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Making crowns with a CAD/CAM
system. J.M. van der Zel, Elephant
Holding B.V., Problem: CAD/CAM stands for Computer Aided Design/Computer
Aided Manufacturing, thus computerized design and production. CAD/CAM has
received much attention in the news because of a strong increase in
IT-applications that work on a PC. Processes where mainframe computers were
necessary, can now be now be executed on normal PC’s, because of increased
memory capacity, high capacity hard disks and much higher calculation speed.
The latest application for the PC is CAD/CAM. Conclusion: Many programming tools have been developed that can
now be used in dentistry, specifically in the design and production of
indirect dental restorations. Published in SPIN Bulletin,
Ministry of Economic Affairs, No. 4, December 1988, p. 11-12. Maximum functional occlusion
for a metal ceramic crown with the “ Statement of the problem: The Cicero-system is a CAD/CAM (Computer Aided
Design/Computer Aided Manufacturing) system for the production of
“state-of-the-art” ceramic-fused-to-metal (CFM) restorations that makes use
of near net-shape metal and ceramic sintering techniques. Existing CAD/CAM
applications for the production of restorations are based on milling of
massive materials, which has evident negative effects on esthetics. A novel
sintering technique makes it possible to build-up and model the restoration
in different layers such as metal, opaque, dentin and incisal porcelain for
maximum esthetics. It is to be used for the production of restorations with
maximal static and dynamic occlusion. Material
and methods: A first mandibular premolar (46) was designed. The
preparation and its immediate surroundings and antagonists were digitized
with a laser-strip surface scanner. The theoretical 46 crown was deformed by
a seven step algorithm to give maximum tooth-to tooth contact with the
antagonist. The occlusal surface of the machined crowns were tested for
efficacy in static and dynamic occlusion. Conclusion: It could be
concluded that occlusion in porcelain can be obtained by the automated way of
production with the Published as Abstract No. Influence of Cement gap Design
on Fracture Resistance of Statement of the problem: The CICERO CAD/CAM system not only produces
porcelain restorations supported with sintered metal or high-strength
ceramic, but also full-porcelain restorations. The latter might be more susceptible
to cracking by localized stresses depending on the way the restoration is
supported. Aim: The aim of this
study was to investigate the influence of cement gap design on the fracture
resistance. A master steel die with a rounded chamfer preparation was
duplicated in gypsum and scanned. Forty identical crowns were produced with
four different cement gap geometries and cemented under constant load on the
master steel die with zinc phosphate cement. Specimens were tested in a Zwick
1454 universal testing machine with a crosshead speed of 0.5 mm/min. The
types of cement gap design (restoration inside) were: even cement gap (A),
supporting ridge at the margin (B), supporting ridge Published: Van der Zel, J.M.,
and Davidson, C.L (1997): Influence of Cement gap Design on Fracture
Resistance of Influence
of Crown Layer Build-up on Fracture Resistance of The CICERO CAD/CAM system produces ceramic
restorations supported with high-strength high-alumina core ceramic
(Synthoceram, Elephant), but also full-porcelain restorations. The novel
supporting ceramic understructure material is based on a
alumina-zirconia-mullite-system with a modulus of rupture of 350 MPa. The
core is sintered on a pre-milled refractory die. This supporting material
might provide the restorations with the necessary survival durability. The
aim of this study was to investigate the influence of crown layer build-up on
the fracture resistance. A master steel die with a rounded chamfer
preparation was duplicated in gypsum and scanned. Twenty identical crowns
were produced with two different layer make-ups and cemented under constant
load on the master steel die with zinc phosphate cement. The cementgap design
provided for a supporting ridge Published: Van der Zel, J.M.,
and Davidson, C.L. (1998): Influence of Crown Layer Build-up on Fracture
Resistance of Dispersion
Strengthening of Statement
of the problem: The CICERO CAD/CAM
system automatically produces ceramic restorations supported by an
high-strength high-alumina core ceramic (Synthoceram, Elephant)*. The novel
supporting ceramic understructure material is based on aluminiumoxide
ceramics with a glassy phase. The strength of the material might be increased
if the glassy component is strengthened. Aim:
The aim of this study was to investigate the influence of the addition of
zirconia on the fracture resistance of the alumina-glass composite. The two
groups of alumina-glass composites tested were: with 4 wt.-% zirconia (A) and
without (B) the addition of zirconia to the glassy phase. Material and methods: For each group
twenty specimens were prepared for three points bending tests, according to
ISO 6872. Specimens were tested in a Zwick 1454 universal testing machine
with a crosshead speed of 0.5 mm/min. The specimens were investigated with
scanning electron microscopy. Results:
The results showed that the mean flexural strength of group A (412.4±18.7
MPa) was significantly higher than group B (332.5±14.2 MPa) (p<0.01). SEM
investigation in combination with Energy Dispersive X-ray Analysis showed
evidence of the presence zirconia crystals in the glassy phase that can
attribute to an higher strength of the material. Conclusion: Hence, we conclude that strengthening Published: Van der Zel, J.M. and
Davidson C.L. (1999): Dispersion Strengthening of
Effect of condylar jaw movements
on the occlusal contacts of Statement of the problem:
The CICERO CAD/CAM system makes it possible to automatically produce
all-ceramic crowns with a precision-milled occlusal surface and allows the
imput of 3D condylar jaw movements for occlusal adjustments during
articulation. The aim of this study was to evaluate the effect of different
articulation concepts on the number of contact points on a standard 46 molar
in the same patient model. Two groups of articulation computer models were
used as imput and compared with static occlusion as a control: group 1:
articulation using the average default values of a fully adjustable
articulator with Published: Olthoff, L.W., Van
der Zel, J.M., and Bosman, F. (1999): Effect of condylar jaw movements on
occlusal contacts of Computer Copings for Partial Coverage,
H.W. Denissen,J.M. van der Zel, J. Reisig, S. Vlaar, W. de Ruiter, M.A.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Occlusal
contact distance, mm |
STA CON DEF |
|
0.00
- 0.05 (contact) |
14 11 0 |
|
0.05
- 0.10 |
15 15 4 |
|
0.10
- 0.15 |
17 17 7 |
|
0.15
- 0.20 |
25 22 28 |
Results: Electronic
registration creates more contact points than the default articulator
setting. No static contact points were found after articulation in group DEF.
The results showed clear differences in the occlusal morphology of the
occlusal surface after intrusal corrections between the groups CON and DEF
compared to group STA, especially in the disto-buccal part. The number of
contact points of group CON and group STA was higher than group DEF. However, these differences were not
statistically significant. Conclusions:
It is concluded that using electronic registration as imput for the CICERO
CAD/CAM system creates a functional occlusion without disturbances with more
contact points than an average default setting of an articulator.
Published
IADR
Measurement
of the Margins of Partial-Coverage Tooth Preparations for CAD/CAM,
H. W. Denissen,
Purpose:
This study tested the hypothesis that a scanning laser 3-dimensional
digitizer is a precise and accurate instrument to measure chamfered and
beveled margins of partial-coverage tooth preparations fffor computer-aided
design/computer-aided manufacturing (CAD/CAM). Material and methods: The margins were measured by the digitizer
on stone dies and calculated by triangulation into a 3-D representation.
Instrument precision was defined as the ability to reproduce the same margin
in repeated measurements and expressed as the coefficinet of variation as a
percentage. Instrument accuracy for chamfered and beveled margins was
estimated by correlating their measurements to the measurement of the margin
of a spherical calibration “phantom” with known dimensions. Accuracy was
expressed as the standard deviation. Results:
The precision errors for the box- and cusp-chamfered margins and cusp-beveled
margins were 3.9%, 3.4%, and 2.4%, respectively. With regard to accuracy the
standard deviations of the measurements of the box- and cusp-chamfered
margins and cusp-beveled margins were 19 µm, 21 µm, and 24 µm, respectively,
compared to 15 µm for the phantom. Conclusion:
Measurements of chamfered and beveled margins by a scanning laser 3-D
digitizer for CAD/CAM are (1) precise (error < 4%) and (2) accurate, with
a standard deviation of less than 9 µm compared to optimal measurements of
the spherical margin of the phantom.
Published: Int J Prosthodont
1999; 12:395-400.
Marginal fit and
short-term clinical performance of porcelain-veneered CICERO, CEREC, and
Procera onlays. Denissen
H, Dozic A, van der Zel J, van Waas
M. Department
of Oral Function and Prosthetic Dentistry, Academic Centre for Dentistry
Statement
of the problem: Onlay preparations are very complex
surfaces for computer surface digitization, CAD, and
Partial
coverage copings by computer, H.W. Denissen, J.M. van
der Zel, M.A.
Aim: Aim
of the study was to evaluate the Computer Integrated Ceramic Reconstruction
(CICERO®)-system and the Ceramic Reconstruction (CEREC®)-system
for the production of all ceramic copings for partial coverage. Material and methods: Posterior teeth
were prepared and the stone dies were made. Accuracy analyses were performed
on ceramic restorations made by means of the
Published:
Ned. Tijdschrift Tandheelkunde 106 (1999)
Clinical
Preparation Parameters for
Statement
of the problem: With the advent of dental CAD/CAM as a new fabrication
technology, is is likely that some paradigms on preparation technique will
change, especially because CAD/CAM will likely increase the use of full
ceramic restorations. Opposed to metal-ceramic crowns, full-ceramic crowns
are prone to cracking by local stresses, as a ductile stress relief mechanism
is absent. Full-ceramic restorations will therefore put more emphasis on
"proper" preparation techniques. The
CICEROR CAD/CAM system automatically produces shaded copings of an
high-strength high-alumina core ceramic (Synthoceram, Elephant) to be finished in the dental laboratory. Purpose: The purpose of this
study was to collect data on clinical preparation parameters, such as axial
reduction and shoulder angle in a clinical fieldtest of 100 CAD/CAM crowns. Material and methods: The gypsum dies
received, were optically scanned and the axial reduction and shoulder angle
were determined in four sections of the digitized surface. The results were
compared against manufacturers' preparation instructions. For the field-test
a group of 80 patients were selected randomly from group practices by general
practitioners in the region north of
Strength Comparison of
Alumina Copings of Procera and CICERO. H.F. Kappert and Krah, Department of dental
materials,
Objective: The objective of the study was to compare the mechanical
strength of veneered aluminiumoxide copings produced by the Integrated
Ceramic Reconstruction (CICERO®) -system and the Procera®-system,
by applying an increasing static load until fracture occurs. A clinical
canine type crown with a deep chamfer preparation and wall thickness in the
range of
System
|
Static break strength, N |
Standard
deviation, N |
|
Procera (Nobel Biocare, |
929 |
291 |
|
CICERO ( |
1045 |
79 |
Results: Statistical analysis on two groups of ceramic restorations
revealed that the veneered copings made by the
Unpublished
report Uni Freiburg, November 2000.
Thermal compatibility of
Objective: The objective of the study was to compare the
thermal shock resistance of veneered aluminiumoxide copings produced by the
Computer Integrated Ceramic Reconstruction (CICERO®) -system and
three metal-ceramic. A clinical canine type crown with a deep chamfer
preparation and wall thickness in the range of
|
Temperature in oC |
Number
of cracked crowns after the thermal shock test |
|||
|
Cicero-Sintagon |
Galvano-Response |
Degudent-Response |
Golden gate |
|
|
105 |
0 |
0 |
0 |
0 |
|
120 |
0 |
0 |
0 |
0 |
|
135 |
0 |
1 |
0 |
0 |
|
150 |
0 |
0 |
2 |
2 |
|
165 |
0 |
1 |
0 |
4 |
|
Survived: |
6 |
4 |
4 |
0 |
Results: By inspection of the crowns after the thermal shock
test using temperatures up to 165oC no changes of the veneer
material of
Unpublished report Uni Freiburg,November 2000
Computer modeling of occlusal surfaces of posterior teeth with the
OLTHOFF, L.W., VAN DER ZEL, J.M., DE RUITER, W.J. BOSMAN, F.
Statement of the problem: Static
and dynamic occlusal interference frequently needs to be corrected by
selective grinding of the occlusal surface of conventional cast and
ceramic-fused-to-metal restorations. CAD/CAM techniques allow control of the
dimensional contours of these restorations. However, parameters responsible
for the occlusal form need to be determined. In most articulators, these
parameters are set as default values. Which technique is best for minimizing
the introduction of occlusal interference in restorations has not been
determined. Purpose: This study
investigated differences in crown structure of a crown designed in static
occlusion (STA) with designs adapted for dynamic occlusal interferences.
Therefore, values from an optoelectronic registration system
(String-Condylocomp, KAVO), an occlusal generated path (OGP) technique and
default settings (DEF) were used in the CICERO CAD/CAM system. Material and
Methods: Morphology of CON, DEF, and OGP crowns was compared with that of the
STA crown with respect to differences in a buccolingual section and frequency
of occlusal distances in an interocclusal range of
Published: J Prosthet Dent. 2000
Aug;84(2):154-62.
The influence of
porcelain layer thickness on the final shade of ceramic restorations.
Dozic A, Kleverlaan CJ, Meegdes
M, van der Zel J, Feilzer AJ. Department
of Dental Materials Science, ACTA,
Statement
of the problem: Ceramic restorations should be made of
porcelain layers of different opacity, shade, and thickness in order to
provide a natural appearance. By means of CAD/CAM layering technology such as
Published: J Prosthet Dent. 2003 Dec;90(6):563-70.
A simple method to gain digital
color information for use in CAD/CAM procedures.
Statement of the problem:
In CAD/CAM restorative procedures, the determination of color is one of the
last things that is still carried out manually. Therefore is there a need for
digital color mapping algorithms that can be stored in computer memory for
use in crown production. To improve the quality of whole-tooth-surface color
representation, however, the accuracy of color determination must first
increase and the results must be available as digital data. Purpose: Our aim was to investigate
whether photographs made with a commercially available digital camera can
provide us with color information (expressed in L* a* b* values) that
corresponds to spectrophotometer color measurement data. Materials and methods: The ceramic specimen (Synthagon, Elephant
Dental B.V.) in shade A3 was photographed with: Coolpix 990 (Nikon) and
Camedia 2.1 (
Published IADR Abstract 2003
Effect of Shoulder Design on Failure Load of
PTZ Crowns.
Objectives:
To evaluate the effect of shoulder design on the failure load of
Press-to-Zirconia (PTZ). Methods:
Two groups were studied: Overpressed crowns with a zirconia free PTZ shoulder
(CS) and overpressed crowns with zirconia up to the margin (CC). The
zirconia-free shoulder extended
Published:
CD IADR Hawai 2004.
Computer
Aided Diagnosis and Design of Implant Abutments. J.M.
VAN DER ZEL,
Departement of dental material science, Academic Centre for Dentistry
Amsterdam, Universiteit van Amsterdam and Vrije Universiteit Amsterdam, The
Netherlands.
Statement of the problem: Minimal
invasive implant therapy has recently gained a growing interest as a standard
prosthodontic treatment, providing complete restoration of the occlusal
function. Computer aided pre-surgical implant planning based on computer
tomography scan data and computer aided design of individualized abutments by
using optical scan data are well established, although two distinctly
separate techniques. A new treatment method (CADDIMA) is recently developed
which combines both CT- and laser-scan data for planning and design of drill
guides and implant abutments. Objectives: 1) To evaluate the
possibility for implant diagnosis and drill hole planning using a combined CT
and optical imaging method; 2) To evaluate the possibility for abutment
design in the same stage. Methods:
Published: IADR CED-NOF Meeting 2005, 53:#159.
Influence
of Crown Layer Build-up on Fracture Resistance of
The CICERO CAD/CAM system produces ceramic restorations
supported with high-strength high-alumina core ceramic (Synthoceram,
Elephant), but also full-porcelain restorations. The novel supporting ceramic
understructure material is based on a alumina-zirconia-mullite-system with a
modulus of rupture of 350 MPa. The core is sintered on a pre-milled
refractory die. This supporting material might provide the restorations with
the necessary survival durability. The aim of this study was to investigate
the influence of crown layer build-up on the fracture resistance. A master
steel die with a rounded chamfer preparation was duplicated in gypsum and
scanned. Twenty identical crowns were produced with two different layer
make-ups and cemented under constant load on the master steel die with zinc
phosphate cement. The cementgap design provided for a supporting ridge
Published: Van der Zel, J.M.,
and Davidson, C.L. (1998): Influence of Crown Layer Build-up on Fracture
Resistance of
Effectiveness of
preparation guidelines for an all-ceramic restorative system.
Begazo CC, van der Zel JM, van
Waas MA, Feilzer AJ. Department of Oral
Function, Academic Centre of Dentistry
Purpose: To
evaluate, in a clinical field-test, the implementation of manufacturer's
preparation guidelines for the all-ceramic
Published:
Am J Dent. 2004 Dec;17(6):437-42.
Validation
of glass-ceramic veneered 3Y-TZP zirconia for dental restorations. J.M.
van der Zel, Department of Dental Materials Science,
Statement
of the problem: The research on the use of zirconia
ceramics as biomaterials started about twenty years ago, and now zirconia
(Y-YZP) is in clinical use in THR, but developments are in progress for
application in dental devices. A newly developed esthetic glass-ceramic
Sakura® (Elephant Dental B.V., Hoorn, The Netherlands) can be
applied to CADCAM derived 3Y-TZP zirconia structures by automatic
heat-pressing or with slib-casting by hand. The validation study involved the
investigation of bonding properties and phase changes by thermal expansion
mismatch stress between the glass-ceramic and zirconia core ceramic and by
fatigue loading.
Material
and methods: Biaxial flexion of bilayered disks was used to determine the flexural strength
before and after fatigue loading in a simulated physiological environment.
Low-angle XRD was used to study phase changes at the interface boundary. The
reliability of strength was analyzed with the Weibull distribution. SEM was
used to identify the initial crack and characterize the fracture mode.
Results:
It became clear that the Weibull modulus for the
fatigue failures was consistent with previously reported work on other
ceramics. Tetragonal-to-monoclinic zirconia phase transformation was
observed after some handling steps such as airborn alumina abrasion. However
heat treatment above 850oC a complete reversal to secondary
tetragonal phase was observed. A thermodynamic explanation for this
phenomenon is given. Fatigue loading did not reduce the flexural strength.
Failure of disk specimens was caused by typical inherent flaws commonly observed
in ceramics.
Significance:
The contribution of strong and tough zirconia core to the performance of
all-ceramics restorations may be offset by the weaker veneering glass-ceramic
if the actual distribution of the tensile stresses within the restoration is
not taken into consideration.
Published:
Transactions Euromat Prague 2005
Computer
Aided Diagnosis and Design of Implant Abutments. J.M.
VAN DER ZEL,
Department of dental material science, Academic Centre for Dentistry
Amsterdam, Universiteit van Amsterdam and Vrije Universiteit Amsterdam, The
Netherlands.
Statement of the problem:
Minimal invasive implant therapy has recently gained a growing interest as a
standard prosthodontic treatment, providing complete restoration of the
occlusal function. Computer aided pre-surgical implant planning based on
computer tomography scan data and computer aided design of individualized
abutments by using optical scan data are well established, although two
distinctly separate techniques. A new treatment method (CADDIMA) is recently
developed which combines both CT- and laser-scan data for planning and design
of drill guides and implant abutments. Objectives: 1) To evaluate the
possibility for implant diagnosis and drill hole planning using a combined CT
and optical imaging method; 2) To evaluate the possibility for abutment
design in the same stage. Methods:
Published: IADR CED-NOF Meeting 2005, 53:#159.
Dental
Glass Pressed-To-Zirconia Interface Study. Jef M. van
der Zel , Academic Centre for
Dentistry Amsterdam, Amsterdam NL.
Statement
of the problem: The demand for bio-inert, metalfree dental restorations
has put pressure on industry to develop zirconia-base materials because of
its promise for durability and longevity. Zirconia structures are produced by
slib casting or by milling. Because of the opaqueness of zirconia a
tooth-coloured dental glass is used to bring the proper natural aesthetics to
the zirconia-base. Although the traditional layering technique could be used,
thermal pressing of dental glass into a lost wax form is a more effective and
economic way. It was hypothesised that partially stabilised zirconia under
the coating stresses at the interface some conversion from tetragonal to
monoclinic would take place with an accompanying volume increase. This volume
increase could be the cause for defects in the zirconia surface and explains
the frequently observed failure at the interface of dental glass and
zirconia. Material and methods: A
dental glass (PTZ) with a pressing temperature of
Conclusion:
The study revealed that the interface had an extreme integrity with some
diffusion of zirconia into the glass. Fatique cycling did not cause the
formation of a monocline zirconia layer at the interface between dental glass
and zirconia.
Published
as abstract in NKV proceedings 2005.
Survey on
Cyrtina® copings and bridges. I. Vervoort, S.J.
Objective:
To validate the bridge quality of a new CAD/CAM system (CyrtinaCAD, Oratio B.V.,
Zwaag, The Netherlands) together with the veneering ceramic Sakura
Interaction (Elephant Dental B.V., Hoorn, The Netherlands. Methods: Gypsum models were send in
by fourteen dental laboratories in
Internal
report available on request.
Effect of
core material on stresses in veneered crowns. N. De Jager,
Objective:
All ceramic restorations without metal have great advantages in their
biocompatibility and aesthetic aspects. With the introduction of new core
materials, the cores are sufficiently strong to produce long lasting
all-ceramic restorations, however the stresses in the veneering porcelain
could still determine the longevity. The objective of this study was to
evaluate, by finite element analysis (FEA), the influence of different core
materials on the stress distribution in dental crowns. Material and methods: The model
of a multi-layer all-ceramic crown for
posterior tooth 46 produced with CAD-CAM-technology was translated into a
three-dimensional FEA program. This crown model was made with gold, zirconia,
and alumina-based porcelain core and their matching veneering
porcelains. The stress distribution
due to the combined influences of bite forces, residual stresses
caused by the difference in expansion coefficient of the core material and
the veneering porcelain, and the influence of shrinkage of the cement was investigated. Results: Stiffer core material does not always for various
reasons result in lower stresses in the veneering porcelain. Significance: This study indicates
that the actual distribution of the tensile stresses and the design of
restorations must be taken into account; otherwise, the significant
contribution of stronger and tougher core materials to the performance of all-ceramic
restorations may be offset by the weaker veneering porcelain.
Published
in Dental Materials 2005.
The
influence of different abutment material on the FEA-determined stress
distribution in dental implant systems.
Objective:
The objective of this study was to evaluate by finite element analysis (FEA)
the influence of different abutment materials on the stress distribution in
two dental implant abutments for the “Dyna Helix” implant system (Dyna Dental
Engineering B.V., Bergen op Zoom, The Netherlands): with an internal and an
experimental external octagon respectively. Methods: Two implant abutment
designs were built in a three-dimensional FEA program. The abutment materials
used were Titanium grade 5 and Y-TZP zirconia. The stress distribution due to the
combined influences of bite forces and the torque on the fixation screw was
investigated. Results: For the implant system with an internal octagon the higher tensile
stresses in the zirconia abutment offset the advantage of the higher strength
of this material. The implant system with an external octagon is a better
design for zirconia abutments. Significance:
This study indicates that to exploit the high strength of zirconia as
abutment material the actual distribution of the tensile stresses and the
design of the dental implant system must be taken into account.
Dental Materials
Introduction: The need for proper validation and
verification methodology for CAD/CAM systems is becoming an interest to
dental professionals and custom dental device manufacturers. CAD/CAM systems
existing of an optical impression system, design software and a fabrication
machine have to perform to a certain level, whereby manufacturers needs to
prove the effectiveness of the system as a whole. However, especially when
dental surface digitization devices are used as open, stand-alone
applications in dental outsourcing, a reliable standard test for comparison
is necessary. Purpose: This study evaluates a proposed test method to be used to quantify
“digitizing quality” with respect to accuracy and reproducibility of two
dental surface digitization devices. Comparability of the characteristics
should become ensured. Method: Two laser light section scanners: “DentaScopeII” (microSystems
Published in Int Dent J
2006.
Influence
of thermal expansion mismatch and fatigue loading on phase changes in
porcelain veneered Y-TZP zirconia.
a
and c PhD
researcher, Department of Dental Material Science, Academisch Centrum
Tandheelkunde Amsterdam, Universiteit van Amsterdam and Vrije Universiteit,
The Netherlands.b Department of Dental Material Science,
Academisch Centrum Tandheelkunde Amsterdam, Universiteit van Amsterdam and
Vrije Universiteit, The Netherlands.d Professor of Computerized
Dentistry, Department of Dental Material Science, Academisch Centrum
Tandheelkunde Amsterdam, Universiteit van Amsterdam and Vrije Universiteit,
The Netherlands.
Objectives:
This study was conducted to test the hypothesis that
mismatch in coefficient of thermal expansion between porcelain and Y-TZP
zirconia as used for all-ceramic dental crowns cause transformation of the
tetragonal structure to the monoclinic structure in Y-TZP at the interface
boundary, when exposed to fatigue loading. Methods: Three groups of porcelain veneered Y-TZP (Cercon®
base 38, DeguDent GmbH,
Published
in J Oral rehab 2006.
Augmented
Reality Model for Dentistry,
Introduction: Minimal-invasive computer-aided
implant planning and placement with surgical guides, computer aided
regulation with orthodontic guides and occlusion rehabilitation with dental
CADCAM are becoming well established applications, although mainly used
separately as stand-alone applications in isolated dental practices. Because of their present character of these
applications they have never reached the integration necessary to realize the
virtual dental surgery with augmented reality. Mehods: To make computerized dentistry
available to every dental clinic at the Point of Care an internet accessible
product line of computerized dental treatments is proposed driven by a
decision-support module. Results:
ARMADA was developed as a model architecture that takes the
applications into a common collaborative framework in which the different
aspects of dental treatment are integrated and share the same main
stakeholders’ concerns: Imaging, Diagnosis and Treatment. By clientless internet access to the ARMADA application
server the virtual dental surgery can
now outsource regional scan and local or off-shore diagnostic services
and remote high-quality custom dental device production in a cost-effective
way, bringing computerized dental treatment inside the reach of each dental
clinic.
Published PEF Dublin 2006
Effect of virtual articulator
settings on occlusal morphology of CADCAM restorations. Lambert
Olthoff, DDS, PhDa / Ivar
Meijerb / William de Ruiterc, Frederik Bosman, PhDd and
a
Assistant professor, Department of Oral-Maxillofacial Surgery, Prosthodontics
and Special Dental Care, University Medical Center Utrecht, Utrecht, The Netherlands
b IT
Engineer, CyberTech Telecom B.V., Heerhugowaard, The
c IT Engineer, Oratio B.V., Zwaag, The
dEmeritus professor, Department of
Oral-Maxillofacial Surgery, Prosthodontics and Special Dental Care,
University Medical Center Utrecht, Utrecht, The Netherlands.
eProfessor Computerized Dentistry,
Academic Centre for Dentistry Amsterdam, The Netherlands.
Purpose.
Determinants of mandibular movements, like condylar inclination and incisal
guidance should be considered in the fabrication of occlusal restorations to
prevent posterior excursive occlusal interferences. This study investigated
differences in the occlusal morphology of the right mandibular molar
resulting from high, average and low values of settings for determinants of
anteroposterior and transverse mandibular movement using a virtual
articulation model. Material and methods. The
articulation functionalities of a computer integrated restorative technology
by imaging and new acquisition (CYRTINA) were used as a tool to examine the
potential effect of determinants of mandibular movement on occlusal molar
design. High, average and low values for condylar guide inclination, incisal
guide angle and intercuspal contact area (antero-posterior determinants) and
laterotrusion, mandibular lateral translation and intercuspal contact area
(transverse determinants) were introduced and differences in molar morphology
studied. The latter was done by comparing mesiodistal and buccolingual
sections of the occlusal designs. These interocclusal differences were
quantified as differences in frequency of occlusal distances in an
interocclusal range of
Published:
Journal Computerized Dentistry
Comparison
of Manual and Guided Implant Placement. S.T. VLAAR and J.M. VAN DER ZEL*,
Statement
of the problem: Precision of manual placement of implants
remains highly dependent on the skill of the operator. A higher accuracy of
positioning of the implant is claimed when using drill guides. This study is
an in-vitro validation of two methods of implant placement: manually and with
the use of planning and drilling with drill guides using a new implant
planning system to compare the accuracy of angulation and position. Material and methods: A partial
dentate patient case was used for the study. Between the 44 and
Published as Abstract IADR