AN EVALUATION OF THE EFFECT OF RESIDUAL OVERJET ON THE STABILITY OF MAXILLARY ANTERIOR ALIGNMENT FOLLOWING FIXED APPLIANCE-BASED ORTHODONTIC TREATMENT

Aim To compare the post-treatment stability of maxillary anterior alignment in subjects treated either to a Class I incisor relationship (2-4mm) or an overjet in excess of 4mm following fixed appliance-based orthodontic treatment. Materials and Methods A case-control study was undertaken in the Orthodontic Department at the Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London. Recruitment took place over a 4-year period (February 2017 to September 2021). The stability of the maxillary anterior teeth was assessed with two indices: Little’s Irregularity Index (LII) and the novel Orthodontic Alignment Index (OAI). Results Eighty-two participants were included in the analysis. A positive correlation was observed between LII and OAI at the 12-month post-treatment review; a 1mm increase in LII was associated with an increase of 2.01 units of OAI (P4mm) and the alignment of the maxillary anterior segment when assessed with OAI (P=0.389) and LII (P=0.577). Furthermore, age, gender, extraction protocols and retention regime were not predictive of post-treatment change. Conclusions There was limited post-treatment relapse in alignment of the upper labial segment in both groups over a 12-month period. The degree of post-treatment change was independent of the magnitude of overjet at the end of treatment. On the basis of this retrospective evaluation, the attainment of a normal overjet at the end of treatment may have no influence on the post-treatment stability at 12 months