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cerecdoctors.com
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quarter 4
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2012
7
8
9
10
11
5
6
(
Figs. 5-6). Care must be taken to reduce
an adequate amount so that the CAD-
Temp material will be sufficiently thick
for milling, yet not reduced so much that
the CAD-Temp shell will not fully seat
once the crowns are removed and prepa-
rations are refined intraorally.
CEREC SW 4.0.2 is then opened on the
Bluecam AC and pertinent patient infor-
mation is entered to create a new case. In
the Administration phase, Bridge Mode
was selected with teeth #7 and #10 being
the distal-most extensions. The individual
restorations are defined: lateral incisors
as pontics, created in Biogeneric Copy
mode, and central incisors as crowns, also
in Biogeneric Copy (Fig. 7).
In theAcquisitionphase, theun-prepped
model is scanned into theupperBiogeneric
Copy folder to include teeth #7 through
#10,
and at least one additional tooth distal
on each side to act as stitching abutments.
The “prepped” model is then scanned
in similar fashion, being sure to capture
images along the proper path of draw of
the central incisors (Fig. 8).
The case is then brought to the model
phase where margins are “arbitrarily”
designated utilizing the gingival margin
landmarks on the centrals and desired
ovate pontic locations on the laterals
(
Fig. 9). The insertion axis is adjusted
and approved, after which the copy line is
drawn on each tooth individually, making
sure to capture as much clean data as
possible to minimize adjustments of the
Biogeneric Copy proposals.
Once the copy lines are complete, the
software is then allowed to generate the
bridge proposal. Patiencemust be exercised
as this can be a lengthy process. Once the
proposals are rendered, appropriate design
tools are used to idealize the contours,
embrasures and connector areas (Fig. 10).
Once satisfied with the proposal, the
bridge is milled out of the appropriate
CAD-Temp block. With the precision
milling of the MCXL, the shells that will
cover the centrals can be finished extremely
thin. This minimizes the possibility of
binding in the mouth when the crowns are
removedandthebridgeshellisfittedoverthe
existing central incisor preps. At this point, I
recommend removing the sprue, trying the
restoration on themodel, and polishingwith
a rag wheel and pumice —but NOT refining
embrasuresandcontours, as this canweaken
the shell and connectors, leading to fractures
prior to relining in themouth (Fig. 11).
Now that the milled interim prosthesis
is ready for placement, the surgery can
be performed. My preference in this
particular case was to remove the central
incisor crowns prior to surgery to avoid
Figs. 5 and 6: The pre-operative model is
prepared to serve as a guide for the shell
tempoararies.
Fig. 7: The restoration is marked in the
administration phase of the CEREC
software.
Fig. 8: The Scan of the prep and the wax-
up integrated in the CEREC software.
Fig. 9: The margins of the proposed
provisional bridge are marked.
Fig. 10: The initial proposals with the 4.0
software.
Fig. 11: The milled shell provisional.
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