The use of patient-controlled transcutaneous electronic nerve stimulation (TENS) to decrease the discomfort of regional anaesthesia in dentistry: a randomised controlled clinical trial

Objective: To compare the use of topical anaesthesia and transcutaneous electronic nerve stimulation (TENS) as means of reducing the discomfort of inferior dental block injections. Methods: One hundred adult dental patients received 2% lignocaine with 1:80000 adrenaline for long buccal and inferior dental block anaesthesia. The long buccal injections were given first with no prior mucosal preparation. Patients received inferior dental blocks after one of the following mucosal preparations: (1) no pretreatment; (2) a 2 min application of 20% benzocaine topical anaesthetic; (3) application of patient-controlled TENS at the injection site. Patients scored injection discomfort after each administration on a 100 mm visual analogue scale. Results: The discomfort of the long buccal injection did not differ between the three groups of patients (F2,97 = 1.0). There were significant differences in the pain scores for the inferior dental block injections (F2,97 = 5.3; p < 0.01). Injection discomfort following TENS was less than that following no pretreatment (p < 0.01) and after topical anaesthetic application (p < 0.05). The use of topical anaesthesia did not produce a significant change in injection discomfort compared with no pretreatment. Conclusion: The use of TENS reduces injection discomfort during inferior dental block anaesthesia.