Dental soft tissue regeneration using novel tissue engineering techniques versus traditional techniques .

1. Dental Soft tissue regeneration using novel tissue engineering techniques
(Comparison between traditional and novel techniques)
Mohamed Mahmoud Abdul-Monem Abdul-Aziz
Dental Biomaterials Department
Faculty of dentistry
Alexandria University
Egypt
2019
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2. 2
Contents
1.Introduction.
2.Traditional techniques for periodontal soft tissue regeneration.
2.1 Autologous grafts
2.2 Allogenic grafts
2.3 Xenogenic grafts
2.4 Non-resorbable alloplasts
3.Novel techniques for periodontal soft tissue regeneration.
3.1 Tissue engineering using biodegradable alloplasts
3.2 3D printing
3.3 Lasers
3.4 Ozone treatment
3.5 Gene therapy
4.Comparison between traditional and novel techniques.
5.Conclusion

3. 1.Introduction
1.1 Definition of soft tissue
In anatomy, soft tissue includes the tissues that connect, support,
or surround other structures and organs of the body.
Soft tissue includes :
• Tendons, ligaments, fascia, skin, fats and synovial
membranes (which are connective tissues).
• Muscles, nerves and blood vessels (which are not connective
tissues) .
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4. 4
Repair vs Regeneration
Tissue repair is a dynamic
restorative cell proliferation which
leads to the formation of
granulation or fibrous tissue .
Tissue regeneration recovers
organ/tissue structure and
function.

5. 5
Uses of
soft
tissue
reg.
Gingiva
PDL
SkinMuscles
TMJ Disc

6. 1.2 Periodontium regeneration
•The periodontium is a complex structure composed
of both soft (gingiva, periodontal ligament) and hard
(alveolar bone, cementum) tissues .
•The primary aim of mucogingival surgical therapies
is the complete restoration of the anatomy of the
mucogingival complex and the regeneration of the
attachment apparatus of the tooth, ultimately
restoring esthetics and relieving dental
hypersensitivity .
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7. 1.3 Guided tissue
regeneration (GTR)
•Guided tissue regeneration (GTR) is defined by
the American Academy of Periodontology as a
procedure attempting to regenerate lost
periodontal structures through differential tissue
responses.
•It involves the use of resorbable or non-
resorbable barriers (membranes) to exclude
epithelial and connective tissue cells from the
root surface during wound healing.
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8. The barrier membranes in GTR must fulfill five main
criteria:
1. Tissue integration.
2. Cell occlusivity.
3. Clinical manageability.
4. Space-making ability maintained long enough for both PDL and
bone cells to proliferate into the defect.
5. Biocompatibility. (non-toxic, nonantigenic and induce no or little
inflammation).
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9. 1.4 Applications of soft tissue regeneration in
dentistry :
a) Root/implant coverage procedures in the treatment of localized gingival
recessions.
b) Keratinized tissue augmentation in areas where attached gingiva or mucosa is
absent.
c) Soft tissue volume augmentation in edentulous ridge.
d) Removal of aberrant frenulum.
e) Prevention of ridge collapse associated with tooth extraction.
f) Crown lengthening.
g) Gingival preservation at ectopic tooth eruption site.
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10. Pyogenic granuloma Excisional Biopsy Biopsy
Resorbable membrane
Soft tissue regeneration
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Autograft for
implant
surface
coverage to
treat
localized
gingival
recession

12. Soft tissue
augmentation
around dental
implants
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1.5 Other applications of soft tissue regeneration in dentistry
Skin regeneration Muscleregeneration TMJ Disc regeneration
• Adipose tissue derived stem cells
• Bone-marrow derived stem cells
• Skeletal muscle derived stem cells
• Satellite cells
• Endothelial cells
• TMJ derived synovial stem cells

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Techniques for soft tissue regeneration
Traditional
Autografts
Allografts
Xenografts
Non-resorbable
Alloplasts
Novel
Electrospinning
3D Bioprinting
Laser
Ozone treatment
Gene therapy

15. 2.Traditional techniques for periodontal soft tissue regeneration
2.1 Autografts
(A) TISSUE GRAFTS (B) PLATELET-RICH FIBRIN (PRF)
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16. 2.1.Autografts
Autografts
Tissue
grafts
Free gingival
grafts (FGG)
Epithelial &
connective tissue
Connective
tissue grafts
(CTG)
Subcutaneous tissue
PRF
Autogenous leukocytes,
growth factors &
platelets in a fibrin clot
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17. 2.1 Autografts
(a) Tissue grafts (b) PRF
Advantages Disadvantages Advantages
Low risk of infection in grafted area Donor site hemorrhage Autologous
Low risk of disease transmission Anesthesia/paresthesia of
donor site
Rich in cells and growth factors
Low risk of immune reactions Postoperative pain ,discomfort
and infection in donor site
Ease of Preparation
Rich in cells and growth factors. Limited supply
Increased chairside time
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18. 2.2 Allografts
Acellular dermal matrix allograft (ADMA)
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Composition
• Human skin epidermis and
cellular components of the
dermis have been removed.
• Basement membrane and
extracellular matrix
component (ECM) &
collagenous scaffolding
have been maintained.
Advantages
• Avoidance of the palatal
donor site.
• Treatment of multiple
gingival recessions in one
visit.
• Unlimited amounts of
tissue availability.
• High quality of donor
tissue.
• Higher case acceptance rate
and less postoperative
discomfort .
Disadvantages
• Increased risk of disease
transmission
• Increased risk of immune
rejection

19. 2.2 Allografts
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(A)AlloDerm (BioHorizons)
(B) Histological specimen of acellular dermal matrix demonstrating
mucosal tissue (M) overlying the area of graft placement (ADM) and
osseous crest (B).

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2.3 Xenografts Xenografts
ECM
membrane
•3D matrix of collagen &
elastin from animal
dermis or submucosa +
Glycosaminoglycans,
glycoproteins & growth
factors
Disadvantages :
1.Chemical crosslinking
decreases biocompatibility
2.Non-Resorbable
Bilayer collagen
membrane
First layer : thin, smooth, and
low-porosity compact collagen
layer from animal peritoneum.
Second layer : thick, porous
spongy collagen layer from
animal skin .
Advantages :
1.1.Interweaving
biophysical crosslinking
2.2.Resorbable
Function of layers :
First layer : cell occlusivity & protects
against bacterial infiltration .
Second layer : facilitate tissue
adherence, integration and angiogenesis.

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2.3 Xenografts
(A) Bilayer collagen membrane
(B) SEM image
(C ) Histological section

22. 2.3 Xenografts
Advantages Disadvantages
Unlimited supply Increased risk of disease transmission
Decreased postoperative
complications
Increased risk of immune rejection
Decreased surgical time Decreased biocompatibility due to the
use of chemical crosslinking agents in
some types.
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23. 2.4 Non-resorbable alloplasts
1. Polytetrafluorethylene (PTFE)
2. Titanium-reinforced PTFE
3. High density PTFE
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24. 2.4 Non-resorbable Alloplasts
ADVANTAGES
1. Mechanical support .
DISADVANTAGES
1. Second surgical procedure to
remove the membrane .
2. Early and spontaneous exposure in
oral cavity
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25. 3.Novel techniques for periodontal soft tissue
regeneration
3.1 Tissue engineering using biodegradable alloplasts
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26. 3.1 Tissue engineering
1.SCAFFOLD BIOMATERIALS 2.STEM CELLS
• Biocompatible
• Biodegradable
• Bioactive
• Weak mechanical prop.
Natural
polymers
• Biocompatible
• Controlled biodegradation
• High mechanical prop.
Synthetic
polymers
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PDL
derived
stem
cells
Bone
marrow
derived
stem
cells
Dental
pulp
stem
cells
Adipose
tissue
derived
stem
cells

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3.Growth factors
Growth factor Source Effect
Platelet-derived growth factor
(PDGF)
Platelets
Macrophages
Fibroblast chemotaxis
Fibroblast proliferation
ECM synthesis
Fibroblast growth factor (FGF) Macrophages
Endothelial cells
Fibroblast proliferation
Angiogenesis
Transforming growth factors
(TGFSs)
Platelets
Macrophages
Fibroblast chemotaxis
Fibroblast proliferation
Protease inhibitors
Vascular endothelial growth
factor (VEGF)
Keratinocytes
Macrophages
Angiogenesis
Insulin like growth factor (IGF) Neutrophils Activate growth factor
expression in fibroblasts,
macrophages and
keratinocytes.

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A typical electrospinning setup
requires four components:
1. Syringe pump (containing
solution/melt/suspension)
2. Spinneret with a metallic needle
(as a capillary)
3. High-voltage power supply
4. Grounded conducting collector
Electrospinning

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Electrospinning
Advantages
• Mimic ECM
• Controlled degradation rate
• Excellent mechanical prop.
• Inter-connected pores
• Random/aligned nanofiber formation
• Large Surface area to volume ratio
Disadvantages
• Use of toxic solvents.
• Technique sensitive.
• Pore size control

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(a)Aligned electrospun fibers for PDL regeneration
(b)Random electrospun fibers for bone regeneration

31. 3.2 3D bioprinting
•Three-dimensional (3D) bioprinting
technologies have been developed to
offer construction of biological tissue
constructs that mimic the anatomical
and functional features of native tissues
or organs.
•These cutting-edge technologies could
make it possible to precisely place
multiple cell types and biomaterials in
a single 3D tissue construct.
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3D
bioprinting
techniques
Ink –jetting
-Heat or
piezoelectric
effect
-High Resol. 20-
100 μm
-Multiple
cartridges
-Low viscosity
bioinks
Extrusion-
based
-Pnuematic piston
-Multiple cartridge
-Multiple
viscosities
-Low resolution
50-400 µm
Laser-induced
forward
transfer
-Pulsed laser
-Multiple
viscosities
-Rapid gelation of
bioink

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The required properties of hydrogel-based bioinks are:
1. Relatively high viscosity to
provide homogenous cell
suspension and initial structural
integrity.
2. Strong shear-thinning behavior
to minimize cell damage.
3. Rapid gelation to build a 3D
tissue structure.

34. Types of 3D bio-printed scaffolds for periodontal
regeneration
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Triphasic 3D Bioprinted scaffold for
periodontal regeneration

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3.3 Lasersand periodontal soft tissue regeneration
Laser patterned micro-
coagulation
(LPM)
• The creation of microscopic
thermal wounds representing islets
of tissue damage surrounded by
spared normal tissue has been
shown to greatly enhance the
regenerative capacity of the tissue,
resulting in completely scar-free
tissue self-repair.
• Diode laser 980 nm ,20W ,160 ms
relaxation time
Laser-assisted
periodontal therapy
(LAPT)
• Laser de-epithelization
• Laser bacterial
reduction (LBR)
• Biostimulation (Low
level laser therapy
(LLLT) :
• Collagen ,osteoblast and
fibroblast formation
• Angiogenesis
Laser-assisted new
attachment
procedure (LANAP)
• ND:YAG laser 1064
nm pulsed mode .
• Regeneration of the
periodontal tissues
and new connective
tissue attachment
mediated by
cementum

37. Lasers and periodontal soft tissues regeneration
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Role of ozone
• Anti-microbial
• Immunostimulant effect
• Hemostatic
• Biosynthetic
• Increase the local supply of
oxygen
• Increase temperature in the
area of the wound
• Angiogenic
Uses
• PDL regeneration
• Treatment of peri-implantitis
• Treatment of periodontitis
3.4 Ozone treatment and periodontal soft tissues regeneration

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Ozone treatment

40. 3.5 Gene therapy and periodontal soft tissue regeneration
1. Gene augmentation therapy (GAT)
to treat recessive gene disorders.
2. Targeted killing of specific cells ,
Genes encoding toxic compounds
(suicide genes), or prodrugs are used
to kill the transfected/ transformed
cells.
3. Targeted inhibition of gene
expression
4. Targeted gene mutation correction
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41. Gene delivery
Viral Non-Viral
Retrovirus Plasmids
Adenovirus DNA polymer
complexes
Herpes simplex
virus
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Gene
Gun

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Gene therapy
Technical difficulties
• 1. Difficulty in delivery of gene.
• 2. Short-lived nature of gene
therapy.
• 3. Activation of immune response.
• 4. Chance of inducing mutagenesis.
• 5. Safety of vectors.
• 6. Difficulty to treat multigene
disorders.
• 7. Durability and integration.
• 8. Expensive.
Uses
• Platelet derived growth factor gene
(PDGF-g) delivery for soft tissue
regeneration.
• Angiogenic growth factors
gene(AGF-g) delivery.

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5.Conclusion
•In general, the techniques for soft tissue regeneration either dental (gingival mucosa and PDL) or
maxillofacial (skin, muscles and TMJ disc) are the same.
• Traditional techniques such as autograft, allografts, xenografts and non-resorbable alloplasts have been
widely used but all have their corresponding disadvantages.
•Novel techniques such as electrospinning and 3D printing are increasingly being used for soft tissue
regeneration .The concept is the same ,the difference is in the biomaterial used, the type of stem cells for
regeneration and the growth factors that will increase the regeneration capacity.
•Laser and ozone treatments are usually used as a combination therapy to any of the previous techniques .
•Gene therapy is an emerging technique for soft tissue regeneration, but it still needs further research to avoid
any mutagenic effects .

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