Bite forces and their resultants during forceful intercuspal clenching in humans.

We aimed to develop a method of gathering complete information on the system of bite forces acting on the dental arches during clenching with the teeth in maximum intercuspation. Further, we attempted to reduce this system into an equivalent wrench--a force-couple system comprising a single force and a single couple acting along a unique line of action. We investigated the normative distribution of the bite forces and the location and orientation of their resultant wrench in 30 young adults (18-23 yr) with natural dentitions. The number of detected occlusal contacts varied from 12 to 46 (mean: 26.1; SD: 8.4), and was significantly greater for the molars than the premolar and anterior teeth, as were the bite-force magnitudes at individual occlusal contacts (1.2-218.4 N); those resulted in the antero-posteriorly slanted bite-force distribution. The magnitude of the bite-force resultants varied from 246.9 to 2091.9 N, and the points at which the resultant wrench axes intersected the mandibular occlusal plane were located 21.3-37.6mm posterior to the incisal point and less than 8.9 mm from the midline bilaterally. The bite-force resultant was slightly inclined anteriorly from the perpendicular direction to the mandibular occlusal plane. Our method of using pressure-sensitive films to obtain information on all parameters needed to mechanically define a force (such as magnitude, direction, and point of application) is novel. To our knowledge, this is the first study investigating the system of bite forces during forceful intercuspal clenching in six degrees-of-freedom.