Athanasiou, Athanasios E2021-11-182021-11-182018304-2018.41https://repository.mbru.ac.ae/handle/1/605Objectives: To assess treatment outcomes of a graduate orthodontic program during two different periods. Materials and Methods: Consecutive orthodontic patients’ files were selected from the archives of the Graduate Orthodontic Program, Aristotle University of Thessaloniki, Greece. Following the application of certain inclusion criteria, the final sample consisted of 109 patients. The sample was allocated into two groups depending on the time of treatment [Group A: 1998-2003, (n=60); Group B: 2004-2009 (n=49)]. The first period started a few years after the inception of the program and the second 10 years later. All pre- and post-treatment dental casts were blindly assessed by one investigator using the Peer Assessment Rating (PAR) and the Index of Complexity, Outcome and Need (ICON). Statistical analysis included Student’s t-test, Mann-Whitney U test, Pearson Chi-Square test and Spearman correlation coefficient. The level of significance was set at p < 0.05. Results: In Group A, the mean PAR index changed from 28.6 before treatment to 5.5 after treatment and the mean ICON index changed from 71.9 to 23.5. In Group B, the mean PAR index changed from 23.6 before treatment to 4 after treatment and the mean ICON index changed from 62.8 to 19.8. The mean PAR score reduction was 78.4% for the 1st group and 81.4% for the 2nd group, respectively. Ninety percent of the cases of Group A and 89.8% of the cases of Group B had a post-treatment ICON score < 31. The severity of the initial malocclusion was found to be positively correlated with the treatment occlusal outcome. Out of the 109 cases, 68 were considered as substantially or greatly improved, 29 moderately improved, 8 showed minimal improvement and 4 cases were considered as not improved or worse. The mean PAR percentage improvement and the ICON score at the end of treatment were not correlated to the presence or absence of tooth extractions in the treatment plan. There was no correlation between the treatment outcome and the number of graduate residents involved in the therapy. The treatment outcomes were not correlated to the gender or age of patients. Conclusion: Patients treated by graduate orthodontic residents during 1998-2009 demonstrated significant improvement of their occlusion and the quality of the treatment remained constant throughout the years. The outcome of orthodontic treatment was not correlated to the gender and the age of patients, the number of postgraduate students performing the treatment, and the presence of tooth extractions in the treatment plan.enICONPAROrthodontic treatmentGraduate orthodontic educationRoot Mean Square (RMS)Occlusal indicesArticle