Malocclusion is the medical term used to describe the misalignment of teeth between the upper (maxillary) and lower (mandibular) dental arches. Though any dog or cat may suffer from dental malocclusion, this is considered a very common disorder in the world of purebred dogs.
Class I: In this type of malocclusion, the mandible and the maxilla are of equal lengths, but one or more teeth are misaligned.
Class II: This happens when the maxilla is longer than the mandible. This can happen unilaterally (on one side) or bilaterally (on both sides).
Class III: This occurs when the mandible is longer than the maxilla. As with Class II malocclusions, this can happen unilaterally or bilaterally. This malocclusion is considered "normal," in brachycephalic breeds.
Class IV: In this form of malocclusion, one side of the mandible is longer than the maxilla and the other is shorter than the maxilla.
In general, jaw length issues (Class II, III, and IV) are considered genetic, while individual tooth discrepancies (Class I) are considered non-genetic. However, there are some Class I malocclusions that occur more frequently in certain breeds of dogs (Shetland sheepdogs and standard poodles, for example). As such, it's assumed these malocclusions are genetic as well.
The trouble with malocclusions isn't that they're unsightly, it's that misaligned teeth can be painful. Depending on the class of malocclusion, trauma to the lips, palate, or gums can occur.
Symptoms and Identification
Most pets with malocclusions have no symptoms. Even when it's clear from their intraoral injuries that they must be in pain, many pets don't display any outward signs. Some, however, may have visible oral bleeding. Alternatively, their owners may detect an unpleasant odor coming from their mouths.
Malocclusion is usually very easy to spot. Simple observation - even at a very early age (even before the adult teeth come in) - will typically suffice. In some cases, however, diagnosis of a malocclusion cannot definitively be ascertained before the adult teeth are in place. Temporary pediatric malocclusions may resolve, as the mandibular and maxillary bones may experience different growth rates.
Breeds whose head shapes differ most markedly from their proto-dog forbearers seem most likely to suffer these. While dolicocephalics are predisposed as well, brachycephalic breeds are the most dramatically affected. As noted above, certain malocclusions are considered "normal" for brachycephalic breeds.
In most cases, malocclusions don't require any treatment. It may be necessary, however, as a result of painful intraoral lesions caused by the dental misalignment. Depending on the position of the injury to the trauma-inducing tooth, the following solutions may be appropriate:
Extraction of the offending deciduous (baby) tooth/teeth. This tooth's adult counterpart may or may not pose a future problem.
Extraction of the permanent (adult) tooth/teeth.
Moving the offending tooth/teeth via orthodontic means.
Removing the offending area of the tooth/teeth. In these cases, the crown of the tooth (the part of the tooth above the gumline) can be amputated. This approach is more complex than it may initially appear, as the root must be carefully preserved in the process.
Note: Treatment is not recommended for purely cosmetic reasons. Indeed, it is increasingly viewed as unethical to engage in any dental practice for reasons of cosmesis alone.
The veterinary cost of malocclusion depends on the need for treatment. For example, if extraction is necessary, the expenses incurred will vary depending on the age of the offending tooth/teeth involved and how many roots it bears. Extractions generally range in price from $150 to $1,500.
Crown amputation and vital pulp therapy, however, can prove even more expensive, as board-certified veterinary dentists are typically consulted. (Between $1,500 and $3,000 per tooth.)
Orthodontics are similarly expensive, if not more so, as frequent anesthetic procedures are required.
Ongoing expenses should be expected as well, given that many malocclusion patients should be monitored for any changes in their dental alignment. Moreover, a lifetime of follow-up dental X-rays will be required for patients who undergo vital pulp therapy. These future expenses should not be overlooked.
Given that, by the very definition of their breed standard, many breeds of dogs inherently suffer abnormal dental alignment, preventing malocclusion may not be possible in the context of a specific breed of dog.
Ideally, prevention involves changing the breed standards to allow for traits that will minimize the risk of severe malocclusion, particularly among specific brachycephalic breeds.
Bellows JE, Dumais Y, Gioso MA, et al. Clarification of veterinary dental nomenclature. J Vet Dent 2005;22:272-279.
Bellows J. Atlas of canine dentistry: malocclusions and breed standards. Waltham publication.
Hale FA. Juvenile veterinary dentistry. Vet Clin North Am Small Anim Pract 2005;35:789-817.
Harvey CE, Emily PP. Occlusion, occlusal abnormalities, and orthodontic treatment. In: Harvey CE, Emily PP, eds. Small animal dentistry, St. Louis, Mo: Mosby, 1993;266-296.
Neville BW, Damm DD, Allen CM, et al. Abnormalities of teeth. In: Oral and maxillofacial pathology. 2nd ed. Philadelphia, Pa: Saunders, 2002;49-106.
Verhaert L. A removable orthodontic device for the treatment of lingually displaced mandibular canine teeth in dogs. J Vet Dent 1999;16:69-75.
Wiggs RB, Lobprise HB. Oral anatomy and physiology. In: Wiggs RB, Lobprise HB, eds. Veterinary dentistry: principles and practice. Philadelphia, Pa: Lippincott-Raven, 1997;55-86.
Wiggs RB, Lobprise HB. Pedodontics. In: Wiggs RB, Lobprise HB, eds. Veterinary dentistry: principles and practice. Philadelphia, Pa: Lippincott-Raven, 1997;167-185.
Wiggs RB, Lobprise HB. Basics of orthodontics. In: Wiggs RB, Lobprise HB, eds. Veterinary dentistry: principles and practice. Philadelphia, Pa: Lippincott-Raven, 1997;435-481.