Methods: We evaluated 66 characteristics related to TMD as well as MIR from the charts of 250 subjects [56 male/202 female, 31.18 (±14.23) years]. Electromyography of right and left masseter muscles were recorded using our refleximeter (Refleximetro ® UNAM). The inhibitory reflex was elicited by tapping the chin with an electromagnetic hammer. 20 series of records were obtained from each patient and averaged. The faulty inhibitory area, right and left relation potentiation /inhibition and the bilateral reflex symmetry were measured. To identify the functional patterns, conglomerates of MIR variables were used. For the association of the functional patterns and clinical characteristics ANOVA or χ2 were used.
Three functional patterns were found with differential characteristics and alteration in MIR associated with clinical variables such as range of opening/close, TMJ pain with palpation and function, pain in temporalis and pterigoids muscles, joint noises at opening /close and lateral excursions; absent posterior teeth and work/balance contacts. (P<0.01)
The amplitude of MIR is reduced and altered in presence of dysfunction. Three functional patterns were identified in MIR presenting significant association with TMD suggesting that the MIR may be less protective in patients with TMD.
Keywords: Malocclusion, Mastication, Muscle, Neuroscience and TMJ and masticatory muscles