Improvement of masticatory kinematic parameters after correction of unilateral posterior crossbite: Reasons for functional retention.

Abstract

To evaluate reverse-sequencing chewing cycles (RSCC) and their kinematic parameters on both sides before and after correction with the Function Generating Bite (FGB) appliance. Forty-seven patients, 8.3 ± 1.1 (mean ± SD) years of age, with unilateral posterior crossbite (35 on the right side, 12 on the left side) and 18 age-matched controls (9.1 ± 0.8 years) were selected for the study from the orthodontic division of the University of Turin, Italy. The crossbite was corrected in all patients using FGB, and mandibular motion was recorded with a kinesiograph K-7 (Myotronics, Tukwila, Wash), during chewing on both sides of a soft and a hard bolus before and after correction. After correction, the percentage of RSCC significantly decreased for soft and hard (P < .001) boluses and fell within the normal range for 75% of the patients. The indices of the chewing pattern (closure angle, axis, maximum lateral excursion) significantly improved (P < .001), becoming symmetric between sides. The results of this study showed that the functional appliance, FGB, was able to lower the percentage of RSCC significantly, bringing them back to the normal range in 75% of cases, and to improve the kinematic parameters that become symmetric between sides.