Bite force, facial morphology and sucking habits in posterior crossbite

Objectives: Posterior crossbite is a frequent malocclusion in childhood, and the recognition of its possible aetiologies and consequences for the growth and development of craniofacial structures is important in paediatric dentistry. The aims of this study were to evaluate the influence of sucking habits on the presence of functional crossbite and its relation with bite force, facial morphology and body variables, in the deciduous and early mixed dentition. Methods: Sixty-seven children of both genders (aged 3.5-7 years) were divided in four groups: deciduous-normocclusion (DecN Group), deciduous-crossbite (DecCross Group), mixed-normocclusion (MixN Group), and mixed-crossbite (MixCross Group). Facial morphology and asymmetry were determined by frontal photographs: AFH (anterior face height), BFW (bizygomatic facial width), and FAA (facial asymmetry angle). Results: The results showed that MixCross Group presented lower bite force than MixN Group, and AFH/BFW was significantly smaller in DecN than DecCross groups (unpaired t-test). Fisher's exact test showed significant association between sucking habits and crossbite in both stages of the dentition. FAA did not show difference between the groups and weight and height were only significant correlated with bite force in DecCross Group (Pearson correlation test, p<0.05). In the deciduous dentition, AFH/BFW and breast-feeding were positive and negatively associated with crossbite, respectively (multiple logistic regression, p<0.05). In the mixed dentition, breast-feeding and bite force showed negative association (univariate logistic regression, p<0.05), while nonnutritive sucking was a potential predictor of crossbite in all groups (multiple logistic regression, p<0.05). Conclusions: In the studied sample, sucking habits played an important role in the etiology of crossbite, which was associated with lower bite force and long-face tendency.