Journal of Dental Research, Vol 70, 1371-1374, Copyright © 1991 by International & American Associations for Dental Research Online Journals
A quantitative analysis of mineral loss and shrinkage of in vitro demineralized human root surfaces
J. M. Ten Cate, B. Nyvad, Y. M. Van de Plassche-Simons and O. Fejerskov
Department of Cariology & Endodontology, Academic Centre for Dentistry Amsterdam, The Netherlands.
Demineralization of dentin specimens proceeds at a faster rate than that of
enamel. Although this is generally accepted, a quantification of the rate
of formation of root lesions is hampered by the shrinkage of the lesions
when these are dried prior to microradiographic analysis. This leads to a
significant underestimation of the lesion depth and total mineral loss. The
aim of this paper was to quantitate the rate of mineral loss during root
lesion formation in vitro and to determine the shrinkage of root specimens
as a result of drying. Unerupted roots of human teeth were subjected to a
demineralizing system of 0.1 mol/L lactate buffer (pH = 4.8) with 0.2
mmol/L methanehydroxydiphosphonate during four, 11, 22, and 44 days. The
root lesions were assessed by quantitative microradiography. The
demineralizing solutions were analyzed to determine the amounts of root
tissue dissolved. A comparison of these two sets of data showed that, with
the demineralizing system used, root lesions may shrink up to 62%. Fixation
of the specimens in fixative did not affect this shrinkage. Chemical
analysis showed that mineral loss proceeded linearly with time. From the
data-sets of this study, a model was developed to compensate for the
shrinkage in the dentin specimens. In this way, it was possible to
calculate the lesion depth at four demineralization times as being 130,
220, 320, and 530 microns, respectively. These values were in agreement
with a microscopic determination of the lesion depth.
