Morphological characterization of tube-like structures in hypersensitive human radicular dentine

Objectives: The objective of this work was to determine if there were differences in the distribution of tube-like structures within the tubules of biopsies from hypersensitive versus non-sensitive human cervical radicular dentine. Method: Ten pairs of dentine were made from the exposed sensitive and non-sensitive radicular dentine of nine adult patients complaining of dentine sensitivity. The biopsies were made with a small hollow diamond bur. The specimens were submitted to HCl-collagenase treatment to partially digest the surface to permit visualization of subsurface structures. Half of the specimens were embedded in resin to facilitate longitudinal sectioning, and the other half were processed with embedding for SEM and EDS observation. Results: Biopsies from hypersensitive regions exhibited hollow, tube-like structures within the lumina of dentinal tubules in 75.8 +/- 9.4% ((x) over bar +/- S.D.) of the tubules. In biopsies of non-sensitive areas of the same teeth, these tube-like structures were only seen in 20.4 +/- 8.5% of the tubules. In specimens that were embedded prior to treatment with HCl-collagenase, resin tags penetrated many of the tubules from hypersensitive dentine but few of the tubules from non-sensitive dentine. Conclusion: It is speculated that tube-like structures found in hypersensitive dentine play a role in maintaining the patency of the tubules which may prevent physicochemical processes from spontaneously occluding the tubules, thereby maintaining dentine sensitivity.