Effects of lesions to the trigeminal motor nucleus on temporomandibular disc morphology.

Stereotaxic surgery was performed on the trigeminal motor nuclei (TMNu) of 47 actively growing rats in order to test the effects of neuromuscular alterations on TMJ disc morphology. Lesioned animals received a small electrolytic lesion to their left-side TMNu, while shams had their TMNu stimulated without an actual lesion being produced. Both lesioned and sham-lesioned animals demonstrated significant (P less than 0.05; P less than 0.01) morphological alterations of their discs 28, 56, and 84 days postoperatively. Data indicated that (i) TMNu lesions do indeed affect disc morphology, and (ii) even subtle damage to trigeminal motoneurones can influence TMJ disc morphology. It is therefore suggested that at least some TMJ disease processes have a neuromuscular basis.