Influence of time after superior articular cavity anesthesia on pain evaluation in patients with temporomandibular disorders

Clinically, the location of pain in patients with temporomandibular disorders (TMD) is diagnosed by palpation and interview of the patient during mandibular movement. However, some patients cannot clearly indicate the location of the pain. Local anesthesia of the painful region described by the patient is often recommended to block nociceptors and to diagnose the source of pain. However, this method does not consider the time after anesthesia or infiltration of anesthesia into the surrounded tissue with the passage of time.Aims: The aim of this study was to investigate the influence of the time after superior joint cavity anesthesia on the evaluation of pain in patients with unilateral TMD who have both temporomandibular joint (TMJ) and musculature pain.Methods: Thirty-five patients (aged 14-75 years) who had TMD with unilateral TMJ and musculature pain were included. Lidocaine was injected directly into the superior cavity. A set of 13 tests was performed before anesthesia, and 1 and 5 minutes after anesthesia: 3 muscle palpation tests, 2 TMJ palpation tests, 6 comprehensive pain tests, and 2 other evaluations.Results: The pain of the muscle and TMJ significantly decreased in response to joint anesthesia. Joint anesthesia did not affect the results of muscle palpation tests in 14% to 39% of the patients, those of TMJ palpation tests in 29% to 36% of the patients, and those of comprehensive pain tests in 32% to 50% of the patients 1 minute after anesthesia. However, these tests showed no significant pain between 1 minute and 5 minutes after anesthesia except for two of the comprehensive pain tests (chin compression and the distance of mouth opening without pain). Numbness of the front of the pinna, used as an index of the infiltration of anesthetic into the surrounding TMJ, did not differ significantly between before anesthesia and 1 minute after anesthesia, but increased significantly 5 minutes after anesthesia.Conclusion: Tests designed to locate the source of pain in TMD by the direct injection of an anesthetic into the superior cavity should be carried out 1 minute after anesthesia, before the anesthetic has infiltrated into the surrounding tissue.