Page 219 - My FlipBook

THE BtJBBEE DAM. 91

of the thumb-screw will fasten it. Then the rubber dam is to be
prepared and placed. Choose a position in which the right hand
will manipulate the clamp easily while the left holds away the
rubber. There should always be one finger in place to steady the
clamp and prevent it from turning when tightening the sci'ew.
If, in stretching away the rubber dam, the rubber is caught with
the thumb and second finger of the left hand, as in Figure 97,
leaving the first finger free, it will come forward at the instant
needed, or it may be done by the second or third finger of the
right hand which is ready also to come forward against the bow.
Pull the rubber dam well out of the way so that the place to set
the points of the clamp is in full view and give the screw a turn
to fasten it. Then let the rubber draw against the points of the
clamp. Settle the rubber carefully against the attachment of
the gums to the tooth with a pellet of cotton in the foil pliers.
Or the flat burnisher may be passed under the outer margin of
the piece of rubber dam, and its point brought into position
between the gum and the gingival side of the rubber. The gum
may then be pressed back with one side of the instrument point
while the other side is so inclined as to allow the margin of the
hole to draw down next to the tooth. This will give a pei-fect
view of the cavity, keep it perfectly dry and give command of
the conditions for any operation needed. Generally this clamp
may be used as far back as the second bicuspid, and occasionally
on a first molar.
The pairs of root clamps. Figures 91-94, do important serv-
ice in any case in which treatments should be placed in the canal
of a root that has been prepared for an artificial crown or bridge
abutment. These, if carefully placed, will hold securely on any
root upon which a band can be placed. The rubber dam may be
thrown over such a clamp and the treatment made as cleanly
and securely as in any other case. They are a very essential
clamp, and so far the only clamps that will do this work well.
With the most skillful operators, some impossible cases
occur with any and all of these instrmnents. Then resort must
be had to holding the dam in position with an instrument in the
left hand while performing the operation with the right hand.
This is difficult, but practicable, after it has been practiced suffi-
ciently. The best instrument for this purpose is a straight shaft
with a broad flat point cut in the form of a fork or a V-shaped
notch.
Often in proximal cavities, where the gingival wall is very
difficiilt to reach, the rubber may be forced into position and held