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2. Recent Advances in Implant Surface
              Science


             Takahiro Ogawa DDS, PhD
             Ichiro Nishimura DDS, PhD
              John Beumer III DDS, MS
Division of Advanced Prosthodontics, Biomaterials and
             Hospital Dentistry, UCLA
      This program of instruction is protected by copyright ©. No portion of
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Titanium implant surfaces
                      1st Generation
Titanium machined surface
Titanium plasma spray surface
Sand blasted surfaces
Hydroxyl apatite coated titanium surfaces
   Machined       Titanium plasma   Sand blasted
    surface       spray surface       surface
Titanium Surfaces
Problems
       Bone anchorage with machined surfaces was not
       ideal in bone sites exhibiting thin cortical layers
       combined with poor quality trabecular bone, such as
       the posterior maxilla.
        •Some of the initial titanium plasma spray
        surfaces were excessively rough and giant
        cells and macrophages were seen
        phagocytizing portions of the surface
        (particle disease).

       •It was very difficult to remove the
       contaminants from the original
       sand blasted surfaces.
       •The original plasma spray HA-CaP surfaces
       were not predictable
Hydroxyl Apatite - CaP Coatings
Coatings of hydroxyl apatite, because of
their chemical similarity to bone, were
thought to be advantageous.

The HA – CaP surface is more
osteoinductive than titanium and this
leads to more rapid bone deposition
following implant placement.

However the original so-called HA
surfaced implants were mostly
composed of tri-calcium phosphate,
Mechanism of Action: HA-CaP Coatings
         v During  healing Calcium and
            Phosphate ions are released
            from the HA-CaP coating in the
            peri-implant region
         v This leads to the precipitation of a
            biological apatite with various
            proteins which serves as a
            substrate for osteoblastic cells
            producing bone
         v The biological apatite substrate
            promotes cell adhesion, cell
            differentiation and the synthesis
            of mineralized collagen
HA-CaP Coatings
HA surfaces were very osteo-conductive.
 v At six weeks following placement the
    bone appositional index is close to
    70% for HA coated implants compared
    to 30-50% for original titanium
    surfaces (machined and TPS)
    (Weinlander et al, 1993).
However:
 v When the so-called plasma spray HA -
  Cap surface becomes exposed to the
  oral cavity it becomes contaminated
  with oral bacteria
HA-CaP Coatings
                        Clinical Problems
l   Colonization by
     microorganisms leads to
     circum-implant infections.
l   Cracks and fissures in some
     cases led to the entire loss of
     the HA coating.
l   These factors predisposed to
     a higher rate of implant failure   Note the loss of bone
     than seen with titanium            around these HA
                                        coated implants 4
     implants (Wheeler, 1996).          years after insertion.
HA-CaP Coatings
v These data have led most clinicians to switch to the
   titanium surfaces.
v However, new methods of applying the HA-CaP
   coatings with nano-sized crystals are evolving
   which result in direct bonding of bone to the
   surface of the implant eliminating the cement line.


 In summary, HA coated systems have provoked great
 interest and enthusiasm because of there osteo-
 conductivity. The initial problems associated with plasma
 spray application are in the process of being overcome
 and this type of surface may be the surface of the future.
Ideal Implant Surface Properties
v Promote  adsorption of proteins
v Promote adhesion and differentiation of bone
   producing cells
v Tissue integration
Implant Surface Science
v   The biological events leading to osseointegration
     are influenced by:
     v Surface chemistry
     v Surface topography of the implant
     v Hydrophilicity of the surface (wetability)


v   Research efforts in the last twenty years have
     attempted to idealize these properties on dental
     implants in order to:
     v Decrease healing time
     v Enable use in compromised bone sites
     v Improve the quality of the bone implant interface
The Jane and Jerry Weintraub Center for
      Reconstructive Biotechnology
      UCLA School of Dentistry
       Ichiro Nishimura DDS, PhD, Director
            Takahiro Ogawa DDS, PhD
                 Neil Garrett PhD
                 Anna Jewitt PhD
                 Kumar Shah DDS
               Eleni Roumanas DDS
               Ting Ling Chang DDS
                Evelyn Chung DDS
              James Kelley DDS, MS
              John Beumer DDS, MS
Uncovering the secrets of

l Discover  insights into the molecular
   basis of osseointegration
l Develop the next generation of implant
   surfaces
l Objectives
   l Earlierloading
   l Immediate loading
   l Predictability in compromised sites

*Ichiro Nishimura DDS, PhD and Takahiro Ogawa DDS, PhD
Titanium Implants - Surface Modifications
                        2nd Generation
                    1st break through
             The micro-rough surface implants




Ti Grit blasted   Electrolytically
                                     Sand blast-   Acid etched
                    enhanced
                                     acid etched
Titanium Implants – 2nd Generation
Surface roughness (Micro-topography)
    Electrolytically modified
    Acid etched surfaces
    Combination acid etched and sand blasted surfaces


                            1 micron
Titanium Implants - Surface Modifications
                2nd Generation
               1st break through
        The micro-rough surface implants
How are the new surfaces different from the old surfaces?
Why do we get better bone anchorage with these new
surfaces?

Are these surfaces more bioreactive? Do they accelerate the
process of osseointegration?

If so, what has been the impact on implant biomechanics, early
and immediate loading and treatment planning?
Current Implant Surfaces
	
 Micro-rough surface textures – Why are
   they a significant improvement?
         Initial stabilization is improved
              Maximize the volume of interlocking mineralized bone with
              the implant surface
                                               Double acid       Machined
Torque Removal                                   etched           surface
   v Reverse torque test
   v Data recorded in N/cm
   v Double acid etched vs
   	
          Machined
       v 2 month data (1997)
       v 1, 2, 3 months (2001)

 Klokkevold et al, 1997, 2001
Initial anchorage -Torque removal studies
v 10 New Zealand White Rabbits
v 2 Custom-designed implants (distal femur)
     v   Machined
     v   Double acid etched (Osseotite)




                    Klokkevold et al, 1997, 2001)
Initial anchorage -Torque removal studies
    Reverse torque rotation to removal (failure)




                          Klokkevold et al,1997; 2001)
Initial anchorage -Torque removal studies
                     Results – 2 months data




                  Machined = 4.95 ± 1.61 Ncm
                  Double acid etched = 20.50 ± 6.59 Ncm
Klokkevold et al, 1997
Initial anchorage -Torque removal studies


  Why the difference?
       vBetter mechanical
       	
      anchorage?
       vBone contact area?
       vQuality of the bone
       	
      at the
       interface?
  	
Klokkevold et al, 1997
Titanium Implants - Surface Modification
    Surface roughness and the bone contact area

Animal studies have shown that the bone contact
area achieved is 50% greater with micro -rough
surfaces as compared to machined surfaces
(Buser et al, 1991, Weinlander, 1993, Hamada, 1995,
Nishimura and Ogawa, 2000, 2003).
50 µm

        Histomorphometry
Acid etched vs Machine surface   Near zone
                                  Far zone
                Machined
                Acid etched

  (%)
 80
                *
 60

 40     *
 20
                              (Ogawa and
  0
        W2          W4        Nishimura, 2000,
        Bone-implant          2003),
        contact ratio
Bone contact area
    Microrough surfaces (Weinlander et al, 2004)




Electrolytically   Titanium       Double acid   Sandblast acid
  Modified         plasma spray    etched         etched
Implant anchorage data
Shear Strength obtained with a push out test
   Studies



Acid etched   Machined
  surface      surface

     Experimental
     Rat implant
Implant anchorage data
                obtained with a push out test
                  This test measures the strength of
                  implant tissue interface rather than
Push-in value (N) the strength of the surrounding bone.

         60      Machined
                                            *
                 Etched
         40
                                *
         20               *
          0
                0         2      4          8   *p<0.05
                    Healing period (week)
Current Implant Surfaces
Micro-rough surfaces and osseointegration

           What biologic phenomenon
           are affected by the changes
           in surface micro
           topography?
Current Implant Surfaces
	
 Why are these surfaces
   more bioreactive?
     vRate of plasma protein
      absorption
     vFibrin clot retention
     vCell Adhesion
     vCell differentiation
     vGene expression
Rate of plasma protein absorption
v Rate   of plasma protein absorption
  v Enhanced by hydrophilic surfaces
  v Enhanced by micro-rough surfaces
  v Reduced as the surface ages

v Promotes cell adhesion
v Promotes cell differentiation
Fibrin Clot Retention
        Micro-rough surfaces
vDavies (1998) showed that micro-rough
surfaces captured and retained the fibrin
clot initially deposited on the implant
surface more effectively than machined
surfaces

v As a result the initial crticial events
(plasma protein adsorption, clot formation,
angiogenesis, mesenchymal stem cell
migration etc.) associated with
osseointegration were facilitated.
Differentiation of mesenchymal stem
     cells (MSC) into functioning
              osteoblasts
                              Functioning osteoblast




vStem cells migrate to the implant surface and
	
   into the osteotomy site via the fibrin network
vThe micro-rough facilitates this process
Micro – rough Implant Surfaces

Ogawa and Nishimura set out to determine whether or
not the double acid etched surface result in:
    Earlier osseointegration?
   Better bone anchorage?
   Determine what factors are responsible for the different bone
profiles seen on different surface textures of titanium implants.
They were particularly interested in the gene expression of the
differentiating osteoblasts




                  Osseotite- Double Acid Etched
Gene expression data obtained with a T-cell
        model developed by Davies
T-cell implant     Machined          Acid-etched




                 v They implanted T-cell implants into
                 the femurs of rats and retrieved the
                 specimens at various time intervals.

                 vThey hypothesized that gene
                 expression is controlled at local levels
                 by the surface texture of the implant.
Why was the double acid etched surface
superior to the machined surface?
Why was the bone different?
Nishimura and Ogawa suggested
several reasons including:
  Bone repair and generation may not be the
  primary prerequisite for osseointegration
  Might it be an implant dependent mechanism?
  Hypothesis:
  A set of genes that are NOT involved in bone
  repair initiate and/or regulate the process of
  osseointegration                      Ogawa and Nishimura,
                                           2000, 2002, and 2003
Purpose of the study
Identify the genes that are expressed around implants
but not in non-implant wound healing of bone.

                                          Non-implant defect
                                          Turned implant
                                          Etched implant


  Screening of candidate
  osseointegration-specific genes


                Differential display
                polymerase chain
                reaction (DD-PCR)
Testing the candidate DD-PCR products

 From 1853 DD-PCR products,
       19 implant-specific (- + +)
       2 acid-etched-specific (- - +)



        42 different clones



3 Osseointegration-specific genes
         (TO1, TO2, TO3)
mRNA expression of TO1
              Day 3          Week 1            Week 2          Week 4
                          Non-implant defect
                          Turned implant
                          Etched implant                         Untreated control

  TO1

GAPDH



        0.2
                      Etched implant                    Turned implant



        0.1


                                       Non-implant defect

                      Day 3 Week 1             Week 2                    Week 4
mRNA expression of TO2
              Day 3        Week 1            Week 2        Week 4
                        Non-implant defect
                        Turned implant
                        Etched implant                       Untreated control

  TO2

GAPDH


        0.6


        0.4                                           Turned implant
                      Etched implant


        0.2
                              Non-implant defect

                      Day 3 Week 1           Week 2                 Week 4
mRNA expression of TO3
              Day 3         Week 1            Week 2          Week 4
                         Non-implant defect
                         Turned implant
                         Etched implant                          Untreated control

  TO3

GAPDH


        1.2
                                     Etched implant


        0.8
                                                       Turned implant

        0.4
                             Non-implant defect

                      Day 3 Week 1            Week 2                    Week 4
TO genes showed

Osseointegration-specific expression

Upregulation in early stages of
   implantation
Accelerated expression for the double
   acid etched surface
TO3 happens to be P4H
 Enhanced gene expression of
 prolyl 4-hydroxylase (P4H)
 Collagen synthesis considerably
 higher
Collagen and P4H
      -




P4H
Why was the accelerated
 expression of P4H on micro-
 rough surfaces significant?

Collagen density and orientation, as well as the
degree of mineralization are contributing
factors relative to the microhardness and elastic
modulus of bone
Bone Implant Interface
        Double Acid Etched Surfaces
A different combination of collagenous and
noncollagenous proteins make up the bone deposited
on the dual acid etched surface as compared to a
machined surface.



Resorption and remodeling of bone deposited on acid
etched surfaces appeared to be different than bone
on machined surfaces.
Nano Indentation Test
   3 times stiffer bone on dual acid etched
                     2000nm indentation depth

                                 P=0.0252
Elastic modulus
                                         P=0.0339
    (GPa) 0.2




          0.1




           0
                  Bone on        Bone on            Bone on
                  Polystyrene   Machined Ti          DAE
Nano indentation test
     2 times harder bone on dual acid etched
                     200mN maximum load
                                   P=.0005
                                             P=0.0153
                        P=0.0130
Nanohardness
   (GPa)0.8

        0.6

        0.4

        0.2

         0
               Bone on         Bone on                  Bone on
               Polystyrene    Machined Ti                DAE
Nanoindentation: in vivo bone




Bone around machined surfaces is as hard as the trabecular
bone, while the bone around the DAE surfaces is as hard as
the cortical bone.                         Ogawa et al, 2005
Day 28
                         Day 14
                              7
                         Day 21
                              0
                              3
Distinct pattern of osteogenesis on DAE




         Osteoblast
                                    Non-collagenous matrix



               Mineral deposition
                                                 Collagen matrix
Current Implant Surfaces
Micro-rough surface textures – Why are they a
 significant improvement

Shape of the cell affects its gene expression
and the micro-environment affects cell behavior.

    Improved adsorption of plasma proteins
Micro-rough surfaces – Why are they superior?


vImproved clot retention (Davies, 1998)
vInitial absorption of plasma proteins is
enhanced (fibronectin, vitronectin etc) (Kohavi
(2010)
vMSC differentiate much faster on micro-
rough surfaces as compared to smooth
surfaces (Ogawa et al, 2003)
vMicro-rough surfaces changes gene
expression of the differentiating osteoblasts
(Ogawa and Nishimura (2000,2003 and 2004, 2006)
vBone deposited on micro-rough surfaces is
harder and stiffer than bone deposited on
machined surfaces (Butz,2006; Takeuchi et al,
2005)
Impact of Strengthened Peri-implant Bone
                                          Trabecular
                                             bone



                                           Cortical
                                            bone




Cortical bone:
  l   Very dense
  l   Less subject to
       resorption or
       remodeling
Enhancement of current titanium
         surfaces
SLA active (implant packaged in saline)
 (Strauman)
    Maintains the wetability of the surface
       Wetable surfaces significantly enhances
      initial adsorption of plasma proteins
      This, in turn facilitates migration, adhesion and
      differentiation of mesenchymal stem cells
Other means of increasing
  wetability of the implant surface
v Incorporate calcium, magnesium or
  fluoride ions into the titanium oxide surface
  v Thisis referred to as “electro-wetting” and
    allows the plasma proteins to flow freely onto
    the implant surface and into the irregularities
    of the micro-roughened surface immediately
    upon insertion of the implant
Enhancement of titanium surfaces
Fluoride treated surfaces (Astra)
  vImproves   the wetability of the surface
  vCbfa expression is high for the grit
    blasted fluoride prepared surface (Isa et
    al, 2006)
     Cbfa is a transcription protein that promotes
     cell differentiation of osteoprogenitor cells)
     Accelerates the events leading to
     deposition of bone on the implant surface
Biological aging and
photofunctionalization
        of TiO2
   UV-treatment
 Tak Ogawa DDS, PhD
 Weintraub LA, UCLA
Biological aging and photofunctionalization
                  of TiO2
v Present day implants are packaged in plastic
v They are then sterilized with gamma radiation
v This process releases hydrocarbons which
   contaminate the implant surface
     Bioreactivity of the implant surface is impaired
       The surface charge is changed from positive to
       negative
       The surface becomes less wetable
       Adsorption of plasma proteins is inhibited
Impact of UV-treatment on
                       biomechanical strength
                                                              *p<0.0001
                      Original   Light-treated                **p<0.05
Push-in value
                                                                   N=9
(N) 50                             50                  *

    40                             40        *

    30                             30


    20                 **          20


                **                 10
    10


     0                              0
            Day 14     Day 28              Day 14    Day 28
           Machined surface               Acid-etched surface
Week 4 peri-implant bone morphogenesis
             Bone contact area
                                                                 *p<0.0001
Light-treated acid-etched surface         Original    Light          N=4

                                    100               *
                                     80      *
                                     60

                                     40

                                     20

                                      0
                                            Day 14   Day 28
                                          Bone–implant contact
Control
             UV-Effects (6 h)
v UV Enhanced protein absorption

vUV Enhanced migration of MSC
	
   	
   to Ti surface

v UV Promotes more rapid 	
	
     	
    differentiation of MSC into
	
    functioning osteoblasts

v UV Enhanced adhesion, spreading
	
    behavior and cytoskeleton
	
    arrangement of osteoblasts
                                           Light treated
Proposed mechanism for improved
  osteoblast affinity on UV treated TiO2

                                                 Cx
                                                 Hy

         UV-pretreated TiO2                     TiO2
                                            R

                                            C
           O                         O          O
  Ti4+          Ti4+
           O                  (h+)          O
                         hv          Ti4+       Ti4+
                                            O
Titanium Oxide is photocatalytic. Following UV exposure
free radicals are formed which absorb the hydrocarbons on
the implant surface.
Benefits of UV Light
v Improved    wetability
v Changes the surface charge from negative
   to positive
v These factors dramatically improve initial
   absorption of plasma proteins during the
   initial stages of healing (10-20 minutes
   immediately following implant placement)


                              Aita et al, 2009; Atta et al, 2009
Benefits of UV Light
       Possible future clinical applications
Treatment of the failing implant
  v Decontaminating   implant surfaces in vivo with UV
    light




                                 Courtesy G Perri
Titanium Implant Surfaces
 1st generation         2nd generation         3rd generation

 Machined surface                            Nano-enhanced
                        Ti blasted surface   surfaces
 Sand-blasted surface
                                             v HA- CaP crystal
 TPS                    Sand-blasted,        	
      deposition
 HA coated surface      acid-etched          vTitanium particle
(plasma spray)          surface
                                             Genetically
                         Dual acid-etched    engineered
                         surface
                                             Recombinant
                         Electrolytically    proteins-BMP
                         enhanced
3rd Generation of Implant Surfaces

  Genetically engineered implant surfaces
  Adding recombinant peptides to the surface
  (BMP’s etc)
  Nano-enhanced surface topography
  Coatings to enhance surface chemistry
    HA-CaP crystal deposition
    Pico to nanometer thin TiO2 coating
Application of TO genes:
       Non-viral Plasmid DNA
          Gene Transfer




                               TO2
Impact of TO2 gene delivery (1 week)




                            P=.0055
Push-in value
   (N)   16
         14                                    DAE
         12                                    Machined
         10
          8
          6
          4
          2
          0
                Untreated             Matrix
                control                TO2
Genetically Engineered Implant Surfaces
Potential advantages of
    gene delivery
   Doesn’t degrade
      Low doses
       Associated with the
     !   normal cell cascade
Disadvantages
	
      Regulatory issues
         Time to market
        Cost/Benefit ratio
Surfaces enhanced with recombinant peptides

Recombinant peptide delivery (BMP-2) has not proven
               to be effecticve. Why?
  Production issues
        During sterilization much of BMP may be deactivated

      They require high doses which may be toxic

  They are not associated with the normal !             cellular
 cascade
      Retention and release difficult to control

      High cost
 	
                                            Schliephake et al, 2005
Nano-enhancement of the implant
           surface
v Increased surface area
v Enhanced wetability and adsorption of
   plasma proteins
v More favorable surface chemistry with HA-
   CaP coatings and TiO2 pico-nanometer
   coatings
Nanotechnology
                                Current	
  Defini6on
           1. Size:	
  1	
  to	
  100	
  nanometer	
  range
           2. Novel	
  proper6es	
  due	
  to	
  its	
  small	
  size
           3. Incorporated	
  into	
  large	
  material	
  components
l   Research and technology development at the atomic, molecular or macromolecular levels,
     in the length scale of approximately 1 - 100 nanometer range, to provide a fundamental
     understanding of phenomena and materials at the nanoscale and to create and use
     structures, devices and systems that have novel properties and functions because of their
     small and/or intermediate size. The novel and differentiating properties and functions are
     developed at a critical length scale of matter typically under 100 nm.
l   Nanotechnology research and development includes manipulation under control of the
     nanoscale structures and their integration into larger material components, systems and
     architectures. Within these larger scale assemblies, the control and construction of their
     structures and components remains at the nanometer scale. In some particular cases, the
     critical length scale for novel properties and phenomena may be under 1 nm (e.g.,
     manipulation of atoms at ~0.1 nm) or be larger than 100 nm (e.g., nanoparticle reinforced
     polymers have the unique feature at ~ 200-300 nm as a function of the local bridges or
     bonds between the nano particles and the polymer).
l   DEFINITION of NANOTECHNOLOGY by NSET, 2002: Subcommittee on Nanoscale
     Science, Engineering and Technology for the U.S. National Science and Technology
     Council under President G.W. Bush
Effect of Nano-Structure: Cell response
    Overwhelming numbers of studies report significant
     effect of nano-structure on cellular behaviors




Human	
  corneal	
  epithelial	
  cells	
  with	
      Fibroblast	
  growth	
  was	
  
70nm	
  groove	
  (A)	
  or	
  flat	
  surface	
  (B)   prohibited	
  on	
  nano-­‐structured	
  
                                                       surface
Effect of Nano-Structure: Cell response
	
 On nanometer particle size ceramics such as alumina,
   titania and hydroxyapatite, osteoblast adhesion
   increased while fibroblast adhesion decreased.

                                                                Osteoblast                       Fibroblast




   Webster	
  et	
  al,	
  Biomaterials,	
  1999   Richert	
  et	
  al,	
  Orthoped	
  Res	
  Soc	
  	
  abstract,	
  2006
Effect of Nano-Structure:
               Controlled protein adsorption
                                                                   v Protein adsorption to
                                                                      nano-structured
                                                                      surfaces requires
                                                                      less energy than to
                                                                      flat surface
                                                                   v Nano-structure
                                                                      orients the direction
                                                                      of adsorbed protein

Sabirianov	
  et	
  al,	
  Enhanced	
  iniJal	
  protein	
  adsorpJon	
  on	
  engineered	
  nanostructured	
  cubic	
  
zirconia	
  
Effect of Nano-Structure:
           Controlled protein adsorption
                                                                 v Protein adsorption
                                                                    increased
                                                                    significantly on
                                                                    ~30nm structured
                                                                    TiOx surface.
                                                                 v Surface nano-
                                                                    structure determines
                                                                    the protein
                                                                    adsorption

ScopelliJ	
  et	
  al,	
  The	
  effect	
  of	
  surface	
  nanometre-­‐scale	
  morphology	
  on	
  protein	
  adsorpJon,	
  
PlosOne,	
  2010	
  
Effect of Nano-Structure:
Long-term stability of osseointegration

                       v   Recent theoretical
                            models indicates
                            increased
                            mechanical
                            interlocking of bone
                            with nano-structured
                            surfaces.



                       Loberg	
  et	
  al,	
  Open	
  Biomater	
  J,	
  2010
                       Hansson	
  et	
  al,	
  Open	
  Biomater	
  J,	
  2010
Conclusion
v   In the advent of Nanotechnology development,
     dental implant surface modifications now employ a
     variety of new processing methods at nano-scales.
v   While micro-structured implants entered in the
     discount, generic manufacturing, nano-structured
     implant surfaces present the new generation of
     dental implants.
v   Advantages of nano-structured implants include
     selective cellular behaviors and controlled protein
     adsorption leading to a “tailored” biological
     regulation.
v   Once osseointegration is established, bone-implant
     mechanical interlocking may be better maintained
     on the nano-structured implant, potentially
     contributing to the long-term stability.
Nano-coating of HA-CaP Crystals
applied to the surface of the implant
Changes Nano-Surface Topography
         and Chemistry
       Before        After
HA-CaP Coatings
Mechanism of Action
  v   During healing Calcium and Phosphate ions are released
       from the HA-CaP coating in the peri-implant region

  v   This leads to the precipitation of a biological apatite with
       various proteins incorporated which serves as a substrate
       for osteoblastic cells producing bone

  v   The biological apatite substrate promotes cell adhesion,
       cell differentiation and the synthesis of mineralized
       collagen

  v   The CaP coatings promote direct bone bonding as
       compared to noncoated surfaces
Shear Strength (MPa) DAE Ti-nanoHA
            Chemical Bonding?
     Machined Ti
     DAE Ti
     DAE Ti-nanoHA
     Shear strength at 2 wk

                              S=F/A [N/mm2]
Synergistic effect of DAE topography and HA –
          CaP nano-crystal deposition
                                                 Nishimura and
                                                 Butz et al, 2004




When nano-HA coating was added to conventional smooth and
DAE implants, bone anchorage was increased over 100%. In fact
DAE Ti-nanoHA implant showed the accelerated bone-implant
integration at the level that has never been reported.
Bone-implant integration
         Machined               DAE+HA-nano-topography


                                                 bone




Weak Link – Cement Line
  Smooth implant was almost naked because surrounding bone
did not stay on implant.

  DAE plus nano-HA was covered by the surrounding bone
indicating that bonding was so strong the push-in force
fractured the bone.
Bone-implant integration
 Machined          DAE+HA-nano-topography



                                  bone




The bond between the bone and
implant surface was greater than
between the new bone and old bone.

        No cement line?
HA – CaP Enhanced Surfaces




              HA-Ca P crystal deposition

Additional advantages for potential future
applications
  v Gene delivery
  v Growth factors, osteogenic protein, antibiotic
  	
      delivery etc.
Titanium Implants - Surface Modifications
Nano-surface modification of titanium surface
    Further enhancement of the surface topography by physical
    vapor deposition (Ogawa et al, 2007; Sugita et al, 2011)
     l   Increased surface area for bone deposition
     l   Surface topography created similar to mineralized bone matrix
     l   Enhanced osteoblast adhesion, proliferation and differentiation
     l   Promotion of osteoblast function
     l   Greater strength of osseointegration
Pico-super-thin surface
              modification of Ti
v   Ogawa and associates have shown that a pico-
     meter thin TiO2 coating improves the
     bioreactivity of microrough implant surfaces by
     modulating its surface chemistry while
     preserving the existing surface morphology




                                         Sugita et al, 2011
Pico-super-thin surface modification of TiO2
  Method
  Slow-rate sputter coating of liquidified nanoscale
  TiO2 particles
  Optimal exposure time – 15 min

                Liquidified TiO2-
   Control Ti      coated Ti




                                              Sugita et al, 2011
No surface thin as 300 pm change before and after
         As topography
          The coating is as thin as 300 pm
Control Ti                    Liquid TiO2 - 15 min




The micro-rough topgraphy is unchanged by the coating
                                              Sugita et al, 2011
Effects of pico-nanometer TiO2 Coating
Impact on osteoblasts
  v Improves cell attachment
  v Enhances spreading behavior
  v Increased proliferation
  v Accelerates differentiation
Enhanced bone cell attachment (6 h)
                            P<0.05



  WST-1/cell


      0.2




      0.1




        0
               Control Ti      Liquid TiO2 coated
                                                            N=3
                                                    Sugita et al, 2011
Expedited and enhanced
      Enhanced Cell spreading and
   cellular settlement and spread
 cytoskeleton arrangement of osteoblasts
            Control Ti                Liquid TiO2 coated
  Overlay                        Overlay min
                                       15




                         50µm                          50µm

Uncoated surface                15 minute TiO2 coated surface

                                                    Sugita et al, 2011
Increased osteoblast
                     proliferation (Day 2)
                             P<0.05



BrdU incorporation
/ cell
      0.3




      0.2


      0.1



      0
                 Untreated      Liquid TiO2 coated
                                                     N=3 Sugita et al, 2011
Rate of Osteoblastic
    Differentiation Enhanced bone cell
                  function (Day 5)
                       P<0.05



ALP activity

       0.15



        0.1



       0.05



          0
               Untreated   Liquid TiO2 coated           N=3
                                                Sugita et al, 2011
Bone-related gene expression (Days 7 and 14)




                                      Sugita et
                                      al, 2011
Mineral deposition (Day 14)




                              Sugita et al, 2011
Control   Liquid TiO2 coated



Mineralized nodule
  area at day 14
     (arizarin red)


  Control     Liquid TiO2 coated




                                              Sugita et al, 2011
Significance:
vFor the first time, pico-super-thin
coating of TiO2 was applied, which
did not to alter the existing micro -
topography of Ti.

vSurface chemistry of TiO2 is an
important factor determining the
bioreactivity of the implant surface.

vThis technology may have opened
a new avenue of surface
enhancement for endosseous
implants.                               Sugita et al, 2011
Clinical Impact of advances in
   implant surface science?
The biologic events leading to
osseointegration have been accelerated
Better bone anchorage
Implants in Compromised Sites
  Can we use shorter implants?
Posterior maxilla
Posterior mandible over the
inferior alveolar nerve in partially
edentulous patients
Craniofacial application Theoretically perhaps.
                            However we need well
                            designed clinical
                            outcome studies to
                            determine predictability
Coming soon

vEdentulous Mandible – Overlay Dentures
vEdentulous Maxilla – Overlay Dentures
v Visit ffofr.org for hundreds of additional lectures
   on Complete Dentures, Implant Dentistry,
   Removable Partial Dentures, Esthetic Dentistry
   and Maxillofacial Prosthetics.
v The lectures are free.
v Our objective is to create the best and most
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Recent Advances in Implant Surface Science

  • 1. 2. Recent Advances in Implant Surface Science Takahiro Ogawa DDS, PhD Ichiro Nishimura DDS, PhD John Beumer III DDS, MS Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA This program of instruction is protected by copyright ©. No portion of this program of instruction may be reproduced, recorded or transferred by any means electronic, digital, photographic, mechanical etc., or by any information storage or retrieval system, without prior permission.
  • 2. Titanium implant surfaces 1st Generation Titanium machined surface Titanium plasma spray surface Sand blasted surfaces Hydroxyl apatite coated titanium surfaces Machined Titanium plasma Sand blasted surface spray surface surface
  • 3. Titanium Surfaces Problems Bone anchorage with machined surfaces was not ideal in bone sites exhibiting thin cortical layers combined with poor quality trabecular bone, such as the posterior maxilla. •Some of the initial titanium plasma spray surfaces were excessively rough and giant cells and macrophages were seen phagocytizing portions of the surface (particle disease). •It was very difficult to remove the contaminants from the original sand blasted surfaces. •The original plasma spray HA-CaP surfaces were not predictable
  • 4. Hydroxyl Apatite - CaP Coatings Coatings of hydroxyl apatite, because of their chemical similarity to bone, were thought to be advantageous. The HA – CaP surface is more osteoinductive than titanium and this leads to more rapid bone deposition following implant placement. However the original so-called HA surfaced implants were mostly composed of tri-calcium phosphate,
  • 5. Mechanism of Action: HA-CaP Coatings v During healing Calcium and Phosphate ions are released from the HA-CaP coating in the peri-implant region v This leads to the precipitation of a biological apatite with various proteins which serves as a substrate for osteoblastic cells producing bone v The biological apatite substrate promotes cell adhesion, cell differentiation and the synthesis of mineralized collagen
  • 6. HA-CaP Coatings HA surfaces were very osteo-conductive. v At six weeks following placement the bone appositional index is close to 70% for HA coated implants compared to 30-50% for original titanium surfaces (machined and TPS) (Weinlander et al, 1993). However: v When the so-called plasma spray HA - Cap surface becomes exposed to the oral cavity it becomes contaminated with oral bacteria
  • 7. HA-CaP Coatings Clinical Problems l Colonization by microorganisms leads to circum-implant infections. l Cracks and fissures in some cases led to the entire loss of the HA coating. l These factors predisposed to a higher rate of implant failure Note the loss of bone than seen with titanium around these HA coated implants 4 implants (Wheeler, 1996). years after insertion.
  • 8. HA-CaP Coatings v These data have led most clinicians to switch to the titanium surfaces. v However, new methods of applying the HA-CaP coatings with nano-sized crystals are evolving which result in direct bonding of bone to the surface of the implant eliminating the cement line. In summary, HA coated systems have provoked great interest and enthusiasm because of there osteo- conductivity. The initial problems associated with plasma spray application are in the process of being overcome and this type of surface may be the surface of the future.
  • 9. Ideal Implant Surface Properties v Promote adsorption of proteins v Promote adhesion and differentiation of bone producing cells v Tissue integration
  • 10. Implant Surface Science v The biological events leading to osseointegration are influenced by: v Surface chemistry v Surface topography of the implant v Hydrophilicity of the surface (wetability) v Research efforts in the last twenty years have attempted to idealize these properties on dental implants in order to: v Decrease healing time v Enable use in compromised bone sites v Improve the quality of the bone implant interface
  • 11. The Jane and Jerry Weintraub Center for Reconstructive Biotechnology UCLA School of Dentistry Ichiro Nishimura DDS, PhD, Director Takahiro Ogawa DDS, PhD Neil Garrett PhD Anna Jewitt PhD Kumar Shah DDS Eleni Roumanas DDS Ting Ling Chang DDS Evelyn Chung DDS James Kelley DDS, MS John Beumer DDS, MS
  • 12. Uncovering the secrets of l Discover insights into the molecular basis of osseointegration l Develop the next generation of implant surfaces l Objectives l Earlierloading l Immediate loading l Predictability in compromised sites *Ichiro Nishimura DDS, PhD and Takahiro Ogawa DDS, PhD
  • 13. Titanium Implants - Surface Modifications 2nd Generation 1st break through The micro-rough surface implants Ti Grit blasted Electrolytically Sand blast- Acid etched enhanced acid etched
  • 14. Titanium Implants – 2nd Generation Surface roughness (Micro-topography) Electrolytically modified Acid etched surfaces Combination acid etched and sand blasted surfaces 1 micron
  • 15. Titanium Implants - Surface Modifications 2nd Generation 1st break through The micro-rough surface implants How are the new surfaces different from the old surfaces? Why do we get better bone anchorage with these new surfaces? Are these surfaces more bioreactive? Do they accelerate the process of osseointegration? If so, what has been the impact on implant biomechanics, early and immediate loading and treatment planning?
  • 16. Current Implant Surfaces Micro-rough surface textures – Why are they a significant improvement? Initial stabilization is improved Maximize the volume of interlocking mineralized bone with the implant surface Double acid Machined Torque Removal etched surface v Reverse torque test v Data recorded in N/cm v Double acid etched vs Machined v 2 month data (1997) v 1, 2, 3 months (2001) Klokkevold et al, 1997, 2001
  • 17. Initial anchorage -Torque removal studies v 10 New Zealand White Rabbits v 2 Custom-designed implants (distal femur) v Machined v Double acid etched (Osseotite) Klokkevold et al, 1997, 2001)
  • 18. Initial anchorage -Torque removal studies Reverse torque rotation to removal (failure) Klokkevold et al,1997; 2001)
  • 19. Initial anchorage -Torque removal studies Results – 2 months data Machined = 4.95 ± 1.61 Ncm Double acid etched = 20.50 ± 6.59 Ncm Klokkevold et al, 1997
  • 20. Initial anchorage -Torque removal studies Why the difference? vBetter mechanical anchorage? vBone contact area? vQuality of the bone at the interface? Klokkevold et al, 1997
  • 21. Titanium Implants - Surface Modification Surface roughness and the bone contact area Animal studies have shown that the bone contact area achieved is 50% greater with micro -rough surfaces as compared to machined surfaces (Buser et al, 1991, Weinlander, 1993, Hamada, 1995, Nishimura and Ogawa, 2000, 2003).
  • 22. 50 µm Histomorphometry Acid etched vs Machine surface Near zone Far zone Machined Acid etched (%) 80 * 60 40 * 20 (Ogawa and 0 W2 W4 Nishimura, 2000, Bone-implant 2003), contact ratio
  • 23. Bone contact area Microrough surfaces (Weinlander et al, 2004) Electrolytically Titanium Double acid Sandblast acid Modified plasma spray etched etched
  • 24. Implant anchorage data Shear Strength obtained with a push out test Studies Acid etched Machined surface surface Experimental Rat implant
  • 25. Implant anchorage data obtained with a push out test This test measures the strength of implant tissue interface rather than Push-in value (N) the strength of the surrounding bone. 60 Machined * Etched 40 * 20 * 0 0 2 4 8 *p<0.05 Healing period (week)
  • 26. Current Implant Surfaces Micro-rough surfaces and osseointegration What biologic phenomenon are affected by the changes in surface micro topography?
  • 27. Current Implant Surfaces Why are these surfaces more bioreactive? vRate of plasma protein absorption vFibrin clot retention vCell Adhesion vCell differentiation vGene expression
  • 28. Rate of plasma protein absorption v Rate of plasma protein absorption v Enhanced by hydrophilic surfaces v Enhanced by micro-rough surfaces v Reduced as the surface ages v Promotes cell adhesion v Promotes cell differentiation
  • 29. Fibrin Clot Retention Micro-rough surfaces vDavies (1998) showed that micro-rough surfaces captured and retained the fibrin clot initially deposited on the implant surface more effectively than machined surfaces v As a result the initial crticial events (plasma protein adsorption, clot formation, angiogenesis, mesenchymal stem cell migration etc.) associated with osseointegration were facilitated.
  • 30. Differentiation of mesenchymal stem cells (MSC) into functioning osteoblasts Functioning osteoblast vStem cells migrate to the implant surface and into the osteotomy site via the fibrin network vThe micro-rough facilitates this process
  • 31. Micro – rough Implant Surfaces Ogawa and Nishimura set out to determine whether or not the double acid etched surface result in: Earlier osseointegration? Better bone anchorage? Determine what factors are responsible for the different bone profiles seen on different surface textures of titanium implants. They were particularly interested in the gene expression of the differentiating osteoblasts Osseotite- Double Acid Etched
  • 32. Gene expression data obtained with a T-cell model developed by Davies T-cell implant Machined Acid-etched v They implanted T-cell implants into the femurs of rats and retrieved the specimens at various time intervals. vThey hypothesized that gene expression is controlled at local levels by the surface texture of the implant.
  • 33. Why was the double acid etched surface superior to the machined surface? Why was the bone different? Nishimura and Ogawa suggested several reasons including: Bone repair and generation may not be the primary prerequisite for osseointegration Might it be an implant dependent mechanism? Hypothesis: A set of genes that are NOT involved in bone repair initiate and/or regulate the process of osseointegration Ogawa and Nishimura, 2000, 2002, and 2003
  • 34. Purpose of the study Identify the genes that are expressed around implants but not in non-implant wound healing of bone. Non-implant defect Turned implant Etched implant Screening of candidate osseointegration-specific genes Differential display polymerase chain reaction (DD-PCR)
  • 35. Testing the candidate DD-PCR products From 1853 DD-PCR products, 19 implant-specific (- + +) 2 acid-etched-specific (- - +) 42 different clones 3 Osseointegration-specific genes (TO1, TO2, TO3)
  • 36. mRNA expression of TO1 Day 3 Week 1 Week 2 Week 4 Non-implant defect Turned implant Etched implant Untreated control TO1 GAPDH 0.2 Etched implant Turned implant 0.1 Non-implant defect Day 3 Week 1 Week 2 Week 4
  • 37. mRNA expression of TO2 Day 3 Week 1 Week 2 Week 4 Non-implant defect Turned implant Etched implant Untreated control TO2 GAPDH 0.6 0.4 Turned implant Etched implant 0.2 Non-implant defect Day 3 Week 1 Week 2 Week 4
  • 38. mRNA expression of TO3 Day 3 Week 1 Week 2 Week 4 Non-implant defect Turned implant Etched implant Untreated control TO3 GAPDH 1.2 Etched implant 0.8 Turned implant 0.4 Non-implant defect Day 3 Week 1 Week 2 Week 4
  • 39. TO genes showed Osseointegration-specific expression Upregulation in early stages of implantation Accelerated expression for the double acid etched surface
  • 40. TO3 happens to be P4H Enhanced gene expression of prolyl 4-hydroxylase (P4H) Collagen synthesis considerably higher
  • 42. Why was the accelerated expression of P4H on micro- rough surfaces significant? Collagen density and orientation, as well as the degree of mineralization are contributing factors relative to the microhardness and elastic modulus of bone
  • 43. Bone Implant Interface Double Acid Etched Surfaces A different combination of collagenous and noncollagenous proteins make up the bone deposited on the dual acid etched surface as compared to a machined surface. Resorption and remodeling of bone deposited on acid etched surfaces appeared to be different than bone on machined surfaces.
  • 44. Nano Indentation Test 3 times stiffer bone on dual acid etched 2000nm indentation depth P=0.0252 Elastic modulus P=0.0339 (GPa) 0.2 0.1 0 Bone on Bone on Bone on Polystyrene Machined Ti DAE
  • 45. Nano indentation test 2 times harder bone on dual acid etched 200mN maximum load P=.0005 P=0.0153 P=0.0130 Nanohardness (GPa)0.8 0.6 0.4 0.2 0 Bone on Bone on Bone on Polystyrene Machined Ti DAE
  • 46. Nanoindentation: in vivo bone Bone around machined surfaces is as hard as the trabecular bone, while the bone around the DAE surfaces is as hard as the cortical bone. Ogawa et al, 2005
  • 47. Day 28 Day 14 7 Day 21 0 3 Distinct pattern of osteogenesis on DAE Osteoblast Non-collagenous matrix Mineral deposition Collagen matrix
  • 48. Current Implant Surfaces Micro-rough surface textures – Why are they a significant improvement Shape of the cell affects its gene expression and the micro-environment affects cell behavior. Improved adsorption of plasma proteins
  • 49. Micro-rough surfaces – Why are they superior? vImproved clot retention (Davies, 1998) vInitial absorption of plasma proteins is enhanced (fibronectin, vitronectin etc) (Kohavi (2010) vMSC differentiate much faster on micro- rough surfaces as compared to smooth surfaces (Ogawa et al, 2003) vMicro-rough surfaces changes gene expression of the differentiating osteoblasts (Ogawa and Nishimura (2000,2003 and 2004, 2006) vBone deposited on micro-rough surfaces is harder and stiffer than bone deposited on machined surfaces (Butz,2006; Takeuchi et al, 2005)
  • 50. Impact of Strengthened Peri-implant Bone Trabecular bone Cortical bone Cortical bone: l Very dense l Less subject to resorption or remodeling
  • 51. Enhancement of current titanium surfaces SLA active (implant packaged in saline) (Strauman) Maintains the wetability of the surface Wetable surfaces significantly enhances initial adsorption of plasma proteins This, in turn facilitates migration, adhesion and differentiation of mesenchymal stem cells
  • 52. Other means of increasing wetability of the implant surface v Incorporate calcium, magnesium or fluoride ions into the titanium oxide surface v Thisis referred to as “electro-wetting” and allows the plasma proteins to flow freely onto the implant surface and into the irregularities of the micro-roughened surface immediately upon insertion of the implant
  • 53. Enhancement of titanium surfaces Fluoride treated surfaces (Astra) vImproves the wetability of the surface vCbfa expression is high for the grit blasted fluoride prepared surface (Isa et al, 2006) Cbfa is a transcription protein that promotes cell differentiation of osteoprogenitor cells) Accelerates the events leading to deposition of bone on the implant surface
  • 54. Biological aging and photofunctionalization of TiO2 UV-treatment Tak Ogawa DDS, PhD Weintraub LA, UCLA
  • 55. Biological aging and photofunctionalization of TiO2 v Present day implants are packaged in plastic v They are then sterilized with gamma radiation v This process releases hydrocarbons which contaminate the implant surface Bioreactivity of the implant surface is impaired The surface charge is changed from positive to negative The surface becomes less wetable Adsorption of plasma proteins is inhibited
  • 56. Impact of UV-treatment on biomechanical strength *p<0.0001 Original Light-treated **p<0.05 Push-in value N=9 (N) 50 50 * 40 40 * 30 30 20 ** 20 ** 10 10 0 0 Day 14 Day 28 Day 14 Day 28 Machined surface Acid-etched surface
  • 57. Week 4 peri-implant bone morphogenesis Bone contact area *p<0.0001 Light-treated acid-etched surface Original Light N=4 100 * 80 * 60 40 20 0 Day 14 Day 28 Bone–implant contact
  • 58. Control UV-Effects (6 h) v UV Enhanced protein absorption vUV Enhanced migration of MSC to Ti surface v UV Promotes more rapid differentiation of MSC into functioning osteoblasts v UV Enhanced adhesion, spreading behavior and cytoskeleton arrangement of osteoblasts Light treated
  • 59. Proposed mechanism for improved osteoblast affinity on UV treated TiO2 Cx Hy UV-pretreated TiO2 TiO2 R C O O O Ti4+ Ti4+ O (h+) O hv Ti4+ Ti4+ O Titanium Oxide is photocatalytic. Following UV exposure free radicals are formed which absorb the hydrocarbons on the implant surface.
  • 60. Benefits of UV Light v Improved wetability v Changes the surface charge from negative to positive v These factors dramatically improve initial absorption of plasma proteins during the initial stages of healing (10-20 minutes immediately following implant placement) Aita et al, 2009; Atta et al, 2009
  • 61. Benefits of UV Light Possible future clinical applications Treatment of the failing implant v Decontaminating implant surfaces in vivo with UV light Courtesy G Perri
  • 62. Titanium Implant Surfaces 1st generation 2nd generation 3rd generation Machined surface Nano-enhanced Ti blasted surface surfaces Sand-blasted surface v HA- CaP crystal TPS Sand-blasted, deposition HA coated surface acid-etched vTitanium particle (plasma spray) surface Genetically Dual acid-etched engineered surface Recombinant Electrolytically proteins-BMP enhanced
  • 63. 3rd Generation of Implant Surfaces Genetically engineered implant surfaces Adding recombinant peptides to the surface (BMP’s etc) Nano-enhanced surface topography Coatings to enhance surface chemistry HA-CaP crystal deposition Pico to nanometer thin TiO2 coating
  • 64. Application of TO genes: Non-viral Plasmid DNA Gene Transfer TO2
  • 65. Impact of TO2 gene delivery (1 week) P=.0055 Push-in value (N) 16 14 DAE 12 Machined 10 8 6 4 2 0 Untreated Matrix control TO2
  • 66. Genetically Engineered Implant Surfaces Potential advantages of gene delivery Doesn’t degrade Low doses Associated with the ! normal cell cascade Disadvantages Regulatory issues Time to market Cost/Benefit ratio
  • 67. Surfaces enhanced with recombinant peptides Recombinant peptide delivery (BMP-2) has not proven to be effecticve. Why? Production issues During sterilization much of BMP may be deactivated They require high doses which may be toxic They are not associated with the normal ! cellular cascade Retention and release difficult to control High cost Schliephake et al, 2005
  • 68. Nano-enhancement of the implant surface v Increased surface area v Enhanced wetability and adsorption of plasma proteins v More favorable surface chemistry with HA- CaP coatings and TiO2 pico-nanometer coatings
  • 69. Nanotechnology Current  Defini6on 1. Size:  1  to  100  nanometer  range 2. Novel  proper6es  due  to  its  small  size 3. Incorporated  into  large  material  components l Research and technology development at the atomic, molecular or macromolecular levels, in the length scale of approximately 1 - 100 nanometer range, to provide a fundamental understanding of phenomena and materials at the nanoscale and to create and use structures, devices and systems that have novel properties and functions because of their small and/or intermediate size. The novel and differentiating properties and functions are developed at a critical length scale of matter typically under 100 nm. l Nanotechnology research and development includes manipulation under control of the nanoscale structures and their integration into larger material components, systems and architectures. Within these larger scale assemblies, the control and construction of their structures and components remains at the nanometer scale. In some particular cases, the critical length scale for novel properties and phenomena may be under 1 nm (e.g., manipulation of atoms at ~0.1 nm) or be larger than 100 nm (e.g., nanoparticle reinforced polymers have the unique feature at ~ 200-300 nm as a function of the local bridges or bonds between the nano particles and the polymer). l DEFINITION of NANOTECHNOLOGY by NSET, 2002: Subcommittee on Nanoscale Science, Engineering and Technology for the U.S. National Science and Technology Council under President G.W. Bush
  • 70. Effect of Nano-Structure: Cell response Overwhelming numbers of studies report significant effect of nano-structure on cellular behaviors Human  corneal  epithelial  cells  with   Fibroblast  growth  was   70nm  groove  (A)  or  flat  surface  (B) prohibited  on  nano-­‐structured   surface
  • 71. Effect of Nano-Structure: Cell response On nanometer particle size ceramics such as alumina, titania and hydroxyapatite, osteoblast adhesion increased while fibroblast adhesion decreased. Osteoblast Fibroblast Webster  et  al,  Biomaterials,  1999 Richert  et  al,  Orthoped  Res  Soc    abstract,  2006
  • 72. Effect of Nano-Structure: Controlled protein adsorption v Protein adsorption to nano-structured surfaces requires less energy than to flat surface v Nano-structure orients the direction of adsorbed protein Sabirianov  et  al,  Enhanced  iniJal  protein  adsorpJon  on  engineered  nanostructured  cubic   zirconia  
  • 73. Effect of Nano-Structure: Controlled protein adsorption v Protein adsorption increased significantly on ~30nm structured TiOx surface. v Surface nano- structure determines the protein adsorption ScopelliJ  et  al,  The  effect  of  surface  nanometre-­‐scale  morphology  on  protein  adsorpJon,   PlosOne,  2010  
  • 74. Effect of Nano-Structure: Long-term stability of osseointegration v Recent theoretical models indicates increased mechanical interlocking of bone with nano-structured surfaces. Loberg  et  al,  Open  Biomater  J,  2010 Hansson  et  al,  Open  Biomater  J,  2010
  • 75. Conclusion v In the advent of Nanotechnology development, dental implant surface modifications now employ a variety of new processing methods at nano-scales. v While micro-structured implants entered in the discount, generic manufacturing, nano-structured implant surfaces present the new generation of dental implants. v Advantages of nano-structured implants include selective cellular behaviors and controlled protein adsorption leading to a “tailored” biological regulation. v Once osseointegration is established, bone-implant mechanical interlocking may be better maintained on the nano-structured implant, potentially contributing to the long-term stability.
  • 76. Nano-coating of HA-CaP Crystals applied to the surface of the implant
  • 77. Changes Nano-Surface Topography and Chemistry Before After
  • 78. HA-CaP Coatings Mechanism of Action v During healing Calcium and Phosphate ions are released from the HA-CaP coating in the peri-implant region v This leads to the precipitation of a biological apatite with various proteins incorporated which serves as a substrate for osteoblastic cells producing bone v The biological apatite substrate promotes cell adhesion, cell differentiation and the synthesis of mineralized collagen v The CaP coatings promote direct bone bonding as compared to noncoated surfaces
  • 79. Shear Strength (MPa) DAE Ti-nanoHA Chemical Bonding? Machined Ti DAE Ti DAE Ti-nanoHA Shear strength at 2 wk S=F/A [N/mm2]
  • 80. Synergistic effect of DAE topography and HA – CaP nano-crystal deposition Nishimura and Butz et al, 2004 When nano-HA coating was added to conventional smooth and DAE implants, bone anchorage was increased over 100%. In fact DAE Ti-nanoHA implant showed the accelerated bone-implant integration at the level that has never been reported.
  • 81. Bone-implant integration Machined DAE+HA-nano-topography bone Weak Link – Cement Line Smooth implant was almost naked because surrounding bone did not stay on implant. DAE plus nano-HA was covered by the surrounding bone indicating that bonding was so strong the push-in force fractured the bone.
  • 82. Bone-implant integration Machined DAE+HA-nano-topography bone The bond between the bone and implant surface was greater than between the new bone and old bone. No cement line?
  • 83. HA – CaP Enhanced Surfaces HA-Ca P crystal deposition Additional advantages for potential future applications v Gene delivery v Growth factors, osteogenic protein, antibiotic delivery etc.
  • 84. Titanium Implants - Surface Modifications Nano-surface modification of titanium surface Further enhancement of the surface topography by physical vapor deposition (Ogawa et al, 2007; Sugita et al, 2011) l Increased surface area for bone deposition l Surface topography created similar to mineralized bone matrix l Enhanced osteoblast adhesion, proliferation and differentiation l Promotion of osteoblast function l Greater strength of osseointegration
  • 85. Pico-super-thin surface modification of Ti v Ogawa and associates have shown that a pico- meter thin TiO2 coating improves the bioreactivity of microrough implant surfaces by modulating its surface chemistry while preserving the existing surface morphology Sugita et al, 2011
  • 86. Pico-super-thin surface modification of TiO2 Method Slow-rate sputter coating of liquidified nanoscale TiO2 particles Optimal exposure time – 15 min Liquidified TiO2- Control Ti coated Ti Sugita et al, 2011
  • 87. No surface thin as 300 pm change before and after As topography The coating is as thin as 300 pm Control Ti Liquid TiO2 - 15 min The micro-rough topgraphy is unchanged by the coating Sugita et al, 2011
  • 88. Effects of pico-nanometer TiO2 Coating Impact on osteoblasts v Improves cell attachment v Enhances spreading behavior v Increased proliferation v Accelerates differentiation
  • 89. Enhanced bone cell attachment (6 h) P<0.05 WST-1/cell 0.2 0.1 0 Control Ti Liquid TiO2 coated N=3 Sugita et al, 2011
  • 90. Expedited and enhanced Enhanced Cell spreading and cellular settlement and spread cytoskeleton arrangement of osteoblasts Control Ti Liquid TiO2 coated Overlay Overlay min 15 50µm 50µm Uncoated surface 15 minute TiO2 coated surface Sugita et al, 2011
  • 91. Increased osteoblast proliferation (Day 2) P<0.05 BrdU incorporation / cell 0.3 0.2 0.1 0 Untreated Liquid TiO2 coated N=3 Sugita et al, 2011
  • 92. Rate of Osteoblastic Differentiation Enhanced bone cell function (Day 5) P<0.05 ALP activity 0.15 0.1 0.05 0 Untreated Liquid TiO2 coated N=3 Sugita et al, 2011
  • 93. Bone-related gene expression (Days 7 and 14) Sugita et al, 2011
  • 94. Mineral deposition (Day 14) Sugita et al, 2011
  • 95. Control Liquid TiO2 coated Mineralized nodule area at day 14 (arizarin red) Control Liquid TiO2 coated Sugita et al, 2011
  • 96. Significance: vFor the first time, pico-super-thin coating of TiO2 was applied, which did not to alter the existing micro - topography of Ti. vSurface chemistry of TiO2 is an important factor determining the bioreactivity of the implant surface. vThis technology may have opened a new avenue of surface enhancement for endosseous implants. Sugita et al, 2011
  • 97. Clinical Impact of advances in implant surface science? The biologic events leading to osseointegration have been accelerated Better bone anchorage
  • 98. Implants in Compromised Sites Can we use shorter implants? Posterior maxilla Posterior mandible over the inferior alveolar nerve in partially edentulous patients Craniofacial application Theoretically perhaps. However we need well designed clinical outcome studies to determine predictability
  • 99. Coming soon vEdentulous Mandible – Overlay Dentures vEdentulous Maxilla – Overlay Dentures
  • 100. v Visit ffofr.org for hundreds of additional lectures on Complete Dentures, Implant Dentistry, Removable Partial Dentures, Esthetic Dentistry and Maxillofacial Prosthetics. v The lectures are free. v Our objective is to create the best and most comprehensive online programs of instruction in Prosthodontics