Category:Teeth - Pathology

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Introduction

See anatomy and physiology of the teeth

Functional Anatomy

• The gingival crevice is an important site for disease processes in mouth to begin.

• In ruminants and rodents teeth may fail to oppose properly or to allow side to side movement of jaws. This produces uneven wear (especially in horse). Sharp edges are produced on the outside of the teeth in the upper jaw and inside of the teeth in the lower jaw, which causes painful feeding and inanition (not eating).
  • Approximately 75% of wasting horses have dental abnormalities.

• This is not a problem in carnivores as do they not use teeth for mastication.

• If a teeth is lost the opposing teeth may become very long and stop mouth closing properly.
  • Seen mostly in rodents - teeth may even penetrate through lip.

Defence Mechanisms

Developmental Pathology

Erythropoietic Porphyra.

Photosensitisation

Abnormal Wear of Teeth

Abnormal Numbers of Teeth

Infection of teeth

Alveolar Periostitis

Granulomatous and pyogranulomatous Inflammation

Mandibular Osteomyelitis

Odontoclastic resorptive lesions

• Cats
  • Odontoclasts attack external and internal to the tooth.
  • Initially start at the neck/cervical region and extend into tooth root and also enter the root via the apical foramen (stage 3 lesions)
  • 20%+ of cats have them
  • Different from caries – demineralization by bacteria fermenting CHO on the enamel.
  • ORLs – only occur when odontoclasts resorb the tooth/bone
    • continues with remodeling of alveolar bone until ankylosis
    • fixation of periodontal ligament and lamina dura so that the tooth is permanently fixed to the bone.
• Odontoclasts normally only active in young animals to resorb the deciduous teeth to make way for the permanent teeth – so represents abnormal activation in adults.
• Can have inflammatory infiltrates into the resportive lesions

Eosinophilic Inflammation

Necrotizing Inflammation

Lymphocytic and plasmacytic Inflammation

Proliferative Pathology

Hyperplastic

Focal fibrous hyperplasia^[1]

• 44% of cases.
• Dense collagenous tissue, with ulceration/superficial inflammation
• Dystrophic calcificaition within the fibrous connective tissue stroma (often highly cellular, with 'young stellate fibroblasts'
• No odontogenic epithelium seen.
• Occasional strands of surface epithelium growing down into the stroma.
• Most of these were previously diagnosed as fibromatous or ossifying epulides.

Neoplastic

Peripheral odontogenic fibroma^[1]

• aka: Fibromatous epulis of periodontal ligament origin
• 17% of cases.
• Proliferation of fibrous tissue with variety of osteoid, cementum or dentine-like material.
• Isolated strands or islands of odontogenic epithelium always present (ie: suggesting induction of connective tissue by the epithelial cells).
• The stroma contains neoplastic fibroblasts, with varying cellularity.
• The overlying epitheluim is normal.

Peripheral ameloblastoma^[1]

• aka: basal cell carcinoma, acanthomatous ameloblastoma, acanthomatous epulis
• 18% of cases.
• Islands and sheets of mature odontogenic epithelium within a collagenous fibrous connective tissue stroma of low/moderate cellularity.
• Each of the islands bounded by a row of tall columnnar cells.
• These palisading cells exhibit polarisation away from the basement membrane and had cytoplasmic vacuolation.
• Central cells had a basaloid appearance.
• Often infiiltrating into the underlying bone.
• Synonymous with basal cell carcinoma.

Central ameloblastoma^[1]

• Different from peripheral ameloblastoma - cystic changes and follicular arrangement of ameloblasts and stellate reticulum cells, resembling the basic structure of the enamel organ.

Degenerative Pathology

Odontodystrophy

• Damage to ameloblasts (which form enamel) in utero upsets permanent incisor formation.
• Enamel is marked by pits, lines etc.

In ruminants:

• Damage to enamel formation most often caused by fluoride poisoning.
• Seen in cattle grazing on pasture contaminated by cement works effluent.
• Chalky mottling and yellow brown pitting of tooth.

In canines:

Very severe systemic disease early in life / or in utero may result in severe discoloration or pitting of teeth due to effect on enamel formation. (e.g. distemper in dog)

Metabolic Pathology

Nutritiona Pathology

Traumatic Pathology

Vascular Pathology

References

With thanks to Andrew Jefferies (Cambridge) and Alun Williams (RVC) for providing access to their lecture materials

1. ↑ ^{1.0 1.1 1.2 1.3} J Comp. Path. 1992 (106), 169-182 The Histological Nature of Epulides in Dogs F. J. M. Verstraete*, A. J. Ligthelmf and A. WeberT. ... review of 154 oral 'epulis' from dogs reviewed with the current (at the time) human literature.

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