Journal of Dental Research, Vol 67, 1254-1256, Copyright © 1988 by International & American Associations for Dental Research Online Journals
Improvement of the caries resistance of human dental roots by a two-step conversion of the root mineral into fluoridated hydroxylapatite
P. M. Hoppenbrouwers, E. Groenendijk, N. R. Tewarie and F. C. Driessens
Dental School, University of Nijmegen, The Netherlands.
Roots of extracted human molars were treated for both 10 and 30 min with a
saturated solution of dicalcium phosphate dihydrate (DCPD) of pH 2.4 and
subsequently with a 5.3 mmol.L-1 solution of sodium fluoride of pH 7.0. The
objective of these combined treatments was to convert the highly-soluble
root mineral into the less-soluble fluoridated hydroxylapatite, with DCPD
as an intermediate, to improve caries resistance. The mineral content of
the surface layer was not affected in a significant way. Roots treated in
this way were subjected to 50 mmol.L-1 acetate buffer solutions of pH 5.5
and with pIOHA-values of 112, 116, and 122. The proportional reduction of
the rate of demineralization (Vdem) of similarly treated roots subjected to
buffer solutions of pIOHA 112 and 116 appeared to be equal initially. Since
fluoridated hydroxylapatite is insoluble under these conditions, these
findings are in agreement with expectations. The reduction of V dem
amounted to about 45 and 70% for roots treated for 10 and 30 min,
respectively. When roots were treated for 10 and 30 min and then exposed to
buffer solutions with a pIOHA 122, reductions of V dem of about 30 and 55%,
respectively, were found. Conversion of the root mineral into fluoridated
hydroxylapatite can eliminate, in principle, the existing difference in
caries susceptibility of the root and of the dental enamel.
