Objective: To determine the incidence and severity of inferior alveolar nerve (IAN) injury in mandible fractures before and after treatment.
Methods: Consenting patients with mandibular fractures (excluding dentoalveolar, pathologic, previous fractures or mandibular surgery) were prospectively evaluated for subjective neurosensory disturbance (NSD) and underwent neurosensory testing (NST) before treatment, then 1 week, 1.5, 3, 6 and 12 months after treatment.
Results: Seventy-three patients with 114 fracture sides (41 bilateral) were studied; 83.6% were male; mean age was 29.2 years (SD 12.5). Injury etiology included violence (37.0%), falls (27.4%), motor vehicle accidents (26.0%) and sports injuries (6.8%). Half (52.6%) of fractures involved the IAN-bearing posterior mandible; all condylar fractures (12.3%) had no NSD. Treatment included open reduction and internal fixation [ORIF] (76.3%), closed reduction and fixation (21.9%) or no treatment (1.8%). ORIF cases had 43.7% NSD with 18.3% abnormal NST results postoperatively.
Of 40 anterior fractures, 17.5% had NSD only; after treatment, 40.0% had NSD with 17.5% abnormal NST. Of 60 posterior fractures, 55.0% had NSD with 28.3% abnormal NST (64.7% had a fracture gap ≥5 mm). After treatment, 71.7% had NSD with 58.3% abnormal NST. Significant IAN injury indicated by severe sensory impairment 3 months postoperatively, occurred in 0–2.5% of anterior and 1.7–10.0% of posterior fractures.
IAN injury occurs more commonly in posterior fractures.
More severe IAN injury with ORIF may be from treating more severe fractures with ORIF and intraoperative IAN manipulation.
Posterior mandibular fracture gaps of ≥5 mm have greater likelihood of IAN dysfunction.
Conflict of interest: None declared.