Forces on the Incisor Teeth During Odontoplasty of the Cheek Teeth in Sedated Horses

Mouth specula with incisor bite plates shift the pressure from all teeth exclusively to the incisors in the opening phase which leads to increased forces on dental, osseous, and soft tissue structures of the horse's head. The potentially pathological character of these forces is described clinically by single reports of maxilla and mandible fractures occurring during the use of opened mouth specula. This study describes these forces on incisor teeth in horses during odontoplasty of cheek teeth under sedation. Measurements were documented using a modified "Günther" mouth speculum fitted with a force transducer along the force axis. Forces were recorded for different incisor separation distances and for dental rasping at a defined incisor separation distance. The results showed a significant difference in the median loads on the incisors at 82 mm (198.88 N), 92 mm (214.18 N), and 102 mm (293.95 N) incisor separation distance, and between active treatment with a mechanical bur (173.28 N) and no active mechanical bur (237.81 N) with maximum peaks up to 3783.60 N. Increasing bodyweight and mandible length showed a correlation with increasing forces, whereas age, gender and regularity of dental treatments did not suggest any influence on force development.