Consideration of effect of the amount of mandibular setback on the submental region in the planning of orthodontic-orthognathic treatment

Abstract

Aesthetic outcome has gained in importance in the treatment of patients with orthognathic problems. Historically, Class III malocclusions have historically been treated by isolated mandibular setback and maxillary advancement, whereas bimaxillary procedures have recently become the more common option. Functional outcome and stability have been discussed previously. The aim of this observational study was to evaluate the effect of mandibular setback (BSSO) on the cervical region. We studied 38 Class III patients (20 women and 18 men, mean (SD) age 25 (0.8) years) who we identified from our clinical records and who were treated between 1 January 2002 and 30 December 2012 with mandibular setback procedures and followed up for 6 months. To study the effect of the amount of mandibular setback on the aesthetic outcome we have distinguished between patients with less than 5mm setback and those with 5mm or more. In patients whose mandibular setback was less than 5mm there was no significant change in cervical length. However, it decreased significantly in patients in whom the movement was 5mm or more. Postoperatively the lip-chin-throat angle (p=0.02), the length of the lower lip (p=0.002), and the length of the upper lip (p=0.003) from the aesthetic line also differed significantly between the 2 groups. Our observations strongly suggest that all these relations should be considered when treatment is being planned to avoid an unpleasant aesthetic impact on the chin region.

Keywords: Mandibular setback; Orthodontic and orthognathic treatment; Submental region.