The functional relevance of cusp angles in naturally healthy dentition

Three-dimensional scans and measurements were taken of casts of the maxillary arches of 18 subjects with naturally healthy tooth structures. The cusp angles of the premolars and molars and the palatal inclines of the canines were determined. The functional measurements in relation to the joints were taken using the Cadiax Compact. The results of the measured tooth angles showed a sequential decrease in the palatal incline of the buccal cusps from the canines towards the second molars, whereas the buccal angles of the palatal cusps increased from mesial to distal. The inner angle between the two cusp angles at the flanks sloping towards the fissure widened from mesial to distal in all casts. In principle, this confirmed the occlusal scheme of sequential guidance, with canine dominance through the general distribution of cusp angles. A direct relationship between the cusp angles and the measurements of condylar function (as it exists between the horizontal condylar guidance inclination and Bennett's angle) could not be verified (r 0.6 and P > 0 according to Spearman's rank correlation coefficient). However, evidence of other complex relationships became apparent. A steep condylar path and canine guidance indicated that the lateral cusps were just as steep. A wide Bennett angle resulted in flat cusp angles. Considering the fact that it is not the individual cusp angles, but the three-dimensional torsion curve of sequential cusp angles that is influenced, there are clear dependencies with bilateral symmetry (with r >= 0.6 and P 0.05). This interdependence is found between two indices: one is derived from the quotient of the sums of the buccal divided by the palatal cusp angles and the other index is derived from the addition of the canine inclination angle with the contralateral condylar path and the subtraction of the respective Bennett angle. Keywords: Bennett angle, condylar path, cusp angle