An experimental approach to evaluate the correspondence between wear facet position and occlusal movements

The position of dental wear facets depends on crown morphology, antagonistic relation, and occlusal movements. The correspondence between specific directions of movements and the position of wear facets cannot be easily evaluated in vivo and has never been tested experimentally. An experimental analysis was carried out to provide evidence that explicit occlusal movements are responsible for the spatial position of wears facets. Unworn dental stone replicas of modern human prosthetic molar were mounted in a physical dental articulator, and the upper dental arch was ground against the lowers to create a wear facet pattern. The relief guided movements were constrained sequentially by means of three different condyle box setups: (1) experienced-based mean values for sagittal condyle inclination, lateroretrusion, Benett angle, and transversal condyle inclination were used; (2) pure retrusion and immediate side shift movements were added; (3) retrusion and immediate side shift were increased. Finally, the upper and lower first molars were surface scanned and macrowear facets were quantified in four wear stages. The results show that a wear facet pattern was created similar to what is seen on human molars in vivo occlusion. Some facets only developed if specific directions of movement were carried out. Therefore, we posit that an analysis of wear facet patterns is useful in recreating the individual occlusal movements. This information can be used not only to guide reproducible functional reconstructions of crown relief and dental arches but also to deduce jaw movements when, for example, isolated primate teeth are discovered in paleontological contexts.