Page 246 - My FlipBook

218 THE MICRO-OEOANISMS OF THE HUMAN MOUTH.

assume an acid reaction ; tliese are both excitino; causes of decay.
Pregnancy itself can only be regarded as a predisposing cause
in so far as it effects a loosening of the gums or a change in the
structure of the teeth by a withdrawal of the lime-salts to build
up the fcEtal skeleton. Whether such an extraction takes place
has not been definitely ascertained.
7. Many believe that a predisposition to caries may be inher-
ited. It cannot be denied that badly developed, irregular teeth
may be and are inherited, and in so far inheritance may be con-
sidered as a predisposing cause of caries.
8. Wedl, Tomes, and others mention as predisposing causes
various general diseases, as rheumatism, gout, diabetes, gastro-
enteritis, dyspepsia, cancer of the stomach, scrofula, rachitis, and
tuberculosis. These diseases may indeed furnish the exciting
causes of caries by imparting an acid reaction to the buccal
juices, but how they can predispose the teeth themselves to caries
is not readily apparent, unless they render them more easy of
access to the exciting causes by concomitant gum-diseases as
described under 5.
I doubt whether climatic or geological conditions have much
to do with the origin of caries. Esquimaux, Lapps, Icelanders,
Arabs in Nubia, Patagonians, etc., have the best teeth in spite
of unfavorable climatic conditions.

INFLUENCE OF CIVILIZATION ON DECAY.
That decay of the teeth is not a disease peculiar to civilization
is proved by the manifold observations which have been made
on the skulls of ancient and modern uncivilized races in Europe
and America. A visit to any anatomical or anthropological
museum and an examination of a large number of race-skulls
will convince every one of the correctness of this assertion. Such
examinations have been made by Broca, Magitot,^^ Mummery ,^^
Barrett,^^ myself,'^ and many others, and invariably led to the
same conclusion, that decay has occurred in all races, civilized
i/
as well as uncivilized, and at all times.
Races subsisting solely on meat (Greenlanders, etc.) come near
forming an exception to the rule, yet they appear to be not abso-
lutely exempt from decay. (See page 221.)