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BIOLOGICAL STUDIES ON FUNGI OF HUMAN MOUTH. 827
4. The po.ssession of a peptonizing action by a large number of these
fungi readily accounts for the solution of the decalciiied dentine.^
5. Any one of these fungi which can produce acid by fermentation of
carbohydrates or can dissolve the decalciiied dentine may aid in the pro-
duction of caries, while any one which combines both
these properties—as many of them do—may alone Fig. 437.
bring about the phenomenon of dental caries. A solu-
tion of the dentine or enamel without previous decalci-
fication cannot take place. The fact which I have so
often affirmed, and which was denied by Milles and
Underwood—that one continually meets with large
tracts of softened, non-infected dentine—has been com-
pletely confirmed by Arkovy and Matrai. They say : '' The invasion
extends, however, only to a certain depth, and only isolated tubules
show a deeper invasion, sometimes to twice the depth, and reach the
border of the normal dentine," the whole territory between the isolated
tubules being free from invasion.
6. The comparative or complete independence of many of these
organisms of the free access of air renders their propagation within
the dentine or under fillings M^here softened, non-
Fig. 438. sterilized dentine has been left an easy matter.
7. The fact that dentine and enamel form so
exceedingly poor culture substrata for schizomy-
cetes is an additional proof of the position that
their attack upon the teeth is only secondary
i. e. they owe their rapid devel-
Fig. 439.
opment to the secretions, deposits,
etc. of the oral cavity ; and not
until the tissue of the tooth has
undero^one a certain change—first
decalcification, second peptoniza-
tion—can they adapt it to their
nourishment. The decalcification
is produced chiefly by acid resulting from the action of the organisms
upon certain carbohydrates in the human mouth, while the peptoniza-
tion is produced either by the direct action of the protoplasm of the
organisms upon the decalcified dentine or by the action of a ferment
which they produce.
A knowledge of the properties of the fungi of the human mouth, as
' Not a little confusion has been introduced by attempted artificial definitions of
putrefaction and fermentation. The idea that every chansje in nitrogenous organic
substances must be of the nature of putrefaction is particularly misleading. A ferment
of the nature of pepsin which dissolves coagulated albumen is widely distributed among
the fungi of fermentation as well as putrefaction, and the schizomycetes in general
require nitrogenous substances in some shape for their nutrition. The dissolution of
the organic portion of dentine is by no means dependent upon tlie ])res'^nce of
putrefactive organism, but may be accomplished equally well by fermentation. As
previously stated, I never found a putrefactive organism in the deeper portions of carious
dentine. Moreover, the acid reaction of carious dentine is highly unfavorable to the
development of such organisms. I intend to repeat and extend my experiments on
this point. The presence of putrefactive organisms, while it would accelerate the sec-
ond stage of caries, could only retard the first.
BIOLOGICAL STUDIES ON FUNGI OF HUMAN MOUTH. 827
4. The po.ssession of a peptonizing action by a large number of these
fungi readily accounts for the solution of the decalciiied dentine.^
5. Any one of these fungi which can produce acid by fermentation of
carbohydrates or can dissolve the decalciiied dentine may aid in the pro-
duction of caries, while any one which combines both
these properties—as many of them do—may alone Fig. 437.
bring about the phenomenon of dental caries. A solu-
tion of the dentine or enamel without previous decalci-
fication cannot take place. The fact which I have so
often affirmed, and which was denied by Milles and
Underwood—that one continually meets with large
tracts of softened, non-infected dentine—has been com-
pletely confirmed by Arkovy and Matrai. They say : '' The invasion
extends, however, only to a certain depth, and only isolated tubules
show a deeper invasion, sometimes to twice the depth, and reach the
border of the normal dentine," the whole territory between the isolated
tubules being free from invasion.
6. The comparative or complete independence of many of these
organisms of the free access of air renders their propagation within
the dentine or under fillings M^here softened, non-
Fig. 438. sterilized dentine has been left an easy matter.
7. The fact that dentine and enamel form so
exceedingly poor culture substrata for schizomy-
cetes is an additional proof of the position that
their attack upon the teeth is only secondary
i. e. they owe their rapid devel-
Fig. 439.
opment to the secretions, deposits,
etc. of the oral cavity ; and not
until the tissue of the tooth has
undero^one a certain change—first
decalcification, second peptoniza-
tion—can they adapt it to their
nourishment. The decalcification
is produced chiefly by acid resulting from the action of the organisms
upon certain carbohydrates in the human mouth, while the peptoniza-
tion is produced either by the direct action of the protoplasm of the
organisms upon the decalcified dentine or by the action of a ferment
which they produce.
A knowledge of the properties of the fungi of the human mouth, as
' Not a little confusion has been introduced by attempted artificial definitions of
putrefaction and fermentation. The idea that every chansje in nitrogenous organic
substances must be of the nature of putrefaction is particularly misleading. A ferment
of the nature of pepsin which dissolves coagulated albumen is widely distributed among
the fungi of fermentation as well as putrefaction, and the schizomycetes in general
require nitrogenous substances in some shape for their nutrition. The dissolution of
the organic portion of dentine is by no means dependent upon tlie ])res'^nce of
putrefactive organism, but may be accomplished equally well by fermentation. As
previously stated, I never found a putrefactive organism in the deeper portions of carious
dentine. Moreover, the acid reaction of carious dentine is highly unfavorable to the
development of such organisms. I intend to repeat and extend my experiments on
this point. The presence of putrefactive organisms, while it would accelerate the sec-
ond stage of caries, could only retard the first.
