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30 | CERECDOCTORS.COM | QUARTER 1 | 2014
required for scanning. One approach to
preventing contamination of this kind is
to apply a liquid dam — similar to what
is used in dental bleaching — to protect
the gingiva (Fig. 8).
Less effort is required if the tooth
is not extracted until scanning has
been completed. However, in this case,
greater effort is required in preparing
the virtual model as the tooth must be
manually erased on the screen. As the
initial situation was digitalized, the orig-
inal, natural tooth shapes are provided
via the occlusion catalog as a template
for modeling (Fig. 9).
Alternatively, replication mode or the
dental database can also be used for the
purpose of correlation. If a tooth has
already been lost before the patient pres-
ents at the practice (e.g., as a result of an
accident), a prosthetic tooth attached to
the adjacent teeth can be used for digi-
talizing the initial situation as a template
(Fig. 10).
For bridge constructions, the connect-
ing elements should be designed to be as
large as possible so they do not weaken
the stability of the restoration. The
minimum specifications provided by the
manufacturer must always be observed:
in the case of anterior bridges with up to
two pontics and posterior bridges with
one pontic, this is 12 mm2; in the case
of posterior bridges with two pontics,
this is 16 mm2. Regarding the wall
thickness, a circular value of 0.8 mm
and occlusal value of 1.5 mm must be
observed.
Using the virtual display of the multi-
layer blanks in the milling preview, the
final model can be precisely positioned
in the block (Fig. 11). If the small milling
machine is used, the milling unit water
tank must be replaced before you begin
milling by a specially modified tank
that is equipped with a four-phase filter
system adapted to the acrylic mate-
rial. Finally, the fully milled temporary
bridge is finished and polished (Fig. 12).
The patient was very satisfied with the
result (Figs. 13-14).
Fig. 9: During modeling, the initial
situation can be displayed as a guide
Fig. 10: To provide a modeling template,
a prosthetic tooth can be bonded in
the patient's mouth and digitalized
Fig. 11: In the milling preview, the
model is precisely positioned in the
multilayer blank
Fig. 12: Finalized long-term temporary
Fig. 13: Long-term temporary in situ
Fig. 14: The patient is satisfied with
the result
Fig. 15: Gingival contours that are less
than ideal and lacking in esthetics can,
with the aid of a long-term temporary ...
Fig. 16: ... be
significantly
improved before
a new, final
restoration is
fabricated
| | | W E R L I N G
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SALES ARGUMENTS
Although some colleagues initially
consider the fabrication of temporaries
using CAD/CAM technology to be an
extremely complicated process, there
are numerous benefits, and practitioners
can arrange to charge for the additional
effort required. The final restoration
can, in return, be offered at a slightly less
expensive rate.
This approach is justifiable, given that
almost no reworking is required for the
final restoration if the shape and func-
tionality have already been correctly
determined when fabricating the tempo-
rary. The data file for the long-term
Based on clinical
experience, the
material has proven
its worth, even worn
over a period of up
to two years.
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