Page 156 - My FlipBook

I
I40 THE TREATMENT OF TEETH
question of the possibility oi' the advisability of
properly preparing a cavity for gold that the use of
the precious metal mainly depends.
White Cement.—The white cement fillings are
usually oxyehoride of zinc (a powder of specially
prepared oxide of zinc, and a liquid of chloride of
zinc), or what are variously termed oxyphosphate of
zinc or phosphate of zinc. These oxyphosphate or
phosphate fillings also consist of a powder (some
form of sjDecially prepared oxide of zinc), and a liquid,
principally, if not entirely, composed of phosphoric
acid. The general term osteo, or osteo filling, has
also been given to these various white cements,
probably because one of the earlier productions was
labelled " Os artificiel," or artificial bone. The oxy-
chloride is now comparatively rarely used. It is more
troublesome to work than many of the oxyphos-
phates, and must not only be kept perfectly dry
during insertion, but also carefully protected from
moisture for some considerable time afterwards by
careful varnishing. It appears to be harder than
the average oxyphosphate, but is, as a rule, not so
durable in the mouth. It often causes pain on
insertion, and is said to have a hardening and pre-
servative effect on soft dentine ; but this is very
doubtful. It is considered to make an excellent
root tilling—one that will remain moisture-tight