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164 MEC?IANICAL DENTISTRY AND METALLURGY.

crown neck shall fit under the edge of the gum. Fig. 125
shows the method and its result, and the cross-section shows
how the cement incases the pin. The suitahle preparation
of the hifurcated roots of some hicuspids and c^f all the
Fic. 126.

molars is a matter involving difficulties of an unusual char-
acter and requiring good judgment. The feasihility of
splitting the post of a Logan crown to adapt it to the bifur-
cated root of a bicuspid, and the adjusting of the crown to
a single rooted bicuspid or where the bifurcation is not
marked, as well as the best method of bending the Logan
crown pin is exhibited in Fig. 126.
Fig. 127.

The fitting of a Logan crown to a root may be done with
a wet corundum or carborundum wheel in the engine hand-
piece, as shown in Fig. 127. A safe-side corundum-wheel