Page 164 - My FlipBook

Miller, in his experimental work, decalcified teeth, boiled
the remaining portion and obtained the gelatin—for this matrix
is a glue-giving substance—from these teeth, and planted these
micro-organisms upon it, giving them no other means of nutri-
tion than this gelatin, and he found that they would grow and
develop upon this, the only nutriment they had. Now, this
organic matrix of the dentin, then, is slowly digested, and
serves as the food for the micro-organisms that are growing
there. They have other food, however ; they have more or less-
sugar and starchy material, that percolates into the cavity ;.
otherwise they would form no acids, for these micro-organisms
must have the hydrocarbons in some such form in order to
form an acid-waste product. They form other waste prod-
ucts, however. How poisonous these may be we do^ not know,,
but from close observations the indications are that those other
waste products are poisonous to the tissues, for a pulp becomes
inflamed when it becomes exposed to the carious process, even,
if not exposed to the saliva.
/ want to speak of some of the practical features relating
to this invasion of micro-organisms in connection zvith the
preparation of cavities. We have all around this invasion of
the micro-organisms what is called the hyaline zone of Tomes.
When Tomes first discovered this hyaline zone and found it
to be generally in living, progressing caries of the teeth, his
supposition was that it was a deposit of an increased amount of
lime salts, building a barrier against the progress of decay, and
this supposition was in vogue for a number of years, until,
other experimenters, making sections and examining the den-
tin under different conditions, discovered that this zone was
not a hardened zone by the deposit of more lime salts, but it
was a zone from which a part of the lime salts had been re-
moved, exactly the opposite condition, a condition which Tomes
recognized before his death. In that hyaline zone we have no^
micro-organisms. Then, if you have removed all the decay,,
all softened material, from a cavity, you have rendered that
cavity aseptic by such removal—no micro-organisms are leftp
hence it is entirely unnecessary to- use an antiseptic in a pre-
pared cavity. There is no good reason for using an antiseptic
in such a position, for you have already made it aseptic me-
chanically by removing everything from it that contains micro-
organisms. Again, in the outer layers of carious dentin will be

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