EFFECTS OF A MYOFUNCTIONAL APPLIANCE ON OROFACIAL MUSCLE-ACTIVITY ANDSTRUCTURES

The aim of the study was to examine the effect of an oral shield treat ment on orofacial muscle activity and facial morphology in children wi th lip and/or tongue dysfunction. The sample consisted of 7 girls and 2 boys, 7 to 12 years old. EMG recordings with and without the shield in situ were obtained when the shield was placed, and 3, 6, and 12 mon ths later. Lateral cephalograms were obtained at the initial and 1-yea r stages. The lip muscles showed dominant activity when the subjects w e re sucking on an empty straw and during swallowing; this was stronge st during the fi rst 3 months. The mentalis, buccinator, and digastric muscles generally showed weaker activity. The anterior temporal muscl e showed dominant activity during maximal clench, but after the 3-mont h stage a significant decrease was noted. After 1 year of treatment, n o significant changes in overjet or overbite were observed. Most of th e craniofacial growth changes were normal for the age group. The resul ts indicate that treatment with an oral shield caused a decrease in or ofacial muscle activity during oral fu notions. Although there was a s light average retraction of the maxillary incisors, the change in posi tion was not statistically significant.