Pacific Coast Society of Orthodontists Bulletin Fall 2016 - 22

PCSO Resident Research Review Oregon Health & Science University Resident Research Review Dr. Rachel Hoffman Second-Year Resident Oregon Health & Science University Abstract Over the years, research projects conducted at the Oregon Health & Science University postdoctoral orthodontic program have focused on a variety of clinical topics. In this review, three longitudinal research topics are briefly discussed: resin infiltration for treatment of white spot lesions, use of cone-beam computed tomography for assessing alveolar bone height, and comparisons of indirect bonding techniques. Research theses completed each year by the residents of Oregon Health & Science University's 30-month Master of Science graduate program in orthodontics have focused on a wide variety of clinically related and relevant topics. While the range of subject matter varies from year to year, a great many of the projects boost ongoing lines of research that can be assumed by current residents for continued study. Recent themes have included the use of resin infiltration for treatment of white spot lesions (WSLs), use of cone-beam computed tomography (CBCT) in evaluating alveolar bone, and comparisons of indirect bonding techniques. Other projects have been based on new ideas of interest to a particular resident; these tend to be singular projects. Given the efforts and capabilities of the residents and their mentors, all projects of either approach culminate in novel, thought-provoking results with the potential for publication. In order to provide an appraisal of past research efforts, I will describe three project lines that were continued by several residents, including graduates of the Class of 2015. Resin Infiltration for Treatment of White Spot Lesions Kaitlyn Darcy, a graduate of the Marquette University School of Dentistry, followed up on earlier projects in the OHSU graduate program investigating resin infiltration of WSLs. Her benchtop study using artificially created WSLs on bovine incisors aimed at comparing three approaches for simulating clinical WSLs, including continual acid exposure, cycling between acid exposure 22 and remineralization solutions, and bacteria culture. Her results also provided insight into reasons for the esthetic variability in clinical treatment results with use of resin infiltration. Her study was mentored by Dr. Jack Ferracane, Chair of Restorative Dentistry at OHSU and the current President of the American Association for Dental Research. A previous study published in JADA by Seth Senestraro (Class of 2012) and coworkers used visual comparisons of photographic images and area measurements of WSLs treated with resin infiltration.1 The study demonstrated improvements in the esthetics of nearly all WSLs, yet responses among lesions varied from excellent to partial improvement. In a continuation study simulating long-term staining characteristics of WSLs restored with resin infiltration, Patra Alatsis (Class of 2014) demonstrated that differential staining of resin compared to enamel was in some cases highly notable, whereas in other cases it was minimal, depending on the staining media. A clinically relevant finding in her study was that staining tended to affect only the most superficial region of the resin restorations, and thus could potentially be removed with light polishing. Kaitlyn Darcy's in vitro study used three methods to create WSLs and compared two etch protocols during the resin infiltration process. Her results shed light on sources of outcome variability with use of different resin infiltration procedures. Kaitlyn found that the deepest lesions were created by using the bacteria culture method while the shallowest lesions were created by cycling between an acidic solution and a remineralization solution. From cross sections cut through the infiltrated lesions, it was determined that resin tended to penetrate up to 150 μm into the lesion; thus, with deeper lesions, resin fill was incomplete. With only partial penetration of the resin, the color of the restored enamel as assessed with a spectrophotometer was less ideal relative to unaffected enamel or shallow lesions treated with resin infiltration. Analysis of the cross sections also showed that with PCSO Bulletin  Fall 2016

Table of Contents for the Digital Edition of Pacific Coast Society of Orthodontists Bulletin Fall 2016