Molar bite force in relation to occlusion, craniofacial dimensions, and head posture in pre-orthodontic children.

The present study examined bite force in relation to occlusion, craniofacial dimensions, and head posture. The sample comprised 88 children (48 girls, 40 boys) aged 7-13 years, sequentially admitted for orthodontic treatment of malocclusions entiling health risks. Bite force was measured in the molar region by means of a pressure transducer. Angle classification, number of teeth and contact in the intercuspal position (ICP) were recorded and dental arch widths were measured on plaster casts. Craniofacial dimensions and head posture were recorded from lateral cephalometric radiographs taken with the subject standing with their head in a standardized posture (mirror position). Associations were assessed by Spearman correlations and multiple stepwise regression analyses.The maximum bite force increased significantly with age in girls, with teeth in occlusal contact in boys, and with increasing number of erupted teeth in both genders. Bite force did not vary significantly between the Angle malocclusion types. Only in boys was there a clear correlation between bite force and craniofacial morphology: cranial base length (n-ba, n-ar), posterior face height (s-tgo, ar-tgo), vertical jaw relationship (NL-ML), mandibular inclination (NSL-ML), form (ML-RL) and length (pg-tgo), and inclination of the lower incisors (Ili-ML). Multiple regression analysis showed that the vertical jaw relationship (P < 0.001) and the number of teeth present (P < 0.01) were the most important factors for the magnitude of bite force in boys. In girls, the most important factor was the number of teeth present (P < 0.001). No correlations between bite force and head posture were found.