Sensory abnormalities associated with mandibular fractures: incidence and natural history

The aims of this study were to determine the incidence of inferior alveolar nerve (IAN) abnormalities in patients with mandibular fractures and to document the natural history and spontaneous recovery rate in patients with a sensory disturbance.

This was a retrospective evaluation of patients (n = 150) with mandibular fractures at risk for IAN injury admitted to the Oral and Maxillofacial Surgery Service between 1985 and 1995. The inclusion criteria were: 1) fractures between the mandibular and mental foramina, 2) availability of the results of a post-injury, preoperative sensory examination, and 3) at least 1 year follow-up. Fracture characteristics, physical examination findings, hospital course, operative treatment, and follow-up were documented. Patient interviews were conducted to determine the incidence of long-term sensory disturbance and associated morbidity. The results were evaluated with chi-square analysis.

Fifty-six percent of patients (84 of 150) had a post-injury/pretreatment IAN abnormality. Patients with sensory disturbance had a significantly higher frequency of displaced fractures than those without sensory disturbance (P < .001). Sixteen of 24 patients (66.7%) with an abnormal post-injury/ pretreatment sensory examination reported a permanent sensory deficit (mean follow-up, 74.3 months); 55% of these patients complained of impairment.

The incidence of postinjury IAN deficits in patients with mandibular fractures was greater than 50% and was related to fracture displacement. One third of these patients regained normal sensation; the remaining two thirds reported a persistent sensory deficit. A significant number of these patients complained of discomfort and impairment after a mean follow-up of greater than 6 years.