Effect of occlusal adjustment on post-orthodontic relapse in extraction cases: a randomized clinical trial.

Abstract

Objectives: Maintaining post-treatment occlusal stability remains a major challenge in orthodontics. Premature occlusal contacts may contribute to relapse. This study aimed to evaluate the effect of selective occlusal adjustment on relapse six months after debonding.

Materials and methods: Thirty Class I patients (17-28 years) with severe crowding, treated with fixed appliances and extraction of first premolars, were randomly assigned to an intervention group (occlusal adjustment one month after debonding) and a control group (no adjustment). Relapse was assessed on dental casts immediately post-debonding and six months later, measuring inter-canine width, intermolar width, arch length, and Modified Little's Irregularity Index. Data were analyzed using independent and paired t-tests, Mann-Whitney, Wilcoxon, and chi-square tests (α = 0.05).

Results: This study demonstrated that after occlusal adjustment, the maxilla showed significant increases in intermolar width, intercanine width, and arch Circumference compared with the controls after six months post-debonding (p = 0.009, 0.011, 0.041). In the mandible, the changes in intermolar width and arch Circumference were significantly greater than those in the control group (p = 0.037 and p = 0.010, respectively), and the irregularity index in the intervention group decreased in the maxilla and increased in the mandible compared to the control group; however, these changes were not significant in either arch.

Conclusion: Selective occlusal adjustment may enhance transverse arch stability after orthodontic treatment; however, its isolated effect on anterior alignment relapse remains inconclusive.