Page 236 - My FlipBook

208 THE MICRO-ORGANISMS OF THE HUMAN MOUTH.

sugar (saccliarose) and milk-sugar become fermentable only after
hydratizatiou.
C,Afin + H2O = CJI,,0, -f C,II,,0,. CeH^^O, = 20311,03
Ciine-sugar. Dextrose. Levulose. Lactic acid.
There seems to be no considerable difference of time in respect
to tbe beginning of the fermentation of the grape-sugar and
cane-sugar groups : the one is apparently about as detrimental
to the teeth as the other.
Fermentable albuminous substances mixed with saliva de-
velop but small quantities of acid, which soon disappear. They
are not injurious to the teeth, even though retained for some
length of time ; they may even retard the progress of decay by
neutralizing the acid through their alkaline products. The most
diverging opinions prevail in regard to the participation of differ-
ent substances in fermentations arising in the mouth, none of
which rest on solid foundations. Above all, the conception that
albuminous substances (meat) putrefying in the mouth produce
acids is totally erroneous.
The facts mentioned on pages 27 and 115 cannot leave us in
doubt on this point. It seemed to me desirable, however, to
refute the above views experimentally, and at the same time to
establish the relative significance of different carbohydrates as
acidifiers. For this purpose I made over two hundred experi-
ments with human saliva, and also a few with the saliva of dogs
and rabbits. 4.0 c.cm. of fi'esli saliva were mixed ^^dth 0.5 g. of
the food to be tested, and the reaction as well as the quantity
of free acid determined after the lapse of a certain time.
The results obtained are given in the following table. The
" acid unit" signifies that quantity of acid which is necessary to
neutralize 0.1 c.cm. of a 0.5 per cent, solution of caustic potash.

Material. Duration of experiment. Acid formed in acid units
Bread (dry) . .12 and 30 hours 22 and 72
Starch 20 a 42
Oana-sugar 17 li 37
Grape-sugar 19 4( 40
Potato (boiled) 24 11 75
a
Oorn (in milk) 24 77