American Board of Orthodontics - model grading assessment: A comparison of post-treatment and post-retention models

The American Board of Orthodontics (ABO) has made an attempt to improve our profession and attempted to quantify the proper arrangement of teeth after they have received orthodontic treatment. They developed a Model Grading System in order for orthodontists to assess the adequacy and quality of their orthodontic treatment more objectively. This system was developed in the early 90's and has been used since then. It relies on eight criteria to determine the adequacy of the treatment result. They are: alignment, marginal ridges, buccolingual inclination, occlusal relationships, occlusal contacts, overjet, interproximal contacts, and root angulation. Each one of these criterion is essential to proper orthodontic treatment.;This study was an attempt to quantify the relationship of the ABO's Model Grading System to an overall excellent orthodontic result. It also attempted to address the areas that are of concern to orthodontists post-treatment. Which of the eight criteria are more likely to get worse post-treatment and which will improve.;This study was a retrospective study that utilized plaster models from the patient's final records and post-treatment records that were previously taken and recorded. Thirty cases were selected based on completeness of records treated by a single orthodontist (R.G. "Wick" Alexander, D.D.S., MSD). Each of the thirty cases was assigned a number 1-30 to identify them. The inclusion criterion for the study was that both arches were treated orthodontically. The exclusion criterion excluded lower incisor extraction cases from the study.;An initial Discrepancy Index for each of the selected thirty cases was performed to determine the difficulty of each case. The final models of each case was then graded using the ABO Model Grading Assessment immediately post-treatment (T2) and at post-retention (T3).;Statistical Analysis was performed on the eight Model Grading System criteria including Paired t-tests and Pearson product correlations. It was shown that marginal ridges and occlusal contacts scored less well at T2 partly because of Dr. Alexander's bracket prescription. These criteria showed a highly significant decrease in score between T2 and T3. The average total score showed a highly significant decrease between T2 and T3 partly because of the large decrease in previous two criteria. Further research needs to be done utilizing more cases treated by more than one orthodontist. This will conclusively determine which of the eight criteria get better or worse with time.