Maximum voluntary molar bite force in subjects with normal occlusion.

The aims of this investigation were to determine whether stabilization of maximum voluntary bite force (MVBF) occurs between 15 and 18 years of age in subjects with a normal occlusion, and to assess the influence of gender, body mass index (BMI), morphological occlusion, and jaw function measured by the number of occlusal contacts, overjet, overbite, maximal mouth opening, mandibular deflection during opening, sagittal slide between the retruded contact position and the intercuspal position, and number of dental restorations. The sample comprised 60 Caucasian subjects aged 15 (15 males and 15 females) and 18 (14 males and 16 females) years with a neutral occlusion, balanced facial profile, and absence of a previous orthodontic history. Bite force measurements were undertaken using a portable occlusal force gauge on both the left and the right sides of the jaw in the first molar region during maximal clenching. Two independent samples t-tests and multiple regression were used for statistical analysis. MVBFs were age and gender related (P<0.05). Males showed a significant increase in bite force between 15 and 18 years of age (P=0.002), but gender differences were significant only in the 18-year-olds (P=0.003). In subjects with a neutral occlusion, MVBF could best be predicted using multiple regression from age and gender. The regression model accounted for 31.3 percent of the variance in MVBF (P=0.031), with gender contributing 17.9 percent and age 7.9 percent. Morphological occlusion, jaw function, and BMI explained the remaining 5.5 percent of variance. While controlling for all other parameters, the independent contribution of gender to the prediction of MVBF was 16.2 percent, age 6 percent, number of occlusal contacts 3.2 percent, and BMI 1.3 percent.