Independent movement of cusps during occlusal loading.

An integrated experimental and theoretical approach is proposed for the evaluation of stress within a natural tooth during bruxing. A physical model was developed that used strain gauges bonded to the buccal and lingual heights of contour of extracted, intact maxillary premolar teeth for the validation of a two-dimensional finite element model of a natural, intact maxillary premolar tooth. Results from the finite element model were in good agreement with the experimental results. The tooth exhibits "cuspal independence", which describes the relative independence of the loaded cusp from the remaining cusp that is not loaded. In other words, the control cusp does not demonstrate significant strain when the adjacent cusp is loaded. The overall stiffness of the tooth does not appear to be significantly affected by separation of the enamel of the two cusps and appears to be primarily a function of the dentin.