Page 150 - My FlipBook

CHAPTER XXIV.
THE USE OF CEMENTS IN FILLING TEETH.

Varieties. There are five main varieties of cement available for
silicate, cement, oxyphosphate
use in the operation of filling teeth ;
of zinc, oxychloride of zinc, sulphate of zinc, and oxyphosphate of
copper.
Cavity Preparation for cement when the entire filling is to be of
cement is not unlike that for any other filling, except that the eavo-
surface angle is left the same as that produced by the cleavage of
the enamel, omitting the marginal bevel. The cavity should be given
the usual retention form, and the matrix must be employed in cav-
ities to supply the missing wall that the cement may be introduced
with pressure to condense and create close adaptation to walls.
The rules given for dryness in the manipulation of gold and amal-
gam are also to be observed in cement filling.
The silicate cements have been evolved in an effort to produce a
cement that would more nearly harmonize with the color of the
teeth ; to better withstand the action of the oral fluids and the abrad-
ing effects of mastication. Berylite is a prominent illustration of a
silicate cement. Some of the silicates are now used as independent
fillings and are not suitable for use as a cement. This material as
a silicate filling is given full consideration in Chapter XXV.
Oxyphosphate of Zinc has many uses in the cavities of teeth as
a partial filling and in some instances for the complete filling. Be-
ing a poor conductor, it makes an excellent agent as an intermediate
between metal fillings and closely approached pulps.
Its adhesive quality gives it great value as a means of adding re-
tention to all kinds of metal fillings. This quality together with its
harmonious color with tooth substance makes it invaluable for lin-
ing weakened enamel walls which have lost much of their support-
ing dentine.
Its Chief Fault is its tendency to dissolve in the fluids of the
mouth, which renders it comparatively temporary. However there
is a considerable variation in its behavior in different mouths; in
some instances it wears for years.
Oxychloride of Zinc is indicated in pulpless teeth to fill the pulp
chamber, after the canals have been previously filled with gutta-
percha, and for the lining of cavities for the preservation of color
where adhesiveness is not of importance. It is not indicated in
146