[A preliminary study on the occlusal contact changes during retention in adolescent patients]

To evaluate the changes of the occlusal contact characteristics in adolescent patients during 12 months after active orthodontic treatment.

Twenty adolescent patients with Hawley retainers after active orthodontic treatment were divided into none occlusal interference group and occlusal interference group. The occlusion of the patients was examined with T-Scan II system directly after the appliance removal (T1) and after an average retention period of 12 months (T2). The changes of occlusal contact characteristics were observed.

The disclusion time during protrusion, left and right lateral movements reduced significantly. The average disclusion time decreased [from (1.07 ± 0.87), (0.91 ± 0.47), (0.76 ± 0.43) s to (0.43 ± 0.25), (0.67 ± 0.41), (0.50 ± 0.27) s] significantly (P < 0.05). The occlusal interference disappeared in 4 patients and 1 patient with occlusal interference showed masticatory muscle symptom. The dynamic occlusion [from (1.25 ± 1.11), (0.84 ± 0.15), (0.52 ± 0.49) s to (0.35 ± 0.15), (0.36 ± 0.15), (0.33 ± 0.11) s] improved significantly (P < 0.05) in none occlusal interference group after retention and no statistical differences were found in the occlusal interference group (P > 0.05).

The overall dynamic occlusion improved after retention in patients with retainers. The presence of occlusal interference affected the self-improvement process and increased the chance of the disorders of stomatognathic system, such as mandibular abnormal movements. Therefore, functional occlusion evaluation and final detailing were needed before appliance removal.