Functional treatment of bilateral posterior crossbite improves mandibular kinematics during chewing

Objectives: To evaluate the effects of treatment of bilateral posterior crossbite (BPXB) on mandibular kinematics by the percentage of reverse chewing cycles (RCCs) during soft and hard bolus chewing before and after the correction of the malocclusion with function-generating bite (FGB). Materials and methods: This prospective study included 71 subjects: 19 patients with occlusally symmetric BPXB (M = 9; F = 10; mean age 9.3 +/- 2.2[yr.mo]), 32 patients with occlusally asymmetric BPXB (19 with more teeth in crossbite on the right side (right prevalent side), M = 7; F = 12; mean age 8.2 +/- 1.6 [yr.mo] and 13 on the left side, M = 7; F = 6; mean age 9.6 +/- 1.9 [yr.mo]) and 20 controls without malocclusion (M = 8; F = 12; mean age 10.2 +/- 1.7 [yr.mo]). Masticatory patterns were recorded before (T0) and after (T1) the correction of the malocclusion with FGB, with the K7-I (R) kinesiograph using standardized soft and hard boluses. Results: BPXB was corrected in all included patients. At T0, the percentage of RCCs in BPXB was significantly increased compared to controls (P < .0001); symmetric BPXB showed no difference in RCCs between the sides, whereas asymmetric BPXB showed significantly more RCCs on the side with more teeth in crossbite (prevalent side). After treatment with FGB (T1), the percentage of RCCs was significantly reduced in both symmetric BPXB patients (soft bolus, P = .003; hard bolus, P < .001) and asymmetric BPXB patients (prevalent side: soft and hard bolus, P < .00001; non-prevalent side: soft bolus, P = .01 and hard bolus, P = .0002). Conclusion: Functional correction of BPXB with FGB significantly improved mandibular kinematics during chewing.