Statement of problem. It is recognized that high or misdirected forces can cause occlusal trauma. It is also known that the coefficient of friction between contacting teeth depends on (salivary) lubrication and on the material surfaces in contact. Friction changes the directions and magnitudes of contact forces, but the exact influence of friction on occlusal trauma is unknown. Purpose. The purpose of this mathematical study was to ascertain the influence of changed friction (as a result of xerostomia or a restoration) on the forces experienced by contacting teeth and the temporomandibular joint (TMJ). Material and methods. Equations were derived for the forces on teeth and the TMJ. To assess the effects of friction on these forces, a parametric analysis was performed in which the coefficient of friction between teeth was set to 0.0 (idealized frictionless contact), 0.2 (salivary lubrication), 0.4 (xerostomia), or 1.0 (some artificial saliva lubrication). Results. The computations indicated that a change in friction influences the directions and magnitudes of the forces experienced by teeth and the TMJ. The effect can be subtle or profound depending on the cusp angle and the direction of impending motion. Conclusion. Within the limitations of this study, the results suggest that change in friction between teeth, for any reason, should be considered a possible cause of occlusal trauma.
ASJC Scopus subject areas
- Oral Surgery