Feline Resorption Lesion Stages/Types

  • Stage 1 (RL 1) extend into cementum only on the root surface. At one time, stage 1 referred to lesions that only involved enamel. This definition is outdated.
  • Stage 2 (RL2) have destroyed a significant amount of dentin and cementum but has spared the pulp.
  • Stage 3 (RL3) enter the pulp without extensive crown destruction.
  • Stage 4 (RL4 ) have extensive root and crown damage.
  • Stage 5 (RL5) lack a clinical crown but root fragments remain on radiographs.
  • Type I lesions arise in the cervical area of the tooth and extend inward and/or up and down the root. Type I lesions are inflammatory in nature. Radiographically Type I lesions have relatively normal root structure.
  • The more common Type II lesion begins subgingivally. Radiographically the roots appear to be resorbing. The periodontal ligament will not be readily recognizable due to ankylosis in Type II lesions.

Click on any image below to see a larger view
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Stage 2 (RL2)
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Radiograph showing enamel and dentin involvement
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Stage 3 (RL3) mandibular first molar

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Radiograph showing resorption into the pulp of the mandibular third premolar
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Stage 4 partial crown remains (RL4)
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Stage 5 crown cannot be visualized (RL5)

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Radiograph showing remaining root fragment in stage 5 resorptive lesion

Type 1
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Note, cervical lesion on the fourth premolar with normal appearing apical root structure
Type 2
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Root replacement resorption and ankylosis of the mandibular canines

Table of Contents
Smile Book IV
Small Animal Dental Anatomy, Pathology, and Charting
Jan Bellows, D.V.M. Diplomate, American Veterinary Dental College
About The Author
Dental Charting
Normal Canine Dental Anatomy
Normal Feline Dental Anatomy
Congenital Dental Pathology
Periodontal Disease
Periodontal Examination
The Traumatized Tooth
Fractured Tooth Classification
Odontoclastic Resorption
Benign Oral Masses
Malignant Oral Masses
Drug Inserts

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Smile Book Series


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Jan Bellows, DVM
All Pets Dental Clinic
17100 Arvida Parkway
Weston, FL 33326
(954) 349-5800