Page 209 - My FlipBook

TWENTIETH LECTURE.
March 6, 1901.
When the hand of my watch got around in my last lec-
ture I was talking about filling and the necessity of making
fillings watertight in order that they might be curative. Fill-
ings cure purely and simply by shutting out everything from
contact with dentin. They should be alcohol-tight, and alco-
hol will go in where water fails ; acids will go in where plain
pure water fails to enter. How small these molecules are
we do not know. Now fillings are not curative in the same
sense that vaccination is curative against smallpox — preven-
tive, that is to say, fillings do not remove the tendency to
caries, and the curative effect of a filling is literally no broader
than its outlines. However, the filling has beyond this a
prophylactic effect that is important, and how far this will
extend will depend directly upon the skill displayed in laying
the outlines of the filling. If the outlines are so laid that
microbic plaques cover it and lap over its margins it will not

protect the area of liability ; decay will begin again close be-
side the filling. The margin is the vulnerable point. The
filling itself, its own area, if it is made well and of material
that is durable in the mouth, as gold, as the amalgam, is in-
vulnerable ; it should last a lifetime. But its margins are not
invulnerable. The enamel composing its margins is soluble
in acids, and if these margins are laid in portions of the area
of liability, decay is liable to recur immediately along the
margins and the filling be rapidly undermined. Then, in or-
der that we may make this filling protective, we must study
the area of liability in which it is placed, as I have indicated
numbers of times, and so lay the margins of the cavity in its
preparation that it will include the vulnerable portions of
this area. Remember always that we do not cure in the sense
of removing the liability, except as we replace the area of
liability with an indestructible material. It is only in this
sense that fillings are curative.
Fillings are prophylactic in a very much broader sense, in
this, that a cavity that affords lodgment and opportunities
for collection of material for fermentation and formation of
acid, is stopped, and if the contact point is properly made in

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