Malocclusions in the canine mouth need to be diagnosed and addressed by the general practitioner because they can cause soft tissue trauma, dental
trauma, dysphagia, and excessive tartar and calculus build up. Treatment may be by exodontic, orthodontic, or coronoplasty dependent on the malocclusion, skill of the practitioner, and available funds of the owner. Three common malocclusions will be discussed;
rostral crossbite, mesioversion of maxillary canines, and linguoversion of mandibular canines.
Rostral or anterior crossbite occurs when one or more of the mandibular incisors have reversed occlusal orientation with their maxillary counterparts which can be dental or skeletal in origin. Normally, the mandibular incisor occludes palatally to the maxillary incisor at the cingulum of the maxillary incisor. If anterior crossbite is the only malocclusion (all other occlusal parameters normal) it may be assumed that the causative agent was trauma, nutrition, disease, or retention of deciduous teeth and not genetic. The importance of genetics is that it is considered unethical to treat animals orthodontically if they are reproductively intact. The most common orthodontic method of correction is by the use of the Maryland Bridge technique. This, and most orthodontic work, is usually referred to a veterinary dentist. Interceptive exodontics can be done by the general practitioner if the anterior crossbite is discovered while the deciduous teeth are present. The deciduous incisors are removed to break the dental interlock and enable the "short maxilla" to out-grow the mandible.
Mesioversion or rostral displacement of the maxillary canine, also called "lance canine", is thought to be the result of retained deciduous teeth and Shetland sheepdogs seem to be predisposed to this condition and as such, the breeding of Shelties with lance canine should be greatly discouraged. This malocclusion can lead to the attrition of the enamel on the mesial aspect of the maxillary canine and the distal aspect of the mandibular canine often leading to endodontic involvement. Once again, it is important to watch for evidence of eruption of the permanent maxillary canines (5-7 months). A dental rule of thumb is that deciduous teeth should be extracted as soon as the permanent teeth are erupting, even if they are lose. Orthodontic treatment is available.
Linguoversion of lingual displacement of the mandibular canine commonly referred to as "base narrow canines" is common in doliocephalic dogs and is thought to be the result of retained deciduous teeth. This malocclusion can be insidious, in that it is easily missed by casual observance by owner and practitioner alike. These animals often present with dysphagia if the problem goes unnoticed or uncorrected. The base narrow canines can damage the palate, cause pain, and possibly oronasalfistuli. They also may contact the maxillary canines and cause attrition. There are three main procedures to correct this problem. The first is removal of the base narrow canines. This can be difficult and the possibility of mandibular fracture during the extraction can be daunting. The second is blunting of the mandibular canines and pulpotomy. The pulpotomy and sealing of the canal must be done to keep the tooth vital and eliminate endodontic involvement. This procedure may have to be repeated if the canine tooth erupts further. The third is orthodontic treatment by a veterinary dentist, this can be a very involved route to take. If the correct space (between the lateral incisor and the maxillary canine) is not wide enough to allow proper dental interlock it must be corrected prior to movement of the mandibular canines by another orthodontic appliance.
In conclusion, dental malocclusions are often under-diagnosed or ignored pathology. Understanding and treating these conditions can lead to healthier patients and happier owners. The sooner the malocclusion is diagnosed, the shorter the treatment time will be. You are encouraged to refer cases to a veterinary dentist where applicable, but you must know enough about the problem to be sincere to the client when recommending often very expensive treatments.
J. Aylward, BS, Class of 1996
- Edited by H. L. Thacker, DVM, PhD