Long-term occlusal changes assessed by the American Board of Orthodontics' model grading system.
BACKGROUND
The purpose of this study was to assess the long-term posttreatment changes in all criteria of the American Board of Orthodontics' (ABO) model grading system.


METHODS
We used plaster models from patients' final and posttreatment records. Thirty patients treated by 1 orthodontist using 1 bracket prescription were selected. An initial discrepancy index for each subject was performed to determine the complexity of each case. The final models were then graded using the ABO's model grading system immediately at posttreatment and postretention. Statistical analysis was performed on the 8 criteria of the model grading system, including paired t tests and Pearson correlations. An alpha of 0.05 was considered statistically significant.


RESULTS
The average length of time between the posttreatment and postretention records was 12.7 ± 4.4 years. It was shown that alignment and rotations worsened by postretention (P = 0.014), and a weak statistically significant correlation at posttreatment and postretention was found (0.44; P = 0.016). Both marginal ridges and occlusal contacts scored less well at posttreatment. These criteria showed a significant decrease in scores between posttreatment and postretention (P <0.001), but the correlations were not statistically significant. The average total score showed a significant decrease between posttreatment and postretention (P <0.001), partly because of the large decrease in the previous 2 criteria.


CONCLUSIONS
Higher scores for occlusal contacts and marginal ridges were found at the end of treatment; however, those scores and the overall scores for the 30 subjects improved in the postretention phase.
Private practice, Hamburg, NY.
Robert M
RM
Aszkler
Professor and chair, Department of Orthodontics, School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY.
Charles B
CB
Preston
PhD candidate and resident, Orthodontic Graduate Program, School of Dentistry, University of Alberta, Edmonton, Alberta, Canada. Electronic address: saltaji@ualberta.ca./
Humam
H
Saltaji
Assistant professor, Department of Orthodontics, School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY.
Sawsan
S
Tabbaa
D002508:Cephalometry / Q000379:methods; D003724:Dental Arch / Q000000981:diagnostic imaging; D003766:Dental Occlusion; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008310:Malocclusion / Q000473:pathology / Q000628:therapy; D008334:Mandible / Q000000981:diagnostic imaging; D008437:Maxilla / Q000000981:diagnostic imaging; D018704:Orthodontic Retainers; D009970:Orthodontics / Q000592:standards; D009971:Orthodontics, Corrective / Q000145:classification* / Q000592:standards; D057887:Overbite / Q000000981:diagnostic imaging; D011859:Radiography; D012008:Recurrence; D012953:Societies, Dental; D014070:Tooth / Q000000981:diagnostic imaging; D014092:Tooth Root / Q000000981:diagnostic imaging; D016896:Treatment Outcome