Local anesthesia does not block mustard-oil-induced temporomandibular inflammation.
Temporomandibular joint (TMJ) disorders and rheumatoid arthritis are two conditions in which neurogenic mechanisms may play a critical role. We investigated the neurogenic contribution underlying acute TMJ inflammation by evaluating effects of local anesthetic blockade of afferent innervation on the development of mustard oil (MO)-induced edema in the rat TMJ area. Groups of eight adult male Sprague-Dawley rats were anesthetized by intraperitoneal alpha-chloralose and urethane. A saline injection into the right TMJ followed by MO (1% to 60%) 6 min later elicited dose-dependent edema development (P < 0.05, repeated measures analysis of variance). Lidocaine (5%) or bupivacaine (0.5%) followed by MO (1% or 40%) did not produce edema development different from saline controls (P > 0.05, repeated measures analysis of variance). The failure of local anesthetic blockade to prevent MO-induced edema is not consistent with MO acting through a neurogenic mechanism, as traditionally perceived.


CONCLUSIONS
Inflammation found in temporomandibular disorders and rheumatoid arthritis may result from mediators released by pain-sensing neurons. Local anesthesia failed to block simulated neurogenic temporomandibular inflammation in a rat model, suggesting that functional neuronal input may not be necessary for the promotion of inflammation.
Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
J K
JK
Wong
D A
DA
Haas
J W
JW
Hu
D000779:Anesthetics, Local / Q000627:therapeutic use*; D000818:Animals; D001168:Arthritis / Q000139:chemically induced / Q000517:prevention & control*; D002045:Bupivacaine / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004487:Edema / Q000139:chemically induced / Q000473:pathology; D004576:Electromyography; D008012:Lidocaine / Q000627:therapeutic use*; D008297:Male; D008406:Masseter Muscle / Q000187:drug effects / Q000503:physiopathology; D009149:Mustard Plant; D010936:Plant Extracts; D010938:Plant Oils; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects; D013705:Temporomandibular Joint Disorders / Q000139:chemically induced / Q000517:prevention & control*
D000779:Anesthetics, Local; D010936:Plant Extracts; D010938:Plant Oils; D008012:Lidocaine; C027793:mustard oil; D002045:Bupivacaine