Bovis ISSN 2398-2993

Teeth: impaction and malocclusion

Synonym(s): over-shot jaw, under-shot jaw

Contributor(s): Ben Dustan , John Tulloch

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Introduction

  • Cause:
    • Impaction:
      • Rare - tooth or teeth are prevented from erupting by:
        • Adjacent teeth.
        • Dense overlying bone.
        • Excessive soft tissue.
        • A genetic abnormality.
    • Malocclusion:
      • Rare - teeth and jaws fail to line up correctly as the result of:
        • Congenital abnormalities (eg over-shot (brachygnathia) or under-shot jaws (prognathia), cleft palate and/or lip).
        • Trauma/injury.
        • Tumors affecting the oral cavity/jaw.
        • Abnormally shaped or impacted teeth.
  • Diagnosis: clinical examination, radiography.
  • Treatment: correct underlying cause if possible to do so, e.g. jaw fracture may require setting or an impacted tooth removal. Majority of congenital abnormalities are incurable and require changes in management or if severe, euthanasia.

Pathogenesis

Etiology

Impaction

  • Tooth or teeth eruption is prevented by any, some or all of the following:
    • Proximity of adjacent teeth.
    • Density of the overlying bone capping the tooth socket.
    • Excessive soft tissue surrounding the socket.
    • A genetic abnormality that prevents tooth eruption.
  • Typically failure of eruption is the result of a physical obstruction to emergence.

Malocclusion

  • Congenital over-shot (brachygnathia) and under-shot (prognathia) jaws are rare in cattle and are the result of reduced length of the mandible and maxilla respectively.
  • Trauma/injury and/or neoplasia can lead to a physical deviation of the jaws such that alignment is incorrect.

Timecourse

  • Impaction: typically gradual onset depending on tooth/teeth affected and normal eruption time.
  • Malocclusion: depends on cause: congenital from birth, acquired may be acute (injury/trauma) or chronic (secondary to neoplasia).

Epidemiology

  • Typically rare conditions affecting individual animals.
  • Heritability of congenital over-shot or under-shot jaws not currently known.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Ingham B (2001) Abattoir survey of dental defects in cull cows. Vet Rec 148 (24), 739-742 PubMed.

Other sources of information

  • Smith B P (2002) Dental and Periodontal Diseases, Diseases of the Alimentary Tract. In: Large Animal Internal Medicine. 3rd edn. pp 694-696.
  • Blowey R W & Weaver A D (1991) Dental Problems, Alimentary Disorders. In: A Color Atlas of Diseases and Disorders of Cattle. pp 55-60.


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