MASTICATORY MUSCLE PAIN BEFORE, DURING AND AFTER TREATMENT WITH ORTHOPEDIC PROTRACTION HEADGEAR - A PILOT-STUDY

Protraction headgear has been used in conjunction with a palatal expan sion appliance to correct Class III malocclusion with maxillary defici ency and/or mandibular prognathism. In general, 800 gm of orthopedic f orce is used to protract the maxilla, and 75% of this force is transmi tted to the temporomandibular joint (TMJ) area via the mandible. The e ffect of this heavy intermittent force on the TMJ has not been reporte d in the literature. The objectives of this study were to determine th e level of masticatory muscle pain and EMG activity in patients treate d with maxillary protraction headgear. Ten patients with skeletal Clas s III malocclusion whose treatment plan called for maxillary protracti on headgear treatment participated in this study. Nocturnal masticator y muscle activity was determined using a portable electromyographic (E MG) recording device. Subjects wore the EMG device 14 nights before tr eatment, 14 nights during treatment, and 14 nights 1 month after activ e treatment. Masticatory muscle pain level was determined by muscle pa lpation, scored on a scale of 0 to 3 each period, according to the met hod of Gross and Gale. The examiner followed a sequence outlined by Bu rch to examine the masticatory muscles. Results showed no significant differences for masticatory muscle activities before, during, and afte r treatment. Only a few patients experienced level 1 masticatory pain during treatment. None of the patients experienced masticatory muscle pain 1 month after treatment. These results demonstrate no significant increase in masticatory muscle activity or muscle pain associated wit h orthopedic treatment using maxillary protraction headgear.