The biomechanical integrity of the stomatognathic system is closely linked to occlusal dynamics. Variations in incisor and cheek tooth occlusion parameters may not only reflect underlying orodental pathologies but also serve as potential indicators for grading their severity and biomechanical impact. By exploring these relationships, occlusion metrics could be utilized as a diagnostic tool to assess orodental health and guide risk stratification in clinical evaluations.

The aim of this retrospective study was to investigate the causal association between the global severity of orodental pathologies and occlusion parameters of the incisors and cheek teeth in horses. Dental examination records from 605 horses treated by a single equine veterinary dentist were evaluated. Static and dynamic clinical orthodontic parameters–including horizontal over-/underbite (also termed overjet/underjet, OJ/UJ), incisor midline deviation in neutral cheek tooth position (OC), lateral excursion to separation (LETS), as well as transverse (TA) and sagittal (SA) incisor occlusal angles–were measured before and after incisor treatment. Horses were categorized into three groups based on a global severity score of their orodental pathologies: Group 1 (no pathologies), Group 2 (mild to moderate), and Group 3 (severe). Group 3 included horses with either multiple concurrent pathologies resulting in high cumulative scores or at least one pathology classified as severe. The data were statistically analysed linking global severity scores and orthodontic parameters.

Horses that had never received any dental treatment showed a significantly higher total severity score. Pathologies occurred more frequently and at higher severity in the lower jaw quadrants, while overall no laterality was observed. Comparing groups, the age of horses increased with increasing severity classes. The presence and severity of an OJ was positively associated with the degree of orodental pathologies. Only younger horses with low total scores showed slight OJ reductions after dental prophylaxis. However, prophylaxis is likely to have only a minor immediate influence on the relative rostrocaudal jaw mobility overall. UJ was absent in group 1 and observed in <1.4% of horses in other groups, with UJ increasing with higher total pathology scores. Horses in group 3 exhibited slightly greater OC measures, but there was no strong overall association with the severity or side of orodental pathologies. LETS was 1.2 times higher pre-treatment but differed significantly between sides, with left cheek tooth arcades contacting later. No clear association was found between LETS magnitude and pathology scores or laterality. 80% of horses exhibited a TA diagonal malocclusion 3 (DGL3) and 10% a DGL4 pre-treatment. TA measurements did not relate to side differences in global pathology scores, but severe pathologies more often led to a higher amplitude of the diagonal malocclusion. Most horses (86%) showed a SA plane running above the temporomandibular joint level with minimal age dependency and consistent values across groups.

This study shows that the severity of orodental pathologies can globally affect occlusion parameters. Measuring these parameters is essential for biomechanical assessment of mastication. Further research is needed to clarify links between specific occlusion metrics and particular pathologies.