Page 104 - My FlipBook

100 OPERA'TlVE DENTISTRY
axial line angles, luntil the inlay has beeii cast and fitted. It
should then be removed arid the dentine over-lying the pulp, if
hypersensitive to thermal changes, given a eoat of cavity varnish.
AUoAving this softened dentine to remain during the interim be-
tAveen the making of the pattern and the setting of the inlay, wiW
protect the pulp against irritation and save devitalization before
setting the inlay.
The Finishing of the Enamel Walls will necessarily come in at
this point as all cutting of the external outline of the cavity must
be completed before proceeding to make the pattern. The only
change advisable is that the cavo-surface angle should be more ob-
tuse, and the bevel angle should not be as deeply buried, which
results in a thinner metal edge.
This Avill assist in burnishing the margins to a closer adaptation
in the final finish.
More Beveling at the Cavo-surface Angle should be resorted to
for tAvo reasons. First, the gold inlay should have a margin of
rather an acute angle in order that the material may be burnished
more closely to the margin. Second, during the process of setting
the inlay and burnishing the margins, the cavo-surface angle stands
in great danger of being fractured.
The Toilet of the Cavity for Gold Inlays. Herein lies the great-
est Aveakness in inlay methods. No cavity margin is surgically
clean after it has been moistened or been in contact Avith the inlay
Avax pattern.
After the pattern has been formed and removed our methods
Avill not permit of again planing the cavity surfaces and particu-
larly the margins, Avhich is the only Avay to render them entirely
clean.
Hence Ave are forced to Avash the cavity Avails just before setting
the inlay Avith solvents of the substances Avhich haA'e contaminated
them. Without going into detail, it is adAdsed that the cavity be
thoroughly scrubbed Avith chloroform, then absolute alcohol as a
second cavity toilet, and immediately the cavity be floAved Avith the
cement, introducing the inlay under dry conditions.
Line of Approach. In inlay Avork the cavities should be ap-
proached from the direction in Avhich they are to receive stress
during service.
In AvithdraAving the Avax pattern and Avhen the inlay is placed,
each should travel parallel Avith a line draAvn from the seat of the
cavity to the source of the force of mastication. This line of ap-
proach is good practice Avith any filling, but is more essential Avith