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38 THE TECHNICAL PROCEDURES IN FILLING TEETH.

gingival wall, or only slightly, but to the lingual or buccal
(labial in the incisors and cuspids), and the groove should be
close against the axio-buccal or axio-lingual line angle. In this
method of cutting these starting points the square end of the bur
gives a square floor to the pit at the point where the first piece
of gold is placed, which prevents any tendency of the gold to
roll from side to side in the first efforts to condense it, so that a
very shallow pit, a mere corner or sharp angle, so to speak, is
all that is necessary. It should be remembered always that
these convenience points are not anchorage points for the filling,
but are simply starting points for the temporary anchorage of the
first pieces of gold.
The use of drills should be confined to certain especial
purposes. These should be used when for any reason it becomes
necessary to cut into the pulp-chamber of a sound tooth, or one
that has already been filled. This necessity occurs frequently
because of hyperaemia of, or death of, the pulp after a filling has
been made, or from death of the pulp from a blow or some
unknown cause. In these cases it is often necessary to cut from
the surface of the tooth to the pulp-chamber, either through a
filling or through the enamel and dentine. The bur is not suit-
able for this work. The flat drill, bi-beveled to a point, is the
proper instrument, or the drill followed by a round bur to enlarge
the opening. In doing this where considerable tissue is to be
cut through, it is best to use a small drill first, and when this has
penetrated some distance, enlarge the opening with a larger drill
or a round bur, then penetrate further with the small drill and
again enlarge. Proceed in this way until the pulp-chamber is
reached. In the attempt to drill deeply with a small flat drill the
instrument does not clear itself of chips readily and is apt to
heat ; also, it is likely to be broken by any movement of the
patient.
The drill is also the best instrument for enlarging root-canals
for setting posts or pins for artificial crowns. It will be seen that
these uses of the drill are aside from cavity excavation.
The Use of Water.
The use made of water in operative dentistry is very impor-
tant. Every dental office should have a liberal supply of both
warm and cold water. The use of water for the hands of the