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.

Conclusions:

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  IAN injury occurs more commonly in posterior fractures.

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  More severe IAN injury with ORIF may be from treating more severe fractures with ORIF and intraoperative IAN manipulation.

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  Posterior mandibular fracture gaps of ≥5 mm have greater likelihood of IAN dysfunction.

Conflict of interest: None declared.