Page 278 - My FlipBook

148 PATHOLOGY OF THE HARD TISSUES OF THE TEETH.
rapidly in teeth that have been so treated and filled that no
septic matter, saliva, or other extraneous decomposable mate-
rial has reached the dentin, than in those in which the dentin
has been exposed to such material. This much has been clearly
shown by my own examinations of the physical characters of the
teeth. In cases in which there is much abrasion, deposits of sec-
ondary dentin on the walls of the pulp chamber often obliterate,
or very nearly obliterate, the crown portion of the pulp. The
pulpal ends of the dentinal tubules are closed, cutting off the
fibrils of the crown of the tooth from the pulp. Figures 160, 161.
Where this is complete, as often occurs, the crown of the tooth
has lost its vitality and undergoes degeneration, the same as in
teeth that have lost their pulps. Often the deterioration will be
greater in these, because, apparently, of the wide area of dentin
exposed to the fluids of the mouth. A perfect enamel covering,
or, in case of a cavity, a perfect filling, serves to limit deteriora-
tion. Filling operations in such teeth should always be con-
ducted on the hypothesis that they are, or will become, less strong
than normal.
How, when and by what agency are the dentinal fibrils
destroyed in dental caries? This question has often been asked
and variously answered, but I know of no answer based upon
evidence that seems to me conclusive. My own conclusion,
derived from combined clinical and laboratory study, has been
that the fibrils are practically destroyed between the line of
beginning solution of calcium salts and the invasion of micro-
organisms. In other words, that the death of the fibrils is not
the result of actual contact of organisms, but always a little in
advance of them. Also that many of the fibrils — not all — are
destroyed for a considerable distance in advance of the softening
process, or even to the pulp itself, and that this, in some way,
produces the flamelike cloud or hyaline area of Tomes, streaking
away toward the pulp from a carious area. This whole subject,
however, will require much close investigation before it is satis-
factorily made out.

OBTUNDING SENSITIVE DENTIN.
The treatment of sensitive dentin for the purpose of reliev-
ing or limiting the pain in the excavation of cavities, has been
prominently before the dental profession since the first discovery
of anassthesia, and, perhaps, for many years before that time.
Personally, I have watched the progress of this effort through