Evaluation of mandibular condylar and ramal asymmetry in unilateral posterior crossbite before and after functional treatment with FGB

Aim: this study aimed to evaluate the effects of unilateral posterior crossbite (UPXB) treatment with the appliance Function Generating Bite (FGB) on the asymmetry of mandibular condyles and rami. Methods: this retrospective study included 156 subjects: 52 patients with UPXB (F = 30, M = 22, mean age±SD = 7.9±1.5 [yr.mo]) treated with FGB, 104 age and gender-matched control subjects without the malocclusion (control – T0: N = 52, F = 30, M = 22, mean age±SD = 8.2±1.3; control – T1, N = 52, F = 30, M = 22, mean age±SD = 9.7±1.2). The asymmetry index of mandibular condyles and rami was evaluated on pre- (T0) and post-treatment (T1) orthopantomographies by measuring the height of the outlines of the condyles and rami and computing the percentage difference between the sides, following the method proposed by Habets et al. (1988). Results: before treatment (T0), the asymmetry indexes of condyles and rami were significantly increased in UPXB patients compared to controls (p <0.0001 and p <0.01, respectively). After treatment with FGB (T1), there was no significant difference between the groups’ asymmetry indexes of condyles and rami. The condylar asymmetry index in UPXB patients also showed a significant improvement between T0 and T1 (p <0.01), i.e., it was significantly reduced. Conclusions: functional treatment of UPXB with FGB was associated with a significant improvement in condylar asymmetry, indicating a rebalancing of mandibular growth in these growing patients.