Page 467 - My FlipBook

THE BOOT-CANAL FILLING. 465

weight of evidence clearly teaches that such canals may be filled at
once, and little or no reaction occur.
Freshly mixed zinc oxychlorid being markedly irritating to vital
tissues, it is usual to place between the paste and the tissues of the
apical region a barrier to the former. This may be of gutta-percha. A
very fine cone of gutta-percha about one-quarter inch long is dipped in
oil of eucalyptus or oil of cajuput to soften it ; it is then carried to the
apex of the root upon a fine probe and pressed into position. Or, a
small pellet of cotton is dipped in a strong solution of thymol or aristol.
It is extremely probable that when the freshly mixed oxychlorid is
placed over it, the cotton becomes converted into amyloid which her-
metically and permanently seals the apical foramen the same change
;
occurs in the cotton upon which the oxychlorid is carried into position.
Slender wisps of cotton are rolled thin enough to pass readily into the
canals. A thin paste of oxychlorid is mixed, the cotton wisps are
rolled in it until the meshes are full, when the extremity of a wisp is
caught upon the end of a long, smooth, and slender canal plugger and
carried up the canal to contact v/ith the guard at the apex ; the plugger
is withdrawn about one-eighth of an inch, and that length of the cotton
is crimped upon itself; the remainder of the canal is plugged in the
same manner until it is full, when the surplus length of the cotton is
cut oif and bibulous paper is pressed against the canal filling to absorb
the surplus zinc chlorid. The floor of the pulp chamber may be covered
with the stiffening paste from the mixing slab.
A method by Avhich cotton fiber loaded with the oxychlorid may be
carried to the root apex with great accuracy and precision is as follows :
The smallest size Donaldson bristle with smooth sides has its hooked
end cut off with the scissors and the cut end made flat by rubbing
lightly upon a fine Arkansas stone. This may be readily done by
grasping the bristle very near to its point between the thumb and index
finger and lightly rubbing it back and forth upon the surface of the
stone. The bristle is then laid flat upon a glass slab and burnished
from heel to point until the surface is perfectly smooth and any burr
turned upon the point by the action of the burnisher is fully re-
moved. A few fibers of cotton wool are then held between the thumb
and index finger of the left hand, the direction of the fibers being in
the line of the long axis of the index finger. The point of the prepared
broach is then laid upon the cotton fil)crs, and both broach and cotton
are rolled together between the finger and thumb. The rolling action
of the finger and thumb serves to felt the cotton fiber on to the broach,
and should be continued until the cotton is evenly felted over the
squared end of the broach. The whole operation is done by the left
hand. The broach is not twirled into the cotton with the right hand as
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