OBJECTIVETo study the effects of transection of inferior alveolar nerve (IAN) on the healing of mandibular fracture by investigating the changes of inflammatory factors expression, including tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1) and interleukin-6 (IL-6) in the denervated rabbits' bony callus.

METHODS50 Chinese rabbits were randomly divided into the experimental group and control group, the experimental group underwent mandibular fracture and transection of IAN and the control group underwent mandibular fracture only. The bony callus were collected at 1, 2, 3, 5 and 7 d after operation, respectively. The expression of TNF-alpha, IL-1 and IL-6 in callus was detected by enzyme linked immunosorbent assay (ELISA), and the mRNA of TNF-alpha was detected by reverse transcription-polymerase chain reaction(RT-PCR).

RESULTSIn the experimental group, at the 1st day after operation, the expression of TNF-alpha (75.1%), IL-1 (68.3%) and IL-6 (72.7%) was lower than that in control group (P < 0.05). At the 2nd day, the expression of IL-1 (75.5%) was still lower than that in control group, but the expression of TNF-alpha was higher than that in control group. In the next observation points, all inflammatory factors decreased, and there was no difference between experimental and control groups. In RT-PCR, the detection of TNF-alpha mRNA in the experimental group was lower than that in control group.

CONCLUSIONIn the haematoma of mandibular fracture healing, transection of IAN causes neurohumor decrease, depression and delay of inflammatory reaction. It is unfavorable to fracture healing.