Orthodontic treatment following orthognathic surgery: how long does it take and why? A retrospective study.

PURPOSE: This study was conducted to examine the duration of postoperative orthodontic treatment of patients who underwent combined orthodontic and orthognathic treatment and investigate factors that might influence this, to assess the strength of association between preoperative and postoperative orthodontic treatment duration, and to perform a retrospective power calculation to assess the likelihood of this study detecting a clinically significant (weeks) difference. PATIENTS AND METHODS: Records of patients who had undergone combined orthodontic and orthognathic treatment between 1998 and 2003 (n = 69) were obtained from 3 consultant orthodontists at 3 major hospitals in Leeds, UK. The duration of postoperative orthodontic treatment was calculated as the date of the operation to the date of fixed appliance removal. Variables investigated included patient age and gender, malocclusion, type of operation, presence of open bite, extractions (excluding third molars), hospital, operator, missed appointments/breakages and debonding, and retainer arrangements.
RESULTS: The median duration of postoperative treatment was 7.5 months (range, 5 to 11 months). None of the variables clearly affected this duration; no correlation was found between preoperative and postoperative treatment times (r(s) = -.07; P > .05). A retrospective power calculation demonstrated a 57.5% likelihood of this study detecting a difference of 8 weeks between 2 groups.
CONCLUSIONS: Patients should be informed that the postoperative orthodontic phase of combined orthognathic-orthodontic treatment may last approximately 5 to 11 months. No association was found between preoperative and postoperative treatment duration. Many more patients will have to be recruited to assess whether specific variables result in a clinically significant difference in treatment duration.