Dental Corner with Dr. Thatcher

Mickey is an 8 year old mixed breed dog that presented to the specialty dentistry service for assessment and treatment for a discoloured lower right canine tooth (404). The tooth was unresponsive to electric pulp testing and had periapical lucency on radiographs indicating that the tooth was non-vital. Root canal treatment was done in order to preserve this tooth. The radiographs presented in the newsletter were of incidental findings in Mickey, which are also seen on a regular basis in general practice. The first radiograph is a tooth bud of 411.

This is a poorly developed and unerupted molar that is seen as a radiodensity below 410. This can lead to a dentigerous cyst, which is a fluid filled structure that arises from the enamel forming organ. This consists of cells called ameloblasts, which are worn away in a normally erupting tooth. Dentigerous cysts are usually slow to develop and usually go undetected without dental radiography. These cysts can grow large, become quite disfiguring and require major surgical correction. Dentigerous cysts can also become infected, resulting in acute swelling and pain. These cases can easily be misdiagnosed as abscesses.

Since Mickey is a senior dog and there has been no cyst formation yet, surgery to remove the tooth bud was not recommended. This will be monitored for radiographic changes during his annual dental cleaning. It is generally accepted that all unerupted teeth should be removed in dogs three years of age and younger, as the risk of dentigerous cyst formation decreases significantly after this time. The second radiograph is of Mickey’s upper premolars on the left side. He has two first premolars (205), which is known as supernumerary (SN). Without radiography, it is not known whether these teeth are health or have independent roots. Luckily, in Mickey’s case the developmentally divided teeth (twinning) is complete and resulted in normal appearing teeth. Twinning most commonly occurs as a single tooth with bifid crowns. Supernumerary roots can also occur in cats and dogs. In feline maxillary third premolar teeth, there is approximately a 10% incidence of a third root and SN cusp, which tend to occur palatally mid-tooth. Extraction of this tooth could be disastrous without knowledge of that extra root. Both of these abnormalities found in Mickey help to out line the importance of dental radiography. Without dental radiographs, the best treatment plan for our patients would not be possible.