While pet tooth resporption is typically thought of as a feline condition, we are seeing more and more of this in our canine patients as well. This problem is very common in cats, with studies suggesting that up to 60% of cats over 6 years of age are affected. Feline tooth resorption is second only to periodontal disease in the overall incidence of oral disease.
As of yet, we do not know exactly causes pet tooth resorption. What we do know is that they result from the activation of cells called odontoclasts. These cells are responsible for the normal remodeling of tooth structure. In this disease process, the odontoclasts inappropriately continue to resorb tooth structure until in some instances the entire tooth is lost.
Tooth resorption lesions start on the roots of the pet’s teeth where the cells start destroying the underlying root structure. Over time, the resorption typically extends into the crown of the pet tooth (the part of the tooth that you can see above the gumline). The tooth’s outerenamel is undermined which will cause it to break off, exposing the underlying tooth structure which is called dentin. The dentin layer is very sensitive, and when the protective enamel layer is lost tooth pain results. Tooth resorption therefore becomes very painful, especially when the lesions are advanced. If you probe one of the lesions even under general anesthesia, the cat will react. However, most cats will not show evidence of oral pain, even when the tooth is fractured with an exposed root canal. In fact, the teeth can be so painful that even cats under general anesthesia often react with a pain response when these teeth are probed with dental instruments.
Because tooth resorption starts below the gumline and progress into the crown of the tooth, they are first seen at the gumline. The teeth most commonly affected are the premolars, followed by the molars and finally the canine (fang) teeth. The majority of the lesions are on the outer (cheek) surface of the tooth, however they can also seen on the inside (tongue) side of the tooth as well.
Diagnosis is made by a combination of visual and tactile examination in addition to dental x-ray. Resorptive lesions are initially seen as little erosions along the gumline with associated gum inflammation. These lesions can progress to large holes in the teeth, eventually destroying most of the tooth. In severe cases, the entire crown of the tooth can be lost, with only the roots remaining under the gumline. These areas will usually be rough along the gumline when an explorer instrument is rubbed over the suspected lesion.
Veterinary dental x-rays are absolutely critical for treating patients with tooth resorption. First of all, x-rays are necessary to diagnose (find) lesions under the gumline. Secondly, x-rays are also required in order to determine the proper method of therapy and ultimately resolve the painful condition.(See below).
Currently, the only accepted method of treatment for tooth resorption is extraction. In general, complete extraction of the tooth and all root structure is recommended. However, extraction of these teeth is often quite challenging. This is because it is very common for the roots to be significantly resorbed and replaced by bone, making extraction by a surgical approach necessary. On occasion, the roots can be completely replaced by bone. This finding has led to the development of a technique called crown amputation, where the crown of the tooth (the part of the tooth above the gumline within the mouth) is removed, the area smoothed and sutured closed, allowing the body to continue resorbing the roots. This is a much less invasive procedure than a surgical extraction.
However, crown amputation can only be performed with advanced resorptive lesions if no root structure remains. Veterinary dental x-rays are required to determine this. Always insist on dental x-rays when taking your pet to the veterinarian for a dental procedure.
Restoring (filling) tooth resorptive lesions is no longer recommended. This is because there is no way to stop or slow down the resorptive process and it just continues to progress under the filling. In a short period of time (usually around 6 months), the tooth loss will progress to the point where the filling falls out and extraction is necessary. Appropriate initial treatment will save the pet from enduring continued tooth pain.