Equine Odontoclastic Tooth Resorption and Hypercementosis: Histopathologic Features.
Authors: Smedley R C, Earley E T, Galloway S S, Baratt R M, Rawlinson J E
Journal: Veterinary pathology
Summary
# Editorial Summary: Equine Odontoclastic Tooth Resorption and Hypercementosis Equine odontoclastic tooth resorption and hypercementosis (EOTRH) represents a poorly understood, progressive and painful condition affecting multiple teeth in older horses, yet remains underrecognised in veterinary pathology circles and is sometimes misdiagnosed as benign cementoblastoma. Smedley and colleagues examined histopathological specimens from 17 affected horses, ranging from individual teeth to complete rostral jaw sections, to establish the distinctive microscopic features of this condition and improve clinical recognition. The hallmark findings included cemental hyperplasia with concurrent lysis causing bulbous enlargement of the intra-alveolar tooth portions, dentinal lysis in affected teeth, secondary endodontic disease (inflammation, necrosis, and aberrant mineralisation within the pulp), and moderate lymphoplasmacytic periodontal inflammation; notably, necrotic debris, bacteria and plant material were identified within areas of cemental breakdown. The evidence suggests EOTRH initiates externally on the tooth surface rather than from within the pulp cavity—a critical distinction for understanding disease progression. For practitioners, accurate diagnosis requires integration of clinical history (number and location of affected teeth), oral examination findings, and radiographic assessment, as these elements together differentiate EOTRH from other odontopathies and support informed treatment planning and extraction decisions.
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Practical Takeaways
- •EOTRH is a painful progressive condition in older horses affecting multiple teeth; early recognition based on characteristic patterns of canine and incisor involvement is important for diagnosis and treatment planning
- •Diagnosis requires integration of clinical history (number and location of affected teeth), gross examination of hard/soft tissue changes, and radiographic findings; histopathology can confirm but is not required for clinical diagnosis
- •The condition begins at the external tooth surface, so preventive strategies and management should focus on maintaining periodontal health and addressing any systemic factors contributing to inflammation
Key Findings
- •EOTRH affects multiple teeth including canines and incisors in older horses and is characterized by cemental hyperplasia, lysis, and dentinal resorption
- •Tooth resorption begins on the external tooth surface rather than within the pulp cavity, distinguishing it from endodontic-driven resorption
- •All 17 affected horses exhibited dentinal lysis and endodontic disease with inflammation, necrotic debris, and fibrosis present in pulp cavities
- •Periodontal disease with moderate lymphoplasmacytic inflammation is a common concurrent finding in EOTRH cases