Page 139 - My FlipBook

APPROXIMAL CAVITIES IN MOLARS.
1*5

bicuspid at Fig. 128. The filling may be retained by grooves along
the borders at a and b, and the gold may be introduced readily with
even a small space, being passed in at the buccal aspect. Where a
encroaches
similar cavity upon the palatal surface, it is much more
difficult. If the tooth be on the left upper side of the jaw, I turn the
patient's head so that, looking across the roof of the mouth, I may
place the first
see into the cavity through its palatal extension, and I
pellet through this aperture, packing it into the extreme buccal end.
From this I build toward and finish at the On the
palatal part. right
side I follow the same
general rule, save that here one must resort
more to the mouth-mirror. In the lower jaw all is different. To fill
with gold with any hope of success, the widest possible separation is
needed, and even then it will often be found difficult, if not impossible,
to pack the gold properly should the tooth be long. If the cavity in
it will be
addition should be on the distal surface, trebly troublesome.
Therefore, where I decide to use gold, I most often extend the cavity
toward the crown, as shown in Fig. 133, in extreme cases even cutting-
through to the crown proper. Where such extension is decided upon
I do not make much of a groove along the gingival border a, but I
make a linguo-gingival extension at b, at which point I start the filling,
and place grooves along the borders at c and d, of decreasing depth
as they approach the crown.
Fig. 134 shows a very unpleasant condition. It is what we term a
saucer-shaped approximal cavity, in a molar. Where the dentine is
very sensitive, we often find it almost impossible to obtain any anchor-
ages along the gingival border, and, strictly speaking, it is not needed,
can be perfectly retained without of
for the filling disturbing this part
the tooth other than to cleanse it of all decay. Once more I should
depend upon lateral grooves along the buccal border, and the palatal,
or lingual if it be the lower tooth. But these grooves would be the re-
verse ofthose in Fig. 1 33. There they were deepest nearer the gingival
Now I should begin by making an extension into the crown
portion.
as shown at a, with lateral wings or dovetails indicated at b,b. From
these dovetails I would carry my grooves deep into the tooth-sub-
stance, decreasing the depth until they emerged at d,d. Between these
points d,d we have the gingival border c, which I have said may be the
But
most sensitive part of the dentine, and we need no undercutting.
where the dovetailing into the crown would leave the lateral walls weak,
then we will simply be forced to abandon that plan, making the lateral
grooves as deep as consistent with strength, and forming a gingival
as far as we are enabled.
groove
shows the loss of the buccal corner as well as the
Fig. 135 palatal,
so that a full contour is required. Where only one corner is absent,
ihe filling may be anchored chiefly into a deep undercut into that