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FILLING CAVITIES WITH GOLD, BY CLASSES. ^ 289

usage required of these, must have good anchorage and must be
well and solidly built.
Many have seemed to think the simi)le groove for the incisal
step shown in Figure 277 insufficient to hold such a filling. The
gold built into such a groove, if so inserted between the parallel
walls as to make use of the full available grip of these walls upon
it, will never slip out with any stress. Drilling of holes in the
pulpal wall of such a groove is useless. It might be broken where
it joins the proximal portion of the filling. Its strength against
this breakage depends upon the gold built over it. When this
has been made sufficient, there is no danger that the anchorage
will fail.
Class 5. Cavities in the Gingival Third — not Pit Cavities
— OF the Buccal and Labial Surfaces of the Teeth.

The buccal and labial cavities are, with few exceptions, so
easy of approach that the jjroper lines of force are easily
obtained and free choice of these can be made. In general, when
the cavity preparation is finished with the rubber dam in place
and held by a suitable clamp, the whole cavity is exposed to plain
view in all of its parts. The filling may be begun in the most
convenient angle and carried over to the next by the use of the
holding instrument and one of the parallelogram pluggers and
thus proceeded with to completion without hindrance. It some-
times appears that this very simplicity becomes a menace to
the most perfect operating, which occurs from maintaining some
particularly easy position when the lines of force should be
shifted for the wedging of gold against some part of a wall.
While great strength is not a special requirement in this class of
cavities, the most perfect adaptation to the cavity walls must
be made in order that the fillings may be successful. This is to
be done on the general principles of gold building that have been
laid down in previous pages.
Among this class of cavities there will be a much larger
proportion that are broad and shallow than in anj' other class.
There is much building of gold over a broad axial wall. This
building should be so contrived in each case in the covering of
such walls that it will proceed step by step from a secure anchor-
age. Slight grooving of long reaches of walls assist very mate-
rially in assuring safety in such building. In all of the work,
the most scrupulous care is demanded in the wedging process.
The positions in which the access to these cavities is not
good are found in the second and third molars. It often hap-