Electron microscopy of dentinal tubule sclerosis in the enamel-free region of the rat molar.

Ultrastructural changes in dentinal tubule contents were followed for periods up to 6 weeks following tooth eruption into the mouth. Characteristic odontoblast processes were observed in some tubules throughout the enamel-free dentine. Many dentinal tubules contained shrunken odontoblast processes, large collagen fibres and/or accumulations of mineral in various forms. The mineralization patterns suggest mechanisms of tubule occlusion other than simple formation of peritubular dentine. Both the degenerating odontoblast processes and collagen fibres appear to provide an organic framework for deposition of mineral. This region of rat molar dentine is recommended as useful for study of naturally-occurring tubular sclerosis.