Abstract: Objective　 To analyze the change of occlusal contacts of patients before and after the wearing clear overlay retainers and explore the effect of clear overlay retainers on the occlusion during orthodontic retention. Methods　 The T-Scan III digital occlusion analysis system was used to collect and analyze the occlusion contacts in maximum intercuspal position of 34 patients. The occlusion data was collected immediately after the end of fixed orthodontic treatment (T0) and after wearing clear overlay retainers for 3 months (T1). The number of occlusal contacts (NOC), the area of occlusal contacts (AOC) and sagittal displacement of the center point of force (COF) before and after wearing clear overlay retainers were compared. Paired t test and wilcoxon rank sum test were utilized in the data analysis. Results　 The patients’ occlusal contacts in maximum intercuspal position changed after wearing clear overlay retainers for 3 months. From the end of fixed orthodontic treatment (T0) to wearing clear overlay retainers for 3 months (T1) ,the total number and area of occlusal contacts decreased significantly (p＜0.05) , while the number and area of anterior dental arch increased (p＜0.05) and posterior dental arch decreased (p＜0.05). The center point of occlusal force was obviously shifted mesially (p＜0.05). Conclusions　 The use of clear overlay retainers changed the occlusion contacts of the patients after fixed orthodontic treatment. After wearing the clear overlay retainers for 3 months, the total occlusal contact in maximum intercuspal position became shallower, in which the posterior occlusal area got shallower and the anterior area got deeper.

Key words: Clear overlay retainers, T-Scan, Occlusal contacts