Vectorial analysis of the equilibrium of forces transmitted to TMJ and occlusal biteplane splints

A mechanical model (link quadrilateral bell crank) is used to demonstrate the equilibrium of normal force vectors transmitted to the masticatory system and maxillary occlusal biteplane splints with different designs. Occlusal contacts were imposed on the proposed models under the action of a masticatory force vector with an arbitrary value of 40 kgf. The consequence of this force action created different responses within the joint and at the level of the dentition. When compared to the intercuspal position in centric occlusion, intra-oral appliances with either smooth contacting surfaces or indentations, both with increased vertical dimension, forced the mandible to assume an anterior position with a concurrent increase of joint forces. The bite-splint that produced the least amount of joint force was the stabilization type with minimal increase of vertical dimension.