Occlusal angles of equine cheek teeth

• Occlusal cheek tooth angles were determined in 3D-reconstructions of equine skulls.
• Identification of exact anatomical reference planes allowed reliable measurements.
• Angles ranged from 15.1° to 20.2° with staggered increase in caudal direction.
• No statistical differences between the jaw quadrants were present.

The aim of this work was to determine occlusal cheek tooth angles in horses. The complex spatial shape of the equine skull hampers exact measurements of the occlusal cheek tooth angles in anatomical specimens and as well in living horses. Therefore a method was developed to perform measurements by using detailed 3D-reconstructions of equine skulls. 3D-models were constructed from CT-datasets by manual identification of relevant anatomical structures and by use of a computer software. Within 3D-skulls anatomical landmarks were identified and reference lines and planes were determined. Subsequently, occlusal angles of check teeth were measured in relation to the median plane. Results for mean values of cheek teeth angles ranged from 15.1° to 20.2°. Angles increased stepwise from rostral to caudal. Considering the total amount of data (20 horses with permanent dentition), there were no significant differences between the jaw quadrants when teeth in same Triadan positions were compared. However, in individuals there was a significant difference between the left and right side of the jaw. Angles of antagonistic teeth correlate with each other. The results are expected to provide a substantial basis for preventive and therapeutic treatments as well as for further biomechanical studies about equine mastication.