The currently developed scope of dental restorations and prosthodontics’ rehabilitation through the use of CAD/CAM system is to create an appropriate design and fitness of different dental restorations like zirconium crown, fixed bridges, dental (veneers, inlays, onlays), dental implant restorations, orthodontic appliances, and removable dentures (complete and/or partial).

1. Milling Machines &
3D Printers in FPDs
By:
Radwa Ibrahim El-Tahawi

2. What is a CAD/CAM System?
✘ It’s to the integration of Computer-
aided design (CAD) and Computer-
aided manufacturing (CAM).
✘ Both of these require powerful
computers.
2

3. “
The currently developed scope of dental restorations
and prosthodontics’ rehabilitation through the use of
CAD/CAM system is to create an appropriate design
and fitness of different dental restorations like
zirconium crown, fixed bridges, dental (veneers, inlays,
onlays), dental implant restorations, orthodontic
appliances, and removable dentures (complete
and/or partial).
3

4. Components of CAD/CAM Sytems
✘ The first Component is the scanning phase (computer
surface digitization):
1. Optical scanning .
2. Mechanical scanning.
4

5. Components of CAD/CAM Sytems
✘ The second component is the
designing phase.
✘ Different designs of restorations
are done using specific CAD
software, which in turn send
orders to the CAM unit to
fabricate restoration through a
milling machine.
5

6. Components of CAD/CAM Sytems
✘ The Third and final component is
manufacturing phase.
✘ This step transforms the digital
data of the restoration into a
physical product.
6

7. Additive Vs Substractive Methods
✘ Additive manufacturing: processes building objects by
adding material layer by layer.
✘ Subtractive manufacturing: removes material to create a
specific object.
✘ Other systems combined the two techniques "additive
and subtractive methods".
7

8. Additive Vs Substractive Methods
✘ Additive manufacturing methods includes 3D printing and
laser melting technologies.
✘ Subtractive manufacturing methods include machining
and milling (CAM) and laser ablation technologies.
8

9. 9
Overview of CAD/CAM manufacturing systems for dentistry

10. Our process is easy
Scan Design
Mill/
Print
10

11. 1.
MILLING PROCESSING
DEVICES
11

12. “
✘ Numerically controlled milling machines used for
manufacturing of dental prostheses are one of the
key links of CAD-CAM technology flow.
✘ Presently they are available on the market to
operating in dental offices (chair side solution),
dental laboratories (lab side solution) or industrial
milling centers of dental prostheses.
12

13. “
✘ In accordance with ISO 841 and ISO 2806
standards the milling machines are capable of
guiding the processing tool of prosthetic material
by tracking the axes of the space coordinate
system X, Y, and Z or in rotary mode, where the
rotary axes A, B, and C are disposed around the
aforementioned linear axes.
13

14. 14

15. “
✘ The direction of the X axis is usually horizontal,
depending on the spatial position of main spindle
of the milling machine.
✘ The Z axis is parallel to the main spindle axis of the
milling machine.
✘ The Y axis is perpendicular to the X and Z axes.
15

16. Milling Processing Devices
✘ The digitizing data designed with a specific CAD software are
transferred to a physical product (strips) for the CAM- processing
phase then transformed to the milling machine .
✘ According to the number of milling axes manufactured devices can
be divided into:
a. 3-axes milling devices
b. 4-axes milling devices
c. 5-axes milling devices.
16

17. A. Three-axes Milling
✘ Three-axes milling has a degree
movement in a path of three axial
directions denoted by (X ,Y, Z values).
✘ It can also turn the component in
180° in the cycle of milling process.
✘ E.g. "inLab (Sirona)®, Lava® (3M
ESPE), Cercon® brain (DeguDent)".
17

18. A. Three-axes Milling
✘ Advantages: short time of milling
procedure, easily control, less cost
compared with other type of milling.
✘ Disadvantages: lack of control
concerning the contact point
between the cutting tool and the
prosthetic piece, which reduces the
physical integrity of the dental
prosthesis surface.
18

19. B. Four-axes Milling
✘ The 4-axes milling machines use 3
translational movements on the X, Y
and Z axes and a rotating motion on
the A axis.
✘ Can approach the retentions only in
the YZ plane given by the rotation
axis A.
19

20. B. Four-axes Milling
✘ In this type, the tension bridge can
also be turned without any limitation
during work which makes it easy to
control bridge fabrication with a long
displacement in a vertical direction
into the usual mold dimension.
✘ Advantages: saving both milling time
and used materials.
✘ E.g. Zenoo® "Wieland-Imes".
20

21. C. Five-axes Milling
✘ In 5-axes milling machines, a second
rotary motion is added along the B
axis. Practically only 3 axes are used
continuously.
✘ Besides the YZ plane given by the
rotation axis A, perform the
retentions processing in the XZ plane
given by the axis rotation B or any
other plane given by simultaneous
rotation on axes A and B, as well.
21

22. C. Five-axes Milling
✘ This is indicated in the construction
of crown and fixed bridge for inclined
abutment teeth "when molar tipped
towards the medial plane".
22

23. “
Milling Variants
23

24. A) Dry Field Milling
✘ This field of milling is mostly applied to mill ZrO2 blanks
having lower degree of pre-sintering.
✘ One of dry milling process recommended by
manufacturers is milling a resin material for the
construction of different temporary and permanent
restorations were designed using CAD-CAM system.
24

25. 25

26. ✘ Advantages
1. Low costs are used as a milling
procedure.
2. No need for drying of the ZrO2
frame prior to sintering because
there is no moisture absorption
by the die ZrO2 mold.
A) Dry Field Milling
✘ Disadvantages:
1. Higher shrinkage values where
obtained for the frameworks are
due to the lower degree of pre-
sintering.
26

27. B) Wet Field Milling
✘ In this process as a protection, a spray bath of cooling
system applied to reduce overheating within the milled
material by the use of diamond or carbide burs.
✘ This Wet field milling is indicated for all metal-alloys and
glass- ceramic to prevent damages by heat generation.
✘ When ZrO2-ceramic with high degree of pre-sintering
lead to minimize the shrinkage factor and less sinter
distortion.
27

28. 28

29. Which materials can be processed
with wet or dry mill?
Wet Milling:
1. Hybrid Composite
2. Glass ceramics
3. Metal alloys
Dry Milling:
1. Zirconia
2. PEEK
3. PMMA
4. Composite Resin
5. Wax
6. Glass Fiber Composite
7. Gypsum
8. Pre-sintered CoCr Metal
29

30. A Closer Look at the Milling Machines
TYPES OF 4-AXIS MILLING
MACHINE TOOLS FOR
DENTAL TECHNOLOGY
30

31. 1. Ceramill Mikro 4X (Amann Girrbach)
✘ It processes the supplied CAD data set in open STL
format through CAM milling program Ceramill
Match2.
✘ It processes the dental prosthetic materials such as
milling waxes, synthetic resins, zirconium dioxide,
hybrid ceramics, PEEK and sintered Co-Cr alloys.
✘ The replacement of milling material rolls is done
manually.
31

32. 2. CORITEC 140i (imes-icore)
✘ Wet processing of prosthetic work pieces provided
with 6 types of milling tools and filtering system.
✘ It uses STL-based CAD processing programs and a
CAM open program for almost all CAM manufacturing
systems.
✘ The replacement of milling material rolls is done
manually.
32

33. 2. CORITEC 140i (imes-icore)
✘ It can mill prefabricated implant abutments,
zirconium dioxide, aluminum oxide, PMMA, synthetic
resins, composites, waxes, glass ceramics, CAD-CAM
blocks of hybrid ceramic, Maxi blocks, nt-Trading
prefabricated implant abutments, Medentika
PreFace abutments.
33

34. 3. InLab MC XL (Sirona Dental System)
✘ With inLab custom CAD interface software and the
possibility of importing STL data.
✘ It owns the CAM proprietary CAM program inLab CAM,
but is also provided with an open CAM mode interface.
34

35. 3. InLab MC XL (Sirona Dental System)
✘ It processes materials such as zirconia, PMMA,
composites, hybrid ceramics, glass ceramics, lithium
disilicate ceramics, sintered Co-Cr alloys.
✘ The replacement of burs and prosthetic materials is
done manually.
35

36. 4. SilaMill N4 (Siladent)
✘ with a cutting angle between 190° and -10° using CAD
open interface software and a custom CAM
integrated milling program, vhf Cam.
✘ It can mill blocks of ceramic glass, zirconia, composite
or titanium using 8 automatic burs.
36

37. A Closer Look at the Milling Machines
TYPES OF 5-AXIS MILLING
MACHINE TOOLS FOR
DENTAL TECHNOLOGY
37

38. 1. inLab MC X5 (Sirona Dental System)
✘ Dry or wet processing
✘ With inLab custom CAD software that has the import
capability for STL data.
✘ It has its CAM proprietary CAM software program
inLab CAM and a CAM open interface.
38

39. 1. inLab MC X5 (Sirona Dental System)
✘ It can process dental materials such as zirconium
dioxide, PMMA, wax, composite, hybrid ceramics, glass
ceramics, lithium disilicate ceramics, sintered Co-Cr
alloys, prefabricated titanium.
✘ Automatic replacement of the drilling tools.
✘ However the replacement of prosthetic materials is
done manually.
39

40. 2. DWX-52DC (DGSHAPE)
✘ Dry processing.
✘ Uses STL-based CAD software programs and an open
CAM program Millbox Power Sum3D for 3rd party CAM
programs.
✘ It manufactures zirconium dioxide, waxes, PMMA,
composites, PEEK, gypsum, sintered Co-Cr.
✘ Using in dry environment 15 types of dedicated milling
tools.
40

41. 3. CORITEC 650i (imes-icore)
✘ Dry and wet processing milling system.
✘ Covers all dental prosthetic materials and
indications of prosthetic pieces.
✘ Using open CAD programs in STL format and an
open CAM milling program.
✘ Using 32 types of milling tools and manual or
automatic replacement of prosthetic materials.
41

42. 4. PrograMill PM7 (Ivoclar Vivadent)
✘ An automatic hybrid switching system between dry
and wet milling.
✘ Using the 3Shape Dental System CAD open
software and any other CAD software working in
open system with STL files.
✘ It works with a CAM program known as PrograMill
CAM V4.
42

43. 4. PrograMill PM7 (Ivoclar Vivadent)
✘ It is equipped with 20 types of automatically
changed milling tools and an automatic installation
for selected 8-rolls pickup or 48 blocks of
prosthetic materials.
43

44. 5. cara Mill Mill 3.5 / cara Mill 3.5L
(Kulzer)
✘ Dry and wet processing system.
✘ Based on Dental Designer (3Shape) CAD processing
program, STL-compatible programs belonging to
cara CAD milling centers, open systems compatible
with STL, PLY, ASC data sets and CAM milling
program cara CAM Mill 4 & 5.
44

45. 5. cara Mill Mill 3.5 / cara Mill 3.5L
(Kulzer)
✘ Process rolls of Wax, PMMA, zirconia, ceramics,
hybrid ceramics, Co-Cr alloys or titanium alloys.
✘ using maximum 20 types of milling tools, which can
be angled up to 30 °.
✘ It is also equipped with a protective device against
splinter spreading (chassis Mill 3.5)
✘ Uses an automatic replacement system of milling
rolls (cara Mill 3.5L).
45

46. 6. Organical® Desktop 8-S
(Metaux Precieux Dental)
✘ Dry and wet milling.
✘ The CAM program is open and can import any STL
data set.
✘ It can process any rolls of prosthetic material with
a diameter of maximum 120 mm, regardless of its
hardness, as well as IPS blocks e.max CAD.
46

47. 6. Organical® Desktop 8-S
(Metaux Precieux Dental)
✘ It is more accurate than other milling machine
tools by its maximum performance in reproduction
of details because it can grave 75 μm diameter
grooves.
✘ It is equipped with a signaling sensor of milling tool
cracks and has the possibility to automatically
replace 18 types of milling tools.
47

48. 7. Datron C5 Linear Scales (Datron AG)
✘ Uses CAD interface software (3Shape, Exocad,
Dentalwings) and CAM software (DATRON CAM,
Hyperdent, WorkNC).
✘ It can process steel alloy, non-ferrous alloys,
synthetic resins, zirconium dioxide, Co-Cr or
titanium alloys by using 22 types of
interchangeable milling tools.
48

49. 7. Datron C5 Linear Scales (Datron AG)
✘ It is also equipped with a sensor of milling tool
break during the production of prosthetic pieces.
✘ Allows replacement of 56 rolls of dental materials
automatically picked up from an external storage
box.
49

50. 8. Zfx ™ Inhouse5x wet & dry (Zfx)
✘ Wet and dry processing system.
✘ With CAD open interface software using STL files
and HyperDent inkl. Zfx Templates CAM milling
software.
✘ Simultaneous processing of materials of various
consistencies (hard, brittle or soft).
50

51. 8. Zfx ™ Inhouse5x wet & dry (Zfx)
✘ It can process zirconium dioxide-type prosthetic
materials, Co-Cr, PMMA, Wax, Titanium, ZLS
(zirconia arsenic lithium silicate ceramic), hybrid
ceramics, feldspath ceramics, glass ceramic
enforced leucit, lithium disilicate glass.
✘ Using 28 automatic replaced milling tools.
✘ It’s equipped with a crack detection tool.
51

52. Drawbacks of the Subtractive Techniques
Fit Problems
Microscropic
Cracks
52

53. 2.
3D Printers

54. History
✘ In 1986, Charles Hull introduced the first three-
dimensional (3D) printing technology, and the industry
developed many different manufacturing technologies,
which have been applied to numerous fields.
54

55. History
✘ In 1986, Hull patented stereolithography (SLA) and built
and developed a 3D printing system.
✘ In 1990, Scott Crump received a patent for fused
deposition modeling (FDM).
✘ Since then, 3D printing has been increasingly progressing.
55

56. Additive Manufacturing
✘ The process of joining materials to make objects from
3D model data, usually layer upon layer, as opposed to
subtractive manufacturing methodologies.
✘ The “joining” of each new predetermined layer upon the
previous layer is based on melting, fusing or a
polymerization process.
56

57. Additive Manufacturing
✘ Engineering has invented various technologies for
additive manufacturing.
✘ The most used methods in dentistry:
1. Stereo lithography,
2. Fused deposition modeling,
3. Selective electron beam melting,
4. Laser powder forming and
5. Inkjet printing.
57

58. Additive Manufacturing
✘ For the purpose of layer-by-layer structuring of the real
dental restoration, first, the digital image of the object is
sliced in the CAD unit by special software.
✘ Then the manufacturing of the 3D prosthesis continues
with a process almost similar to printing on paper – one
layer on top of another.
✘ It is the so-called “3D-printing”
58

59. The Process of 3D-Printing
✘ Creation of a virtual design of the object.
✘ Most common file format is STL & VRML.
✘ Using a scanner to create a 3D model.
✘ The 3D model is sliced then fed into 3D printer of a compatible
brand and type.
✘ The 3D printer reads every slice (as a 2D image) and create a 3D
object.
59

60. The Process of 3D-Printing
60

61. The Process of 3D-Printing
61

62. Advantages
✘ Printing objects from different materials with a dense structure and
predetermined surface roughness,
✘ Manufacturing complicated geometrical shapes,
✘ Ability to use different materials in different parts of the same
object,
✘ Excellent internal and marginal fit,
✘ High precision, and personal customization,
✘ Rapid production and
✘ Lower cost.
62

63. 3D PRINTING
TECHNOLOGIES AND MATERIALS
63

64. 1. Fused Deposition Modelling (FDM)
✘ FDM is one of the earliest 3D printing technologies and was used by
the author to produce his first medical model in 1999.
✘ An FDM printer is essentially a robotic glue gun.
✘ Materials must be thermoplastic by definition.
✘ A commonly used material is the biodegradable polymer polylactic
acid; this or similar materials have been used as key components of
scaffold structures used for ‘bioprinting’ – a popular area for
research in tissue engineering.
64

65. 1. Fused Deposition Modelling (FDM)
✘ Building complex geometries usually necessitates the laying down
of support structures which may be either formed from the same
material, or from a second material laid down by a second extruder
– which, for example, might extrude a water soluble support
material.
✘ Accuracy will depend upon the speed of travel of the extruder, as
well as the flow of material and the size of each ‘step’.
65

66. 1. Fused Deposition Modelling (FDM)
✘ This is the process that is used by most low cost ‘home’ 3D printers.
✘ It allows for the printing of crude anatomical models without too
much complexity, – for example, printing an edentulous mandible
might be possible, though printing a detailed maxilla would be a tall
order.
✘ More costly, more accurate FDM printers are available, and have
application in anatomical study-model making, but little else in
dentistry or in surgery.
66

67. 2. Selective Laser Sintering (SLS)
✘ This technology has been available since the mid-1980s.
✘ A scanning laser fuses a fine material powder, to build up structures
layer by layer, as a powder bed drops down incrementally, and a
new fine layer of material is evenly spread over the surface.
✘ A high (60μm) level of resolution may be obtained, and as the
structures that are printed are supported by the surrounding
powder, no support material is required.
67

68. 2. Selective Laser Sintering (SLS)
✘ Polymers used in this process have high melting points (above
autoclave sterilization temperature) and excellent material
properties, making objects made in this way useful as anatomical
study models, cutting and drilling guides, dental models, and for
engineering/design prototypes.
✘ However, some of the materials are difficult to drill and prepare, and
the technology is costly to purchase, maintain, and run, therefore
requiring copious quantities of compressed air.
68

69. 2. Selective Laser Sintering (SLS)
✘ The materials are intrinsically dusty, have some health and safety
requirements, and are rather messy to work with.
✘ Materials available include nylon, which is perhaps the most
versatile, flexible elastomeric materials, and metal-containing
nylon mixtures.
✘ An interesting possibility for medical implants is the use of
polyether ether ketone (PEEK), although this requires high
temperatures and complex control – and a great deal of wastage.
69

70. 2. Selective Laser Sintering (SLS)
✘ Titanium, titanium alloys, cobalt chrome alloys, and stainless steel,
partial dentures and prosthesis frameworks are already being
made in this way, and for implant bridge frameworks technology
may be combined with milling processes to provide high precision
connections.
✘ The technology is broadly the same as that described for polymers,
but these apparatus may also be described by different
manufacturers as, ‘selective laser melting’, or ‘direct metal laser
sintering’.
70

71. 2. Selective Laser Sintering (SLS)
✘ In small batch production the technology is costly and casting
continues to have many attractions.
✘ However, in a large dedicated machine it is possible to
simultaneously print 400–500 crown copings in a 24 hour period.
✘ Furthermore, copings may be printed in lower cost materials that
are traditionally harder to work with than gold alloys, such as cobalt
chrome, but which offer good porcelain bonding strengths and
excellent mechanical properties.
71

72. SLS printed prepared
teeth, printed from
data from an intra oral
scanner
72

73. 3D manufacture of metal crown copings. (a) Selective laser sintering in
progress. (b) Printed copings in cobalt chrome alloy tethered to build
platform by support structure.
73

74. 3. Steriolithography (SLA, SL)
✘ A stereolithography apparatus uses a scanning laser to build parts
one layer at a time, in a vat of light-cured photopolymer resin.
✘ Each layer is traced-out by the laser on the surface of the liquid
resin, at which point a ‘build platform’ descends, and another layer
of resin is wiped over the surface, and the process repeated.
74

75. 3. Steriolithography (SLA, SL)
✘ Supports must be generated in the CAD software, and printed to
resist the wiping action and to resist gravity, and must later be
removed from the finished product.
✘ Post-processing involves removal of excess resin and a hardening
process in a UV oven.
✘ The process is costly when used for large objects, but this
technology is commonly used for the industrial production of 3D
printed implant drill guides.
75

76. 4. Photopolymer Jetting (PPJ)
✘ This technology uses light cured resin materials and print heads
rather like those found in an inkjet printer (but considerably more
costly), to lay down layers of photopolymer which are light cured
with each pass of the print head.
✘ A variety of materials may be printed including resins and waxes for
casting, as well as some silicone-like rubber materials.
✘ Complex geometry and very fine detail is possible– as little as 16
microns resolution.
76

77. 4. Photopolymer Jetting (PPJ)
✘ The drawback is that the equipment, and materials are costly to
purchase and run, and the support materials can be tenacious and
rather unpleasant to remove.
✘ They are useful for printing dental or anatomical study models, but
these are expensive when produced in this way.
✘ Implant drill guides may be quickly and cheaply produced with this
technology as they are less bulky.
77

78. 4. Photopolymer Jetting (PPJ)
✘ A particular advantage of this technology is that the use of multiple
print heads allows simultaneous printing with different materials,
and graduated mixtures of materials, makes it possible to vary the
properties of the printed object, which may for example have
flexible and rigid parts.
✘ e.g. for the production of indirect orthodontic bracket splints.
78

79. 5. Powder Binder Printers (PBP)
✘ These apparatus use a modified inkjet head to print using, what is
essentially, liquid droplets to infiltrate a layer of powder, layer by
layer.
✘ Typically a pigmented liquid, which is mostly water, is used to print
onto the powder, which is mostly plaster of Paris.
✘ Again, a model is built up in layers as the powder bed drops
incrementally, and a new fine layer of powder is swept over the
surface.
79

80. 5. Powder Binder Printers (PBP)
✘ The model is supported by un-infiltrated powder, and so no support
material is required.
✘ Post-processing to infiltrate the delicate printed model with a
cyanoacrylate or epoxy resin will improve strength and surface
hardness.
✘ The resulting models are useful as study models or visual
prototypes, but accuracy is limited and the models are rather
fragile despite the post-processing.
✘ Ability to print models in full color.
80

81. 5. Powder Binder Printers (PBP)
✘ from a surgical perspective the drawback is that the models may
not be sterilized or directly manipulated at operation.
✘ Accuracy is inadequate for prosthodontic applications.
✘ The machines and materials are lower cost, but still not
inexpensive.
✘ As the material is mostly plaster of Paris, there is some
compatibility with having the apparatus situated in a dental
laboratory plaster room.
81

82. Industrial powder binder printer and example bust of author captured with 3D
photography and printed in full color plaster of Paris
82

83. Materials Used
83
Silver
Steel
Titanium
Polyamide PLA
Nylon
Epoxy Resin
Glass Filled PLA
Photopolymer
Polycarbonate
Hydroxyapatite
Cells
Wood
Chocolate

84. 3D Printing Modalities And Materials
84

85. 3D Printing Modalities And Materials
85

86. Advantages
✘ Printing objects from different materials with a dense structure and
predetermined surface roughness,
✘ Manufacturing complicated geometrical shapes,
✘ Ability to use different materials in different parts of the same
object,
✘ Excellent internal and marginal fit,
✘ High precision, and personal customization,
✘ Rapid production and
✘ Lower cost.
86

87. Materials and Main Advantages of
3D Printing Technologies
87

88. Disadvantages
✘ High cost of the equipment, the materials, maintenance, and repair,
✘ Often accompanied by a need for messy cleaning,
✘ Difficult post-processing, and
✘ Sometimes onerous health and safety concerns.
88

89. Uses of
3D Printing
in Prosthodontics
89

90. 1. Fabrication of All Ceramic Restorations
✘ Using Direct Inkjet Technology
✘ It fabricates green zirconia all ceramic restorations
90

91. 2. Fabrication of Wax Pattern
✘ Automatic build up of numbers of wax patterns for different dental
constructions.
✘ Printed by Rapid prototyping.
91

92. 3. Fabrication of Metal Frameworks and Copings
✘ Selective Lase Sintering/
Selective Laser Melting SLS/SLM.
✘ No need fro the long process of
conventional lost wax laboratory
technique.
✘ Low risk of failure of complex
metal constructions.
92

93. 4. Printing of Molds for Complete Dentures
✘ Needs:
a. 3D graphic records of artificial teeth
b. 3D data of the edentulous rims
c. Centric relation record
93

94. 5. Printing of Molds for Facial Prosthesis
✘ Shortens the process.
✘ Allow for multiple pours from a single mold.
94

95. 6. Others
✘ Custom trays
✘ Provisional crowns and bridges
✘ Removable partial dentures
✘ Surgical guides
✘ Preventive splints & appliances
✘ Dental implants
95

96. Comparison of 3-D Printing and 5-axis Milling for the
Production of Dental e-models from
Intra-oral Scanning
✘ In this paper, a patient with mal-positioned mandible
was initially selected. Through an intra-oral scanner, the
3D STL model of the patient’s denture was created. After
that, a computer-aided virtual orthodontic treatment
was planned. After planning, 8 steps were respectively
fabricated by CNC milling machine and 3D printer. These
models were digitized via a scanner and then compared
with the original data from the virtual planning of
orthodontic treatment.
96

97. Comparison of 3-D Printing and 5-axis Milling for the
Production of Dental e-models from
Intra-oral Scanning
✘ In the experiment, it is found that the smoothness and
repeatability for CNC machining is better than for 3D
printing, especially for inclined and curved surfaces such
as occlusal surfaces.
✘ However, the 3D printer could produce concave and
intricate geometry that is often not achievable by
milling.
97

98. Comparison of Intaglio Surface Trueness of Interim Dental
Crowns Fabricated with SLA 3D Printing, DLP 3D Printing,
and Milling Technologies
✘ Interim dental crowns were fabricated based on CRM
using two types of 3D printer technologies (SLA & digital
light processing) and one type of milling machine. The
fabricated interim crowns were obtained via 3D
modeling of the intaglio surface using a laboratory
scanner and designated as CAD test models (CTMs). The
alignment and 3D comparison of CRM and CTM were
performed based on the intaglio surface using a 3D
inspection software program (Geomagic Control X).
98

99. Comparison of Intaglio Surface Trueness of Interim Dental
Crowns Fabricated with SLA 3D Printing, DLP 3D Printing,
and Milling Technologies
✘ The 3D printing and milling technologies used in this
study showed clinically acceptable intaglio surface
trueness (<100 μm) of interim crowns. The milling
technology showed inferior trueness in the reproduction
of angle region than occlusal region.
✘ However, interim crowns fabricated with 3D printing
technologies (SLAand DLP) can reproduce more uniform
and superior intaglio surface trueness than milling
technology. 99

100. Trueness and Precision of 3d-printed Versus Milled
Monolithic Zirconia Crowns:
An In Vitro Study
✘ 10 MZCs (test) were 3D-printed with a Lithography-
based Ceramic Manufacturing (LCM) printer and 10 MZCs
(control) were milled using a 5-axis machine. All MZCs
were sintered and scanned with the same scanner. The
surface data of each sample (overall crown, marginal
area, occlusal surface) were superimposed to the
original CAD file to evaluate trueness. Finally, the clinical
precision (marginal adaptation, interproximal contacts)
was investigated on a split-cast model.
100

101. Trueness and Precision of 3d-printed Versus Milled
Monolithic Zirconia Crowns:
An In Vitro Study
✘ The study found that milled MZCs have a statistically
significant higher trueness than 3D-printed MZCs. In this
study, both 3D-printed and milled crowns showed high
precision, compatible with the clinical use.
✘ However, more research is certainly needed to evaluate
the clinical precision and mechanical resistance of 3D
printed zirconia restorations, and to validate their
clinical use.
101

102. Ceramic Printing-Comparative Study of the Flexural
Strength of 3D-Printed and Milled Zirconia
✘ A total of 30 bars of an experimental 3D-printed 3 mol%
yttria-stabilized zirconia and 10 bars of milled isostatic
pressed zirconia were utilized. The printed zirconia bars
were divided into three groups: (1) untreated (control);
(2) thermocycled; and (3) tested after chewing
simulation.
✘ A flexural strength test was performed on all samples
using a three-point bending test in an Instron Universal
testing machine.
102

103. Ceramic Printing-Comparative Study of the Flexural
Strength of 3D-Printed and Milled Zirconia
✘ One-way analysis of variance on ranks was used to
compare milled to printed zirconia. The effects of
thermocycling and load cycling on 3D-printed zirconia
were also determined.
✘ There was no statistically significant difference in
flexural strength between the milled and printed
zirconia. No statistically significant differences were
observed between the control 3D-printed zirconia group
and the thermocycled or load-cycled printed zirconia.
103

104. Ceramic Printing-Comparative Study of the Flexural
Strength of 3D-Printed and Milled Zirconia
✘ Printed 3 mol% yttria-stabilized zirconia has
comparable flexural strength to milled yttria-stabilized
isostatic pressed zirconia.
✘ The thermocycling and chewing simulation used in this
study did not significantly alter the flexural strength of
the printed 3 mol% yttria-stabilized zirconia.
104

105. thanks!
Any questions?
You can find me at
@Radwa_Eltahawi
Radwa.ibrahim87@gmail.com
105