Page 205 - My FlipBook

ARSENIOUS ACID. 203

arsenious acid may be made. Upon the removal of the arsenic,
an application of tannin and glycerin should be made in order to
harden the devitalized pulp and render its removal easy in the
form of an entire mass ; then apply some efficient antiseptic
dressing to pulp-canal, first washing out with peroxide of hydro-
gen. The use of dialyzed iron is also recommended, after the
removal of the arsenic, as it is not always certain that the
latter agent has been carefully applied. The dialyzed iron is
introduced into the cavity on a piece of wood. The cavity
should be kept free of moisture from the time of the application
of the arsenic up to the time of the application of the dialyzed
iron.
When arsenious acid is applied to the surface of an exposed
pulp, its first effect is stimulating, followed by paralysis of the
sensory nerves, inflammation being excited the degree of which
depends upon the quantity of arsenious acid employed. After
the stimulating effect passes off the arsenic is gradually absorbed
and the pulp slowly dies. Too large a quantity of the arsenic
will cause violent inflammatory action, increase the congestion
and prevent the pulp from absorbing the agent ; and experience
has shown that recently exposed pulps are more readily devital-
ized by arsenious acid than those which have been exposed for a
considerable time. It is therefore advisable to employ minute
quantities of arsenic as a devitalizing agent, and to avoid pres-
sure on the pulp when applying it, so that the pain occasioned
by its action may be limited to the space of one hour on an
average. The danger of an excess of arsenic passing through
the apical foramen of the root to the peridental membrane must
always be guarded against by carefully regulating the quantity of
the agent ; on the other hand all extraneous matters that will
interfere with the action and application of the arsenic to the
exposed surface of the pulp must be removed, or irritation and
pain and not devitalization will result. For the application of
arsenious acid to the surface of a fractured tooth, where it is dif-
ficult to retain it, the filling may be ligatured in place, after being
covered with a thin layer of gutta percha. Dr. E. C. Kirk uses
for such a purpose surgeon's rubber plaster, carrying it around