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Endodontics > Research
OHSU Grad Endo Research
The microbiology laboratory
in the Department of Endodontology is directed by Dr. J. Craig Baumgartner.
Our laboratory has been 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, have made significant contributions
to the lab.
The studies in our state-of-the-art anaerobic laboratory have 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 even specific virulence factors.
We have recently cultivated and sequenced the 16 S RDNA gene of
bacteria named Prevotella tannerae.
Present endodontic
resident projects:
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
Abstract:
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.
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. Submitted and Accepted for Publication J Endodon.
Abstract:
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.
Antimicrobial Efficacy of Irrigation with the EndoActivator
Michael Wheatley DDS, J. Craig Baumgartner, DDS, PhD
Abstract:
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.
Nerve Growth Factor Promotes Postnatal Maturation of Trigeminal Ganglion Neurons In Vitro: Effects on Survival, Cell Body Diameter, and Synaptophysin Expression.
Leila Tarsa, Loi T. Nguyen, Hui-ya Hsieh, and Agnieszka Balkowiec. Submitted and Accepted for Publication in Neuropeptides.
Abstract:
The role of growth factors in postnatal maturation of trigeminal ganglion (TG) neurons is poorly understood. The goal of the present study was to examine the effects of neurotrophic factors known to be expressed by TG neurons and/or their targets, on early postnatal maturation of these neurons. Postnatal day (P) 0, P1, and P7 rat TG neurons were grown for 3 daysin the presence or absence of neurotrophic factors, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and glial cell line-derived neurotrophic factor (GDNF), followed by immunostaining for pan-neuronal markers Neurofilament 68/160 and Protein Gene Product 9.5 (PGP 9.5), and the synaptic vesicle marker synaptophysin (Syp). NGF (1, 10, 50 ng/ml) strongly and dose-dependently increased survival of TG neurons derived from early P0 animals, whereas its survival effect on neurons derived from animals older than P0 was apparent only in neuron-enriched cultures, in which the number of non-neuronal cells was significantly reduced. The survival effect of GDNF was significant only in neuron-enriched cultures. In P1 TG cultures, NGF (50 ng/ml) and BDNF (50 ng/ml), but not other growth factors, significantly increased soma diameter. The NGF effect on soma diameter was also present in P7 cultures. Moreover, NGF (100 ng/ml) reduced the number of PGP 9.5-immunoreactive cell bodies labeled for Syp, while increasing a relative density of Syp staining in distal vs. proximal axons. Together, our data indicate that NGF is involved in early postnatal maturation of TG neurons, including regulation of soma diameter and formation of synaptic connections. |
