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76 THE TECHNICAL PEOCEDXJEES IN FILLING TEETH.

shown in Figure 67. Note particularly that the fingers grasp the
rubber dam on the gingival side up to this point. At this point,
hold the thumbs in position, release the hold of the rubber with
the fingers and allow it to draw around the neck of the tooth
before loosing the pressure with the thumbs. This is the second
movement. Figure 68. Note that the fingers have released the
rubber dam, but the thumbs are still holding it against the
gingivae. Generally, the rubber will be felt to draw around the
thumbs, and then they should be given a slight shaldng motion,
which will allow the rubber to draw around the tooth. This last
must be assured before releasing the pressure of the thumbs and
removing them. Otherwise, the rubber may be pulled off of the
tooth in removing the thumbs. When the rubber is applied in
this way, it will generally be found to cling to the neck of the
tooth, and to have its cut edge turned under the gingivae. Repeat
this motion with each hole in the rubber, grasping it anew, and
in the same manner for each, and pass it over the appropriate
tooth with a similar motion. This grasp and these motions will
answer for all of the upper teeth as far back as the first molars.
When applying it with this grasp to the teeth of the left side,
the face of the patient should be turned strongly to the right ; or
the operator should pass to the left side of the patient.
The SECOND grasp is a modification of the first, which allows
the left hand of the operator to be passed aroimd the head of the
patient, when standing in the position right side behind. This
will generally be found more convenient for the upper teeth of
the left side as far back as the bicuspids. In this, the rubber is
grasped with the right hand in the same way as before, but with
the left hand the grasp is inverted so that the forefinger takes
the place of the thumb, or is on the occlusal side of the rubber,
wliile the thumb is on the gingival side about opposite the first
joint of the finger. The finger and thumb on the occlusal side of
the rubber ai*e just over the margin of the hole to be used when
the rubber is stretched, as shown in Figure 69. In applying the
dam with this grasp to the upper teeth of the left side, the oper-
ator's position is right side behind, the thuml) of the right hand
is placed on the lingual side of tlie tooth and the forefinger of
the left on the labial, or buccal, side. Otherwise than this change
of position, the motions with which the rubber is placed are the
same as with the first grasp. The first movement. Figure 70, and
the second movement. Figure 71, must be distinctly sepai-ate.
This grasp is also suitahle in applying the rubber to the lower
teeth of the right side, as far back as the second bicuspid.