[Analysis of mandibular movements in present-day humans by examination of the striae found on the facets of wear]. / Analyse des mouvements mandibulaires chez l'homme contemporain par l'observation des stries rencontrées sur les facettes d'usure.

The analysis of the microscopic appearance of the dental wear facets in contemporary european subjects has been conducted using the replica method. It showed the presence of numerous striae running in various directions. The angle of each stria with the sagittal plane was measured: 1540 angle values were recorded on 6 facet types belonging to 3 groups of teeth. Statistical analysis showed that the striae distribution on the various facets studied was not random. The facets of the palatal edges and facets of the upper central incisors showed mainly parasagittal striae indicating propelling movements. The striae of the wear facets of the canine tips showed no definite direction. The palatal facets of canines as well as the working and non-working facets of the molars showed 2 groups of striae oriented obliquely, forward and inside and also forward and outside. The molar working facets also had parasagittal striae. The significance of the 2 groups of oblique striae is discussed in relation to the occlusal kinematic during mastication.