Journal of Dental Research, Vol 73, 1197-1204, Copyright © 1994 by International & American Associations for Dental Research Online Journals
Occlusion of dentinal tubules with calcium phosphate using acidic calcium phosphate solution followed by neutralization
K. Ishikawa, T. Suge, M. Yoshiyama, A. Kawasaki, K. Asaoka and S. Ebisu
Department of Dental Engineering, School of Dentistry, Tokushima University, Japan.
The occlusion of dentinal tubules with calcium phosphate, by a calcium
phosphate precipitation method (CPP method), was investigated in vitro for
evaluation of the potential value of this method for the treatment of
dentin hypersensitivity. The method consists of treating the dentinal
surface with a CPP solution, i.e., an acidic solution that contains both
calcium and phosphate, followed by neutralization with basic post-treatment
solution. The CPP solutions used in this study ([Ca] = 0.2 - 1.0 mol/L,
[PO4] = 0.2 - 4.0 mol/L) were prepared by dissolving Ca(OH)2 or CaHPO4 x
2H2O in H3PO4 or HCl, and 1 mol/L NaOH solution was used for the
post-treatment solution. Sections of human dentin disks treated by the CPP
method were observed by scanning electron microscopy, and the precipitate
in the dentinal tubules was subjected to x-ray micro-analysis. After
treatment by the CPP method, dentinal tubules were occluded to a distance
of approximately 15 microns from the surface, and the precipitate showed a
Ca/P molar ratio of 1.03 +/- 0.01 To obtain a larger amount of precipitated
mineral for further analysis, we used the same procedure with glass tubes
(inside diameter, 1 mm). Powder x-ray diffraction analysis and FT-IR
measurement revealed that the precipitate was dicalcium phosphate dihydrate
(CaHPO4 x 2H2O). The instant precipitation of calcium phosphate mineral in
the dentinal tubules demonstrated the potential value of the CPP method for
the occlusion of dentinal tubules, this occlusion may be useful for the
treatment of dentin hypersensitivity.
