Page 373 - My FlipBook

INLAYS COMPARED WITH OTHER FILLINGS. 371

while it resists perfectly the action of the oral fluids, it so utterly lacks
the other ideal attributes/ as already enumerated, that with front teeth,
soft teeth, and teeth of nervous patients its manifest disadvantages
more than counterbalance its advantages.
Soft gold is open to the same objections, but it has the advantages
of resistance to wear, resistance to oral fluids, and, to a less degree,
exclusion of bacteria.
Tin has to a marked degree the good and bad attributes of soft gold,
but it turns black.
Amalgam bulges under mastication, chips on the edges, rusts, and
leaks ; it prevents decay, however, through antiseptic action. When
rusty it is a moderately poor conductor of heat, it is easy of adap-
tation both for operator and patient, and calls for a manner of manipu-
lation that is conservative of healthy tooth structure. It is therefore
often available where gold is not.
Oxyphosphate of zinc has all the advantages lacking in cohesive gold
with the exception of color, and lacks all the advantages that cohesive
gold possesses. Its edge strength is solely due to its great adhesion.
It wears under mastication, dissolves in the fluids of the mouth, and
usually absorbs bacteria ; but, on the other hand, it prevents the growth
of germs, is a non-conductor of heat, has better color than gold, is
easy of insertion for patient and operator, preserves weak walls, and
does not require undercuts.
The same may be said of oxychlorid of zinc, except that it causes
pain to sensitive dentin and exposed gums.
Gutta-percha, in a similar way, with the exception of color, possesses
the good points lacking in cohesive gold, and lacks the good points pos-
sessed by cohesive gold. It loses shape and wears under mastication,
has feeble resistance to fluids of the mouth, has poor color, and leaks
micro-organisms ; but, on the other hand, it inhibits from further growth
the germs that enter, is a non-conductor of heat, is easy of insertion for
both patient and dentist, and has a manipulation that tends to conserve
frail though healthy walls.
When we come to inlays we have a filling in which the good points
of the cement are combined with those of amalgam, gold, or porcelain
in such a way as to insure the advantages of both in the largest degree,
and to reduce to a minimum the disadvantages of each.
When a cavity is lined with a thin zinc cement squeezed out by the
insertion of soft amalgam, this amalgam afterward having as much as
possible of its mercury removed and the edges of the metal burnished
to the cavity margins, an inlay of amalgam is to all intents and purposes
made. This treatment takes away from the amalgam three of its objec-
tionable features, conductivity of heat, lack of adhesion to the cavity,