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NODULAR DENTINE. 913
diet-table, so far as the nutrition of their teeth is concerned, is the un-
usual number of cases of arrested caries and the formation of so-called
secondary dentine As showing still further the abundance of
bone-forming material with which the blood is supplied, I have re-
moved in two cases large pulp-nodules from the sixth-year molars of
children not over eleven years of age."
Without extending the argument farther, it may be assumed that the
facts warrant the opinion that the new formation in the tubuli is in
direct ratio to the density.
The eifect of irritation is well known to be a cause of new formations.
The increased development of the cementum at the apex of roots
familiarly known as exostosis—is produced by a slight irritation, as the
wearing of a plate over a root, the jar of clasps attached to a plate, the
malocclusion of teeth, etc., etc. On the other hand, an excessive irrita-
tion produces absorption or destructive pathological conditions. Rea-
soning from this well-understood fact, it would be expected that the law
of hypertrophy, as applied to bone, would give equal results with den-
tine, so nearly allied to it in character. The very familiar example of
the wearing away of the anterior teeth furnishes us with an answer to
this proposition. New formations proceed equally in proportion to
wear, provided that wear is not too rapid. If the process is very slow,
secondary dentine will develop gradually until the entire coronal pulp
is obliterated and the tooth worn down to the gum-border. On the
other hand, if too rapid, the pulp is quickly exposed. This is exactly
a repetition of the before-mentioned result in slow caries. The progress
of the disease produces an amount of irritation to develop new forma-
tion. In medium- or soft-structured teeth this is not possible ; hence
rapid destruction.
AVhen we extend this familiar process of formation and destruction to
the growth of new formations of the pulp, we are led at once to the
conclusion that irritation is the principal—though possibly not the only
—cause of secondary deposits. It is very probable that the process of
mastication has very much to do with nutrition and increased inorganic
deposits. It has long been observed that those teeth in constant use are
more perfectly formed and resist caries better than (hose rarely brought
under the forces of mastication. This can be accounted for only by the
constant jar and slight irritation producing the before-mentioned result.
It has yet to be demonstrated by actual observation whether these teeth
are more liable to nodular calcifications than others, but theoretically this
should be the case.
The effect of caries in producing new formations in direct line with
the disease is beautifully shown in an illustration from Schlenker.^ In
this case the new formation is clearly the result of irritation carried
through the tissue and proceeding in proportion to the caries. The
same result is seen in Fig. 482, from the same author, in which the new
formation extends over a still greater surface. By the wear from a
clasp, a metal filling, especially gold, may produce a similar result by
the constant, though slight, irritation through changes of temperature.
A similar effect is usually expected from capping pulps ; but this expec-
' Untersuchungen iiber die Verknocherung der Zahnnerven. Vierteljahrsschrift. f. Z.
Vol. I.—68
NODULAR DENTINE. 913
diet-table, so far as the nutrition of their teeth is concerned, is the un-
usual number of cases of arrested caries and the formation of so-called
secondary dentine As showing still further the abundance of
bone-forming material with which the blood is supplied, I have re-
moved in two cases large pulp-nodules from the sixth-year molars of
children not over eleven years of age."
Without extending the argument farther, it may be assumed that the
facts warrant the opinion that the new formation in the tubuli is in
direct ratio to the density.
The eifect of irritation is well known to be a cause of new formations.
The increased development of the cementum at the apex of roots
familiarly known as exostosis—is produced by a slight irritation, as the
wearing of a plate over a root, the jar of clasps attached to a plate, the
malocclusion of teeth, etc., etc. On the other hand, an excessive irrita-
tion produces absorption or destructive pathological conditions. Rea-
soning from this well-understood fact, it would be expected that the law
of hypertrophy, as applied to bone, would give equal results with den-
tine, so nearly allied to it in character. The very familiar example of
the wearing away of the anterior teeth furnishes us with an answer to
this proposition. New formations proceed equally in proportion to
wear, provided that wear is not too rapid. If the process is very slow,
secondary dentine will develop gradually until the entire coronal pulp
is obliterated and the tooth worn down to the gum-border. On the
other hand, if too rapid, the pulp is quickly exposed. This is exactly
a repetition of the before-mentioned result in slow caries. The progress
of the disease produces an amount of irritation to develop new forma-
tion. In medium- or soft-structured teeth this is not possible ; hence
rapid destruction.
AVhen we extend this familiar process of formation and destruction to
the growth of new formations of the pulp, we are led at once to the
conclusion that irritation is the principal—though possibly not the only
—cause of secondary deposits. It is very probable that the process of
mastication has very much to do with nutrition and increased inorganic
deposits. It has long been observed that those teeth in constant use are
more perfectly formed and resist caries better than (hose rarely brought
under the forces of mastication. This can be accounted for only by the
constant jar and slight irritation producing the before-mentioned result.
It has yet to be demonstrated by actual observation whether these teeth
are more liable to nodular calcifications than others, but theoretically this
should be the case.
The effect of caries in producing new formations in direct line with
the disease is beautifully shown in an illustration from Schlenker.^ In
this case the new formation is clearly the result of irritation carried
through the tissue and proceeding in proportion to the caries. The
same result is seen in Fig. 482, from the same author, in which the new
formation extends over a still greater surface. By the wear from a
clasp, a metal filling, especially gold, may produce a similar result by
the constant, though slight, irritation through changes of temperature.
A similar effect is usually expected from capping pulps ; but this expec-
' Untersuchungen iiber die Verknocherung der Zahnnerven. Vierteljahrsschrift. f. Z.
Vol. I.—68
