The dependence of mandibular dysfunction in children on functional and morphologic malocclusion.

The influence of dental status, occlusal interference, occlusal anomalies, and general background variables on bruxism and subjective symptoms and clinical signs of mandibular dysfunction has been studied in children. Three samples of children, aged 7, 11, and 15 years, were included. The interrelations were analyzed by rank-correlation and stepwise multiple regression. In the rank-correlation analyses, dental wear and age were significantly correlated to all of the dysfunction variables. Bruxism (reported by the subjects) was not found to be significantly correlated to any of the independent variables in the regression analysis. Subjective symptoms of dysfunction could be explained to a small extent by the independent variables, of which dental wear and sucking habits were found to be the most important. Recurrent headache was, to a certain extent, dependent upon age and sex. TMJ clicking was positively correlated with dental wear and unilateral contact in the retruded contact position but was most influenced by age and sex; TMJ clicking increased with age and was more common in girls than in boys. The clinical dysfunction index of Helkimo and tenderness of the masticatory muscles on palpation were explainable, although to a minor degree, by the influence of a combination of age, occlusal interference, motor activity, and psychological factors. Functional malocclusion (occlusal interference) is more important than morphologic malocclusion in explaining the existence of mandibular dysfunction. Nevertheless, morphologic malocclusion such as Class II and Class III occlusion, frontal open-bite, and cross-bite, when associated with functional malocclusion, may create a predisposition to mandibular dysfunction. The study confirms the multifactorial etiology of mandibular dysfunction.