THE DENSITY AND BRANCHING OF DENTINAL TUBULES IN HUMAN TEETH

Detailed knowledge of dentine structure, and especially that of the de ntinal tubules, is essential in order to understand dentine permeabili ty and to interpret data from investigations on dentine adhesive mater ials. The aim here was to examine the density and branching of dentina l tubules in human teeth by light and scanning electron microscopy. St ained and unstained demineralized sections and undemineralized fractur ed specimens were studied. Statistically significant differences in th e density of tubules were found depending on location. Differences in density of tubules between the peripheral and inner aspects were more marked in the crown than in root. The mean number of dentinal tubules in the middle part of the root was significantly lower than in the mid dle part of the crown. The density of the tubules in the outer dentine at the cusp location was also significantly different from that subja cent to the occlusal fissure. The number of branches of dentinal tubul es was particularly abundant in locations where the density of tubules was low. The branching patterns revealed an intricate and profuse can alicular, anastomosing system, criss-crossing the intertubular dentine . Three types of branches, major, fine and microbranches, were identif ied on the basis of size, direction and location. Major branches, 0.5- 1.0 mu m dia., were the typical delta branchings found peripherally. F ine branches, 300-700 nm dia., forked off at 45 degrees and were abund ant in areas such as in the root where the density of the tubules was relatively low. Microbranches, 25-200 nm dia., extended at right angle s from the tubules in all parts of the dentine. The findings emphasize the need for detailed characterization of dentine substrates for adhe sive testing and of samples used in permeability studies. Copyright (C ) 1996 Elsevier Science Ltd.