Assessing treatment outcomes from the postgraduate orthodontic program, Chulalongkorn university
Authors:   , Kongboonvijit Tanyapak 
Published: May 2023

Objective:  To evaluate the quality of orthodontic treatment outcomes by using Peer Assessment Rating index (PAR), American Board of Orthodontics Objective Grading System (ABO-OGS) and lateral cephalometric analysis in the cases completed from the postgraduate orthodontic clinic, Chulalongkorn University. And to determine whether any contributing factors correlate with the orthodontic treatment outcomes.

Materials and Methods:  100 patients who had completed treatment since 2017 were included in this study. Inclusion criteria included patients with full upper and lower edgewise appliances and completed treatment records. Exclusion criteria included patients with craniofacial syndromes or debond before treatment completion. One calibrated examiner assessed DI, pretreatment PAR index and lateral cephalometric analysis. To evaluated treatment outcomes, ABO-OGS, posttreatment PAR index and lateral cephalometric analysis were assessed. Patient data included age, gender, Angle’s classification, types of treatment and treatment duration were also collected.  The reliability and validity of the measurements were evaluated using the intraclass correlation coefficient (ICC). Data were analyzed with Wilcoxon signed ranks test, Pearson Chi-square test, Spearman rank correlation, univariate and multivariate linear regression models.

Results: Of the 100 patients, 58% were females and 42% were males. The mean age of the sample was 19.22±7.01 years. The types of malocclusion were included: 33% Class I, 33% Class II, and 34% Class III. 47% were camouflaged, 19% were surgery and 5% received 2-phase treatment. The average treatment time was 36.28±8.21 months, with a range from 14 to 57 months. ICC showed very good intra-observer and inter-observer reliability in every index. The analysis showed that the average DI score was 25.69±16.12 points. The mean pretreatment and posttreatment PAR scores were 33.53±12.42 and 0.48±0.67 points respectively. 77% were greatly improved and 23% improved. The average score of ABO-OGS was 11.38±6.34 points. 91% were in the pass group and 9% undetermined. After treatment, there were statistically significant improvements in ANB, Wits, LI-NB (mm), UI-LI, upper lip to E-line and H-angle (p-value<0.01).  Spearman rank correlation and linear regression models showed no statistically significant correlation between DI score, pretreatment PAR score, age and gender to posttreatment PAR score and ABO-OGS score. Meanwhile, pretreatment FMA and treatment duration were statistically significant correlated with posttreatment PAR score (p-value<0.05). There were statistically significant correlation between initial Angle’s classification, pretreatment ANB, Wits, LI-NB angle, types of treatment  and treatment duration with ABO-OGS score (p-value<0.05).

Conclusion: Most of the patients treated in the postgraduate orthodontic clinic, Chulalongkorn University had satisfactorily orthodontic treatment outcomes. Initial severity of skeletal discrepancy and duration of treatment were significantly associated with the quality of the final outcomes.