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I. Definition and Scope of Disease
I. Definition and Scope of Disease
• Definition: TR involves the progressive loss or destruction of mineralized dental tissues, specifically the enamel, dentin, and cementum, potentially leading to the loss of the entire tooth structure.
• Definition: TR involves the progressive loss or destruction of mineralized dental tissues, specifically the enamel, dentin, and cementum, potentially leading to the loss of the entire tooth structure.
• Significance: TR is a major cause of tooth loss and is painful.
• Significance: TR is a major cause of tooth loss and is painful.
• Prevalence: It occurs most frequently in domestic cats. It has been reported that more than 60% of cats will show evidence of TR within their lifetime. TR also occurs sporadically in other species, including humans.
• Prevalence: It occurs most frequently in domestic cats. It has been reported that more than 60% of cats will show evidence of TR within their lifetime. TR also occurs sporadically in other species, including humans.
• Risk Factors in Cats: An increased incidence is observed in older cats and purebred cats.
• Risk Factors in Cats: An increased incidence is observed in older cats and purebred cats.
II. Etiology and Pathogenesis
II. Etiology and Pathogenesis
• Mechanism: Resorption occurs through the action of odontoclasts.
• Mechanism: Resorption occurs through the action of odontoclasts.
◦ Odontoclasts are cells that target the tooth structure, causing resorption by creating a resorptive lacuna. They are virtually identical to osteoclasts (cells responsible for bone remodeling).
◦ Odontoclasts are cells that target the tooth structure, causing resorption by creating a resorptive lacuna. They are virtually identical to osteoclasts (cells responsible for bone remodeling).
◦ Both odontoclasts and osteoclasts cause damage to the tooth and bone, leading to eventual loss or remodeling.
◦ Both odontoclasts and osteoclasts cause damage to the tooth and bone, leading to eventual loss or remodeling.
• Location: TR can occur on the external or internal tooth surface.
• Location: TR can occur on the external or internal tooth surface.
• Progression:
• Progression:
◦ In cats, TR starts with loss of normal periodontal ligament architecture and focal cementum damage on the root surface.
◦ In cats, TR starts with loss of normal periodontal ligament architecture and focal cementum damage on the root surface.
◦ Microscopic areas of root resorption often repair uneventfully in cats.
◦ Microscopic areas of root resorption often repair uneventfully in cats.
◦ If repair fails, resorption progresses into the dentin and extends coronally into the crown, undermining the enamel and creating clinically apparent defects (often at the cervical region or "neck" of the tooth).
◦ If repair fails, resorption progresses into the dentin and extends coronally into the crown, undermining the enamel and creating clinically apparent defects (often at the cervical region or "neck" of the tooth).
◦ Lost tooth structure is often replaced by bone or cementum through concomitant osteoblast and cementoblastic activity.
◦ Lost tooth structure is often replaced by bone or cementum through concomitant osteoblast and cementoblastic activity.
• Stimulating Factors (Known Causes): Odontoclastic activity can be stimulated by:
• Stimulating Factors (Known Causes): Odontoclastic activity can be stimulated by:
◦ Inflammation (e.g., from periodontitis, which is known to cause external resorption).
◦ Inflammation (e.g., from periodontitis, which is known to cause external resorption).
◦ Pressure from adjacent structures.
◦ Pressure from adjacent structures.
◦ Orthodontic tooth movement.
◦ Orthodontic tooth movement.
◦ Normal processes, such as the exfoliation of deciduous teeth.
◦ Normal processes, such as the exfoliation of deciduous teeth.
• Idiopathic Etiology (Unknown Cause):
• Idiopathic Etiology (Unknown Cause):
◦ In general, there is no known specific etiology associated with TR.
◦ In general, there is no known specific etiology associated with TR.
◦ The etiology of idiopathic TR affecting multiple (possibly all) teeth in cats has not yet been identified.
◦ The etiology of idiopathic TR affecting multiple (possibly all) teeth in cats has not yet been identified.
◦ Excessive dietary vitamin D intake has been hypothesized, but no true identified cause of TR has been found in cats.
◦ Excessive dietary vitamin D intake has been hypothesized, but no true identified cause of TR has been found in cats.
III. Clinical Findings and Diagnosis
III. Clinical Findings and Diagnosis
• Clinical Appearance: The most common clinical finding is the loss of tooth structure, frequently occurring at the cementoenamel junction.
• Clinical Appearance: The most common clinical finding is the loss of tooth structure, frequently occurring at the cementoenamel junction.
◦ Gingival inflammation may be associated with the affected tooth.
◦ Gingival inflammation may be associated with the affected tooth.
◦ Small lesions may appear at the gingival margin as inflamed granulation tissue filling a defect, often accompanied by a sharp ledge of enamel.
◦ Small lesions may appear at the gingival margin as inflamed granulation tissue filling a defect, often accompanied by a sharp ledge of enamel.
◦ Internal tooth resorption may sometimes cause a pinkish discoloration of the crown.
◦ Internal tooth resorption may sometimes cause a pinkish discoloration of the crown.
• Commonly Affected Teeth:
• Commonly Affected Teeth:
◦ Cats: The mandibular third premolar (307 and 407, the first cheek tooth) is often the first and most frequently affected tooth. Any tooth can be affected.
◦ Cats: The mandibular third premolar (307 and 407, the first cheek tooth) is often the first and most frequently affected tooth. Any tooth can be affected.
◦ Dogs: Premolar and molar teeth are commonly involved.
◦ Dogs: Premolar and molar teeth are commonly involved.
• Pain/Discomfort: TR lesions exposed to the oral cavity may cause discomfort. Lesions limited to root surfaces are unlikely to cause discomfort unless associated with adjacent bone resorption caused by painful inflammation (periodontal or endodontic disease).
• Pain/Discomfort: TR lesions exposed to the oral cavity may cause discomfort. Lesions limited to root surfaces are unlikely to cause discomfort unless associated with adjacent bone resorption caused by painful inflammation (periodontal or endodontic disease).
A. Diagnostic Procedures
A. Diagnostic Procedures
• Clinical evaluation and periodontal probing are necessary.
• Clinical evaluation and periodontal probing are necessary.
• Intraoral Dental Radiography is imperative for determining the type and stage of resorption.
• Intraoral Dental Radiography is imperative for determining the type and stage of resorption.
◦ Radiography is used to identify the stage and severity of hard tissue loss.
◦ Radiography is used to identify the stage and severity of hard tissue loss.
◦ Internal TR is frequently only identifiable radiographically as round- to oval-shaped areas of decreased radiopacity.
◦ Internal TR is frequently only identifiable radiographically as round- to oval-shaped areas of decreased radiopacity.
• Clinical Identification:
• Clinical Identification:
◦ The explorer end of a periodontal probe-explorer must be used to examine the crown to help identify early lesions.
◦ The explorer end of a periodontal probe-explorer must be used to examine the crown to help identify early lesions.
◦ Meticulous examination of the cementoenamel junction is vital.
◦ Meticulous examination of the cementoenamel junction is vital.
◦ Marginal gingivitis of individual teeth (in the absence of general periodontitis) may indicate an early subgingival lesion.
◦ Marginal gingivitis of individual teeth (in the absence of general periodontitis) may indicate an early subgingival lesion.
◦ Stage 1 lesions are typically identified only on clinical examination, as they have no radiographic evidence of disease.
◦ Stage 1 lesions are typically identified only on clinical examination, as they have no radiographic evidence of disease.
B. Classification of Tooth Resorption
B. Classification of Tooth Resorption
TR is characterized by severity (stage) and radiographic appearance (type).
TR is characterized by severity (stage) and radiographic appearance (type).
Classification Aspect
Classification Aspect
Stage (Severity - 5 Stages)
Stage (Severity - 5 Stages)
Type (Radiographic Appearance - 3 Types)
Type (Radiographic Appearance - 3 Types)
Stage 1
Stage 1
Affects cementum or cementum and enamel; has not yet progressed into the dentin.
Affects cementum or cementum and enamel; has not yet progressed into the dentin.
Type 1 (Inflammatory Resorption)
Type 1 (Inflammatory Resorption)
Stage 2
Stage 2
Affects the dentin.
Affects the dentin.
Focal or multifocal radiolucency present; normal periodontal ligament space; otherwise normal radiopacity.
Focal or multifocal radiolucency present; normal periodontal ligament space; otherwise normal radiopacity.
Stage 3
Stage 3
Affects the pulp cavity, but most of the tooth retains its integrity.
Affects the pulp cavity, but most of the tooth retains its integrity.
Type 2 (Replacement Resorption/Ankylosis)
Type 2 (Replacement Resorption/Ankylosis)
Stage 4
Stage 4
Substantial crown or root damage, with most of the tooth having lost its integrity.
Substantial crown or root damage, with most of the tooth having lost its integrity.
Narrowing or disappearance of the periodontal ligament space (dentoalveolar ankylosis); decreased radiopacity of part of the tooth (moth-eaten "ghost" roots).
Narrowing or disappearance of the periodontal ligament space (dentoalveolar ankylosis); decreased radiopacity of part of the tooth (moth-eaten "ghost" roots).
Stage 5
Stage 5
Only irregular radiopacities remain as remnants of dental hard tissue; gingival covering is complete.
Only irregular radiopacities remain as remnants of dental hard tissue; gingival covering is complete.
Type 3
Type 3
Features of both type 1 and type 2 are present in the same tooth.
Features of both type 1 and type 2 are present in the same tooth.
IV. Treatment and Prevention
IV. Treatment and Prevention
• Goal: Treatment is aimed at eliminating the source of pain and discomfort for the cat.
• Goal: Treatment is aimed at eliminating the source of pain and discomfort for the cat.
• Standard Treatment: TR is a progressive disease, so early diagnosis and intervention are vital. The accepted treatment is surgical extraction of teeth that are exposed to the external environment. Most affected teeth should be extracted.
• Standard Treatment: TR is a progressive disease, so early diagnosis and intervention are vital. The accepted treatment is surgical extraction of teeth that are exposed to the external environment. Most affected teeth should be extracted.
• Alternative Treatment (Limited Use): Surgical crown amputation with intentional root retention can be performed only under specific conditions:
• Alternative Treatment (Limited Use): Surgical crown amputation with intentional root retention can be performed only under specific conditions:
1. The patient must have radiographically confirmed Type 2 lesions.
1. The patient must have radiographically confirmed Type 2 lesions.
2. There must be an absence of periodontitis, endodontic disease, and stomatitis.
2. There must be an absence of periodontitis, endodontic disease, and stomatitis.
• Addressing Secondary Disease:
• Addressing Secondary Disease:
◦ For inflammatory resorptive lesions caused by marginal periodontitis, oral hygiene measures can slow the progression of hard tissue destruction.
◦ For inflammatory resorptive lesions caused by marginal periodontitis, oral hygiene measures can slow the progression of hard tissue destruction.
◦ Root canal therapy or extraction of teeth with primary endodontic compromise (e.g., fracture) prevents resorption of the apex caused by apical periodontitis.
◦ Root canal therapy or extraction of teeth with primary endodontic compromise (e.g., fracture) prevents resorption of the apex caused by apical periodontitis.
• Prevention: Idiopathic lesions cannot be prevented because their etiology is unknown.
• Prevention: Idiopathic lesions cannot be prevented because their etiology is unknown.
• Monitoring: Once TR is identified, annual anesthetized oral examinations with full mouth radiographs should be performed to monitor disease progression.
• Monitoring: Once TR is identified, annual anesthetized oral examinations with full mouth radiographs should be performed to monitor disease progression.
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