Page 255 - My FlipBook

PREPARATORY TO FILLING 239
of zinc makes a non-permeable one. Its use
in the form of the usual oxychloride cements is,
however, difficult. Its removal is usually impos-
sible, and as some fluid usually goes through the
apex, it causes considerable pain for some time after
insertion. The prevention of this by sealing the
apex with a tiny piece of gutta-percha or a small
ball of cotton-wool is excellent in theory, but
extremely hard to properly carry out in practice,
except in fairly large canals that are easy of access,
or in the practices of those who are particularly
skilled in reaming out root canals. The writer has
had the canals of a first lower molar in his own
mouth (two canals in the anterior root) so reamed
out that several strips of cohesive gold were accurately
carried down each canal, and condensed with a
hand mallet. Each strip was packed and con-
densed just as in an ordinary gold filling, but this
is quite exceptional practice, and outside the range
of all ordinary and no doubt equally useful methods.
It has been mentioned that a gutta-percha filling
will not leak against the cavity walls if the tooth is
first varnished with resin dissolved in chloroform,
and a method of overcoming the shrinkage or
permeability of gutta - percha was suggested by
Dr. Goble, in the "Items of Interest," April 1894.
Dr. Goble dissolves about equal parts of rosin and