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CHAPTER XI.

TREATMENT OF FILLINGS WITH RESPECT TO CONTOUR,
AND THE RELATION OF CONTOUR TO PRESERVATION
OF THE INTEGRITY OF APPROXIMAL SURFACES.

By S. H. Guilford, D. D. S., Ph. D.

The treatment of a cavity of decay by filling must have a twofold
object in order to subserve its best purposes : first, the restoration of
the affected part to a healthy condition ; and second, the prevention as
far as possible of a recurrence of the lesion.
The first is accomplished by the removal of all disintegrated tissue
and the perfect filling of the cavity with a suitable and durable material.
The second demands for its success a proper understanding of the cha-
racter of the surfaces operated upon and their mechanical and physio-
logical relations. While the simple filling of a cavity, if properly
done, will generally prevent the extension of decay on exposed surfaces,
the same operation on surflices less favorably situated may utterly fail
to subserve the desired end.
The contiguity of the approximal surfaces of teeth greatly favors
the retention of food and the harboring of micro-organisms, while at
the same time it prevents the free cleansing movement of saliva be-
tween them. For these reasons such surfaces, though originally per-
fect in their continuity, are attacked by caries more frequently than any
others, except the occlusal surfaces where continuity is broken by fis-
sures and pits. When once affected by caries, their restoration by fill-
ing is difficult owing to their inaccessibility, and while the operations
on this account often lack the perfection that would otherwise be secured
and the fillings consequently fail, the recurrence of decay is more largely
due to the same influences that brought about the initial lesion.
This being the case it is obvious that the original conditions must be
changed if immunity from future decay is to be expected. This
principle was early recognized and the first attempt to alter the con-
ditions was by filing or cutting the approximal surfaces so as to free
them from contact, on the principle of '* no contact, no decay." Where
all of the teeth were thus separated immunity from decay was generally
secured, although at the cost of great loss of masticating surface, much
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