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FITTING THE CROWN. 311

living. After it is removed, the canal is to be
enlarged to a suitable size, with the appropriate
drill. If there is any remaining sensitiveness of the
dentine, as is very seldom the case, the bur drill may
be used for this purpose ; but if not, then the com-

mon spear-pointed drill will be best. Where, how-
ever, the canal takes the form of a mere fissure,

either the bur drill or the four-sided broach may be
employed. The depth to which the canal should be
enlarged, will be determined by the length of the
root ; but it should, in all cases, be sufficient, firmly
to retain a pivot—which is from one to two lines
;
and the diameter of the hole will be determined by the
size of the root. The drills should be frequently
moistened with water, to prevent their clogging.
The shaft of the instrument, in the operation, should

be in a line with the cutting edges of the two adjoin-
ing teeth, and midway between them ; and the drill
itself should follow the natural canal as nearly as
possible.

FITTING THE CROWN.

The tooth selected should be of a size, shape, and

color to correspond with the natural crown which it
is to represent. It should not be ground on the
sides or point 3 and according to general opinion,
ought not to be touched with the emery-wheel at all.