Journal of Dental Research, Vol 75, 949-954, Copyright © 1996 by International & American Associations for Dental Research Online Journals
Transmission electron microscopy of cementum crystals correlated with Ca and F distribution in normal and carious human root surfaces
H. Tohda, O. Fejerskov and T. Yanagisawa
Department of Ultrastructural Science, Tokyo Dental College, Chiba City, Japan.
Root-surface caries, like enamel caries, develops as a subsurface type of
mineral loss. Very little is known about the composition of the surface
zone covering the body of the lesion, and the ultrastructure and
composition of carious cementum are not known. The aim of this study was to
correlate the ultrastructure and arrangement of the cementum crystals with
the distribution of fluoride and calcium in root cementum from human teeth
with sound, unexposed, or exposed root surfaces as well as in early stages
of root-surface caries. Microradiographically, unexposed specimens showed a
relatively homogeneous mineral distribution contrasting with the formation
of an apparently highly mineralized surface layer in exposed and, in
particular, in carious cementum. The electron-probe findings showed a
substantial fluoride peak corresponding to the surface layers in carious
tissues in particular, whereas the calcium profile in the surface did not
reflect the apparent increase in mineralization. A substantial increase in
size of the cementum crystals was found in specimens with formation of the
fluoride-rich, well-mineralized surface zone. The crystal lattice intervals
when observed along the (001) plane showed a hydroxyapatite spacing. The
findings indicated that a significant crystal growth can be achieved in
human cementum concomitant with fluoride accumulation.
