Division of Veterinary Clinical Studies, The Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Veterinary Centre, Midlothian EH25 9RG, UK.
Equine Vet J. 2010 Mar;42(2):119-23. doi: 10.2746/042516409X475409.
There is limited knowledge on the thickness of subocclusal secondary dentine in equine cheek teeth (CT).
Subocclusal secondary dentine is of consistent thickness above different pulp horns in individual horses and its thickness increases with age.
408 permanent CT were extracted post mortem from 17 horses aged 4-30 years, with no history of dental disease. The CT were sectioned longitudinally in the medio-lateral (bucco-palatal/lingual) plane through each pulp horn, and the thickness of the secondary dentine overlying each pulp horn was measured directly.
The subocclusal thickness of secondary dentine above the pulp horns of CT varied from a mean thickness (above all pulp horns) of 12.8 mm (range 5-33 mm) in a 4-year-old to 7.5 mm (range 2-24 mm) in a 16-year-old horse. There was wide variation in the depth of subocclusal secondary dentine above different pulp horns, even within the same CT. In contrast to expectations, occlusal secondary dentine thickness did not increase with age. There were no significant differences in occlusal secondary dentine thickness between rostral and caudal, or medial and lateral aspects of the CT, or between contralateral CT. Mandibular CT had significantly thicker subocclusal secondary dentine than maxillary CT. Pink coloured secondary dentine was sometimes found 1-3 mm occlusal to the pulp horn in sectioned CT and this was likely caused by artefactual blood staining from the underlying pulp during sectioning.
The thickness of subocclusal secondary dentine varies greatly between individual pulp horns, teeth and individual horses and can be as low as 2 mm over individual pulp horns.
Due to the great variation in the thickness of subocclusal secondary dentine between horses, and even between pulp horns in individual CT, there is a risk of exposure or thermal damage to pulp and thus of apical infection, even with modest therapeutic reductions of CT occlusal overgrowths. In the light of these findings, great care should be taken when reducing equine CT overgrowths and larger dental overgrowths should be reduced in stages.
马属动物颊齿（CT）的下闭塞继发牙本质厚度知之甚少。
在下闭塞继发牙本质中，不同牙髓角的厚度是一致的，并且随着年龄的增长而增加。
从 17 匹年龄在 4-30 岁之间、无牙科疾病史的马中死后提取了 408 颗永久性 CT。CT 沿颊腭/舌向中线平面进行纵向切片，通过每个牙髓角，直接测量覆盖每个牙髓角的继发牙本质的厚度。
CT 牙髓角上方下闭塞继发牙本质的厚度，从 4 岁马的平均厚度（所有牙髓角上方）12.8 毫米（范围 5-33 毫米）到 16 岁马的 7.5 毫米（范围 2-24 毫米）不等。即使在同一 CT 中，不同牙髓角上方下闭塞继发牙本质的深度也存在很大差异。与预期相反，随着年龄的增长，牙合面继发牙本质的厚度并没有增加。CT 的颅侧和尾侧、内侧和外侧、对侧之间的牙合面继发牙本质厚度无显著差异。下颌 CT 的下闭塞继发牙本质明显比上颌 CT 厚。在切片 CT 中，有时在牙髓角 1-3 毫米处可见粉红色的继发牙本质，这可能是由于在切片过程中来自下方牙髓的人为血液染色造成的。
个体牙髓角、牙齿和个体马之间下闭塞继发牙本质的厚度差异很大，个别牙髓角的厚度甚至可低至 2 毫米。
由于马之间以及个别 CT 中不同牙髓角之间下闭塞继发牙本质厚度的巨大差异，即使是对 CT 牙合面过度生长进行适度的治疗性减小，也存在牙髓暴露或热损伤以及根尖感染的风险。鉴于这些发现，在减小马属动物 CT 过度生长时应格外小心，对于较大的牙生长过度，应分阶段进行减小。
