Page 216 - My FlipBook

214 PRELIMINARY PREPARATION OF CAVITIES, ETC.

retentiveness, therefore they arc not api)lical)le to shallow cavities of
unsuitable form.
The non-metallic may he cither iiutta-))crclia, zinc |)liosphatc, or zinc
oxychlorid. Tiie two latter are the most desirahle, as they adhere
to any well-dried cavity, and havinij:; some irritatinu:; inllucnce on
the tissues tend to induce structural consolidation in addition to their
protective action. They have, howev(n', the disadvanta loss l)v chemical solution, and unless l delusive and in many instances are a deceptive means of preventing the
recurrence of decay. In the employment of these substances due care
should be exercised concerning the proximity of the pulp, in which cases
the previously indicated means of shielding the pul]) walls should be
pursued.
The chief disqualification of gutta-percha is its lack of resistance to
attrition, and when in positions shielded from wear it may be attacked
by low forms of bacterial life, which disintegrate it.
Mechanical protection of cavities is most applicable to teeth of a low
grade of structure and for young children who may not have the ability
to tolerate the more active means needed to reduce dentinal sensitivity.
For these cases gutta-percha stoppings when carefully introduced are a
great boon, since they protect the tissues during the period of completion
and consolidation of the teeth.