Reverse chewing patterns in patients with bilateral posterior crossbite are related to the occlusal features of the malocclusion

Background: Bilateral posterior crossbite (BPXB) is a severe malocclusion associated with maxillary hypoplasia. BPXB may involve the same or a different number of teeth between the sides. Objectives: To evaluate the masticatory function in BPXB and the association between the masticatory alterations and the occlusal features of BPXB. Methods: This observational study included 170 participants: 130 patients with BPXB (65 occlusally symmetric BPXB, i.e. same number and type of posterior teeth in crossbite between the sides, F = 33, M = 32, median age 9.6 (8.2-13) [years.months]; 65 patients occlusally asymmetric BPXB, F = 30, M = 35, median age 9.9 (8.3-13.6)) and 40 controls (F = 25, M = 15, median age 10.2 (9.4-11.6)). The masticatory function was evaluated by the detection of the Reverse Chewing Cycles (RCCs) recorded with a kinesiograph using standardised soft and hard boluses. Results: The frequency of RCCs was significantly increased in all BPXB patients compared to controls (p < .000). In symmetric BPXB patients, there were no significant differences in the frequency of RCCs during chewing on the left or the right side. In asymmetric BPXB patients, the frequency of RCCs was significantly increased during chewing on the side with relatively more teeth in crossbite (p < .000). Conclusions: The masticatory function was significantly altered in all BPXB patients and it was differently affected by symmetric or asymmetric occlusal features of the malocclusion.