An evaluation of the closed mouth mandibular block technique.

This randomised double-blind study compared the efficacy of the closed-mouth and the conventional mandibular block injection techniques in 200 patients requiring anaesthesia for tooth extractions. Results showed the success rate of inferior alveolar nerve anaesthesia with a single injection to be 97% in the conventional group, and 79% in the closed-mouth group. Within 5 min after the injection, 87% of the conventional group as compared with 55% of the closed-mouth group had lip numbness. The conventional and closed-mouth techniques, respectively, yielded 22% and 2% positive aspirations. Long buccal nerve anaesthesia during the closed-mouth injection was achieved in 71% of cases. Both techniques produced similar pain responses, as well as changes in blood pressure and pulse rate. The closed-mouth injection technique produced a greater variety of unexpected symptoms than the conventional. It was concluded that the conventional technique was more effective in blocking the inferior alveolar nerve, and was also faster in producing anaesthesia, but yielded more positive aspirations than the closed-mouth technique.