Assoc. Prof. d-r T. Uzunov, PhD
Digital technology has profoundly impacted the dental profession. Significant progress has already been made in computerized digital
technologies, such as digital cast scanners, intraoral digital impression-capture devices, cone beam computed tomography, laser sintering
units, milling machines and three-dimensional (3D) printers.
VIRTUAL MODEL IS A SET OF THREE
DIMENSIONAL MODELS, WHICH ARE
LOCATED IN THREE-DIMENSIONAL
SPACE AND ARE FULLY ACCURATE
IMAGE OF PHISICAL PRODUCT
The three-dimensional (3D) model represents a physical
body using a collection of points in 3D space, connected by
various geometric entities such as triangles, lines, curved
surfaces, etc.
EVOLUTION OF COMPUTERIZED DENTISTRY
• In the early 1970s, Dr. Francois Duret, conceptualized
how digital technology being used in industry might be
adapted to dentistry for digital impression making.
EVOLUTION OF COMPUTERIZED DENTISTRY • He conceived of the idea of an application of laser imaging to make optical
impressions of teeth and milling out a restoration, representing the original
process for capturing data used in what ultimately became the computer-
assisted design/computer-assisted manufacturing (CAD/CAM) of
dental restorations.
• Dr. Duret first introduced the CAD/CAM concept to dentistry in 1973 in
Lyon, France in his thesis entitled Empreinte Optique, which translates to
Optical Impression. The concept of CAD/CAM systems was further
developed by Dr. Mormann, a Swiss Dentist, and Mr. Brandestini, who was
an electrical engineer.
For the purpose of digital
information acquisition the dentist
can use three technological
devices:
1. Extraoral laboratory scanner
2. Intraoral optical scanner
3. CBCT
3 D DIGITALIZATION
Persson A, Andersson M, Oden A, Sandborgh-Englund G (2006) A three-dimensional
evaluation of a laser scanner and a touch-probe scanner. J Prosthet Dent 95: 194-200.
Within extra oral group of 3D digitization
systems we can use two types of systems:
1) first contact systems,
2) second noncontact optical systems
Lab scanners demonstrate very high
precision and accuracy of impression
acquisition - to 6 micrometers (μm).
At this moment these are the most precise
capture devices in dental profession.
3 D DIGITALIZATION
Persson A, Andersson M, Oden A, Sandborgh-Englund G (2006) A three-dimensional
evaluation of a laser scanner and a touch-probe scanner. J Prosthet Dent 95: 194-200.
Traditional impression
3 D DIGITALIZATION
Persson A, Andersson M, Oden A, Sandborgh-Englund G (2006) A three-dimensional
evaluation of a laser scanner and a touch-probe scanner. J Prosthet Dent 95: 194-200.
Traditional impression
3 D DIGITALIZATION Plaster models
3 D DIGITALIZATION
These devices are
intensively developed in
recent years and are
already recognized as
highly significant in the
field of prosthetics
dentistry.
INTRA ORAL SYSTEMS
3 D DIGITALIZATION
The benefits of using a digital impression
system are many, including the improved
collaboration and treatment planning. You
can see tooth preps in 3D and can catch
any impression glitches while the patient is
still on the chair, and in this way the time is
decreased from the patient’s first visit to final
seating of prosthesis because you won’t
need to send the impression to the
laboratory. You have only to sent the digital
data via Internet.
Condor is innovative intra-oral impression scanner. Developed in
partnership with Professor Duret and subsidized by the European Union,
the technology is radically different from any of the early systems in the
market. It distinguishes itself by simplicity and freedom of use.
3 D DIGITALIZATION
We can use for digital acquisition three scan strategies.
In strategy A, first the buccal surfaces
of the teeth are scanned starting from
the distobuccal aspect of the maxillary
right second molar and returning from
the occlusal-palatal side.
3 D DIGITALIZATION
We can use for digital acquisition three scan strategies.
The second strategy B starts at the occlusal-
palatal surfaces of the maxillary right second
molar, moving towards the other side of the
arch and always including two surfaces, and
returning from the buccal side.
3 D DIGITALIZATION
We can use for digital acquisition three scan strategies.
The third strategy C is sequentially scanning the
three surfaces of a tooth (buccal to occlusal to
palatal), performing an S-type movement from the
maxillary right second molar to the maxillary left
second molar, all in one direction and without
returning to the starting point.
3 D DIGITALIZATION
The second scan strategy has the highest trueness and precision in full-arch scans and
therefore minimizes inaccuracies in the final reconstruction.
3 D DIGITALIZATION
Mangano FG, Veronesi G, Hauschild U, Mijiritsky E, Mangano C (2016)
Trueness and Precision of Four Intraoral Scanners in Oral Implantology: A Comparative in Vitro Study.
PLoS ONE 11(9): e0163107. doi:10.1371/journal. pone.0163107
American Dental
Association (ADA)
specification No. 8 shows
that the luting agent’s type I
thickness should be not
more than 25 μm.
Contemporary optical 3D digitalization devices
offer a measuring accuracy under 20μm. This
means that the resolution of 20 micrometers of
digital intraoral acquisition is quite good for
precise fitting of the fixed dentures.
3 D DIGITALIZATION
Mangano FG, Veronesi G, Hauschild U, Mijiritsky E, Mangano C (2016)
Trueness and Precision of Four Intraoral Scanners in Oral Implantology: A Comparative in Vitro Study.
PLoS ONE 11(9): e0163107. doi:10.1371/journal. pone.0163107
The shorter the distance, the more accurate
results will be achieved with intraoral
scanning. The precision of image acquisition
in case one will be better than in case two.
American Dental
Association (ADA)
specification No. 8 shows
that the luting agent’s type I
thickness should be not
more than 25 μm.
3 D digitalization Virtual design
The third option is to take the
information directly from the
CBCT examination and to use for
digital reconstruction of
anatomical structure. This will
permit planning of implant
treatment as well as surgical
guide and provisional implant
prostheses.
3 D digitalization Virtual design
3 D digitalization Virtual design
After data acquisition and transfer to the CAD software the dentist can virtually make the prototype of prosthetic reconstruction. For example fixed denture. You can choose anatomical patterns from the software library or you can copy and paste the shape and size of the natural teeth from the other side of the dental arch.
All CAD/CAM systems have three functional
components:
1) A digitalization tool/scanner that transforms geometry into
digital data that can be processed by a computer.
2) Software which processes scanner data and produces a data
set readable by a fabrication machine.
3) A manufacturing technology that takes the data set and
transforms it into the desired product by fabricating the restoration.
All CAD/CAM systems have three functional
components:
To fabricate a physical object in
medicine, two different approaches
have been utilized: subtractive and
additive.
SUBTRАCTIVE METHOD
ADDITIVE METHOD
HYBRID
METHOD
SUBTRАCTIVE METHOD
Early CAD/CAM systems relied almost
entirely on cutting a restoration from a
prefabricated block with the use of burs,
diamonds or diamond disks. This is usually
accomplished by conventional numeric
control (NC) machining such as milling.
Subtractive process uses carefully-
controlled tool movements to cut material.
Ø 1.0 mm
Ø 4.0 mm SUBTRACTIVE METHODS
HAVE SOME LIMITATIONS
o The precision fit of the inside contour of the
restoration depends on the size of the
smallest usable tool for each material.
SUBTRАCTIVE METHOD
o In a typical subtractive method in dentistry,
approximately 90 percent of the initial block is removed
and wasted to create a typical dental restoration.
SUBTRАCTIVE METHOD
o In a typical subtractive method in dentistry,
approximately 90 percent of the initial block is removed
and wasted to create a typical dental restoration.
o Milling tools are exposed to heavy abrasion and wear,
therefore, withstanding only short running cycles.
SUBTRАCTIVE METHOD
o In a typical subtractive method in dentistry,
approximately 90 percent of the initial block is removed
and wasted to create a typical dental restoration.
o Milling tools are exposed to heavy abrasion and wear,
therefore, withstanding only short running cycles.
o Microscopic cracks can be introduced into ceramic
surfaces due to machining of this brittle material.
Chipping and cracks caused by milling. (Micrograph
courtesy Dr. Isabelle Denry.)
SUBTRАCTIVE METHOD
o In a typical subtractive method in dentistry,
approximately 90 percent of the initial block is removed
and wasted to create a typical dental restoration.
o Milling tools are exposed to heavy abrasion and wear,
therefore, withstanding only short running cycles.
o Microscopic cracks can be introduced into ceramic
surfaces due to machining of this brittle material.
o It is neither easy nor economic for big, full undercuts and
complex milling parts.
ADDITIVE METHOD
Rapid prototyping (RP) techniques, exhibit the potential to overcome the
described disadvantages. RP simply consists of two phases: virtual
phase (modeling and simulating) and physical phase (fabrication).
ADDITIVE METHOD
This is a process in which the final desired part is manufactured by adding
layers of material on top of one another (layer-by-layer manner). It is a
special class of machine technology that quickly produces models and
prototype parts from 3D data using an additive approach to form the
physical models.
The key idea of this innovative method is that the three
dimensional CAD (3D-CAD) model is sliced into many
thin layers and the manufacturing equipment uses this
geometric data to build each layer step by step until the
part is completed.
• The obtained surface model is usually exported to an STL file format based
on triangular polygons, which is a suitable format for virtual dental
surveying and virtual sculpting environments.
Virtual design
ADDITIVE METHOD
The term “3D Printing” should be clarified to prevent
confusion. Currently in literature and mainstream media, the term
“3D Printing” is being used to refer to all additive technologies
(e.g. fused deposition modeling, selective laser sintering, etc.).
But you have to know that 3D Printing is only one of this 30
technologies - the liquid binder-based inkjet technology.
Orthodontic labs are using it to make models and aligners,
and restorative labs are using it to make patterns for fixed
prosthodontics, surgical guides, and complete removable
dentures.
ADDITIVE METHOD
RAPID PROTOTYPING
SLA - StereoLithography
3D printing
LOM - Laminated Object Manufacturing
SGC - Solid Ground Curing
MJM - Multi jet Modeling
FDM - Fused Deposition Modeling
SLS – Selective Laser Sintering
SLM - Selective Laser Melting
Nowadays 30 different 3 D technologies could be found on the market,
provided by 40 companies.
ADDITIVE METHOD
Stereolithography (SLA) machine
The term “Stereolithography” (SLA)
was introduced in 1986 by Charles
Hull, who patented it as a method
and device for making solid objects
by “printing” thin layers of an
ultraviolet curable material one on top
of the other with a concentrated
beam of ultraviolet light focused onto
the surface of a vat filled with liquid
photopolymer.
The birth of the Additive Manufacturing can be traced back to 1988 when
the first Stereolithography (SLA) machine was introduced.
3D models in medicine (Stratasys J750)
The additive techniques have
been employed to build complex
3D models in medicine since the
1990s. These models can be
produced with undercuts, voids,
intricate internal geometrical
details and anatomical
landmarks such as facial sinuses
and neurovascular canals.
A 3D model, created in collaboration with the
anaplastologist Jan De Cubber (Materialise)
А complex design can be
produced in one
fabrication cycle unlike in
Subtractive Manufacturing
Technology where
different parts would need
to be fabricated and
assembled.
ПРИЛОЖЕНИЕ
The additive technology is currently employed to
improve medical diagnosis and to provide a precise
surgical treatment plan. The innovations in molding
materials and forming procedure have improved the
additive techniques so that this technology is no longer
adopted only for prototyping; it is used for reproduction
of real functional elements.
ПРИЛОЖЕНИЕ
1. Surgical drilling templates during dental implant insertion
2. Orthognathic surgery
3. Prosthesis
4. Orthodontic appliances
1. Surgical drilling templates during dental implant insertion
Start with CBCT examination
After that we have to scan intraorally the dental
arch and the patient’s teeth directly.
With CAD software we can merge the
information from the CBCT and the intraoral
scan. On this fused digital model we design the
surgical guide for implant placement.
The STL file is sent to the 3D printer and the physical objects are produced.
The guided surgical template has metallic sleeves that direct and allow precise implant placement in the three space axes. With the master sleeve integrated into the acrylic guide template we can control initial trajectory and osteotomy depth.
We can control through the master sleeve the angulation of the surgical drill and the depth of penetration.
2. Orthognathic surgery
Conventional orthognathic wafers are made by a process involving manual movement of stone dental models and acrylic laboratory fabrication. In addition, a facebow record and semi-adjustable articulator system are required for maxillary osteotomy cases. In orthognatic surgery we can use the digital design to place in the right central position the lower and upper jaws and digitally to construct wafer. 3D printer will reproduce the real prototype of the wafer, which will be used during the time of surgery. This is a novel process of producing both intermediate and final orthognathic surgical wafers using a combination of computerized digital model simulation and three-dimensional print fabrication, without the need for either a facebow record or the additional ionizing radiation exposure associated with cone beam computerized tomography.
2. Orthognathic surgery
Virtual wafer The plastic wafer fitted on
the models in order to
check the final occlusion
Intra-operative
photographs during
mandibular and maxillary
osteotomies
3. Prosthsis
One of the most popular application of
3D printing is the fabrication of working
models, which have the same features
like the conventional models. Fabricated
using the PolyJet additive manufacturing
process, these models are made with
resolutions down to 30 microns.
Many studies have proved that 3D digital
models of dental casts have the same
accuracy and precision like the traditional
plaster casts.
3. Prosthsis
We can use additive
technology and specially the
wax deposition modeling
(WDM) technology to produce
wax-ups of removable or fixed
dentures with wax-like
materials. These materials
burn-out with no residue,
material shrinkage, cracking or
expansion.
This image shows the progression from 3D Printed framework, to polished part
in the frontal area, and then finally on the right site veneered finished product.
3. Prosthsis
A case of removable partial denture made by selective laser sintering
3. Prosthsis
3. Prosthsis
CONCLUSIONS
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