Equis ISSN 2398-2977

Teeth: retained

Synonym(s): Retained teeth, retained deciduous teeth

Contributor(s): Vetstream Ltd

Introduction

  • Cause: pathophysiological faults in the eruption of the permanent teeth and shedding of the deciduous teeth (caps).
  • Signs: retained fragments of teeth, displacement/maleruption of permanent incisors, halitosis, oral pain/pain on feeding, blood-stained saliva, resistance to accepting the bit.
  • Diagnosis: thorough oral and dental inspection, use of sedation and analgesics, lateral and oblique radiographs.
  • Treatment: tooth removal.
  • Prognosis: good in most cases.
  • There is general agreement on the eruption times (age of eruption) of the deciduous and permanent teeth of the horse.  
  • It is also recognized that there are significant breed variations of these times. Such variations are frequently a consequence of the differences in size and shape of the head and jaws between horses, ponies, miniature horses, and of different breed types.
  • Eruption sequence of deciduous teeth:
    • Central incisors: birth or first week
    • 2nd incisors: 4-6 weeks
    • 3rd incisors: 6-9 weeks
    • 1st, 2nd, 3rd Cheek Teeth: birth or first two weeks
  • Eruption sequence of permanent teeth (Triadan Number):
    • Central incisors: 2½ years (-01)
    • 2nd incisors: 3½ years (-02)
    • 3rd incisors: 4½ years (-03)
    • Canine teeth: 4-5 years (-04)
    • Wolf teeth: 5-6 months (-05)
    • 2nd premolars: 2½ years (-06)
    • 3rd premolars: 3 years (-07)
    • 4th premolars: 4 years (-08)
    • 1st molars: 9-12 months (-09)
    • 2nd molars: 2 years (-10)
    • 3rd molars: 3½-4 years (-11)
  • By definition it is only the deciduous teeth that may be or are retained.

Pathogenesis

Etiology

  • Tooth eruption is an orchestrated process of vascular hyperemia, osteoclastic bone lysis and periodontal fiber traction to move the permanent tooth. 
  • There are continuous changes in tooth position post-eruption, as a result of wear, crown attrition and  changes in size, shape and the maturation of the surrounding bones.
  • Rotation and displacement of the eruption pathway of the permanent teeth is the commonest cause of deciduous tooth retention. 
  • Trauma, eg jaw fractures, may result in loss of the permanent tooth bud and there may be retention of the deciduous tooth   Teeth: partial oligodontia 02  .

If there are no signs of the permanent tooth, do not extract the deciduous one - use as long as possible to make up occlusion.

  • Retention of deciduous tooth remnants, caps   Teeth: premolar cap - maleruption / retention  , etc, is affected by head shape. 
  • Horses and ponies with short faces are more predisposed to deciduous tooth retention.
  • Miniature ponies can have severe problems.

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.
  • Tremaine H & Casey M (2012)A modern approach to equine dentistry 2. Identifying lesions.In Pract34(2), 78-89 VetMedResource.

Other sources of information

  • Baker G J (1999)Abnormalities of Development and Eruption.In:Equine Dentistry. Eds: Baker G J & Easley J. W B Saunders, Philadelphia. pp 49-59.
  • Easley J (1999)Equine Tooth Removal (Exodontia).In:Equine Dentistry. Eds: Baker G J & Easley J. W B Saunders, Philadelphia. pp 220-249.
  • Muylle S (1999)Aging.In:Equine Dentistry. Eds: Baker G J & Easley J. W B Saunders, Philadelphia. pp 35-46.
  • Sisson S (1975)Sisson and Grossmans - The Anatomy of the Domestic Animal.Ed: Getty R. 5th edn. W B Saunders, Philadelphia.


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