A morphometric analysis of the cross-sectional area of dentine occupied by dentinal tubules in human third molar teeth.

The number and the mean percentage tubular cross-sectional area of dentinal tubules per square millimetre were calculated in specimens of coronal dentine of 13 intact human third molar teeth from patients 18 to 28 years of age. The dentine was fractured at various known distances from the dentino-enamel junction. Near the dentino-enamel junction the number of tubules per square millimetre was 22,000 and the mean tubular cross-sectional area was 3.6%. Midway between the pulpal wall and the dentino-enamel junction the number of tubules was 37,000 mm-2 and the mean tubular cross-sectional area was 6.2%. Close to the pulp the number of dentinal tubules was 48,000 mm-2 and the mean cross sectional area of tubules was 10.2 percent. The number of tubules per square millimetre more than doubled and the area occupied by tubules increased threefold from the dentine close to the dentine-enamel junction, to that close to the pulp. These differences in tubular patterns at different depths in dentine are clinically significant in dentine permeability, the treatment of traumatized teeth, and pain transmission in dentine.