The Effect of Head Position on Electromyographic Evaluations of Representative Mandibular Positioning Muscle Groups

Studies have shown that movements of the head, which are controlled by the suboccipital region of the spine, change the rest position of the mandible and stomatognathic system. The importance of head positioning at the time of specific dental procedures, such as recording the bite registration for restorative procedures or equilibration of occlusal prematurities, has been questioned by the dental clinicians and in the dental literature. Since patients with craniocervical dysfunction often present with anterior head posture, the failure to recognize and treat the craniocervical dysfunction in conjunction with craniomandibular therapy often results in relapse of the “rehabilitated” patient. The effect of head position as related to the relative activity of the mandibular positioning muscles should be determined in order to clarify the significance of head position during specific restorative dental procedures and craniomandibular therapy.The purpose of this study is to evaluate electromyographic activity of certain representative mandibular positioning muscles (i.e., anterior temporalis, middle masseter, and anterior digastric muscles) as the head is deliberately positioned anteroposteriorly at the occipital-atlan-toaxial complex.