Page 147 - My FlipBook

CARIES OF DENTIN. 73
This has been found in the examination of some of the older
Indian remains, especially of those tribes that were supposed
to eat much parched corn. The food forced through the cavity
in mastication and out through the broken side kept the surface
worn smooth. The opportunity to know and to watch this among
our own people occurs frequently.
The question as to whether caries is produced by a single
species of microorganism or whether a number of kinds are
acting together is often asked. As to this, there are several
organisms found in the saliva of practically every person that
have physiological characters which seem to fit them for the
production of caries, and no reason is known why they may not
be acting together in the same carious cavity. Dr. Miller seems
to have found them so. In the deepest portion of the carious
area I have usually found but a single variety, the streptococcus.
In the decaying mass, however, pretty much all of the varieties
found growing in the mouth may be found and some of them
penetrate deeply into the softened portion. Especially a white
staphylococcus is often found deep in the dentinal tubules, if
judged of by the difficulty of keeping clear of it in the effort to
get a pure culture of the streptococcus from carious dentin.
Note.— I have often spoken of this staphylococcus as the zigzag coccus, because
of its habit of forming zigzags in its growth in broth. One coccus of a pair divides
on the opposite pole from that upon which the pair has divided, making a square
turn instead of a straight or curved line, as is the more usual habit of the strepto-
cocci. This organism dissolves gelatin freely in artificial culture. It is frequently
found in suppurating pulps and in alveolar abscess, yet it will generally fail to pro-
duce pus when animals are infected with it. It is probably the white staphylococcus
pyogenes modified by continuous residence in the saliva. The streptococcus spoken
of above I have often called "caries fungus," or "streptococcus media," the latter
because of finding larger and smaller varieties occasionally in the saliva. These are
hardly found so continuously as to make the latter term a good one.