Introduction: The goal of mandibular fracture treatment is to restore static and dynamic occlusal functions. Open reduction and internal fixation (ORIF) of these fractures can be associated with an intraoperative and/or postoperative maxillo-mandibular fixation (MMF). The aim of this study was to analyse the use of perioperative MMF and its effects on occlusal outcomes in the management of mandibular fractures.

Material and methods: This multicentric prospective study included adult patients with mandibular fractures treated with ORIF. The following data were collected: age, gender, pre-trauma dental status (dentate, partially dentate), cause of injury, fracture site, associated facial fractures, surgical approach, type of ORIF (rigid, non-rigid or mixed), thickness and number of plates, modality of intraoperative MMF (arch bars, self-tapping and self-drilling screws [STSDSs], manual, other) and duration of postoperative MMF. The primary outcome was malocclusion at 6 weeks and 3 months. Statistical analyses were performed with Fisher's exact test or chi-square test, as appropriate.

Results: Between 1 May 2021 and 30 April 2022, 336 patients, 264 males and 72 females (median age, 28 years) with mandibular fractures (194 single, 124 double and 18 triple fractures) were hospitalized. Intraoperative MMF was performed in all patients. Osteosynthesis was rigid in 75% of single fractures, and rigid or mixed in 85% and 100% of double and triple fractures, respectively. Excluding patients who underwent manual reduction, postoperative MMF (median duration, 3 weeks) was performed in 140 (64%) patients, without differences by type or number of fractures (p > 0.05). No significant difference was found in the incidence of malocclusion in patients with postoperative MMF (5%, 95% confidence interval [CI], 2-10%) compared to those without (4%; 95% IC, 1-11%) (p > 0.05).

Conclusion: Postoperative MMF was performed in more than half of the patients despite adequate fracture osteosynthesis, with wide variability among centers. No evidence of a reduction in the incidence of postoperative malocclusion in patients treated with postoperative MMF was found.