Orthodontic problems are becoming more prevalent in our dogs and cats mostly due to selective breeding. They can occur in any breed and in mixed breed dogs as well. Most orthodontic problems that effect the size of the jaw are considered genetic, and the affected animals should not be used for breeding. At this time, defects of tooth location only are considered non-genetic, and may be treated. This may change as more studies are done.
The standards of the AVMA and ACVD are that all animals are entitled to a healthy mouth, but not a perfect mouth. Aesthetics are not considered important in our pet’s teeth, unless they are used in the show ring. If this is the case, then the mouth is usually being corrected to win shows. The ultimate goal to breed the patient for profit. Thus, the defect is passed on to a new generation. This is why the standards are written, and to correct them is to harm our patients. This means that a malocclusion that is not causing any health problems should not be fixed, as most orthodontic corrections are long term and require numerous anaesthetic procedures. Which is not in the patient’s best interest. If orthodontic correction of a genetic problem is elected, then the patient should be spayed or neutered.
This being said there are times that orthodontic correction is in our patient’s best interest.
The most common orthodontic problems that are treated are retained deciduous teeth, base narrow, crossbite, overshot and undershot, and wry bite.
The most common orthodontic problem in small animal patients is retained deciduous teeth. This is especially common in small breed dogs (Maltese, Yorkshire terriers, and poodles). One of the many reasons the baby teeth exfoliate is that the adult tooth puts pressure on the base of the baby tooth and causes resorbtion of the root structure. In these cases, the adult tooth does not line up correctly with the deciduous tooth; therefore there is no pressure for the baby tooth to come out. This will cause the adult tooth to be deviated to the side, and have two teeth there. This is a problem for several reasons. First, the adult tooth can erupt into an area that will cause either soft tissue or tooth trauma. Second, it can cause an increase in periodontal disease in the area. This is due to the loss of the normal separation between teeth, as well as the fact that the periodontium is not allowed to form correctly. The malformed periodontium will occur very early (days) after the adult tooth erupts. This does not mean full eruption, jut that the adult tooth can be seen above the gumline. This will cause build up of plaque and calculus in the area. Finally, the adult tooth may become impacted. This condition is treated by interceptive orthodontics (extraction of the deciduous tooth). This should be done as soon as the adult tooth is seen erupting to avoid as many of the problems as possible.
Base Narrow Lower Canines
Another common problem is base narrow lower canines. This can be due to a tooth or jaw problem. The tooth variety can be caused by retained deciduous lower canines. This is due to the fact that the adult canines erupt lingual (or inside) the deciduous canines. The deciduous tooth will cause the adult canines to deviate inwards. If there are retained deciduous canines or the patient is base narrow with its deciduous dentition, interceptive orthodontics should be performed as soon as possible to hopefully avoid the problem. The lingual deviation of the adult canines will usually cause palatine trauma and patient discomfort. The jaw variety is due to a genetically narrow jaw. There are two ways to treat this condition. If the malocclusion is slight (usually a tooth problem), then an incline plane or other orthodontic correction can push out the teeth. If the problem is moderate to severe, or there is interlock with the upper canines, then crown amputation and pulp capping is usually the best choice. A wry bite, where the two halves of a jaw don’t grow at the same rate can also cause this problem, and crown amputation is indicated to relieve soft tissue trauma. Our experience has been very unrewarding in treating wry bite orthodontically.
Anterior crossbite is where the upper incisors erupt behind the lower incisors. This is usually not a problem for the patient, as it is usually a “reverse scissors” and comfortable. This can be corrected by orthodontic appliance if it is due to a tooth problem. If it is a jaw problem, this will be much more difficult and the patient should be neutered prior to this lengthy process.
Posterior cross bite is where the upper fourth premolar is inside the lower first molar. This is most common in collies. Correction of this defect is very difficult and is usually not necessary as the teeth function properly in their new alignment.
Undershot (longer lower jaw) and overshot (longer upper jaw) are common problems as well. Undershot jaws can be “Normal” for certain breeds (Persian cats, Lhasa Apso, bull dogs, etc. These conditions can cause problems by allowing for soft tissue trauma by the canines not being in the proper alignment. Overshot jaws can cause the lower canines to strike the upper canine or palate. Severe undershot jaws can cause lip trauma. If the defect is mild and caught early enough, the problem may be avoided. Sometimes, the jaw discrepancy will only be temporary, and the jaws will want to correct over time. However, the dental interlock will not allow the jaw to move. For this reason, if this is discovered early enough, interceptive orthodontics can be performed by extracting the deciduous teeth. This will allow the jaws to move if they want to, but will not make them do so. If the patient already has its permanent dentition orthodontic treatment is difficult to impossible. If the teeth are causing oral trauma, then crown amputation and pulp capping is the treatment of choice.
Rostrally displaced upper canines (Lance Effect) can be caused by a retained deciduous upper canine or can be genetic in nature. This is mostly seen in Shetland sheepdogs. This can cause periodontal disease, as well as tooth attrition from striking the lower teeth. This can be corrected by extraction of the tooth, amputation and pulp capping, or by orthodontic bands. If this is genetic, the patient should be neutered prior to performing orthodontic correction.
Crowded and/or rotated teeth are commonly seen in small breed dogs, especially the bracheocephalic breeds. The major problem they cause is that they greatly increase periodontal disease in the area. These are generally not orthodonticly treated, however extracting them can improve the overall periodontal health of the animal.