PATIENTS AND METHODS: This international, multicenter randomized controlled trial included adults with bilateral mandibular fractures located at either the angle and body, angle and symphysis, or body and symphysis. Patients were treated with either a combination of rigid fixation for the anterior fracture and nonrigid fixation for the posterior fracture (mixed fixation) or nonrigid fixation for both fractures. The primary outcome was complications within 6 weeks after surgery. Secondary outcomes were complications within 3 months, Helkimo dysfunction index, and mandibular mobility at 6 weeks and 3 months after surgery.

RESULTS: Of the 315 patients enrolled, 158 were randomized to the mixed fixation group and 157 to the nonrigid fixation group. The overall complication rate at 6 weeks in the intention-to-treat population was 9.6% (95% confidence interval [CI], 5.3% to 15.6%) in the mixed fixation group and 7.8% (95% CI, 4.0% to 13.5%) in the nonrigid fixation group. With an unadjusted odds ratio of 1.25 (95% CI, 0.51 to 3.17), there were no statistically significant differences in complication rates between the 2 groups (P = .591). A multivariable model for complication risk at 6 weeks found no significant differences between treatment groups, but patients with moderate or severe displacement had a higher complication rate than those with no or minimal displacement (adjusted odds ratio, 4.58; 95% CI, 1.16 to 18.06; P = .030). There were no significant between-group differences in complication rates at 3 months. Moreover, no significant differences in Helkimo dysfunction index and mandibular mobility index at 6 weeks and 3 months were found between groups according to treatment allocated and treatment received.