Risk Factors and Interventional Predictors for Postoperative Malunion and Nonunion in Adult Mandibular Fractures: A Scoping Review.

Abstract

Mandibular fractures are one of the most commonly treated injuries in oral and maxillofacial surgery. While malocclusion has been well studied as a postoperative complication, malunion and nonunion remain comparatively unreported despite being significant complications associated with the healing of facial fractures. This scoping review aims to evaluate risk factors, predictors, surgical variables, and management strategies associated with postoperative malunion or nonunion in mandibular fractures. PubMed, Embase, Web of Science, and Google Scholar were searched for English-language studies published between 2000 and 2025. Eligible studies included prospective and retrospective clinical investigations evaluating malunion and nonunion following surgical or nonsurgical management of mandibular fractures. Systematic reviews, meta-analyses, case reports, pediatric studies, and non-English studies were excluded from this review. Extracted data included fracture location and complexity, treatment modality, fixation method, surgical approach, timing of intervention, and reported postoperative outcomes. Of 1,052 records initially identified, 13 studies met the inclusion criteria. Across study designs, open reduction and internal fixation (ORIF) was consistently associated with lower rates of malunion and nonunion compared with various closed reduction techniques, particularly in comminuted fractures. Delayed surgical intervention, most notably between 6 and 7 days from injury, was associated with increased rates of malunion and nonunion. Additional factors associated with increased complication rates included posterior mandibular fractures, fracture comminution, smoking and alcohol abuse, lack of patient education, and advanced patient age. In conclusion, available evidence suggests that timely ORIF with stable fixation constructs is associated with reduced rates of postoperative malunion/nonunion following mandibular fracture repair. Delayed intervention and inadequate postoperative education protocols are other risk factors and predictors that need to be considered to minimize potential complications.