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250 FTLLTXa MATERIALS.
racter, and the others as of" a teni])orarv nature, whieli, after fulfilling
important uses in this way, are often preparatory to later and permanent
treatment.
Gold.—The properties of u'old whieh adapt it for the restoration of
carious teeth are its pliability and softness, which permit its adaj)tati()n
to the form of the cavity ; its tenacity, which gives facility of introtluc-
tion and consolidation ; and its agreeableness of color, which, when the
surface is solid, smooth, and nnbnrnishcd, a})proaches more nearly the
shade of the teeth than any other metal.
Notwithstanding these ap})ropriate qualities the packing of gold
re(]uires the employment of considerable force to overcome various
resistances to its adaptation and solid condensation. To effect the
requisite degree of density percussive force frequently becomes necessary.
The effect of percussive force, if employed throughout, is liable to be
expended on the margin toward which it is directed, and while this may
not inflict any injury upon the borders of cavities when the dentin and
enamel are dense, it often proves injurious to teeth when the anatomical
elements of the structure are not homogeneous and resistant.
While it may be stated with the strongest assurance that gold pos-
sesses the highest preservative qualities and promises greater durabil-
ity and more satisfactory results than any other material, conditions
are often presented when to persist in its use would lead to unsatis-
factory results; thus, in the approximal cavities of the teeth of children,
when the calcifying process has not become complete and when by the
use of the required force some impairment of the incomplete tissues is
almost certain to ensue. The same maladaptability occurs later in life
when senile conditions have set in, when the teeth not only have lost
their density from the peculiar molecular changes which take place
in the dentin and enamel, but when usually also their resistance to
chemical influences is greatly impaired. These conditions, coupled with
the usual inability to properly care for the teeth, render the use of gold
very questionable.
Similar states of the dental tissues take place in middle life in both
sexes, but more particularly in women during the pregnant state,
when the teeth lose their resistant power, which may later be restored.
AVhile this condition lasts, materials requiring less force should be
selected until restoration of resistance has occurred.
The mode of effecting percussion should be taken into account in
When
estimating the influences which bear against the use of gold.
percussion is effected by the electro-magnetic instruments with proper
precautions with respect to the placement of the first portions of gold,
there is less danger of marginal injury than when percussion is made
with the hand or the automatic mallet.