The prevalence of tooth resorption has been reported1 for a group of 224 adult dogs for which full-mouth diagnostic-quality radiographs were obtained. In that study,1 tooth resorption was diagnosed and classified in accordance with radiographic guidelines described for use in humans.2 Use of the classification method for humans was applicable in 908 of 943 (96.3%) teeth in dogs. To complement these findings, another study was conducted that focused on the veterinary classification of the extent of tooth resorption in dogs.
The classification of any disease process is crucial from a medical standpoint because it enables clinicians to establish optimal diagnoses and treatments, provides a reliable source of information useful for research purposes, and allows comprehensive description in the medical records. The method for classification of tooth resorption in veterinary medicine has evolved as a tool originally intended for staging of resorption lesions in cats and traditionally has been based on the presumption that tooth resorption is an external and progressive process.
Historically, the most widely accepted methods for classification of tooth resorption in animals have been those proposed by investigators for use in cats3,4 and that of the AVDC,5 which is presumed to be applicable to cats as well as other animal species. Some variations of these classifications have been proposed.6 The classification method described in 1 report3 includes 4 stages that are based on clinical and radiographic findings (stage 1, shallow enamel or cementum lesions that do not involve the dentin; stage 2, lesions that have progressed to affect the dentin but that do not involve the tooth pulp; stage 3, lesions that have progressed to involve the pulp; and stage 4, lesions that involve massive loss of tooth substance with or without resultant root ankylosis).
In another study,4 investigators detected different radiographic patterns of tooth resorption in cats and suggested that there may be 2 types of tooth resorption. The 2 types described are similar to external replacement and external inflammatory resorption in humans, as described elsewhere.2 In that study,4 the authors also suggested that tooth resorption in cats can be classified on the basis of the extent of the lesions by use of a classification method similar to that for the 4-stage method.3
The AVDC adopted a 5-stage classification system that was based on the extent of tooth resorption lesions as follows5: stage 1, loss of tissue is limited to enamel or cementum; stage 2, loss of cementum or enamel (or both) and dentin, and the lesion does not involve the pulp cavity; stage 3, resorption has reached the pulp cavity, but the tooth retains its integrity; stage 4, extensive loss of hard tissue (which is further subdivided into 3 subcategories as follows: 4a = the crown and root are equally affected, 4b = the crown is more severely affected than is the root, and 4c = the root is more severely affected than is the crown); and stage 5, complete loss of the crown with the root remnant covered by gingiva. The AVDC classification method does not specify the type or types of tooth resorption for which it is intended. This classification method was developed on the basis of existing classification methods for use in cats, but the current version of the classification method does not make reference to any particular species. Therefore, it is not known whether these criteria should be adjusted for the various types of tooth resorption and the radiographic patterns seen in dogs. The purpose of the study reported here was to determine the applicability of the current AVDC classification guidelines5 for use in tooth resorption in dogs.
American Veterinary Dental College
Peralta S, Verstraete FJ, Kass PH. Radiographic evaluation of the types of tooth resorption in dogs. Am J Vet Res 2010;71:784–793.
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Lyon KF. Subgingival odontoclastic resorptive lesions. Classification, treatment, and results in 58 cats. Vet Clin North Am Small Anim Pract 1992;22:1417–1432.
DuPont GA, DeBowes LJ. Comparison of periodontitis and root replacement in cat teeth with resorptive lesions. J Vet Dent 2002;19:71–75.
Nomenclature Committee of the American Veterinary Dental College. Veterinary dental nomenclature—classification of tooth resorption. Available at: www.avdc.org/Nomenclature.html#resorption. Accessed Mar 31, 2009.
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Fuss Z, Tsesis I, Lin S. Root resorption—diagnosis, classification and treatment choices based on stimulation factors. Dent Traumatol 2003;19:175–182.
Descriptions of the extent of tooth resorption in dogs based on a classification method described by the AVDC.5
|1||Mild loss of dental hard tissue (cementum or cementum and enamel)|
|2||Moderate loss of dental hard tissue (cementum or cementum and enamel, with loss of dentin that does not extend to the pulp cavity)|
|3||Deep loss of dental hard tissue (cementum or cementum and enamel, with loss of dentin that extends to the pulp cavity); most of the tooth retains its integrity|
|4||Extensive loss of dental hard tissue (cementum or cementum and enamel, with loss of dentin that extends to the pulp cavity); most of the tooth has lost its integrity|
|4a||Crown and root are equally affected|
|4b||Crown is more severely affected than the root|
|4c||Root is more severely affected than the crown|
|5||Remnants of dental hard tissue are visible only as irregular opacities on radiographs, and gingiva completely covers the remnant of the resorbing root|