A split-mouth randomised controlled trial (RCT) was conducted in two university hospitals in Brazil.
Patients, referred for bilateral mandibular third molar removal, were randomly allocated to have the procedure performed either on one side (experimental group) with lingual flap retraction or the opposite side without (control group). The procedure was carried out under local or general anaesthesia. Local anaesthesia was also given to all patients under general anaesthesia. Ostectomy to remove buccal bone was performed in all cases, after the buccal flap was raised.
Sensory disturbance was evaluated after 24 h and on postoperative day 7 by an oral and maxillofacial surgeon who was blind to the operation procedure. A pin-prick test was used to confirm nerve injury and to classify the sensory disturbance (anaesthesia, hypoaesthesia, paraesthesia or dysaesthesia).
A total of 55 patients were recruited. The proportion of individuals with sensory disturbance was higher in those operated upon under general/ local anaesthesia (13.8%) than in patients operated upon under local anaesthesia only (3.8%), although the difference was not significant. Lingual nerve sensation disturbance occurred in 9.1% of the experimental group, whereas no cases were recorded in the control group. This difference was statistically significant (P<0.001) as measured by the Cochran test. Of five cases where sensory disturbance was registered, four were classified as paraesthesia and one as hypoaesthesia. All cases were classified as temporary disturbance because after 3 months after the operation there was spontaneous recovery.
Lingual nerve retraction represented a risk factor to temporary lingual nerve damage during mandibular third molar surgery.
Lingual nerve retraction should be avoided during surgical removal of mandibular third molar.