DesignMulticentre, randomised controlled clinical trial.InterventionPatients referred for third molar removal received a digital panoramic radiograph(PR). Adults with one or more lower third molars in a close relationship with the mandibular canal were eligible for the study. Patients randomised to the cone beam computed tomography (CBCT) group received a high resolution CBCT scan in addition to the PR. All lower third molar extractions were performed under local anaesthesia without sedation and without antibiotic prophylaxis. Information on variables such as experience of the surgeon, duration of surgery and technique for third molar removal were recorded.Outcome measureThe primary outcome measure was the number of patient-reported altered sensations one week after surgery. Secondary outcomes included the number of patients with an objective IAN injury; permanent IAN injury (>6 months); occurrence of other postoperative complications (wound infection, alveolar osteitis); Oral Health Related Quality of Life-14, questionnaire responses; pain (VAS score); duration of surgery; number of emergency visits; and number of missed days of work or study.ResultsThree hundred and forty-one patients with 477 lower third molars were randomised from three centres. Two hundred and sixty-eight patients with 320 mandibular third molars were analysed according to the intention-to-treat principle for the primary and secondary outcomes. The overall incidence of patient-reported altered sensations one week after surgery was 6.3%. At one week there was no difference in subjective IAN injury between the CBCT and PR group. No significant differences were noted between the two groups for any of the secondary outcomes recorded.ConclusionsAlthough CBCT is a valuable diagnostic adjunct for identification of an increased risk for IAN injury, the use of CBCT does not translate into a reduction of IAN injury and other postoperative complications, after removal of the complete mandibular third molar. In these selected cases with a high risk for IAN injury, an alternative strategy, such as monitoring or a coronectomy, might be more appropriate.