Page 141 - My FlipBook

CAVITIES IN THE MASTICATING SURFACES.
127
as have suffered no other depredation at this part. I have seen a few
cases where a distinct cavity, truly carious in character, has presented,
seen along the incisive edge only, and not involving either labial or
palatal surface. They are found in the form of tiny dark spots, into
which the fine point of an explorer readily passes, sometimes to a
considerable distance. Such a cavity probably has its inception in an
in the enamel, a
imperfection tiny pit offering a suitable starting- place
for caries. To prepare these, it is only necessary to remove the decay
thoroughly, care being observed not to split off the enamel along
either surface, thereby producing a fracture which would necessitate
To fill, use
an awkward and unsightly filling. gold, in tiny pellets,
When
or better still depend upon crystal. completed it should ap-
pear as a small polished gold dot.
I have seen caries along the full length of the edge of a central
incisor, appearing as a black line and extending to a considerable
When all the is removed from such a no
depth. decay cavity, spe-
cial alteration of shape is needed to achieve retention. The depth,
in connection with the narrowness of the fissure, and the roughness
of the walls, will prove sufficient. To fill with gold, a convenient
method is to select a pellet about the length of the groove, and just
thick enough so that it must be slightly compressed as it passes the
orifice this is an exception which marks the difference between
;
general and special principles. Suppose, however, that such a cavity
should present, the caries having proceeded only to a slight depth.
Then the groove would not be deep enough to retain the filling.
Should it be deepened ? To do so would be unwise. While we must
the condition as it is found in the first instance, we must not
accept
reproduce it in the second, even though it be an effectual retentive
shape. To deepen the cavity would be to render the labial and
walls weaker, and make more probable the
palatal subsequent split-
off of the one or the other. Such an accident would be
ting espe-
to occur in the mouth of a woman,
cially likely
constant women will bite
for despite precautions, FIG. 137.
off threads with their teeth. The cavity is shown
in Fig. 1 37 . It is prepared with a tiny rose bur,
and retention depends upon a slight dip into the
a and
dentine at each end of the cavity, b. It
is evident that this makes the filling after inser-
tion just a trifle longer within, than at the orifice,
which is all sufficient. To fill with gold we
must proceed differently to the method advo-
cated in the deep groove, where I said we might start with a long
Here is better to at one end, and build across to
pellet. it begin
the opposite pit with small pellets. As soon as the floor is thus