Tooth resorption is defined as a loss of tooth substance due to odontoclastic activity and it is considered physiologic during the process of exfoliation of deciduous teeth. However, when tooth resorption (either internal – meaning within the root canal, or external – meaning on the root surface) affects permanent dentition, it is considered pathologic.
Tooth resorption affects 32% – 70% of domestic cats (depending on the study) and the prevalence is higher in older cats. The etiology and pathophysiology is still unclear and the role of vitamin D has not been elucidated. Most commonly affected teeth are mandibular third premolar and first molar teeth, and the lesions are many times bilaterally symmetrical.
Lesions can start anywhere on the root and gradually progress to involve also the pulp which is very painful. Interestingly, pulpal involvement associated with tooth resorption is not associated with the development of radiographically detectable periapical disease. The resorption process leads to tooth loss.
Dental charting and dental radiographs are of utmost importance to diagnose the stage and type of tooth resorption and plan an appropriate treatment. The only stage that may not require treatment in cats is stage 5 (there are only resorbing root remnants visible radiographically while the gingiva covering them is intact). In cases, where lesions are not exposed to the oral cavity, monitoring may be elected, although the lesions will likely progress.
Extraction is needed for all teeth with type 1 tooth resorption lesions. Type 1 lesions are diagnosed when periodontal ligament is radiographically visible in a tooth affected by tooth resorption. Teeth affected with type 2 tooth resorption lesions may be treated by crown amputation in selected cases and basing the decision on dental radiography findings. Type 2 lesions are diagnosed when roots are being replaced by bone radiographically (replacement resorption, no periodontal ligament space is visible).
Currently there is no known treatment that would prevent the disease from progression. Restoration of the early external lesions is possible, but not recommended as it is usually only a short-term solution, because the tooth resorption process continues despite the restoration.
Tooth resorption is also very common in dogs (53,6% of dogs are affected). Increased occurrence was found in older and heavier neutered male dogs, but the reason is unknown. Tooth resorption in dogs is classified differently than in cats to external tooth resorption (external surface resorption, external replacement resorption, external inflammatory resroption, external cervical root surface resorption) and internal tooth resorption (internal inflammatory resorption, internal surface resorption, internal replacement resorption) and several types of tooth resorption may be found in the same dog.
As in cats, dental charting and dental radiographs are needed to diagnose the disease and plan the treatment; in general, lesions, that are exposed to the oral cavity and/or associated with inflammation, require treatment, which is in most cases extraction or endodontic treatment.
If you have noted any problems with your animal, please consult your veterinarian.
Selected references
1. Booij-Vrieling HE, de Vries TJ, Schoenmaker T, Tryfonidou MA, Penning LC, Hazewinkel HA, Everts V (2012). Osteoclast progenitors from cats with and without tooth resorption respond differently to 1,25-dihydroxyvitamin D and interleukin-6. Res Vet Sci 92(2):311-316.
2. DuPont G (2010) Pathologies of the dental hard tissues. In: Small animal dental, oral & maxillofacial disease. BA Niemiec, Ed., CRC Press, Taylor & Francis Group, Boca Raton, pp. 127–157.
3. DuPont GA (2005). Radiographic evaluation and treatment of feline dental resorptive lesions. Vet Clin North Am Small Anim Pract 35(4):943-962.
4. Girard N, Servet E, Biourge V, Hennet P (2008). Feline tooth resorption in a colony of 109 cats. J Vet Dent 25(3):166-174.
5. Gorrel C (2015). Tooth resorption in cats: pathophysiology and treatment options. J Feline Med Surg 17(1):37-43.
6. Lommer MJ (2012). Principles of exodontics. In: Verstraete FJM, Lommer M, eds. Oral and maxillofacial surgery in dogs and cats. Saunders Elsevier, Edinburgh: 97-114.
7. Lommer MJ (2012). Special considerations in feline exodontics. In: Verstraete FJM, Lommer M, eds. Oral and maxillofacial surgery in dogs and cats. Saunders Elsevier, Edinburgh: 141-152.
8. Lommer MJ, Verstraete FJ (2000). Prevalence of odontoclastic resorption lesions and periapical radiographic lucencies in cats: 265 cases (1995-1998). J Am Vet Med Assoc 217(12):1866-1869
9. Mihajlevic SY, Kernmaier A, Mertens-Jentsch S (2012). Radiographic changes associated with tooth resorption type 2 in cats. J Vet Dent 29(1): 20-26.
10. Peralta S, Verstraete FJ, Kass PH (2010). Radiographic evaluation of the types of tooth resorption in dogs. Am J Vet Res 71(7):784-793.
