Pathological studies of cheek teeth apical infections in the horse: 2. Quantitative measurements in normal equine dentine.

Measurements of primary, regular and irregular secondary dentine and pulp dimensions were made on transverse, sub-occlusal and mid-tooth sections, of 40 maxillary and 42 mandibular control equine cheek teeth (CT) of different ages. Maxillary and mandibular CT primary dentine in different age groups had a mean thickness of 922-1,065 microm and 1099-1,179 microm, respectively, on the lateral aspects, and 1,574-2,035 microm and 1155-1,330 microm, respectively, on the medial aspects of pulp horns. Surprisingly, some increase in thickness was found in some mandibular CT primary enamel in the first few years following eruption. Regular secondary dentine thickness increased with age, for example at mid-tooth level in mandibular CT from 124 microm at 3 years dental age to 290 microm at >7 years dental age on the lateral aspect of pulp horns, and from 166 microm to 509 microm on the medial aspects of pulp horns, indicating a deposition rate of 0.5-10 microm/day. This type of dentine was thicker sub-occlusally than in the mid-tooth region. Maxillary dentinal dimensions showed a similar age-related increase in thickness. Maxillary CT dentine was significantly thicker (72% in primary, 43% in regular secondary dentine) on the medial compared to the lateral aspects of pulp horns, but mandibular CT dentine was just 15% and 14% thicker in primary and regular secondary dentine thickness, respectively, on the their medial as compared to their lateral aspects. Dentinal and pulp dimensions varied between individual pulp horns, Triadan tooth position, and dental age, with complex interactions between these variables for some parameters.