[Masticatory movements in cleft lip and palate patients with unilateral buccal cross-bite. The effect of different buccal overlap on pattern of chewing].

Most of unilateral cleft lip and palate patients are accompanied with cross-bite in minor segment. The purpose of this study is to investigate the effect of different buccal overlap on the chewing pattern. Three unilateral cleft lip and palate patients were selected, and 2 different experimental crowns, which were the normal crown with 2 mm horizontal overlap and the cross-bite crown with -2 mm, were fabricated for each subject. The mandibular movement of chewing peanuts was recorded with the MKG. Patterns of chewing cycle in the frontal view, namely the normal pattern, the upper crossed, the lower crossed, the reversed, the contra-lateral and the others were counted in number. And also, the time of chewing cycle was analyzed. The findings were as follows; 1. With the normal crown, the normal patterns were seen more in number, whereas the reversed patterns were seen more with the cross-bite crown. 2. With the normal crown, the value of the lateral component of the chewing cycle was larger than that with the cross-bite crown. 3. With the normal crown, the value of the coefficient of variation in the time of chewing cycle was smaller than that with the cross-bite crown.