PURPOSE

Developing a valid noninvasive animal model to study temporomandibular joint (TMJ) inflammation/pain has proved difficult. However, its has been recently demonstrated that meal pattern analysis, and in particular meal duration, can be used as a biologic marker for TMJ inflammation/pain induced by bilateral injections of complete Freund's adjuvant (CFA). The present study was undertaken to confirm previous findings and extend them by using rofecoxib (VIOXX; Merck and Co, West Point, PA), a selective cyclooxygenase-2 inhibitor (COX-2-I).

MATERIALS AND METHODS

Forty-eight male rats were assigned to 1 of 4 groups: group 1, no CFA and no COX-2-I treatment; group 2, no CFA and treatment with the COX-2-I; group 3, bilateral TMJ CFA injection and no COX-2-I treatment; and group 4, CFA injection and treatment with the COX-2-I. Food intake was recorded by computer 24 hours before and for 48 hours after CFA injection. TMJ swelling, chromodacryorrhea, and meal patterns were quantified.

RESULTS

CFA increased swelling (P <.05), chromodaccryorrhea (P <.05), meal duration at 24 and 48 hours, and TMJ retrodiscal tissue interleukin-1beta (P < 0.01) in group 3, but treatment with the COX-2-I attenuated these effects in group 4, (CFA + COX-2-I).

CONCLUSIONS

These data confirm that meal pattern analysis, and in particular meal duration, is a noninvasive measure of TMJ inflammation/pain. However, this experiment has extended this model as a marker of drug treatment efficacy, specifically the efficacy of COX-2-I in treatment of orofacial inflammation/pain.