| The purpose of this study was to investigate the effect of an intermittent bite registration appliance (Frankel) on the temporomandibular joint architecture and electromyographic activity of the masticatory muscles and compare them to the effect of a continuous bite registration appliance (Herbst).;The sample consisted of 6 female juvenile and 1 male adult cynomologus (Macaca fascicularis) monkeys.;After a 12-week experimental period the following changes were observed. Both the modified Frankel and Herbst appliance appeared to be associated with an increased condylar growth response which however was greater in the animals wearing the Herbst appliances. The animals wearing the Herbst appliance also showed greater mandibular length increases, greater dento-alveolar changes than those wearing the modified Frankel appliance. However, when the total skeletal correction was assessed similar results were observed. The postural electromyographic activity of the 4 muscles analyzed decreased (p $<$ 0.05) after the insertion of either type of appliance. The functional electromyographic activity reported only in the animals wearing the modified Frankel also decreased (p $<$ 0.05) after the activation of the appliance. Thus, the cephalometric changes in the mandibular condyle with either type of appliance could not be the result of increased muscle activity. (Abstract shortened by UMI.). |
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