Page 184 - My FlipBook

168 HUNTER ON THE TEETH.
supposed to have been owing to the deficiency of nourish-
ment from some fault in the vascular system ; but as it begins

mate cause of dental gangrene is inflammation ; and the following
appears to me to be the manner in which it takes place ; when from
cold or any other cause, a tooth becomes inflamed, the part which
suffers the most severely, is unable, from its possessing compara-
tively but a small degree of vital power, to recover from the
effects of inflammation ; and mortification of that part is the
consequence." (1)
Oudet refers the production of caries to original imperfections
in the structure of the dentine, its progress is from within out-
wards, and it is often hereditary. " Caries proceeds from within
outwards. Injured in its vitality, by means which escape our notice,
but which must sometimes affect the pulp, whose delicate tissues
do not enable it to resist the external agents with which the teeth come
in contact, the ivory (dentine) becomes the seat of alterations, which
affect its colour, and the cohesion of its molecules. It becomes of a
yellow or brown colour, and softens in consequence of the changes
which have taken place in it. Greatly altered in its texture and its
composition, it acquires new chemical properties, and becomes an agent
of destruction to the surrounding tissues. The change in the ivory
soon extends to the enamel, gradually invading it as it spreads to the
surface of the tooth. It excavates a cavity which enlarges with the pro-
gress of the disease, reduces the enamel to its superficial layers, until
this substance, deprived of support, breaks away and discovers the
caries." (2)
In order to account for these internal changes in the structure of the
dentine, Oudet gratuitously assumes that an acid is generated in the
imperfectly formed tissue which becomes the agent of its destruction.
Mr. Robertson may be taken as the exponent of the chemical theory
of caries, and has employed many ingenious arguments to prove its
correctness ; but which are summed up in the following passages.
" From the review which we have just taken of decay in the different
classes of teeth, it will be perceived that, in regard to situation, it takes
place on the surfaces of the teeth, in excavations found in them and the
projecting gum, in cavities, indentations, and irregularities on the exter-
nal substance of the tooth itself, and it occurs at their sides, in their

(1) The Anatomy, Physiology, and Diseases of the Teeth, by Thomas Bell,
F.R.S. Second Edition. P. 126. London, 1835.
(2) Recherches sur les Dents et sur leurs Maladies. Par J. E. Oudet, p. 75,
Paris, 1862.