Ivoclar Vivadent IPS e.max CAD Chairside - Manual (Page 45)

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If a plaster working model is used to work
with, which type of plaster should be used to
fabricate the model?
The directions of the manufacturers of the CAD/
CAM system in use should be observed in the fab-
rication of the models. The following basic rule
applies: Depending on the CAD/CAM system and
equipment, special plasters may have to be used
for the fabrication of models and dies to ensure
the quality of the scan. If a special scanning
plaster is unavailable, models and dies can be
fabricated with high-strength stone, which is
sprayed with IPS Contrast Spray chairside or
IPS Contrast Spray labside immediately before the
scanning procedure.
What kind of preparation requirements must
the die demonstrate in order to produce
accurately fitting restorations?
The preparation guidelines for all-ceramic restora-
tions apply to IPS e.max CAD. The thickness of the
incisal edge of prepared anterior teeth (upper and
lower) requires special attention. The prepared
incisal edge should be at least as thick as the
diameter of the bur used in the cavity. The
corresponding instructions of the manufacturer
regarding the dimensions of the grinding
instruments must be observed during preparation.
Can an incisal edge which has become too
thin during preparation be adjusted prior to
scanning to avoid complicating the try-in
procedure after machining?
In cases such as these, we recommend blocking
out the incisal edge of the prepared die until the
thickness matches that of the bur.
Why is it necessary to determine the shade of
the tooth after preparation?
It is necessary to know the
shade of the prepared tooth
because, depending on the
translucency level of the
block used, the shade of the
prepared tooth may have an influence on the
seated all-ceramic restoration. The appropriate
block can be selected using the IPS Natural Die
shade guide.
In what situations are IPS e.max CAD HT
blocks used?
Given their high translucency, HT blocks are
ideally suitable for the fabrication of smaller
restorations (e.g. inlays and onlays). Restorations
made of HT blocks convince users with their true-
to-nature chameleon effect and the exceptional
adaption to the remaining tooth structure. The
brightness may be lower if translucent blocks are
used to fabricate larger restorations (e.g. crowns).
In such cases, it is recommended to use blocks
with lower translucency levels (IPS e.max CAD LT).
In which situations are IPS e.max CAD LT
blocks used?
Due to their high brightness values compared to
the HT blocks, LT blocks are ideally suitable for
the fabrication of larger restorations (e.g. anterior
and posterior crowns). IPS e.max CAD LT restora-
tions convince users with their lifelike brightness
value and chroma. This prevents the incorporated
restorations from greying.
Does the occlusal surface of IPS e.max CAD
restorations have to be ground after the
CAD/CAM processing?
Yes. In order to smooth out the
surface structure created by the
CAD/CAM milling, the occlusal
surface and particularly the func-
tional areas which show antago-
nist contact must be sur-
face-ground with fine diamonds.
Should manual adjustments with grinding
instruments be done before or after
crystallization?
Corrections by grinding should always be carried
out on the blue restoration prior to crystallization.
In doing so, it must be ensured that the restora-
tion is processed using only suitable grinding
instruments, low speed and light pressure to
prevent delamination and chipping at the edges in
particular.
e.max
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Questions and answers
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