3D Printing in dentistry by Dr KAVAN DOSHI.pptx

3D PRINTING IN DENTISTRY
Prepared by:
Dr. KAVAN Y. DOSHI
MAXILLOFACIAL PROSTHODONTIST AND IMPLANTOLOGIST

CONTENTS
• Introduction
• Classification
• Stereolithography
• Selective laser sintering
• Fused deposition modeling
• 3D printing
• Conclusion
• References

Introduction
• For fabrication of a physical prototype (model) , two different propositions are
used: subtractive and additive.
• The subtractive technique is generally achieved by the conventional numerical
control machining (CNC). CNC machining data are obtained from an optical or
contact probe surface digitizer that can reproduced the external structural data but
not the internal tissue data of the preferable anatomical object.
• Therefore, CNC machining is generally used for fabrication of typically small
prototypes; example metallic and/or ceramic crowns in dentistry.
Krishankumar S. Lahoti , Snehal V. Kharwade , Jaykumar R. Gade . Rapid Prototyping: A Modernistic Era in Prosthodontics. International Journal of
Science and Research. September2020;9(9):120-124.

• Whereas, the additive technologies, can fabricate any complicated structures or
internal geometries with minor details. This revolutionary method is called the
"Layered manufacturing", in which a solid 3D CAD design of an object mold into
cross-sectional layer depiction from the bottom up.

• Rapid prototyping (RP) can be defined as a process of producing physical
prototype in a layer by layer manner from their CAD model data, CT and MRI
scan data, and any 3D digitised data without the involvement of any fixtures
particular to the geometry of the model being processed.
• RP technology subjoins liquid, powder, or sheet materials with additive ways to
build shapes, in order to create models.

BASED ON PHYSICAL STATE OF PATTERN RAW
MATERIAL
Pattnaik S, Jha PK, Karunakar DB. A review of rapid prototyping integrated investment casting processes. Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design
and Applications. 2013 Mar 13;228(4):249-77.

Khorsandi D, Fahimipour A, Abasian P, Saber S, Seyedi M, Ghanavati S et al. 3D and 4D printing in dentistry and maxillofacial surgery: Printing techniques, materials, and applications. Acta
Biomaterialia.2021;122:26-49.

STEREOLITHOGRAPHY
• In 1981, Dr . Hideo Kodama developed the first rapid prototyping system known
as “Stereolithography”.
• Further in 1986, Charles W. Hull, founded 3D Systems Inc, which was the first
commercially available stereolithography printer. He aimed to ease the rapid
prototyping of plastic parts. It was used for modeling as well as to manufacture
highly complex and individually designed geometries of composites, metallic or
ceramic specimens
Schmidleithner C, Kalaskar DM. Stereolithography. In: 3D Printing.: InTech; 2018

Principle of stereolithography technology:

• Stereolithography is a vat polymerization method, where layers of the liquid
precursor in a vat are sequentially exposed to ultraviolet (UV) light and thereby
selectively solidified.
• A photoinitiator(PI) molecule in the resin responds to incoming light and upon
irradiation, locally activates the chemical polymerization reaction, which leads to
curing only in the exposed areas.
• After developing the first layer in that manner, a fresh resin film is applied,
irradiated, and cured. Thus, the part incrementally grows layer-after-layer .
Schmidleithner C, Kalaskar DM. Stereolithography. In: 3D Printing.: InTech; 2018

• Advantages of stereolithography technology:
1.SLA parts have probably the best surface quality of all other RP systems, and are
also highly competitive in dimensional accuracy.
2.Also, the latest SLA systems have significantly increased the speed at which
parts can be produced, which is ultimately the goal of RP.
3.Finely detailed features, like thin vertical walls, sharp corners, and tall columns
can be fabricated with ease.
Hazeveld A, Huddleston Slater J, Ren Y. Accuracy and reproducibility of dental replica models reconstructed by different rapid prototyping techniques. American
Journal of Orthodontics and Dentofacial Orthopedics. 2014;145(1):108-115.

• Disadvantage of the SLA process:
• The disadvantages are that the material is expensive, smelly and toxic and must
be shielded from light to avoid premature polymerization; there is also a limited
choice of resins. The parts may be brittle and translucent and they need supports
which may adversely affect the surface finish when removed.
Hazeveld A, Huddleston Slater J, Ren Y. Accuracy and reproducibility of dental replica models reconstructed by different rapid prototyping techniques. American Journal of
Orthodontics and Dentofacial Orthopedics. 2014;145(1):108-115.

Selective Laser Sintering
• The Selective Laser Sintering (SLS) process was developed by Carl Deckard
and Joe Beaman in 1987. It is a second rapid prototyping technology. It based
on the use of powder coated metal additives.
• It is a selective sintering of metal powders . This process is used in manufacturing
moulds, rapid handling of electrodes manufactured, polymer moulds, die casting,
die casting of titanium zirconium, bio-medical applications, pieces of zirconium-
titanium (PZT) and sheet metal parts.
Kumar S. Selective laser sintering: A qualitative and objective approach. JOM. 2003 Oct;55(10):43-7.

Principle of selective laser sintering:

• The powdered material is spread by a roller over the surface of a build cylinder.
The piston in the cylinder moves down one object layer thickness to accommodate
the new layer of powder.
• The powder delivery system is similar in function to the build cylinder, in which a
piston moves upward incrementally to supply a measured quantity of powder for
each layer.
• A laser beam is then traced over the surface of this tightly compacted powder.
1. Liu Q, Leu MC, Schmitt SM. Rapid prototyping in dentistry: technology and application. The International Journal of Advanced Manufacturing Technology. 2005 Aug 17;29(3-4):317-35.

• The interaction of the laser beam with the powder elevates its temperature to
the point of melting, fusing the powder particles and forming a solid mass.
• The energy of the laser beam is modulated to melt the powder only in areas
defined by the object’s geometry at that cross section.
• The fabrication chamber is maintained at a temperature just below the melting
point of the powder so that heat from the laser need only elevate the
temperature slightly to cause sintering. This greatly speeds up the process.

• When the first layer is finished, an additional layer of powder is
deposited via a roller mechanism on top of the previously scanned layer.
• This layer building process is repeated, with each layer fusing to the
layer below it, until the whole part is complete.
• After the building process is completed, the part is removed from the
building chamber and the powder not scanned and fused is removed for
reuse.

• Material used:
• The most common material used are:
a. Wax
b. Paraffin
c. Polymer-metal powders
• Various types of steel alloys, polymers, nylon and carbonates.

• Advantages of SLS technology:
1. Wide Range of Build Materials.
2. High Throughput Capability.
3. Self-Supporting Build Envelope
4. As there is self-supporting powder bed which removes extra material, this material is
again recycled and used for building other parts.
5. Good mechanical strength, broad range of materials

• Disadvantage of SLS technology:
1. Initial Cost of the System is high.
2. Facility Requirements are more.
3. Maintenance and Operation Costs is high.
• Elevated temperatures, local high energy input, uncontrolled porosity, toxic gases.

Fused deposition modeling
• FDM was developed by S. Scott Crump in the late 1980s and was
commercialized in 1990 by Stratasys
• FDM hardware is based on material extrusion. Here a semi-liquid material and
most usually a hot thermoplastic is deposited from a computer-controlled print
head. Others names are 'thermoplastic extrusion', plastic jet printing' (PJP),
the 'fused filament method' (FFM) or 'fused filament fabrication' (FFF).
P. Chennakesava1 and Y. Shivraj Narayan. Fused Deposition Modeling – Insights. International Conference on Advances in Design and Manufacturing. · December 2014;1345-
1350.

Principle of fused deposition modeling:

• It utilizes a temperature-controlled head to extrude thermoplastic material layer by
layer.
• As shown in figure, a plastic filament is unwound from a coil and supplies
material to an extrusion nozzle.
• The nozzle is heated to melt the plastic to a semiliquid state and has a mechanism
which allows the flow of the melted plastic to be turned on and off.

• The system operates in the X, Y, and Z-axes, in effect, drawing the model one
layer at a time. As the nozzle is moved over the table in the required trajectory,
it deposits a thin bead of extruded plastic to form each layer.
• The plastic solidifies immediately after being ejected from the nozzle and
bonds to the layer below. The entire system is contained within a chamber
which is held at a temperature just below the melting point of the plastic

• Material used:
• Most of the existing FDM machines use thermoplastic materials which are in a
filament form for the extrusion and deposition purpose. Acrylonitrile Butadiene
styrene (ABS) and Polylactide (PLA) thermoplastics are predominantly used in
the process.
1. P. Chennakesava1 and Y. Shivraj Narayan. Fused Deposition Modeling – Insights. International Conference on Advances in
Design and Manufacturing. · December 2014;1345-1350.

• Advantages of fused deposition modeling:
1. Complex parts can be produced with good accuracy and with low cost when
compared to conventional manufacturing process.
2. No need for special tooling.
3. As simple as printing of copy from normal inkjet printer.

• Disadvantages of fused deposition modeling:
1. FDM is a costlier process.
2. The size of the output product is limited to a very small size.

3D printing
• Binder jetting technology was initially developed at the Massachusetts Institute
of Technology (MIT) and patented in 1993 by Emanuel Sachs, who developed
the process using a gypsum-type powder and a glycerine /water binder deposited
via printheads.
• The technology was commercialized by the company Z Corporation (Z Corp.),
which added full- colour capability to its platform and dubbed the technology
“3D printing.
1. Mostafaei A, Elliott A, Barnes J, Li F, Tan W, Cramer C et al. Binder jet 3D printing—Process parameters, materials, properties, modeling, and challenges. Progress in Materials
Science. 2021; 119:100707.

Principle of 3D Printing

• 3DP uses a technology similar to the ink-jet printing to spray binder materials on a
thin distribution of powder spread over the surface of a powder bed.
1. It starts by depositing a layer of powder material at the top of a fabrication
chamber.
2. To this end, a measured quantity of powder is first dispensed from a similar
supply chamber by moving a piston upward incrementally.
3. A roller then distributes and compresses the powder at the top of the fabrication
chamber.

4. The multi-channel jetting head subsequently deposits a liquid adhesive in a two-
dimensional pattern onto the layer of the powder, which becomes bonded in the
areas where the adhesive is deposited, to form a layer of the object.
5. Once a layer is finished, the piston that supports the powder bed and the part
lowers so that the next powder layer can be spread and selectively joined.
6. This layer-by-layer process repeats until the whole part is completed.

• Material used for fabrication:
• Material should be in powder consistency –
a. Metal
b. Ceramic
c. Plastic.
Kessler A, Hickel R, Reymus M. 3D Printing in Dentistry—State of the Art. Operative Dentistry. 2020;45(1):30-40.

• Advantages –
1. Safe material
2. Short working time
3. Suitable mechanical performance
• Disadvantages-
1. Low resolution and strength
2. Cannot be heat sterilized.
Kessler A, Hickel R, Reymus M. 3D Printing in Dentistry—State of the Art. Operative Dentistry. 2020;45(1):30-40.

Prosthodontic implication of RP
technology
1. Dental prosthesis wax pattern fabrication:
• The fabrication of the wax pattern is the time consuming
and labour dependent step in manufacturing the porcelain-
fused-to-metal crown, pressed ceramic crown, and RPD
framework. With the invention of RP technology, by using
3D imaging, automatic wax-up fabrication can be done that
reduces the time and increases the production turnover.
1. Lopamoodra Das, Arpita Sarkar, Himadri Pal, Anwesha Adak, Subrata Saha, Subir Sarkar. Rapid Prototyping: A Future of Modern Dentistry. IOSR Journal of Dental and Medical
Sciences. April. 2019 ;18 (4): 08-14.

• RP application has several advantages as follows-
1. Increased production turnover rate by 150 units per hour.
2. Quality control of wax copings, which results in a high precision fit
and constant wall thickness.
3. Less spruing time.
4. Less finishing work needed on cast copings.
Lopamoodra Das, Arpita Sarkar, Himadri Pal, Anwesha Adak, Subrata Saha, Subir Sarkar. Rapid Prototyping: A Future of Modern Dentistry. IOSR Journal of Dental and Medical Sciences.
April. 2019 ;18 (4): 08-14.

2. Direct metal prosthesis fabrication:
• Conventional way to fabricate a metal prosthesis is the lost-wax casting method.
This method are time consuming and labour-dependent process that comprises many
manual steps such as fabricating, embedding and burning out the wax pattern,
metal casting, and post processing. Newly, RP technology, especially selective laser
melting (SLM) and selective laser sintering (SLS) technology, are mainly used for
fabrication of high-precision metal parts.
• CAD/CAM along with RP technologies are used to manufacture metal RPD
structures.
Hazeveld A, Huddleston Slater J, Ren Y. Accuracy and reproducibility of dental replica models reconstructed by different rapid prototyping techniques. American
Journal of Orthodontics and Dentofacial Orthopedics. 2014;145(1):108-115.

• 3) All-ceramic restoration fabrication:
• All ceramic dental restoration can be manufactured by direct inkjet fabrication
‑
technique by using slurry micro extrusion process. The all ceramic dental
‑
restorations will be manufactured in short time, with less material requirement
and high precision.

• 4) Mold for complete dentures:
• In complete denture cases using RP technology, dentures in clinical use are altered to
cope the proper occlusal relation and the mucosal surfaces, scanned through cone beam
computed tomography (CBCT) and then merge as STL data. A 3D measurement device
is used to scan the participant’s face and then the positional relationship between the
face and the dentures in 3D harmony are recreated via data integration by using CAD
software. Afterward, the positions of the artificial teeth get arrange correlating the
corresponding face simulation. The polished denture surfaces are also created on the
basis of arrangement of the artificial teeth. Trial dentures can also get fabricated from
the denture data by applying RP technology
Krishankumar S. Lahoti, Snehal V. Kharwade, Jaykumar R. Gade. Rapid Prototyping: A Modernistic Era in Prosthodontics. International Journal of Science and Research.
September2020;9(9):120-124.

5) Maxillofacial prosthesis fabrication:
RP technology fastened the fabrication of customized 3-D anatomic models with the
complex geometry easily. By which we can obtain detailed complex shapes with internal
features and undercut areas
Applications in maxillofacial prosthodontics are as follows:
 Obturators
 Auricular and nasal prosthesis
September2020;9(9):120-124.

· Surgical stents for patients with large tumours planned for excision
· Lead shields to guard healthy tissue during radiotherapy treatment
 Fabrications of burn stents, where burned area can be scanned rather
than subjecting delicate, sensitive burn tissue to impression - taking
procedures.
September2020;9(9):120-124.

• 6) Fabrication of implant stents:
• Using stereolithographic rapid prototyping technology, surgical guides are fabricated that
will guide in implant position with less bone exposure and flapless method.
• The scanned 3D data obtained can be filed into a computer, which will help in fulfilling the
following primary objectives of implant planning:
1. Detailing of available bone quantity and quality
2. Recognition of any critical anatomic structures
September2020;9(9):120-124.

3. Choosing authentic implants from software-based libraries and catalogues and
4. Simulation of the surgical implants placement that have been overlying on 3D
images, at their defined host sites.
• The advantages of the less invasive flapless surgical procedure include the
following:
1. Shorter duration of surgical procedure.
2. Faster and less complications.
3. Enhanced aesthetic.
September2020;9(9):120-124.

REFERENCES
• Krishankumar S. Lahoti , Snehal V. Kharwade , Jaykumar R. Gade . Rapid Prototyping: A Modernistic Era in
Prosthodontics. International Journal of Science and Research. September2020;9(9):120-124.
• Pattnaik S, Jha PK, Karunakar DB. A review of rapid prototyping integrated investment casting processes.
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and
Applications. 2013 Mar 13;228(4):249-77.
• Schmidleithner C, Kalaskar DM. Stereolithography. In: 3D Printing.: InTech; 2018
• Hazeveld A, Huddleston Slater J, Ren Y. Accuracy and reproducibility of dental replica models reconstructed
by different rapid prototyping techniques. American Journal of Orthodontics and Dentofacial Orthopedics.
2014;145(1):108-115.
• Kumar S. Selective laser sintering: A qualitative and objective approach. JOM. 2003 Oct;55(10):43-7.
• Liu Q, Leu MC, Schmitt SM. Rapid prototyping in dentistry: technology and application. The International
Journal of Advanced Manufacturing Technology. 2005 Aug 17;29(3-4):317-35.
• Lopamoodra Das, Arpita Sarkar, Himadri Pal, Anwesha Adak, Subrata Saha, Subir Sarkar. Rapid Prototyping:
A Future of Modern Dentistry. IOSR Journal of Dental and Medical Sciences. April. 2019 ;18 (4): 08-14.

3D Printing in dentistry by Dr KAVAN DOSHI.pptx

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