Page 43 - My FlipBook

METHODS OF KEEPING CAVITIES DRY.
29
All attempts thus far to produce a rubber of light color result in de-
stroying its elasticity to such an extent that the material becomes unfit
for dental purposes. Thus we are compelled to use a dark-colored
dam, which has a decided disadvantage in that it does not reflect light.
It therefore becomes important to economize the light as much as possi-
ble, by not having any unnecessary creases or folds. As the jaws are
curved, it is plain that holes punched in the dam in a straight row, and
by guess as to distance apart, will not permit the dam to be stretched
over the teeth and lie To obtain the for
smoothly. proper positions
the holes lay the dam over the teeth, stretching it so that the incisive
ends show through ; then make a mark with an excavator, which by
slightly scratching produces a whitish dash over each tooth. Punch
the holes with a instrument that will cut clean round holes.
sharp
By this method the dam may be made to adapt itself without a wrinkle.
The holes should be in size so that
graded they will tightly grasp the
tooth-neck, but they should not be made so small that a tear may
occur at the slightest touch, or while passing over a tooth. Great
care should be used to have the distances between the holes
exactly
right. If too narrow, they stretch to span the gap, leaving a bit of
gum uncovered near the neck of one of the teeth. If too wide,
especially at the space where the operation is to occur, trouble may be
found in forcing the excess between teeth in close contact, or annoy-
ance will occur from the fold produced by it. Where teeth are close
a of waxed floss should be between all of
together, piece passed
them before any attempt is made to apply the dam. If the floss
will not pass, neither will the dam. There may be a rough filling, a
fracture of the enamel, a ragged edge of a cavity, or a bit of tartar,
either of which will tear the dam. A safe-sided saw should be passed
between these teeth, and the obstruction removed. Occasionally
there is adequate space near the neck, but, for example, two incisors
are in such close contact at their corners that neither ligature nor
rubber can be passed between them. In such cases, drive a wedge of
wood at the neck till the teeth slightly separate, when the dam may
be placed with facility ; then remove the wedge. It is frequently ser-
viceable to soap the dam about the holes.
It very rarely happens that the dam can be forced between the teeth
with a ligature, save perhaps in the bicuspid region, where the slant-
favor the method. The too result is,
ing sides of the cusps frequent
that the ligature cuts the dam, so that while it passes into the space
the operator has to contend against a disagreeable leak afterward.
Where such an accident does occur, it is far better at the outset to
remove the dam and apply a new piece.
where
When the cavity to be filled is at the labial festoon, especially
there has been a recession of gum-tissue, and caries has encroached