Endodontic disease of the mandibular first molar tooth secondary to caudal crossbite in a young Shetland sheepdog.

A six month-old intact female Shetland sheepdog was referred to the University of Illinois Veterinary Dental Clinic with a left-sided mandibular deviation and a thickened left ventral mandible in the region of the first molar tooth. On oral examination, left caudal crossbite was diagnosed. Dental radiographs revealed endodontic disease of the mandibular first molar tooth involved in the crossbite. Because of the difficulty of treating caudal crossbite and the potential of a pathological mandibular fracture, the endodontically affected tooth was extracted. Ten months following the extraction, mandibular deviation and alveolar bone lysis were resolved, but alveolar ridge resorption was present. The abnormal occlusal relationship caused by the caudal crossbite may have led to movement of the tooth, resorption of the tooth alveolus, and irreversible pulpal damage. Although not employed in this case, use of alveolar ridge preservation techniques can prevent mandibular bone loss after extractions.