Gross, Computed Tomographic and Histopathological Findings In Mandibular Cheek Teeth Extracted From Horses With Clinical Signs of Pulpitis

Aim: To compare gross, computed tomographic and histological appearances of sectioned mandibular cheek teeth extracted from horses showing clinical signs of pulpitis, and from controls.

Methods: Mandibular cheek teeth extracted from horses showing clinical signs of pulpitis (cases) and from cadavers with no history of dental disease (controls), were imaged using computed tomography in the transverse plane at 1 mm intervals. Teeth were sectioned transversely, photographed and processed histologically. Tomographs were compared to corresponding gross and histological sections. 

Results: Photographs of 188 and 178 gross sections from 18 cases and 15 controls (respectively) were compared to tomographs from corresponding levels in the teeth. Histological sections from 6 cases and 3 controls were compared to gross sections and tomographs. Cement, enamel, dentine and pulp were identifiable grossly and histologically. Cement, dentine and bone had similar ranges of attenuation (550–2000 Hounsfield Units [HU]) in tomographs but could be differentiated from pulp (-400–500 HU) and enamel (2500+ HU). It was not always possible to differentiate primary and secondary dentine grossly or on transverse tomographs. Thirteen discrete dental lesions were identified grossly, 10 of which were characterised histologically. Reactive and reparative dentinogenesis and extensive pulpar calcification, previously undescribed in horses, were identified. Pulpar oedema, neutrophilic inflammation, cement and enamel defects, and reactive cemental deposition were also described. Computed tomographic and pathological findings corresponded well where there was mineralised tissue deposited in the pulpar area or peripherally, defects in mineralised tissue, or food material in the pulpar area. Pulpar and dentinal necrosis and cement destruction, evident grossly and histologically, did not correspond to computed-tomographic changes.

Conclusions: Gross changes in sectioned equine cheek teeth are associated with histological changes. Computed tomography is useful for identifying deposition and defects of mineralised material but less useful for identifying earlier inflammation and tissue destruction. The equine dentin-pulp complex responds to insult with regenerative and reparative changes.

Acknowledgment: The Horse Trust