Page 210 - My FlipBook

208 PRELIMINARY PREPARATION OF CAVITIES, ETC.

tion of the tissue, to a greater or less degree, of one of its elements, viz.
water, and it is more effective in teeth of dense structure, since the sur-
face of these is more easily desiccated than the softer teeth. If it were
possible to remove all the water of the tissue from the surface to the
depth of the irritated part all sensitivity would thereby be overcome, but
generally this can be only imperfectly done ; nevertheless, the benefit
is generally considerable. This means is easily and quickly applied,
and as it presents the simplest method in the cases where it is applicable
it forms therefore the easiest and most available ]>rocedure for this
purpose.
The warmed air may be produced by heating the bull) of a warm-
air SYRINGE (Fig. 157) over a lamp or Bunsen burner, when a continu-

FiG. 157.

Warm-air syringe.

ous stream of air is forced through the nozzle into the cavity. Some tact
is required to deliver the heated air in a manner to cause the least pain
by its impingement. If the nozzle be held too far away from the tooth
the stream of air in passing through the atmosphere takes along with it
so much of the surrounding cool air as to cause pain, and if held too
close the heat is equally painful. In all cases the abstraction of the
water, even when the degree of heat is avcII balanced, produces some

Fig. 158.

Electric warm-air syringe.
unpleasant sensation, which soon passes away and after a few moments
the case is reduced to a state of slight and simple sensitiveness. The