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.
A deciduous pet tooth is considered retained as soon as the permanent (adult) tooth erupts. The permanent pet tooth does not need to be fully erupted for the deciduous to be considered retained.
Cause of retained diciduous (puppy) teeth
The most common cause for a deciduous tooth to be persistent is an incorrect eruption path of the permanent. This will result in the deciduous tooth staying in the mouth and the permanent tooth erupting alongside. This is contrary to the classic but mistaken belief that a retained deciduous tooth causes the permanent tooth to erupt in an unnatural position.
This is most common in toy and small breed dogs, but can occur in any breed as well as cats. The most common teeth affected are the canines, followed by the incisors, and premolars; and it is typically bilateral. Oral exam will reveal additional teeth in the arcades, which often appear crowded. In addition, the adult teeth are typically deflected into an abnormal position.
This unnatural position may cause tooth or gum trauma leading to possible infections of teeth or even the nose. Studies have shown these orthodontic problems can occur within 2 weeks after the adult teeth erupt. In addition to orthodontic consequences, periodontal problems also occur with retained deciduous teeth. This is due to the adult and puppy tooth being crowded together. The abnormal anatomy results in a weakened periodontal attachment and increased susceptibility to future periodontal (gum) disease. This is even more concerning given the fact that the patients who tend to retain teeth (toy and small breeds) are also more prone to periodontal disease.
Treatment for retained diciduous teeth
There should never be two teeth of the same type in the same place at the same time.
Therefore, any persistent deciduous teeth should be extracted as early as possible. Do not waituntil 6 months of age to perform the extractions along with neutering. The time of adult tooth eruption is 3-4 months for incisors and 5-6 months for canines. You should examine your pet’s mouth at least once a week to ensure the prompt removal of these teeth.
Dental radiographs are absolutely critical to the proper performance of deciduous extractions, because there is often some degree of resorption of the deciduous root.
The extraction of deciduous pet teeth can be very difficult due to the considerable length and thin walls of the deciduous tooth. Resorption of the retained deciduous tooth can also compromise the extraction. Dental x-rays provide this information which allows the practitioner to remove the tooth less invasively. In some cases, the root may be completely resorbed, making the extraction simple. However, if the veterinarian does not perform x-rays to find that the root is already gone, they may attempt to surgically remove it, causing unnecessary pain and trauma to the pet. Some veterinary dentists perform surgical extractions for deciduous canines; however, at Veterinary Specialties and Oral Surgery we generally perform a less invasive closed technique.
A retained root tip left behind after an extraction attempt may become infected, or more commonly act as a foreign body and create significant inflammation. There are rarely any clinical signs associated with this, but the patient suffers regardless. Dental radiographs should be exposed following all extractions to confirm complete removal of the deciduous tooth.