients who received dexamethasone or a placebo.

Infiltrate of chronic lymphocytic leukemia appearing as a periapical radiolucent lesion

L.Morgan J. Endodon. 1995;21:475-478

This report presents a case of a mandibular premolar with a vital pul and a periapical radiolucent lesion in a patient with a history of chronic lymphocytic leukemia. Biopsy of the lesion revealed an infiltrate of chronic lymphocytic leukemia in the mandible, which is quite rare. This lesion may have portended a worsening of the patients condition and downgrading of her prognosis.

A 24 week study of the microleakage of four retrofilling materials using a fluid filtration method

Inoue S., Yoshimura M., Tinkle JS, Marshall F.J. J. Endodon. 1991;17:369-375

The microleakage after retrofillings of amalgam, amalgam with cavity varnish, silver-containing glass ionomer cement and intermediate restorative material was compared in vitro. Thirty-six extracted human incisors and canines were instrumented, obturated with gutta-percha without sealer, subjected to apicoectomy and retrofilled with the materials described above. After removal of the gutta-percha filling, the microleakage from both directions (apically and coronally) was measured quantitatively and longitudinally for 24 weeks after filling by a fluid filtration technique. All four retrofilling materials revealed some apical and coronal leakage at all time periods. The amalgam group showed statistically significant (p less than 0.001) apical leakage at 1.5 hours. The use of cavity varnish significantly reduced the apical leakage of the amalgam group at 1.5 hours. The silver-containing glass ionomer cement and intermediate restorative material groups showed significantly (p less than 0.05) less coronal leakage compared with the amalgam group at 1.5 hours. Scanning electron microscopy of selected samples showed marginal defects of approximately 5 microns between the root dentin and the retrofilling material.

Solving endodontic isolation problems using interim buildups of reinforced glass ionomer cement

L.A. Morgan, J.G. Marshall J. Endodon. 1990;16:450-453

A technique is presented for the expedient placement of interim buildups of type II glass ionomer cement as an aid for endodontic isolation of broken down teeth. The bond strength of glass ionomer cement to tooth structure is sufficient to withstand the forces of endodontic manipulation without the need for reinforcing pins. The material also shows promise as an intermediate endodontic seal. Variations of this technique are presented to address some other common isolation problems and the esthetic needs of the patient.

The effects of periodontal ligament injection on pupal and periodontal tissues

Roahen J.O., Marshall F.J. J. Endodon. 1990;16:28-33

This study was designed to investigate histologically the effects of the periodontal ligament injection on the pulp of teeth with or without subsequent amalgam restorations and the effects of the injection on the periodontium. Eighty-eight injections were made on 55 teeth in dogs in intervals from 10-minutes to 30-day prefixation, while 18 teeth were not injected and evaluated as controls. After perfusion fixation, block sections were decalcified, sectioned longitudinally, stained and evaluated microscopically by three independent examiners. The pulps were graded for degree of inflammation and the periodontal ligaments were examined for signs of tissue disruption. The results of the pulp study were evaluated statistically and showed no apparent effect on the pulp from the injection. Several periodontal ligaments showed evidence of the injection, ranging from tissue disruption shortly postinjection to areas of active external root resorption in 30-day specimens. It was concluded that this technique does not have long-term deleterious effects on the pulp but can induce localized external root resorption.

In vitro quantification of the apical sealing ability of retrograde amalgam fillings

M. Yoshimura , F.J. Marshall , J.S. Tinkle J. Endodon. 1990;16:9-12

Retrograde amalgam fillings were placed in 12 extracted human canines. The microleakage from both directions (coronally and apically) was determined using pressurized fluid filtration at 90 minutes, 6 hours, 1 day, 2 days, and 1, 2, 4, and 8 weeks after amalgam filling. Leakage from either direction decreased markedly in the 90-minutes to 6-hours interval after filling. At intervals between 1 day and 8 weeks, only small changes in leakage were noted. After any time period, leakage from the coronal direction was greater than leakage from the apical direction. However, this difference was not statistically significant except at 90 minutes when the coronal leakage was significantly greater. This experimental system was shown to reliably measure microleakage in retrograde amalgam fillings.

The permeability of apical barriers

Beeler W.J., Marshall F.J., Brown A.C. J. Endodon. 1989;15:422-426

The purpose of this work was to measure the permeability (hydraulic conductance) of root canal apical barriers in vitro. In 30 extracted teeth, the pulp tissue was removed and the apical opening standardized and enlarged using endodontic files. One-millimeter thick barriers of either autogenous dentin chips, calcium hydroxide powder, or durapatite particles were placed just inside the apical opening. The prepared teeth were mounted in a special chamber, fluid pressure applied, and the resultant flow measured. The permeability of dentin chip barriers in 10 additional teeth with nonstandardized apical openings was measured also. The standardized canals with the autogenous dentin chip barriers had a mean permeability of 0.0010 µl/s/psi at 20 psi applied pressure. Teeth with calcium hydroxide barriers averaged 0.0012 µl/s/psi. The durapatite particle barriers were much more permeable and averaged 0.0220 µl/s/psi. It was concluded that this technique is useful in evaluating the effectiveness of apical barrier materials. For the materials tested, autogenous dentin chips and calcium hydroxide barriers have significantly lower permeability than durapatite barriers (p=0.05).

Effects of distance from the pulp and thickness on the hydraulic conductance of human radicular dentin

H.M. Fogel,F.M. Marshall, D.H.Pashley

J. Dent. Res. 1988;67:1381-1385

The purposes of this study were: (1) to measure the effect of distance from the pulp on the hydraulic conductance of human radicular dentin; (2) to determine the influence of dentin thickness on the rates of fluid flow; and (3) to attempt to correlate dentinal tubules densities and diameters with root dentin hydraulic conductance. Dentin slabs prepared from extracted, unerupted, human third molar teeth were placed in a split-chamber device to permit quantitation of fluid filtration rate (hydraulic conductance). In the SEM portion of the study, dentinal tubule numbers and diameters were recorded. The results indicated that radicular dentin hydraulic conductance decreased with distance from the pulp and with increasing dentin thickness. Tubule density and diameter correlated well with the measured hydraulic conductances. The relatively low hydraulic conductance of outer root dentin makes it a significant barrier to fluid movement across root structure.

A comparison of two post systems under applied compressive-shear loads

R. Greenfeld , R.H. Roydhouse, B. Schoner, F.J. Marshall. J. Prosthet. Dent. 1989;61:17-24

This study compared a new parallel-tapering, threaded, split-shank post with a well-accepted parallel serrated post under applied compressive-shear loads. The posts were placed in paired, contralateral human teeth to attempt to minimize variation in the tooth model. Both initial and ultimate failure modes were observed and the clinical significance reported. The Flexi-post system compared favorably with the Para-Post system under conditions of this research.

Methylene blue dye: an aid to endodontic surgery

J.V. Cambruzzi , F.J. Marshall, J. Pappin J. Endodon. 1985;11:311-314

Methylene blue dye can be a useful aid in endodontic surgery. The differential staining of methylene blue outlines roots, delineates root dentin from bone, demarks isthmuses between two canals in a single root and outlines cysts for enucleation.

Age-related changes in reducible cross-links of human pulp collagen

C. Nielsen , M. Bentley, F.J. Marshall Arch. Oral Biol. 1983;28:759-764

Coronal pulp of human third molars from patients ranging in age from 16 to 40 years was analysed for collagen, protein, calcium and reducible crosslink content. Dihydrosylsinonorleucine (DHLNL) was the major crosslink; it decreased with age. Hydroxylsinonorleucine (HLNL) and lysinonorleucine (LNL) appeared in insignificant amounts. Calcium content increased with age. Based on the premise that collagen synthesis is characterized by the presence of reducible crosslinks, the study showed that coronal pulp collagen synthesis decreases with age; this is accompanied by a decrease in collagen concentration in terms of dry weight and total protein between 16 and 30 years of age.

Molar Endodontic Surgery

J.Cambruzzi, F.J. Marshall J. Canad. Dent. Assn. 1983;11:61-66

Apicoectomy of molar roots will expose two canals in a significant number of mesiobuccal roots of maxillary molars and mesial and distal roots of mandibular molars. Furthermore, a significant number of these roots will have an isthmus of pulp tissue joining the two canals. This isthmus must be obturated by a retrograde amalgam to ensure periapical healing.

The effectiveness of irrigation in endodontics

S.Sinanan, F.J. Marshall, R. Quinton-Cox J. Canad. Dent. Assn. 1983;11:771-776

The root canal system of a tooth requiring endodontic therapy may contain pulpal tissues in various stages of degeneration, and/or micro-organisms plus their byproducts, and therefore it should be treated like a contaminated wound. Traditional treatment requires various sizes and shapes of instruments to surgically debride the canal and to shape the walls for convenience in obturating the prepared space. Lavage is a necessary adjunct to debridement procedures, since root canal instruments alone do not cleanse adequately. The effectiveness of the devices used in lavage have not been extensively studied, and the purpose of this study was to compare three endodontic irrigating delivery systems: 1) the Endovage syringe with a 27 and 30 gauge IMAX needle. This syringe automatically aspirates following irrigation, when pressure on the plunger is released; 2) a conventional hypodermic needle 7 gauge and luer-lock syringe; and 3) the P.E.R.C. needle, 30 gauge and luer-lock syringe.

The role of dowels in restoring endodontically treated teeth - 12 considerations

R. Greenfeld, F.J. Marshall J. Canad. Dent. Assn. 1983;11:777-783

Practitioners are often confronted with the problem of utilizing dowels when restoring endodontically treated teeth. The purpose of this article is to review the pertinent literature concerning dowels, their characteristics, method of employment and time of insertion. Guidelines based upon sound principles gathered from clinical and laboratory observations are provided.

Reactivity of human lymphocytes to pulp antigens

D.G. Longwill, F.J. Marshall, H.R. Creamer J. Endodon. 1982;8:27-32

Lymphocyte transformation induced by Formocresol-treated and untreated extracts of homologous pulp tissue was evaluated in groups of children who differed in past experience with Formocresol pulpotomies. Significant transformation responses were observed in studies of 25 of the 40 children. Neither the ability to respond nor the level of lymphocyte response to the pulp extracts was related to a clinical history of Formocresol pulpotomy. Sensitization to pulp-related antigens was a common finding in this study and was moderately well-correlated with indexes of past and current dental disease.