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CT of Equine Teeth

CT of Equine Teeth. La Dolce Vita ‘90 QH mare. Two most important dental diseases in horses are apical tooth infections and infundibular caries Pathogenesis of both is poorly understood

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CT of Equine Teeth

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  1. CT of Equine Teeth

  2. La Dolce Vita ‘90 QH mare

  3. Two most important dental diseases in horses are apical tooth infections and infundibular caries • Pathogenesis of both is poorly understood • Infundibulum -cup or funnel shaped invagination of enamel from the occlusal surface of incisor and maxillary cheek teeth • Three main infundibularabnormalities • infundibular caries • infundibularcementalhypoplasia (central infundibularcementalhypoplasia and junctionalcementalhypoplasia) • difficult to differentiate hypoplasiavs caries clincally

  4. Caries-disease of the calcified tissues of teeth, action of microorganisms on carbohydrates leads to demineralization, resulting in destruction of the enamel and dentine, and cavitation of the tooth • Rarely, can progress to involve the enamel which, if breached, will contaminate the dentine leading to pulpitis, necrosis and eventually an apical tooth infection • if severe enough, could spread across the dentine to affect the adjacent infundibulum • Advanced infundibular caries may lead to midline sagittal fractures, pulpal and thus apical infections • upper first molar is most commonly involved in apical infections (in horses ~8 years) and an extension of infundibular caries has recently been shown to cause 16% of maxillary apical infections

  5. Cementalhypoplasia • reported to occur in up to 65% of equine maxillary cheek teeth • pathogenesis unknown- vascular disruption? • may predispose to infundibularcaries

  6. 33 clinically normal horses 3-30y Equine vet. J. (2010)

  7. Infundibularcementalhypoplasia was grossly observed in 22% of all infundibula • previously reported to occur in 65% • more subtle changes were likely detected in that study • some abnormalities classified as miscellaneous may have had low grade hypoplasia • Found most commonly in younger horses (29.2% in 3–5 y and 27.1% in 6–11 y) • developmental defect

  8. Many areas of hypoplasticcementum were situated apically, suggesting that loss of vascular supply from this aspect of infundibula may compromise cemental formation • study also confirmed the presence of an apical blood supply to infundibula in younger horses • Consequences of such apically located defects may not appear until later in life when they first become exposed occlusally and infected by oral bacteria • Did not find an obvious relationship between cementalhypoplasiaand cementalcaries • possibly because once areas of cementalhypoplasia communicate with the occlusal surface they become infected and so were carious at the time of examinations

  9. Caries involving the full length of the infundibulawere present in 8.2%, most commonly in horses 12–20 years old • Upper first molars were most commonly affected with extensive caries • 30 times more common • also the most common site of idiopathic fractures • supports the role of caries in the pathogenesis of these fractures • however, idiopathic fractures were most commonly observed in horses aged 9–10 years, whereas in this studycomplete infundibularcaries were most common in older horses

  10. The rostralinfundibulae of this study had a higher prevalence and greater severity of lesions in comparison to the caudal infundibulae • slightly different vascular supply • in previous studies, cementalhypoplasia also occurred most commonly rostrally

  11. A number of teeth 0–4 years post eruption had lesions visible at the occlusal surface of their infundibulae • caries within these infundibulae were only present superficially at the coronal aspect of the infundibulae • infundibulaeof cheek teeth are open when they are erupting • allows for debris, food and bacteria to enter • by 4–6 years post eruption this area of infundibulae is lost by attrition and the apical infundibulaebecome exposed

  12. Other findings • A lot of findings classified as ‘other’ may have actually represented cementalhypoplasia or caries • (58%) of infundibula • centrally located defect at site of former vasculature with darker localized areas of caries or food staining when these were exposed occlusally • others had areas of more porous cementumthat was dark if connected to the occlusalsurface • Majority (88%) of infundibulawere not completely filled with normal appearing cementum • variations in cemental appearance may be normal findings

  13. CT • 126 cheek teeth evaluated with CT • Clinically normal horses 4-20 y • 1mm slices • Graded infundibularlucencies

  14. Increasing age was associated with decreases in: • pulpar volume • due to the deposition of regular secondary dentine on the periphery of the pulp cavity • the number of interpulparcommunications between pulp horns • the distance the pulp extended apically within individual roots • the length of the reserve crown • The number of apical foramina per root increased with increasing age • The apical extension of the enamel around the roots decreased with age • no enamel could be seen around the roots of teeth >15y post eruption

  15. 1.5 yo Equine vet. J. (2009)

  16. Infundibulae • High incidence of infundibular lesions • 2 infundibulae, rostraland caudal • located within the central portion of the occlusal surface of all maxillary cheek teeth • Extension from the occlusal surface varied with age • 0–2 y -the infundibulae extended up ~75% tooth length • >14 y -the infundibulaeextended up ~50% of the tooth length • Radiolucent area of the occlusalsurface in the center of all infundibulae on CT correlated with the infundibularcementum overlying the central vascular channel • also visible on the occlusal surface as a small dark circular area and in normal infundibulaeno surface defect was associated with this area • this radiolucency did not extend apically in normal infundibulae

  17. Only 10% of the infundibulae had no lesions on either grossly on the occlusal surface or CT examination • 65% of infundibulae had lesions on gross occlusal examination alone, compared to 90% on CT examination

  18. Grade 1a Grade 2a Grade 3a Grade 1b Grade 2b Grade 3b Equine vet. J. (2009)

  19. Hypoplasia or caries • In contrast to Henninger et. al, 2003, which stated • ‘Detection of hypoattenuation representing gas was a sign indicative of severe tooth root infection and was always found in combination with infundibular necrosis and pulpitis. In CT images, cementum of inferior quality with encapsuled gas bubbles could be detected in a diseased tooth.’

  20. sectioning of teeth with grade 3 lesions (apical bulbous expansion)revealed obvious necrosis and/or food material within the apical depths of the infundibulae proposed that grade 3 lesions are indicative of infundibular caries and unlikely to be the result of cementalhypoplasia Equine vet. J. (2009)

  21. Although a wide range of infundibularlesions observed, relatively few pulpar lesions were detected • Implies that infundibularcaries are not the most common pathogenesis for apical pulpitis in horses

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