Chewing pattern before and after unilateral posterior cross-bite therapy with function generating bite: a case report.

Objectives: To evaluate the chewing-cycle closing direction of a patient with a posterior unilateral crossbite, before treatment, six months and one year after correcting the malocclusion with a function generating bite.

Methods And Materials: An 8-year-old girl with right unilateral posterior cross-bite was treated with a function generating bite, which corrected the cross-bite within 5 months. Mandibular movements during mastication of a soft and of a hard bolus were recorded before and after treatment with a K6 I kinesiograph (Myotronics Inc., Seattle, WA-USA).

Results: Initially, there was a marked prevalence of chewing cycles with a reverse direction of closure (92% for the soft bolus and 92% for the hard bolus) during mastication on the cross-bite side. Six months after correction, during mastication on the corrected side, the percentage of chewing cycles with reverse closure decreased to 2% for the soft and 0% for the hard bolus. This decrease was still evident one year after correction (0% for the soft bolus and 18% for the hard bolus). Mastication on the healthy side at all times presented cycles with normal closing direction.

Conclusions: Analysis of masticatory cycles recorded before and after orthodontic therapy showed that not only was anatomic correction achieved by the function generating bite, but also that masticatory function had regained equilibrium and symmetry and both were stable at least 1 year after the cross bite was corrected.