Research: Class of 2001

Chen, P.P. "Evaluating Facial Esthetics Using Frontal and Three-Quarters Views Versus Profile Silhouettes," Orthodontic Certificate Thesis, Oregon Health & Science University, June 2001.


This project sought to determine whether orthodontists will have different perceptions of facial esthetics when evaluating patients using frontal and three-quarters views versus using profile silhouettes. The hypothesis was that there will be differences in the evaluations. To examine this theory forty-seven cases were randomly selected from the archives at the Department of Orthodontics at Oregon Health & Science University. Each pre-treatment lateral cephalometric radiograph was traced to outline only the soft tissue profile of the subject. Subject's photographic slides were then scanned and both the outline and slide were then imported to Microsoft Powerpoint. The compiled survey was presented to a group of eighteen orthodontists with the OHSU Department of Orthodontics. Evaluators were asked two questions: "How would you rate this subject's facial esthetics on a scale of 1-10 (1=very poor, 5=average, 10=very good)?" and "Would you treatment plan to alter the subject's facial esthetics (Y/N)?" Results indicated that orthodontists gave higher esthetic ratings when they were able to observe the patient's face as opposed to profile tracings. The study also suggests that diagnoses and treatment plans that rely heavily on the lateral cephalometric radiograph as the primary tool may not portray the whole picture.  

Chorak, M.D. "Comparison of Post-Treatment Occlusal Settling Alignment and Functional Occlusion Utilizing Hawley Versus Circumferential Maxillary Retainers," Orthodontic Certificate Thesis, Oregon Health & Science University, June 2001.


Orthodontists universally recognize retention devices in post-orthodontic treatment patients as necessary to preserve the stability of the newly-aligned occlusion. Without it, many cases tend to revert to the pre-treatment position. This project--based on a previous study--compared Circumferential and Hawley retainers to test the hypothesis that there was no difference between the two in regard to post-treatment settling. Of the 24 patients evaluated from the previous study, 18 returned for retention evaluation. Results indicated statistically significant differences in the settling properties of the Hawley compared to the Circumferential retainer groups from the time of appliance removal to one year into retention. The findings suggest that the Circumferential retainer allows for settling to occur in the posterior occlusal table. Although the sample size was small, this researcher believes the Circumferential retainer can be recommended over the Hawley for the sake of settling; however, there is no strong evidence that alignment benefits more from the use of this retainer.  

Hartman, B.D. "Identification of Desert Hedgehog Expression in the Murine Palate and the Effects of Exogenous Retinoic Acid and Citral on Desert Hedgehog Expression." Orthodontic Certificate Thesis, Oregon Health & Science University, June 2001.


The goal of this project was to evaluate Desert Hedgehog (Dhh) expression in the murine palate and describe its relationship with retinoic acid. Using the embryonic palatal shelves of Swiss mice, the tissues were cultured and separated into control, all-trans retinoic acid, and citral groups. Palatal shelves were then fixed in Zenker's acetic acid fixative for 2 hours, dehydrated, and sectioned. The sections were cleared through xylene, dehydrated, and examined under a light microscope. Evidence suggests that Dhh may play a crucial role in the process of initial seam formation and complete fusion of the opposite palatal shelves. Palatogenesis is an extremely complex developmental process. The time and site-specific coordinated interactions occur rapidly. Any interruptions produce drastic phenotypes. Increased Dhh expression by exogenous retinoic acid may prolong basement membrane survival and prevent migration and transformation mechanisms, thereby inhibiting medial epithelial edge (aka MEE--a vital anatomical element for absolute palatal fusion) disruption. Further research exploring the role Dhh plays in the MEE during palatal fusion is clearly indicated.  

Oliverson, S.M. "An Investigation of Bond Strengths Achieved in Both Clean and Saliva-Contaminated Fields Using Self-Etching Primer," Orthodontic Certificate Thesis, Oregon Health & Science University, June 2001.


The typical bonding process can be time consuming for both orthodontists and staff. Recently 3M Unitek developed a new material--called Self-Etching Primer (SEP)--that eliminates many of the steps involved in the current bonding process, as well as reduces the time required for the individual steps. This is an advantage if SEP can deliver bond strengths equal to or greater than those already achieved via the conventional method. This study sought to compare bond strengths between Unitek Victory APC brackets and SEP. The effects of contamination and SEP bond strength were also evaluated. Study results found no statistical difference in bond strengths achieved utilizing the standard technique versus the SEP technique. Similarly, no statistical difference existed between the bond strengths of the uncontaminated and contaminated groups, although contaminated groups showed a higher percentage of bond failures at the tooth-adhesive interface when compared with uncontaminated groups. Overall, study results indicate that the SEP technique provides a bond strength statistically similar to the standard technique. These findings validate the SEP advantages of fewer required bonding materials and reduced chair time. 

Safirstein, J.J. "An Assessment of Computer Integration in Private Practice Compared with Postdoctoral Orthodontic Programs," Orthodontic Certificate Thesis, Oregon Health & Science University, June 2001.


This study compared the use and integration of computer technology in postdoctoral orthodontic programs with that utilized in clinical private practice orthodontics. The understanding, attitudes, needs, and competency of practicing orthodontists were assessed and compared with orthodontic programs' inclusion of computers in their curricula. Surveys were mailed to each of the United States' 47 postdoctoral orthodontic program directors. A second, similar survey was mailed to a random subset of 1000 active and associate private practitioners in the Pacific Coast Society of Orthodontists. Analysis of the 358 returned surveys indicated that the use of computers during residency is more focused on diagnosis and presentation, whereas private practice use is more administrative and adjunctive. This leads to the conclusion that programs training residents for private practice would serve their students well by incorporating more comprehensive training in the managerial and administrative uses of information technology.  

Wilson, C.T. "In Vitro Pulp Chamber Temperature Rise Created by Various Curing Lights During Orthodontic Bonding." Orthodontic Certificate Thesis, Oregon Health & Science University, June 2001.


Plasma arc curing lights are the latest generation composite curing lights. Due to a higher energy output, the lights tend to produce a corresponding temperature increase--a fact which has led several investigators to question the possible thermal effects on pulp tissue. This study examined possible increases in intrapulpal temperature when utilizing higher energy curing lights for orthodontic bonding purposes. To this end, ten extracted human lower incisors were selected and an opening large enough to gain access to the pulp canal was created in each. Three light curing systems--the ADT 1000 PAC Plasma Arc Curing System, the Ortholux XT Visible Light Curing Unit, and the Reliance Power Slot curing light system--were employed. Baseline readings were obtained for each of the three curing systems and for each of the ten teeth. An incisor bracket was then placed and cured and the intrapulpal temperature measured for each of the three light curing systems. Results indicated that care is needed when using plasma arc lights. The use of a calibrated radiometer is recommended to supplant manufacturers' recommendations with actual data to confirm the light's efficacy. Because the temperatures generated are greater than those of conventional lights, clinicians may be legitimately concerned about the lights' potential for iatrogenic pulpal thermal insult.