The aims of this study were to evaluate the posttreatment outcomes in a postgraduate orthodontic clinic following a course on American Board of Orthodontics Cast and Radiograph Evaluation (ABO-CRE); to compare the outcomes of postgraduate students who took the course before and after finishing treatment of their cases; and to assess if the need for orthodontic treatment as determined by the Index of Orthodontic Treatment Need (IOTN) at the beginning of treatment affected students' final scores. A course on ABO-CRE was given to second- (group A), third- (group B), and fourth- (group C) year postgraduate students at Yeditepe University, Istanbul, Turkey, in 2012. Pre- and posttreatment plaster models of 253 cases (group A) were treated by students in 2011-12. An additional 251 (group B, 2012-13) and 341 (group C, 2013-14) cases were evaluated in the first and second years after the course, respectively. The models were graded retrospectively using the ABO-CRE and IOTN. The results showed that the total mean scores on the posttreatment plaster models were significantly higher in the pre-course group than the first-and second-year post-course group (p<0.05 and p<0.01, respectively). The borderline cases (grade 3) received a lower score on the ABO-CRE than the cases with need (grade 4) (p<0.01) and severe need (grade 5) (p<0.01) for orthodontic treatment. Increasing awareness by giving information about the ABO-CRE significantly improved the posttreatment success of these postgraduate students. After the course, treatment outcomes in the following year were better than two years later, suggesting it may be useful to teach the course annually to refresh students' knowledge.