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CROWN- AND RRTl)r.l-:-\VORK. 169
the sides of the rkjI, and that the process will he reached
before the root is covered high enough on the labial and
palatal surfaces. IMace the hand thus shaped upon the root,
and if the measurement and each progressive stage have
been accurately performed, it will he found to fit perfectly.
Now press or drive it up carefully, until the point of attach-
ment between the soft tissues and the root are reached
(about one-sixteenth of an inch beyond the gum margin),
which is shown by the slight whitening of the gum. When
this is very marked upon any side, the band should be re-
^"
FiG. 134.
m

moved and relieved by cutting it away at that point, and
then readjusted. A corundum-wheel is now gently passed
over the labial portion of the lower edge of the band, to
bring it down with the face of the root and to render the band
invisible when the crown is finished. In doing this the wheel
used should be revolved toivard tJic root, so it will not irri-
tate the soft tissues, as it would were the force applied in
the opposite direction,—and at the same time it will turn
the feather-edge of metal over the end of the root.
Forming the Base Plate.—Cut a piece of gold (34
gauge) of suitable length and width, anneal, and then press
it against the lower edge of the band with the fingers until it
is nicely adapted ; secure it in this position for soldering by
three or four strands of wire, as shown in Fig.
135. Now^ paint the joint with borax dissolved Trc- I35-
in water, lay a small piece of 20 k. solder against
the back or palatal portion of the band, on the
outside, and hold it in the flame of a Bunsen
burner until the solder floAvs, which will be seen to run en-
tirely around the band, uniting it with the base plate at
15