Canine Tooth Resorption (CORL, cavities, resorptive lesions, carie)

Canine Tooth Resorption has recently been classified as tooth resorption. These lesions can be either internal or external or both. Clinically, they usually present as very painful areas of granulation tissue extending onto the crown surface of the tooth. Often they are not detected until the oral cavity is examined carefully under general anesthesia. Clinicians may be suspicious of TRs when there is a pink tinge to the crown or gingiva appears to cover some of the crown. Sometimes, the crown is loose; often the resorption can be detected only with dental X-rays. These lesions can be very painful for the patient and even under general anesthesia. Internal resorptive lesions with no communication to the oral cavity do not seem to cause pain. It is only when the crown fractures or a lesion progresses coronal to the gingival margin that it becomes evident clinically.

Dental X-rays are very important in both diagnosing and treating TRs. The classic destruction of crown and root are visible as is an irregular pulp chamber and canal. There may be root destruction with ankylosis to the alveolar bone.

We do not understand the complete pathogenesis of TR at this time. It may be similar to that for Type II Feline TR with root replacement. Inflammation at the gingival margin may an initiating event. Other initiating events may include crowding between teeth and aggressive chewing habits that disrupt the vascular supply to the roots. It may be that plaque control is important in the prevention of TRs in susceptible dogs. Recommending daily brushing may help prevent occurrence or progression of the disease.

Drs. Colin Harvey and Peter Emily described a possible pathogenesis for Feline Tooth Resorption lesions (in Small Animal Dentistry, Mosby, 1993, p223). Circulating stem cells are attracted to the inflamed gingiva and differentiate into odontoclastic and osteoclastic cells. Odontoclasts may be along the periodontal attachment tissues (external resorption) or along the pulp tissue (internal resorption) resorbing dentin and cementum. As the defect continues, vascular tissue forms and eventually a bone-cementum tissue is laid down. The periodontal ligament is destroyed in the process; the tooth does not flex with mastication. This is also why extraction of these teeth is challenging since the root is akylosed to the adjacent bone or is replaced with the bone-cementum tissue.

In our experience, Canine TRs often show only internal resorption and may only be dectected by dental X-rays. Often when one tooth is affected, the X-ray shows that the adjacent teeth are also affected. As long as the lesion does not progress into the oral cavity, we will leave the tooth in place as a functional tooth, but alert the owner to the likelihood that the disease may progress and other extractions may be necessary in the future.

The AVDC ( American Veterinary Dental College) Nomenclature Committee has classified the following stages of tooth resorption: Stage1 (TR1): Mild dental hard tissue loss (cementum or cementum and enamel). Stage2 (TR2): Moderage dental hard tissue loss (cementum or cementum and enamel with loss of dentin that does not extend to the pulp cavity). Stage3 (TR3): Deep dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth retains its integrity. Stage4 (TR4): Extensive dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth has lost its integrity. (TR4a) Crown and root are equally affected; (TR4b) Crown is more severely affected than the root; (TR4c) Root is more severely affected than the crown. Stage5 (TR5): Remnants of dental hard tissue are visible only as irregular radiopacities, and gingival covering is complete.