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60 THE TECHNICAli PKOCEDUEES IN FILLING TEETH.

practically all around his chair, finding favorable positions to do
particular things, and also positions that bring other muscles in
play to relieve those that are tired, contributing to comfort and
health while continuing needful operations.
Finger Positions.
ILLUSTIiATIONS : FIGURES 46-61.
In considering positions at the chair and finger positions, it
is necessary in the first instance to use full length illustrations.
But in these it is impossible to give with much defiuiteness the
finger positions in the use of instruments because the pictures are
too small. In this subject the use of rests for the instrument
hand is to be considered, and also the use of the left hand in
holding the tissues away, thus aiding the right hand by exposing
the field of operations to view. Occasionally also the left hand
should aid the right hand more directly by guiding the instru-
ment point with a finger. The guiding by a finger of the left
hand is often a very important item in accurate operating. It
must not be forgotten, however, that a considerable part of
instrumental work in the mouth should be done by the free hand
without any rests whatever. Bests, however, are to be sought
continually, for with a good finger rest the hand becomes very
much steadier than it can possibly be in free-hand work. This
is important in many positions in which an instrument is liable
to slip and do damage. If there is a good finger rest, such slips
are very much better under control than if the finger rest is not
used. It must not be forgotten, however, that finger rests always
limit freedom of motion in an important degree and in this
respect are bad. A dentist should do much of his work without
them.
A finger rest, to be relial>le and definite, must be upon the
teeth of the same jaw with the tooth operated upon. At least,
this is much the best finger rest. In any effort to rest the finger
upon the teeth of the opposite jaw, the movements of the jaws
are apt to derange the relative positions of the instrument and
tooth. Finger rests upon the soft tissues are very much less
reliable than finger rests upon the teeth, and yet they may often
bo used to advantage, particularly if the rest can be made on
portions that are not movable, or where the bones are but thinly
covered with tissue. However, a rest upon the face will gener-
ally come upon the opposite jaw and the movements of the
patient are apt to disturl) it seriously. Such rests must always
be reckoned as unreliable.