Pathological studies of cheek teeth apical infections in the horse: 1. Normal endodontic anatomy and dentinal structure of equine cheek teeth.

Morphological examinations were performed on 100 normal equine cheek teeth (CT) of 1-12 years dental age (i.e. time since eruption), using gross examination, dissection microscopy, computerised axial tomography, and decalcified and undecalcified histology. The CT in Triadan 07-10 positions consistently had five pulp horns, but the 06 CT had an additional pulp horn more rostrally. Mandibular and maxillary Triadan 11s had six and seven pulp horns, respectively. Sections of CT taken 2-6mm below the occlusal surface (variation due to normal undulating occlusal surface) showed the presence of pulp in up to 50% of individual maxillary CT pulp horns, and in up to 25% of individual mandibular CT pulp horns. The histological appearances of primary and secondary dentine were described and it is proposed that the type of dentine present most centrally in every pulp chamber examined, currently termed tertiary dentine, should be re-classified as irregular secondary dentine, and that the term tertiary dentine be reserved for the focal areas of dentine laid down following insult to dentine or pulp.