Orthodontic solutions: What to do with that bite
An overview on how to address malocclusion and other orthodontic problems in pets.
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Orthodontic care in cats and dogs doesn't have to be confusing. Just familiarize yourself with 1) the four basic presentations-the pet has a normal or abnormal bite that is functional or not; and 2) the three treatment options, as outlined on the following pages. See the table below for the forms of malocclusion seen in pets.
Table: Forms of malocclusion in pets as defined by the American Veterinary Dental College
Skeletal malocclusions
- Mandibular distoclusion (class 2 malocclusion): An abnormal rostral-caudal relationship between the dental arches in which the mandibular arch occludes caudal to its normal position relative to the maxillary arch.
- Mandibular mesioclusion (class 3 malocclusion): An abnormal rostral-caudal relationship between the dental arches in which the mandibular arch occludes rostral to its normal position relative to the maxillary arch.
Dental malocclusions
- Distoversion: A tooth that is in its anatomically correct position in the dental arch but abnormally angled in a distal direction.
- Mesioversion: A tooth that is in its anatomically correct position in the dental arch but abnormally angled in a mesial direction.
- Labioversion: An incisor or a canine tooth that is in its anatomically correct position in the dental arch but abnormally angled in a labial direction.
- Linguoversion: A tooth that is in its anatomically correct position in the dental arch but abnormally angled in a lingual direction.
- Crossbite: A malocclusion in which a mandibular tooth or teeth have a more buccal or labial position than the antagonist maxillary tooth. It can be classified as rostral or caudal.
Normal and functional
A normal (for the breed and face type) functional mouth accommodates 30 teeth in cats and 42 teeth in dogs without impingment of the gingiva or interference with other teeth (Photos 1A and 1B). Typical holders of such mouths include the domestic shorthaired cat, beagle, poodle, and Labrador retriever.
Photo 1A: Normal rostral mandibular and maxillary occlusion in a cat. (All photos courtesy Dr. Jan Bellows.)
Photo 1B: Normal incisors, canines and premolar occlusion in a dog.
Normal and nonfunctional
The English bulldog, pug, Boston terrier, Shih Tzu and other brachycephalic breed standards call for a mandibular mesioclusion (underbite) in which the maxillary incisors are located caudal to their mandibular counterparts. In some cases, the teeth in these breeds coexist without issue. In other cases, interference and gingival impingement occur (Photo 2).
Photo 2: Normal but nonfunctional maxillary canines in a bulldog causing gingival penetration and interference with the rostral mandibles.
Abnormal and functional
At times, teeth erupt in positions that are not normal for the breed and face type but do not cause harm to the patient (Photos 3A and 3B).
Photo 3A: A functional left mandibular canine malpositioned caudal to the maxillary canine in a dog.
Photo 3B: A functional supernumerary mandibular premolar in a cat.
Abnormal and nonfunctional
Teeth are considered nonfunctional when they cause trauma to adjacent or opposing teeth or gingiva. Therapy decisions are based on the ultimate goal to decrease or eliminate dental trauma. Options include crown reduction and restoration, movement of teeth with elastics and orthodontic buttons or appliances, or teeth extraction.
Treatment options
Once the diagnosis is made there are three fundamental treatment options.
Option 1: Move the offending or affected teeth
Cementing an acrylic, composite or cast metal telescoping incline plane on the maxillary canines moves the mandibular canine teeth buccally (Photos 4A and 4B) in cases of lingually displaced mandibular canines.
Photo 4A: A right mandibular canine linguoversion traumatizing the maxilla and a retained deciduous canine.
Photo 4B: An incline plane was used to redirect the canine linguoversion.
Over time (weeks), gradual lateral pressure moves the canines to functional positions (Photo 4C).
Photo 4C: Functional occlusion after orthodontic care.
Tooth movement with elastics and buttons involves anchor and target teeth. Anchor teeth with greater surface area are chosen to provide higher resistance to movement compared with target teeth. Ideally, the anchor tooth remains stable, allowing target tooth movement. Healthy anchor teeth and periodontal support are critical to successful target tooth movement (Photos 5A-5C, 6A and 6B).
Read the fine print: Although tooth movement may appear to be easy and straightforward, it should only be undertaken by those who have a deep understanding behind the science as well as procedures of orthodontic practice. Choosing the right client and patient is critical in successful outcomes. Referral to a board-certified veterinary dentist should be considered in these cases.
Photo 5A: Multiple malpositioned teeth in a cat.
Photo 5B: Orthodontic buttons and elastics were used to move the maxillary canine caudally.
Photo 5C: Functional occlusion restored after orthodontic application.
Photo 6A: A rostral cross bite with abnormal incisor contact in a dog.
Photo 6B: The rostral cross bite corrected with orthodontic care.
Option 2: Partially remove the offending teeth
Gingival impingement from dental malposition can be treated with crown reduction, vital pulp therapy and restoration of the offending tooth or teeth (Photos 7A-7C and 8A-8D, p. M8). Advantages of crown reduction are decreased therapy time and less aftercare compared with tooth movement procedures.
The treatment is completed within one or two visits (when the tooth is restored with a laboratory-prepared crown, the patient needs to be anesthetized twice). Yearly follow-up radiographs are necessary. Disadvantages of crown reduction and restoration include exposure of the pulp and potential restoration leakage.
Photo 7A: A right mandibular canine malposition causing lip trauma in a cat.
Photo 7B: The right mandibular canine after crown reduction and restoration.
Photo 7C: Lip trauma eliminated.
Photo 8A: A right mandibular canine penetrating into the maxilla in a dog and a discolored right maxillary second incisor.
Photo 8B: Crown reduction and restoration of the right mandibular canine and root canal therapy of the right maxillary second incisor was performed.
Photo 8C: An intraoral radiograph taken after root canal therapy was performed.
Photo 8D: The impingement was rectified.
Option 3: Completely remove the offending teeth
Extraction of the offending or impinged-upon teeth is performed to allow a functional bite (Photos 9A-9C, 10A and 10B). The advantages of extraction compared with orthodontic movement include less total treatment time, less expense and fewer anesthetic procedures to accomplish therapy.
Photo 9A: Mandibular mesioclusion in a dog.
Photo 9B: The mandibular gingival impingement.
Photo 9C: The right and left first and second maxillary incisors were extracted to alleviate the impingement.
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Photo 10A: Maxillary canine mesioversion in a dog.
Photo 10B: The appearance after maxillary canine extraction.
