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64 THE TECHNICAL PEOCEDXJKES IN FILLING TEETH.

For this use of the broach in any of the lower molars that stand
normallj' in the arch, the shaft of the instrument should cross
the upper teeth at about the median line, when the mouth of the
patient is thrown widely open. The broach will then glide evenly
and smoothly into the canal of the distal root. On the right side
the position would be the right side in front with the instrument
handle crossing the incisors at the median line. If any of the
lower teeth are inclined much to the lingual, the better position
will be over the lateral incisor, or even the cuspid of the right
side of the upper jaw to the molars of the left side, making it
almost a cross-mouth position. Notice particularly the position
of the fingers of the left hand in exposing the parts to view, a
position that is found an excellent one, for, if the field of opera-
tion is not too far back in the mouth, the forefinger of the left
hand may pass across the teeth and keep the tongue out of the
way, while the second finger and thumb control the lips. This
position with its modifications, which are very numerous, is the
position for the greater amount of instrumental work upon the
teeth of the left side of the lower jaw.
Figure 53 illustrates a finger position and form of grasp that
will be found very excellent for the use of the engine in the buccal
surfaces of the lower teeth of the right side. Most operators
will find it diiBcult to obtain facility in the use of this position
and grasp without considerable practice. This is most suitable for
work with the straight hand piece, for by its use we may place the
square end of a bur against the axial wall of a buccal cavity and
make such extensions as may be necessary to the mesial and to
the distal, preserving the flat form of the axial wall. Tliis can
be done as far back as the second molar usually, and, in some
cases, even to the third molar. Of course, this class of cutting
must be done before the rubber dam is placed, or at least without
a clamp in such a position as to interfere. It will be noticed that
the end of the third finger has drawn the lips back and has found
a rest upon the teeth, or upon tlie gums, to the distal of the tooth
operated upon. The instrument ))oint is passed across the finger
and is operating to the mesial of the finger end.
When this position and grasp are once well learned, the
operations are easily done, provided the position is not continued
too long, and generally there will be no necessity for holding it
more than a few minutes at one time, as the work is accom-
plished very quickly.
A position very similar to this may also be found for using
the engine in cutting gingival third cavities in the buccal surfaces