[Objective evaluation of the masseter and temporal muscles in treatment of Class III occlusion with the monoblock....

On ten patients, aged four to 12, with class III functional occlusion, simultaneous electromyographic activity in the masseter and temporal muscles, under conditions of centric occlusion and maximal voluntary contraction, was recorded for 30 seconds. Recording of electromyographic activity was repeated 15 days after initiating treatment with a monoblock device. Results show a lowering of the electrical activity of the aforementioned muscles and, indirectly, of their mechanical capacity during contraction, which may be due to a distention of seid muscles by action of the monoblock. We hereby postulate that, in the muscles under study, a larger previous length results in a lower force of contraction, and such conditions pose a risk of muscular insufficiency.