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CHAPTER VII.
PRELIMINARY PREPARATION OF CAVITIES—TREATMENT
OF HYPERSENSITIVE DENTIN BY SEDATIVES, OBTUND-
ENTS, LOCAL AND GENERAL ANESTHETICS—STERILIZA-
TION, WITH A BRIEF CONSIDERATION OF THE PHYSIO-
LOGICAL AND THERAPEUTIC ACTION OF THE MEDICA-
MENTS USED.

By Louis Jack, D. D. S.

Hypersensitive Dentin.
Dentinal hypersensitiveness frequently presents the most serious
impediment to the procedures connected with the treatment of dental
caries. This condition must be considered an exaltation of the normal
sensitiveness of the dentin, and presents a wide range from slight pain
on contact being made to so high a degree of sensitiveness as to be un-
endurable. In the latter instance persons of the greatest capacity for
tolerating pain will shrink from the most careful instrumentation. Im-
mediately upon the opening of a carious cavity there usually are indica-
tions of excitement of the vital elements of the dentin. This con-
dition may be so slight as to present no obstacle to furtlier procedures,
or it may on the other hand be so excessive as to forbid all instru-
mentation until a reduction of the sensitiveness has been effected.
This altered state of the dentin has been considered by some as one
of inflammation of the dentin. As the opportunity does not exist for
the usual concomitants of inflammation as pathologically defined and
whieli arc induced by the alterations of the circulation of the blood,
viz. heat, redness and swelling, with exaltation of nervous function
caused by the additional supjily of arterial blood, the term inflamma-
tion is a questionable one to apply to a hyperesthetic condition of
dentin. This manifestation is more logically explainable as a disturb-
ance caused by changed relations of a tissue which is naturally pro-
tected by the enamel from irritating influences. The relation of the
enamel and the dentin is analogous to that of the epidermal coat of
the skin and the rete mucosum. Pain caused by abrasion of the
epidermis is immediate and acute, and occurs l)efore th(> increased
supply of blood increases the intensity of it. It is hence induced by
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