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74 THE TECHNICAL PROCEDURES IN FILLING TEETH.

found to be more extended than the decay in the dentin. An
inverted cone bur, i miUimeter in diameter, is placed in the mesio-
gingiwil angle of the cavity with its square end toward the axial
wall, and entered into the dentin just beneath the dento-enamel
junction and carried along the line of whitened enamel to the
point of connection with the filling in the mesial surface. The
enamel is chipped from the incisal wall of this cut with chisel 15
and the cut widened by again passing the bur, cutting the dentin
toward the incisal. This portion of the incisal wall is now
trimmed smoothly to its connection with the incisal wall of the
original' cavity. The same bur is now entered in a similar
manner into the disto- gingival angle of the cavity and carried to
the distal along the line of the whitened enamel to the margin
of the labial surface and slightly over onto the distal surface,
but not connected with the distal cavity. This cut is stopped
at a point upon the distal surface at which the outline of the
distal cavity, when prepared, will cut into it. This cut is now
widened toward the incisal by chipping the enamel with the
chisel and again cutting away the dentin with the bur and
smoothly connected with the incisal wall of the original cavity.
This completes the outline of the cavity. The surrounding
walls are clean and the retention form partially provided for, but
the carious material in the central and deeper portions of the
cavity is undisturbed. It is still a question whether or not the
pulp will be found exposed when this is removed. The right-
hand spoon 20-9-12, used with the palm and thumb grasp, is now
entered under the distal margin of the carious mass and its edge
swept across to the mesial, along the incisal wall, cutting out the
decayed material. Another similar cut is made, directed to the
gingival half of the cavity, by which the last of the carious
material is removed, leaving all parts of the cavity clear and
white. The pulp is found covered by sound Ijard dentin. The
edge of the spoon is now passed carefully over the surface of the
cavity with a scraping motion, to be sure that no softened material
remains. This central portion being deeper than is desirable to
make the surrounding walls, it may be filled for a part of its
depth with zinc oxyphosphate as a protection to the pulp, or
better, its central portion may be covered with a bit of quill after
the anchorage of the filling has been started and the gold built
upon and over it. The anchorage is now to be perfected. The