Abstract
There are close relationships between craniofacial form and activity of human jaw muscles, and the reaction forces (bite forces) they produce at the teeth and articular surface of the temporomandibular joints. To define these associations in human jaw function, correlation between these components are necessary.
The lateral cephalometric radiographs were used for classification of craniofacial form. One loadcell was held in a cast metal framework located the center of first molar. A matching mandibular framework transmitted loads to the cell. Intra-oral forces were then recorded in subjects who carried out repeated clenching tasks under two force vectors. Simultaneous recording of the electrical activity in selected jaw muscle were used to observe relative changes in their contribution to bite forces.
Craniofacial form was classified the short face group and long face group under the orthodontic view points, and was found significant difference between these two group. Masseter and anterior part of temporal muscle was harmonized to get the bite force, and the exponential curve was identified between both muscle activity and bite force.
Significant correlation between medial pterygoid muscle activity and bite force could not be identified, and this muscle activity revealed much variability.
