International Journal of Computerized Dentistry 2/2005, P. 169-178.
The Prefabricated Anatomical Polychrome CAD/CAM Crown for the inLab System
Ulrich R. Mönkmeyer, Frank Poerschke, Andreas Kurbad, Kurt Reichel, Volker Scharl
prefabricated crown blanks, semi-finished product, CAD/CAM crown, plastic jacket crown, layering-induced esthetic effect, Cerec, inLab.
An innovative extension of performance in the area of single crown production is presented. Prefabricated crown blanks
with color layering are inserted in the row of teeth with specially developed software and adapted apically to the stump with a
CAM milling program.
The first CAD/CAM-produced crown was
presented by Francois Duret1 in 1988. In 1990, Jef van
der Zel2 presented with the Cicero system the idea of a
layering technique, which sintered the layers on in individual steps for
mechanical processing. Various authors see the present status of CAD/CAM
technology in the
production of copings, which are machined and
veneered by traditional methods.3-5 The
greatest advantage consists in the
employment of new materials, especially
zirconium oxide.6,7 The standardization
of production processes
and their cost effectiveness are accentuated
differently by different authors
for the different systems, but play a secondary
The few documents and publications of
cases in which complete restorations,
especially crowns, were produced with
CAD/CAM methods show that this
indeed is and remains the exception,
apart from the large number of documented
inlays and partial crowns produced
with the Cerec system.8 The
entire process of crown production
also remains highly interactive and thus
cost-intensive with CAD/CAM methods.9
Basic principle of the artegral crown
The artegral ImCrown developed by
Merz Dental (Lütjenburg, Germany) is
a prefabricated, anatomically formed,
color-layered and characterized crown
made from a plastic material (Fig 1). It
is not milled out from the block. It
merely requires apical adaptation to
|Fig. 1: The anatomical, polychrome crown is dimensioned sufficiently in the marginal
region and available in five different sizes for the left and right incisors as well as
different sizes for the canines for bilateral use.
The crown is inserted and harmoniously aligned digitally in the row of teeth
and with the occlusion with the aid of the software for the Cerec 3D and
inLab (Sirona, Bensheim, Germany).
The suitable size is selected by the
software from the five predetermined crown sizes, and the dimensional
changes made by the user are implemented. The minimum material thickness as
well as the esthetic effect induced by layering are taken into account.
Virtual modeling is not required, since the form of the crown is already
The artegral ImCrown has a natural labial and palatinal
surface design. It can be inserted immediately after polishing. The canine
crown blanks for bilateral use as well as different left and right incisal
crown blanks make up a small assortment, so that one has at hand the correct
solution for the restoration of the maxillary anterior teeth. Because of the
prefabricated surface contour, interacting with the polychrome layering, the
artegral ImCrown is endowed natural esthetics and refraction of light, which
moreover can be modified manually with little effort and can be further
Step-by-step procedure CAD/CAM methods
A duplicate model (scan model) of the
master model produced by the customary
method is produced from
scannable plaster. This also reproduces
the neighboring teeth apart from the
stumps to be processed. Scanning is in
the "Crown preparation" mode. The
inEOS scanner can be used as an alternative.
In this case, the master model
can be scanned directly.
After scanning, the three-dimensional
image of the model segment can be
viewed on the monitor (Fig 2). The
insertion axis is determined first. This
step must be given the greatest attention,
because the internal fit of the
crown can be influenced by it. The
neighboring teeth are then trimmed
virtually. In this way, we obtain an unobstructed
view of the working stumps
(Fig 3). The bottom line is determined
semi-automatically on the working
stump by tracing it with the cursor.
The best possible tooth is proposed
independently by the Cerec 3D software
and inLab, and inserted (Fig 4). A
few design steps are then sufficient to
integrate the crown in the row of teeth
with regard to alignment and size (Figs
5 to 10).
|Fig. 2: The scanned model can be turned by 360 degrees.
||Fig. 3: The preparation margin is marked semi-automatically in the usual manner.
|Fig. 4:The software proposes the crown in the correct size.
|Fig. 5: The crown axis is aligned from the labial view.
||Fig. 6: The crown is shifted mesial-distally, so that a physiological, proximal contact can be created.
|Fig. 7: The crown is not yet aligned in the dental arch.
||Fig. 8: From the incisal view the crown
can be integrated into the dental arch; in this case, one can also tilt it in the
direction of the labial view.
|Fig. 9: From the lateral aspect, both the
correct inclination as well as the correct position of the color layering can be
corrected by shifting in incisal or cervical direction.
||Fig. 10: After releasing, one can assess
whether the proximal contact is sufficient
Following the milling process (Figs 11
and 12), the crown is finished manually
and purely subtractively with regard
to its fit. As a rule, the fit is perfect after
finishing. The proximal contacts are
adjusted working from the cervical and
incisal, and a contact foil should be used
for this purpose.
|Fig. 11 and 12: View of the crown directly after the milling process.
Adapting the functional surface
The incisal edge is best shortened to
the approximate length using a silicone
rubber wheel (Fig 13). The palatinal
functional surface is produced concavely
with a large round bur underneath
the abrasion surface. The marginal
ridges are also created in this way
(Fig 14). The occlusion is checked and
ground in by centric and excursion
movements with a white silicone rubber
wheel and using occlusion foil. The
ridges are then drawn on the neighboring
tooth, and the desired ridges
are transferred to the crown. The
desired ridges are then ground with a
thin diamond conical bur or a correspondingly
finely cross-toothed cutter
(Fig 15). The labial concavities are then
drawn and created with the same tool.
The surface texture is individualized
with a sharp-edged stone or a diamond
|Fig. 13: The incisal edge length is corrected with a rubber wheel.
||Fig. 14: The palatinal functional surface is individualized with a few corrections.
|Fig. 15: The "face" of the tooth is
determined by the correct application of the ridges.
The surface is leveled with a plastic brush
(Figs 16 and 17). This is followed by minimally
abrasive rubber polishing of the
abrasion surfaces and smoothing
exposed places (eg, with a "Brownie"
[Shofu, Ratingen Germany]). Preliminary
and high-gloss polishing is performed
best of all with a goat-hair brush
and polishing paste. The final result is
achieved within a few seconds (Fig 18).
|Fig. 16: The surface texture aimed for is
drawn and "copied".
||Fig. 17: The surface is very quickly given
the required microstructure with a plastic brush.
|Fig. 18: The finished work on the model
shows a result which can be achieved with no other method in such a short time
The artegral ImCrown can be provisionally
cemented with all customary
provisional adhesive materials, but
preferably with artegral T-Cem.
Final adhesion is accomplished with the
enamel/dentin adhesive technique.
For this purpose, the one-component
product artegral One is used on the
moist tooth surface after light curing as
a basis for the dual-curing cement artegral
A 57-year-old male patient came to the
practice because of symptoms and
increasing loosening of teeth 21 and 22.
The radiograph displayed a transverse
root fracture in both teeth. The cause
given in the case history was a sports
accident six weeks previously (Fig 19).
The fractured teeth were removed
carefully (Fig 20) and an immediate
implantation with Straumann TE
implants (Straumann, Basel, Switzerland)
was performed. Thanks to the
high primary stability achieved because
of the good bone structure and the special
design of these implants, delayed
immediate loading was possible.
An impression was taken and a model
produced one week after the implantation.
This was modified to achieve an optimum
emergence profile. Two RN syn-
Octa abutments for temporary
restorations (Straumann) were modified
corresponding to the anatomical
conditions (Fig 21). After the model situation
was scanned, two artegral
crown blanks were fitted virtually by
means of the Cerec inLab CAD/CAM
program (Fig 22). The crowns were
adjusted manually and polished after
milling (Fig 23).
Only 24 hours after taking the impression,
it was possible to insert the
restorations for delayed immediate
loading, thanks to the fast CAD/CAM
production (Fig 24).
|Fig. 19: Initial situation: Condition after
a sports accident 6 weeks previously in a 57-year-old male patient.
||Fig. 20: Fractured teeth 21 and 22 were carefully extracted.
|Fig. 21: RN synOcta abutments for temporary
restorations (Straumann, Basel,Switzerland) are modified corresponding
to the anatomical conditions for delayed immediate loading.
||Fig. 22: Artegral blanks can be adapted
basally to the implant situation with the aid of the Cerec CAD program (Sirona,Bensheim).
|Fig. 23: Apart from the exact seat on
the implant shoulder, modeling an adequate emergence profile is important.
||Fig. 24: The finally adapted and polished artegral crowns are ready for insertion.
For this purpose, the abutments were
first screwed in and then the crowns
were bonded with a provisional
cement. The restoration (Fig 25) is
designed so that it is not functionally
subjected to large loads, but shows a
very good esthetic effect (Fig 26).
The advantage of the procedure with
CAD/CAM-supported use of artegral
crowns is that the crowns can be adapted
perfectly to the clinical situation.
Production can be undertaken very
quickly. In this case, in contrast to previously
produced provisional shell
restorations, no inconvenient modifications
or relining with poorly tissuecompatible
temporary plastics have to
be performed. On the other hand, taking
an impression of the optimum
emergence profile early on makes it
possible to conserve and support the
soft tissue. This means a considerable
advantage for the later definitive
restoration. The patient enjoys the
best possible comfort, good periodontal
hygienic conditions and a very good
esthetic effect by dispensing with an
|Fig. 25: After already largely completed
wound healing, the RN synOcta abutments are screwed in.
||Fig. 26: After cementing with a provisional
adhesive material, the patient has a functional restoration with optimum
esthetics for the entire duration of the healing phase.
Today, the plastic jacket crown produced
in the laboratory is scarcely considered
the standard restoration
because of its material disadvantages
hydrolytic degradation, insufficient
abrasion properties etc. The dental
material IPN used in the artegral crown
is plaque resistant, abrasion proof, and
temperature resistant, and is characterized
by its ability to be machined
very well. In this way, as well as due to
quality-assured, industrial processing
methods, the relevant physical parameters
of the material and the adhesive
bond between crown and tooth
are clearly improved, which may have
a positive influence on the long-term
Since the working method for Cerec
3D and especially for Cerec inLab users
is very economical, it is possible that
any potential disadvantages concerning
the dwell period is compensated. Various
studies already in progress evaluate
the economic advantages (time
requirements), material property
advantages, and product quality advantages.
Currently, crown blanks are available
for teeth 13 to 23 (#611). Work is
being done on experimentally extending
the range to all teeth and on using
Experiments with an innovative material
containing nanofluorapatite, which
contains an enamel and crystal structure
identical to nature in a polymer
network, are very promising.
Experimental work is also being done
on ceramic blanks which can also be
processed additively. Necessary studies
for the use of these materials have
not yet been completed. The experiments
show that their use in the
CAD/CAM production of crowns
would bring considerable economic
advantages. Crowns produced in such
a way would certainly not worsen the
average quality standard of crown
- Duret, F. et al.: CAD/CAM in Dentistry. J Amer Dent Assoc 117, 715-720 (1998).
- Zel, J. M. v. d.: Elephant Symposium, Zandfort (1990).
- Witkowski S. Computer Integrated Manufacturing
als Konzept für das zahntechnische
Labor. Quintessenz Zahntech 2002;
- Luthardt R, et al. Aktuelles CAD-CAM Systeme
zur Herstellung von keramischem
Zahnersatz. Teil 1. ZWR 2001;110:747-
754; Teil 2. ZWR 2001;110:797-802.
- Kern M, et al. Neue Perspektive in der
Zahnheilkunde? Quintessenz Zahntech
- Sudhoff C. Zirkonoxid als Werkstoff für die
Implantat- und Kombitechnik. Quintessenz
- Langschwager A. Die zirkuläre durch
Geschiebe verbundene cercon-Unterkieferbrücke,
Quintessenz Zahntech 2003;
- Jedynakiewicz N. Something of a Paradox.
Int J Comp Dent 2004;7:223-224.
- Kerschbaum Th. Behandlungsbedarf mit
Zahnersatz bis 2020. Quintessenz Zahntech