digital scaffolds

1. Digital scaffolds
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2. Introduction
• Dental scaffolds play an important role in
tissue engineering that is defined as: an
interdisciplinary field of study, which employs
the principles of engineering and life science
to develop⁄ recreate functional biological
tissues.
• Tissue engineering intends to help the body
to produce a material that resembles as much
as possible the body’s own native tissue.
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3. Tissue Engineering Triad
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4. Dental Tissues That Can Be Regenerated:
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5. The Classical Tissue Engineering Strategy
Consists of:
• 1. Isolating specific stem cells through a
biopsy from a patient, growing them on a
scaffold under controlled culture conditions in
presence of growth factors⁄ Morphogens.
• 2. Delivering the resulting construct to the
desired site in the patient’s body.
• 3. Directing the new tissue formation into the
scaffold that can be degraded over time.
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6. Scaffolds
• Scaffolds are: Temporary or permanent
extracellular matrices (ECM) to accommodate
cells and support 3D tissue regenerations.
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7. • Scaffolds: provide a spatially correct position
of cell location.
• And permit sufficient transport of gases,
nutrients, and regulatory factors to allow cell
survival, proliferation, and differentiation.
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8. Role of Scaffolds in Tissue Engineering
• Serve as a framework to support cell
migration into the defect from surrounding
tissues.
• Serve as a delivery vehicle for exogenous cells,
growth factors and genes.
• Serve as a matrix for cell adhesion.
• Structurally reinforce the defect to maintain
the shape of the defect and prevent distortion
of surrounding tissues.
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9. • Finally, serve as a barrier to prevent the
infiltration of surrounding tissues that may
impede the regeneration process.
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10. Ideal Requirements of Scaffolds
• Three-dimensional and highly porous.
• Biocompatible and biodegradable, leaving no
toxic byproducts.
• The rate at which degradation occurs should
coincide with the rate of tissue formation.
• Suitable surface chemistry for cell attachment,
proliferation, and differentation .
• Mechanical properties to match those of the
tissues at the site of implantation.
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11. Types of Scaffolds
Scaffolds
Tissue response
Bioinert
Bioactive
Biodegredable
Material
Natural
Synthetic
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12. • Bioinert: has minimal interaction with its
surrounding tissue. e.g Titanium
• Bioactive: interacts with the surrounding bone
and in some cases, even soft tissue. e.g HA
• Biodegredable: dissolve (resorbed) and slowly
replaced by advancing tissue (such as bone).
e.g Tricalcium phosphate
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13. Biomaterials for Dental Scaffolds
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14. I. Polymeric Scaffolds
Sold State or Hydrogels
Nature Polymers
Protein Origin:
Collagen
Fibrin
Gelatin
Albumin
Silk Protein
Polysaccharide
Origin:
Alginate
Chitosan
Hyaluronic Acid
Synthetic Polymers
Alphatic
polyesters:
PLA
PGA
PLGA
PCL
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15. Polymeric Scaffolds
Solid Porous Scaffolds Hydrogels
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16. • The choice of scaffolding materials depends
on the environment of original ECM due to
specific application for scaffold.
• E.g : Cartilage ECM= Hydrated,
Bone ECM= Dense
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17. Solid Porous Scaffolds
o Application:
• Bone tissue engineering
o Properties:
• Solid and stable porous
structures.
• Usually degrade through
hydrolysis of the chemical
bonds.
Hydrogels
o Application:
• Blood vessels, Skin,
Cartilage, Ligaments, and
Tendons.
o Properties:
• Highly hydrated hydrophilic
polymer networks
• Contain ̴ 90% water.
• Ability to fill irregularly
shaped tissue defects.
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18. II. Metallic Scaffolds
• The most common metallic biomaterials for
scaffold fabrication are:
• Tantalum
• Magnesium and its alloys
(biodegredable)
• Titanium and its alloys
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19. Tantalum Mg
Titanium mesh Porous Ti Granules
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20. Limitations of Metallic Scaffolds
• 1- Lack of biological recognition on the
material surface.
• To overcome, surface coating or surface
modification.
• 2- The possible release of toxic metallic ions
and/or particles through corrosion or wear.
• That could lead to inflammatory and
allergic reactions, which reduce the
biocompatibility and cause tissue loss.
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21. III. Composite Scaffolds
• A composite scaffold made up of two different
scaffold materials like synthetic polymer and
inorganic materials combines the advantages of
each individual material and minimizes their
disadvantages.
• E.g., Polymer materials lack adequate stiffness.
• Addition of stiff materials like glasses and ceramic
overcomes this inherent weakness of polymers.
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22. • Composite scaffolds appear to be a promising
substrate for tissue engineering due to its:
- Excellent mechanical properties,
- Biocompatibility and
- Osteoconductivity.
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23. VI. Ceramic Scaffolds
• This group of scaffolds refers to:
- Calcium/phosphate materials,
- Bioactive glasses and
- Glass ceramics
• These have proved useful in dental tissue
engineering by providing favorable 3D
scaffolds for cells growth and differentiation.
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24. Advantages
• Biodegredable
• Biocompatable
• Low immunogenicity
• Osteoconductivity
• Bone bonding
• Similarity to mineralized
tissues
Disadvantages
• Difficulty of shaping
• Poor mechanical strength
• Brittleness
• Slow degradation rate
• High density
24

25. Fabrication Techniques
Rapid prototyping/AM/Digital
methods
Conventional
Stereolithography
Solvent casting/particulate
leaching
Laser Sintering
Fiber meshing
Extrusion -based rapid prototyping
Melt moulding
Three-dimensional printing
Gas foaming
Four-dimensional printing
Membrane lamination
Freeze drying
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26. I. Conventional techniques
1- Gas foaming and freeze drying
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27. I. Conventional techniques
2- Solvent casting and particulate leaching
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28. I. Conventional techniques
3-Fiber electrospining
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29. II. Digital techniques
Rapid prototyping methods
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30. II. Digital techniques
1- Stereolithography
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31. II. Digital techniques
2- Laser Sintering
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32. II. Digital techniques
3- Extrusion-based rapid prototyping
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33. II. Digital techniques
4- Three-dimensional printing
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34. II. Digital techniques
5- Four-dimensional printing
• A new emerging digital technology for
fabrication of dental scaffolds using smart
materials (that could respond to an external
stimulus) and 4D printers.
• However, up till now there is still no actual
application and production of scaffolds using
this technology.
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35. Architecture
Fiber-mesh Sponge-like
Injectable hydrogels 3D printed
35

36. Applications of Tissue Engineering in
Different Fields of Dentistry.
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Periodontology
Endodontics
Oral and maxillofacial surgery
Restorative dentistry
Prosthodontics

37. Tissue Engineering in Periodontology
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38. 38

39. Tissue Engineering in Endodontics
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40. Tissue Engineering in Oral and
Maxillofacial Surgery
• 1- Tissue engineering of bone defects
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41. 2- Tissue Engineering of TMJ
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42. 3- Tissue Engineering of Skin and Oral
Mucosa
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43. 4- Tissue Engineering of Salivary Glands
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44. 5- Implant Therapy
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45. 6- Cleft Palate
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46. Tissue Engineering in Restorative
Dentistry
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47. Tissue Engineering in Prosthodontics
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48. 48

49. References
• Hu B, Unda F, Bopp-Kuchler S, Jimenez L, Wang XJ, Haikel Y, et al.
Bone marrow cells can give rise to ameloblastlike cells. J Dent Res
2011;85:416-21.
• Young C, Abukawa H, Asrican R, Ravens M, Troulis M, Kaban L, et
al. Tissue-engineered hybrid tooth and bone. Tissue Eng
2009;11:1599-610.
• Murray PE, Garc‫ي‬a-Godoy F. The outlook for implants and
endodontics: A review of the tissue engineering strategies to create
replacement teeth for patients. Dent Clin North Am 2006;50:299-
315, x.
• Huang DD, George TJ. Dental pulp and dentin tissue engineering
and regeneration-advancement and challenge. Front Biosci (Elite
Ed) 2011;3:788.
• Yu J, Shi J, Jin Y. Current approaches and challenges in making a bio-
tooth. Tissue Eng Part B Rev 2015;14:307-19.
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50. II. Smart Dental Materials
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51. Smart Materials
• Definition: Smart materials are the materials
that can significantly alter one or more of
their inherent properties owing to the
application of an external stimulus in a
controlled fashion.
• External stimulus may be: Stress;
Temperature; Moisture; PH; Electric Fields;
Magnetic Fields……
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52. SMART MATERIALS….!!!!
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53. Classification of Smart Materials
• I. Passive smart materials:
• Respond to external change without external
control.
• II. Active smart materials:
• Utilize a feedback loop to enable them to
function like a cognitive response through an
actuator circuit.
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54. Smart Dental Materials
Glass Ionomer Cement
I. Passive Smart Restorative Materials:
Resin Modified GIC
Compomer
Dental Composite
II. Active Smart Restorative Materials:
Smart GIC
1. Restorative Dentistry
Smart Composites - Ariston Phc
- ACP Composites
Smart Prep Burs

55. Smart Ceramics
2. Prosthetic Dentistry
Smart Impression Materials
Shape Memory Alloys.
3. Orthodontics
Fluoride Releasing Pit and Fissure Sealants
4. Pediatric and Preventive Dentistry
ACP Releasing Pit and Fissure Sealants
NiTi rotary instruments.
5. Endodontics
Smart Sutures
6. Oral Surgery
Hollow-core Photonic-Fibers
7. Smart Fibers for Laser Dentistry
Smart antimicrobial peptide
8. Periodontics
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56. Smart Glass Ionomer Cement
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57. • GIC is described as a “smart” restorative
material because the fluoride they contain is
not only released to surrounding tooth
structure but can also be recharged in the
glass ionomer.
• Referred to as the “reservoir effect”: an
important feature of GIC.
• Resin modified GIC, Compomer or Giomer also
exhibit these smart characteristics.
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58. Ariston PH Control Composite
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59. • Ariston PHc; is a light-activated alkaline, nano-
filled dental restorative material.
• Indications: class I and II cavities.
• It has an “intelligent” behavior because it
releases calcium, fluoride, and hydroxyl ions
when the intraoral pH values drop below 5.5.
• This is said to neutralize acid and counteracts the
demineralization and promotes remineralization.
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60. ACP Composites
60

61. • ACP Composite; is referred to as “smart
material” because it releases Ca and
Phosphate ions only when the surrounding pH
drops at or below 5.8.
• 1) Once CaPO4 is released , it will act to
neutralize the acid , buffer the pH.
• 2) ACP converts in to HAP and precipitates,
thus replacing the HAP lost to the acid.
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62. Smart Prep Burs
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63. • Smart Prep Burs; are polymer burs which have
ability cuts only infected dentin.
• The affected dentin which has the ability to
remineralize is left intact.
• The cutting blades will deflect and deform upon
encountering normal or partially decalcified
dentin, thereby enabling the reduction of cutting
efficiency and avoid overcutting of tooth
structure that usually occurs with conventional
burs.
63

64. Smart Ceramics
• E.g., Cercon Zirconium Smart Ceramic
material is a metal-free biocompatible life like
restoration with strength that helps resist
crack formation.
• Has properties of fracture toughness, flexural
strength, reliability, and crystallographic
transformation of zirconium oxide. Thus
resist crack propagation through it.
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65. 65

66. Smart Impression Materials
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67. • Aquasil Ultra Smart Wetting® Impression
Material is an addition silicone impression
material.
 It is designed with:
• A reduced contact angle
• Hydrophilic nature to get void free impression
• Shape memory during elastic recovery.
• And increase in tear strength to resists tearing or
distortion.
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68.  The material is available as:
• a regular- and fast-set rigid (light green),
• heavy (light green),
• monophase (maroon),
• low viscosity (teal), and
• extra-low (orange) viscosities.
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69. Fluoride Releasing Pit and Fissure Sealants
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70. • Fluoride Releasing Pit and Fissure Sealants,
combine the benefits of fluoride release from
glass ionomer cements and good retention and
seal from resins.
• Fluoride contributes to the remineralization of
the tooth. It makes the tooth more acid resistant.
• During remineralization a fluorapatite- like
crystals are formed that are larger and stronger
than the original hydroxyapatite crystals.
• Fluoride may also provide antimicrobial effects.
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71. ACP Releasing Pit and Fissure Sealants
Aegis® products
71

72. • ACP Releasing Pit and Fissure Sealant, is
referred to as a “smart material” because it
only releases calcium and phosphate ions
when the pH drops to 5.8.
• Once the calcium phosphate is released, it will
act to neutralize the acid and buffer the pH.
• It also, has the ability to remineralize tooth
structure by enhancing the tooth’s natural
repair mechanism.
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73. 73

74. Shape Memory Alloys
• These alloys have exceptional properties such as
super elasticity, shape memory, good resistance
to fatigue and wear and relatively good
biocompatibility.
• Ni-Ti alloys are used in orthodontics for
fabrication of brackets and wires.
• In orthodontics, NiTi arch wires are used instead
of stainless steel owing to their limited flexibility
and tensile properties.
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75. Ni-Ti Rotary Instruments
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Ni-Ti Rotary Protaper Files

76. • The introduction of Ni-Ti files in rotary
endodontics has made instrumentation easier
and faster than conventional hand
instrumentation.
• Ni-Ti endodontic files offer shape memory
effect, superelasticity, durability, and
torqueability as compared with stainless steel
files.
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77. • Rotary NiTi files offer the following
advantages:
• 1- Less chances of file breakage during
instrumentation
• 2- Less fatigue to the operator
• 3-Less transportation and decreased incidence
of canal aberration.
• 4- Minimal postoperative pain to the patient.
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78. Smart Sutures
Novel MIT Polymer smart sutures
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79. • They are made up of thermoplastic polymers that
have both shape memory and biodegradable
properties.
• Smart sutures are covered with temperature
sensors and micro-heaters and can detect
infections.
• Sutures are loosely tied , once the temperature is
increased above the thermal transition
temperature; sutures gets shrinked and tightened
79

80. Smart Fibres for Laser
• Laser radiation of high frequency can be
delivered by Hollow-core Photonic-Fibers (PCFs)
which can ablate tooth enamel.
• These photonic fibers are known as Smart Fibres.
• Photonic Smart Fibrers are not only to transport
the high power laser pulse to a tooth surface,
• but can be used for detection and optical
diagnosis through transmit plasma emission.
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81. Smart Antimicrobial Peptide
• Specifically targeted antimicrobial peptides
(STAMP‘s) could be delivered in current oral
care products such as mouthwash, toothpaste,
or dental floss and could help with the
suppression of cariogenic bacteria.
• Smart AMPs, which are targeted against
Streptococcus mutans the causative
microorganism of dental caries.
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82. • The action of AMPs typically involves binding
to the negatively charged functional groups of
microbial membranes (e.g, lipopolysa-
ccharides) and creating a disruption by
inserting into the membranes, causing death
of bacteria.
82

83. References
• Lendlein A, Langer R. Biodegradable, elastic shape-memory
polymers for potential biomedical applications. Science 2012; 296:
1673-6.
• Lars Bergmans, , Johan Van Cleynenbreugel, Martine Wevers, &
Paul Lambrechts. Mechanical Root Canal Preparation With Niti
Rotary Instruments: Rationale, Performance And Safety. American
Journal of Dentistry, Vol. 14, No. 5, October, 2013, 325- 333.
• Luca Testarelli, Gianluca Plotino, Dina Al-Sudani, Valentina
Vincenzi, Alessio Giansiracusa, Nicola M. Grande and Gianluca
Gambarini. Bending Properties of a New Nickel-Titanium Alloy with
a Lower Percent by Weight of Nickel. JOE 2016, 1-3.
• Patel.CKN, McFarlane.RA, Faust.WL. Selective Excitation through
vibrational energy transfer and optical Maser action in N2-CO2.
Physiol Rev1999; 13: 617-619.
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84. Thank you
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