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INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
www.indiandentalacademy.com
Contents…
Introduction
History
Requirements of implant materials
Classification
Metals and alloys
Ceramics & carbon
Polyme...
Contents…
Surface cleanliness
Sterilization
Selection of implant material
Biocompatibility
conclusion
www.indiandentalacad...
Introduction
www.indiandentalacademy.com
www.indiandentalacademy.com
History….
Chinese (4000 years
ago )
Carved bamboo sticks in
the shape of pegs and
drove them into bone for
fixed tooth rep...
History….
Egyptians (2000 years ago)
Used precious metals with a similar peg
design
Europe
A skull was found with a ferrou...
History….
Central america
(Incas Dynasty)
Took pieces of sea
shells and tapped
them into bone to
replace missing
teeth
www...
History…
Albucasis de Condue
(936 to 1013)
 Used ox bone to replace
missing teeth
 First documented
placement of implant...
Recent history
Maggiolo(1809)
Fabricated gold roots which were fixed to pivot
teeth by means of a spring
Harris(1887)
Impl...
Recent history
Payne(1898)
Used a silver capsule as an implant
Scholl(1905)
Demonstrated a porcelain corrugated
root impla...
www.indiandentalacademy.com
Implant
material
requirements
Physical and
mechanical
Corrosion and
biodegradation biological
www.indiandentalacademy.com
Mechanical requirements
Strength
 Strength of the implant material should be
tested under tension , compression and shear...
Mechanical requirements
Fatigue strength
 Upper stress limit decreases with an
increase in number of loading cycles
 In ...
Mechanical requirements
Maximum yield strength
 It represents the stress at which permanent
deformation of the material b...
Mechanical requirements
Creep deformability
 Creep is defined as the time dependent plastic
deformation of the material u...
Mechanical requirements
Modulous of Elasticity
 Implant materials and designs should account
for the modification of shap...
Mechanical requirements
Ductility
 American Society For Testing And Material
(ASTM) , ISO , and ADA :- Require a
minimum ...
ductility
 Mixed microstructural phase
hardening of austenitic
materials with nitrogen and
increasing purity of alloys
he...
Biodegradation
Williams suggested 3 type of corrosion
were most relevent to dental implant
materials
Galvanic
corrosion
St...
Galvanic corrosion
Occurs when two dissimilar metallic materials are
in contact within an electrolyte resulting in current...
Stress corrosion cracking
Corrosion fatigue
Mechanical
stress
Corrosive
environme
nt
Failure
by
cracking
www.indiandentala...
Fretting corrosion
Occurs when there is micromotion and
rubbing contact within a corrosive
environment
Along implant body ...
Biologic considerations
Toxicity
Refers to primary degradation products of
a material
www.indiandentalacademy.com
Toxicity
3 factors which decide toxicity of a
material
Amont dissolved by degradation per time unit
• TE (g/day) = TEA(%) ...
Toxicity
TE( g/day) = TEA (%) x CBR (g/cm2/day)
x
IS(cm2) / 100
 TE toxic element
 TEA toxic elements in alloy
 CBR cor...
Classification
Implant
materials
metallic ceramic polymeric
Polymeric
composite
Titanium
Titanium
alloys
Co Cr alloys
...
Metallic implant materials
Titanium
Gold standard in implant materials
Atomic number 22
Atomic weight 47.9
0.6% of earth’s...
Titanium
Extraction from ore forms
Kroll process
Reduction of TiCl4 by magnesium
Iodide process
 Involves formation of ti...
Properties
Oxidizes or passivates upon contact with room temp air or
normal tissue fluids
Tensile strength
Wrought soft(ro...
Properties
Modulous of elasticity
 5 times greater than that of compact
bone
 Hence enables uniform stress
distribution ...
Advantages
Biologically inert and biocompatible
Excellent resistance to corrosion
Low specific gravity
High heat resistanc...
Advantages
Lowenberg et al (1987)
Titanium & zirconium alloy discs are
biocompatible with gingival fibroblasts
J Dent Rest...
Biocompatibility of Ti
Titanium oxide surface
Brookite oxide layer
• Amorphous in atomic structure
• Formed in normal temp...
Tissue interactions with Ti Oxide
Highest oxide growth area : bone marrow
site
Lowest oxide growth area : cortical regions...
Tissue interactions with Ti
Oxide
Ti Gel conditions
Hydrogen peroxide environment has been shown
to interact with Ti and f...
Tissue interactions with Ti
Oxide
Local and systemic release of ions has been
reported with Ti & Ti alloy implants
 Ion r...
Advantages of TiO2
 Minimizes biocorrosion in absence of
interfacial motion or adverse environmental
conditions
 In vivo...
Advantages of TiO2
Hoar TP , Meals DC (1966)
Breakdown of this oxide layer is unlikely
in altered solutions such as chlori...
limitations
High cost
www.indiandentalacademy.com
limitations
Difficult & dangerous casting
 A high vacuum or ultrapure gas atmosphere is
needed
 Metal has a high melting...
Titanium alloys
3 forms of alloys used in dentistry
 Alpha
 Beta
 Alpha-beta
Most commonly used for dental implants
: a...
Advantages
Strength  wrought alloy condition is about
6 times stronger than compact bone
 Can be fabricated in thinner s...
limitations
Ductility considerably less than Ti
Adverse effects of Al & V biodegradation
on local & systemic tissues
Diff...
Co – Cr – Mo based alloys
Most often used as
 As cast
 Cast & annealed metallurgic condition
High strength permits custo...
Co – Cr – Mo based alloys
Composition
Co
Cr
Mo
Ni
C
Continuous phase for
basic properties
Corrosion resistance
Strength & ...
advantages
high strength  4 times that of
compact bone
Excellent biocompatibility profile
www.indiandentalacademy.com
disadvantages
Less ductile  bending of finished
implants shhould be avoided
www.indiandentalacademy.com
Fe – Cr – Ni based alloys
Surgical stainless steel alloys e.g. 316
low C
Used for orthopedic and dental implant
devices
Us...
Advantages
High strength
High ductility
Cost effective
www.indiandentalacademy.com
Disadvantages
Most subject to crevice and biocorrosion
Ni allergy
Galvanic coupling and biocorrosion with
Ti , Co , Zr and...
Noble metals
Most commonly used noble metals
 Tantalum
 Platinum
 Irridium
 Gold
 Palladium
 Alloys of these metals
...
Advantages
Inert electrochemically
Easily available esp. gold
Do not depend on surface oxides
www.indiandentalacademy.com
Disadvantages
Low strength
Cost per unit weight is high
Weight per unit volume (density) is less
www.indiandentalacademy.c...
Ceramics & carbon
Ceramics are inorganic , non metallic ,
non polymeric materials manufactured
by compacting and sintering...
Bioinert ceramics
Ceramics from Al , Ti , & Zr oxides
Used as
 root form
 endosteal plate form
 pin type dental implant...
properties
www.indiandentalacademy.com
Indications
Anterior root form devices
www.indiandentalacademy.com
Contraindications
Subperiosteal devices as they have low
fracture resistance and high relative cost
of manufacturing
www.i...
Advantages
Minimal thermal and electrical conductivity
Minimal biodegradation
Minimal reactions with bone , soft tissue an...
Disadvantages
Exposure to steam sterlization------>
measurable decrease in strength
Scratches or notches may introduce
fra...
Bioactive & biodegradable
ceramics
Consist of solid or porous particles with
compositions relatively similar to the
minera...
Indications
Ridge retainers : rods and cones for filling tooth
extraction sites
Structural support under high magnitude lo...
Physical properties
Factors affecting :
 Surface area or form of the product
 Porosity
 crystallinity
www.indiandentala...
Chemical properties
Factors affecting
 Ca – P ratio
 Composition
 Elemental impurities such as carbonate
 Ionic substi...
Chemical properties
General formula
M1O
2+ (XO4
3- ) 6 Z2
-1
standard apatite products
 Crystalline monolythic hydroxyapa...
Advantages
Chemistry mimics normal biologic tissue
Excellent biocompatibility
Attachment between CPC and hard and
soft tis...
Disadvantages
Variable chemical and structural
charecteristics
Low mechanical tensile & shear strengths
under fatigue load...
Disadvantages
S.C. Guy , M. J. Quade , M. J Schiedt (1993)
Porous hydroxyapatite has demonstrated the
least fibroblast att...
Carbon compounds
Similar to ceramics
 Chemical inertness
 Absence of ductility
Differenence from ceramics
 Electrical &...
Polymers
Common polymeric materials
 PTFE
 PET
 PMMA
 UHMW-PE
 PP
 PSF
 PDS
 SR
 Can be combined with
 Particula...
limitations
Low strength
Low MOE compared to bone
Higher elongation to fractures
High cold flow charecteristics , creep an...
Indications
Tissue attachment , replacement &
augmentation
Coatings for force transfer to soft tissue
and hard tissue regi...
Surface charecteristics
Surface
coatings
Passivation
Surface
texturing
Ion
implantation
www.indiandentalacademy.com
Surface coatings
Titanium coating
Hydroxyapatite coating
www.indiandentalacademy.com
Titanium coating
Introduced by Hahn & Palich
Reported bone in growth in Ti hybrid
powder plasma sprayed implants
inserted ...
Procedure
Porous or rough Ti surfaces have been
fabricated by plasma spraying a powder form
of molten droplets at high tem...
Microscopic structure
Round or irregular pores that can be
connected to each other
www.indiandentalacademy.com
Advantages
Increases the total surface area upto several
times
Produce attachment by osteoformation
Enhances attachment by...
Disadvantages
Cracking & scaling because of stresses
produced by processing at elevated temp.
Risk of accumulation of abra...
Hydroxyapatite coating
Introduced to dental profession by de
Groot
Procedure
Majority of commercially available HA
coated ...
procedure
A powdered crystalline HA is introduced
and melted by the hot , high velocity
region of a plasma gun and propell...
Limitation of plasma spraying
It can alter the nature of crystalline ceramic
powder and can result in the deposition of
a ...
Advantages
Better organization & mineralization of
adjacent bone
Better biomechanics & initial load
bearing capacity
Impro...
Disadvantages
Partial resorption of CPC may occur due
to remodelling of the osseous interphase
Resorption of coating in in...
Recent advances in HA coatings
Fluorapatite
Heat treated hydroxyapatite coatings ( HA-HT)
Harry et al (1996)
Remaining c...
Passivation
Refers to enhancement of oxide layer to
 Prevent release of metallic ions
 Enhance biocompatibility
2 proced...
Surface texturing
Enhances surface area by upto 6 times
Methods
 Plasma spraying with Ti
 Acid etching
 Particulate Bla...
Acid etching
Ti implants can be etched with
 Nitric acid
 HF acid
Chemically alters the surface
Eliminates some type of ...
Particulate blasting
Can be done with various media such as
 Silica
 Alumina
 Glass beads
Provides irregular rough sur...
Ion implantation
Done by bombarding the surface of
implant with high energy ions upto a
surface depth of 0.1 micron
Increa...
Selection of implant material
Strength of implant material
Quality of bone
Bone height
 8 mm bone  Ti implant failure ra...
Selection of implant material
Fresh extraction sites better initial
stability of HA
Newly grafted sites HA preferred
 G...
Surface cleanliness &
sterlization
Alberkston et al (1985)
Implants that seem functional may fail
even after years of func...
Cases of surface contamination
Lausmaa et al showed large variations in C
contamination loads of Ti implants (20% to
60%) ...
Sterlization
Conventional
steam
sterlization
Radio frequency
glow discharge
technique
(RFGDT)
U.V Light
sterlization
Gamma...
Radio frequency glow
discharge technique
Sterlization under a controlled noble gas
discharge at very low pressure
Gas ions...
Advantages
Baier et al
Provides a clean surface as well as a high
surface energy state
Thinner , more stable oxide films
I...
U. V light sterlization
Effective on spores
Enhances bioreactivity
Cleans the surface safely & rapidly
Grants high surface...
Gamma radiation sterlization
Most metallic systems exposed to radiation
doses exceeding 2.5 mega – rads
Advantages
Packagi...
Disadvantages
Some ceramics can get discoloured
Polymers may be degraded by gamma
radiation exposures
www.indiandentalacad...
Hartman et al (1989)
RFGDT & UV sterlizedimplants show rapid bone
ingrowth and maturation while steam sterlized
implants s...
Biocompatibility
Boca , Raton , Fla (1981)
An appropriate response to a material
(biomaterial) within a device (design) fo...
History
1960
Emphasis on inert & chemically stable
materials
Classic e.g
 High purity ceramics of aluminium oxide
 Carbo...
History
1970s
Biocompatibility of implants was defined
in terms of minimal harm to the host or
to the biomaterial
Stable i...
History
1980s
Focus transferred to bioactive
substrates
Substances which tended to positively
influence tissue response 
...
History
1990s
Emphasis is on chemically & mechanically
anisotropic substances
Growth (mitogenic) & inductive (
morphogenic...
Analysing biocompatibility
Individual constituents :
 Implant materials
 Tissues
Effect on local & systemic tissues
Inte...
ADA criteria
Evaluation of physical properties that ensure sufficient strength
Demonstration of ease of fabrication & ster...
Biocompatibility concerns
Titanium
 Normal Ti levels in humans 50ppm
 May reach upto 300 ppm in tissues surrounding Ti
...
Biocompatibility concerns
Co-Cr alloys & stainless steel
 Potential electrolytic action  galvanic
corrosion
 Release of...
www.indiandentalacademy.com
References
Contemperory implant dentistry : Carl E Misch 3rd
edition
Philips science of dental materials 11 edition
Craig ...
Thank you
For more details please visit
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Implant biomaterials seminar/ dentistry curriculum

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Implant biomaterials seminar/ dentistry curriculum

  1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Contents… Introduction History Requirements of implant materials Classification Metals and alloys Ceramics & carbon Polymers & composites Surfaces charecteristics www.indiandentalacademy.com
  3. 3. Contents… Surface cleanliness Sterilization Selection of implant material Biocompatibility conclusion www.indiandentalacademy.com
  4. 4. Introduction www.indiandentalacademy.com
  5. 5. www.indiandentalacademy.com
  6. 6. History…. Chinese (4000 years ago ) Carved bamboo sticks in the shape of pegs and drove them into bone for fixed tooth replacement www.indiandentalacademy.com
  7. 7. History…. Egyptians (2000 years ago) Used precious metals with a similar peg design Europe A skull was found with a ferrous metal peg shaped tooth inserted into it which dated back to the time of Christ www.indiandentalacademy.com
  8. 8. History…. Central america (Incas Dynasty) Took pieces of sea shells and tapped them into bone to replace missing teeth www.indiandentalacademy.com
  9. 9. History… Albucasis de Condue (936 to 1013)  Used ox bone to replace missing teeth  First documented placement of implants www.indiandentalacademy.com
  10. 10. Recent history Maggiolo(1809) Fabricated gold roots which were fixed to pivot teeth by means of a spring Harris(1887) Implanted a platinum post coated with lead Bonewell (1895) Used gold or irridium tubes implanted into bone www.indiandentalacademy.com
  11. 11. Recent history Payne(1898) Used a silver capsule as an implant Scholl(1905) Demonstrated a porcelain corrugated root implant www.indiandentalacademy.com
  12. 12. www.indiandentalacademy.com
  13. 13. Implant material requirements Physical and mechanical Corrosion and biodegradation biological www.indiandentalacademy.com
  14. 14. Mechanical requirements Strength  Strength of the implant material should be tested under tension , compression and shear force  For most of the implant materials compressive strength is usually greater than the tensile and shear strength www.indiandentalacademy.com
  15. 15. Mechanical requirements Fatigue strength  Upper stress limit decreases with an increase in number of loading cycles  In general , fatigue limit of metallic implant materials reaches approximately 50% of their ultimate tensile strength www.indiandentalacademy.com
  16. 16. Mechanical requirements Maximum yield strength  It represents the stress at which permanent deformation of the material begins  Should not be exceeded by the masticatory stresses www.indiandentalacademy.com
  17. 17. Mechanical requirements Creep deformability  Creep is defined as the time dependent plastic deformation of the material under a static load or constant stress  Materials with high creep values should be selected if o high masticatory forces are expected o Patient has parafunctional habits www.indiandentalacademy.com
  18. 18. Mechanical requirements Modulous of Elasticity  Implant materials and designs should account for the modification of shape of bone in response to application of forces  An attempt to match closely deformability of bone and implant materials led to experimentation of polymeric and carbonitic implant materials www.indiandentalacademy.com
  19. 19. Mechanical requirements Ductility  American Society For Testing And Material (ASTM) , ISO , and ADA :- Require a minimum of 8% ductility to minimize brittle fractures of implant materials  Addition of modifying elements or process hardening often results in an increase in strength but decrease in ductility www.indiandentalacademy.com
  20. 20. ductility  Mixed microstructural phase hardening of austenitic materials with nitrogen and increasing purity of alloys helps increase strength while maintaining high level of plastic deformation www.indiandentalacademy.com
  21. 21. Biodegradation Williams suggested 3 type of corrosion were most relevent to dental implant materials Galvanic corrosion Stress corrosion cracking Fretting corrosion www.indiandentalacademy.com
  22. 22. Galvanic corrosion Occurs when two dissimilar metallic materials are in contact within an electrolyte resulting in current to flow between the two Depends on passivity of oxide layers Lemons et al (1988) Reported on the formation of electrochemical couples as a result of oral implant and restorative procedures Plank and Zitter(1996) Galvanic corrosion can be greater for dental implants than orthopedic implants www.indiandentalacademy.com
  23. 23. Stress corrosion cracking Corrosion fatigue Mechanical stress Corrosive environme nt Failure by cracking www.indiandentalacademy.com
  24. 24. Fretting corrosion Occurs when there is micromotion and rubbing contact within a corrosive environment Along implant body and abutment interphase Along abutment and superstructure interphase www.indiandentalacademy.com
  25. 25. Biologic considerations Toxicity Refers to primary degradation products of a material www.indiandentalacademy.com
  26. 26. Toxicity 3 factors which decide toxicity of a material Amont dissolved by degradation per time unit • TE (g/day) = TEA(%) x CBR x IS / 100 Amount of material removed by metabolic activity in the same time unit Quantities of solid particles and ions deposited in the tissues and any transfers to the systemic system www.indiandentalacademy.com
  27. 27. Toxicity TE( g/day) = TEA (%) x CBR (g/cm2/day) x IS(cm2) / 100  TE toxic element  TEA toxic elements in alloy  CBR corrosion biodegradation rate  IS implant surface www.indiandentalacademy.com
  28. 28. Classification Implant materials metallic ceramic polymeric Polymeric composite Titanium Titanium alloys Co Cr alloys Stainless steel Precious metals Bioinert ceramics Bioactive and biodegradable ceramics www.indiandentalacademy.com
  29. 29. Metallic implant materials Titanium Gold standard in implant materials Atomic number 22 Atomic weight 47.9 0.6% of earth’s crust : million times more abundant than gold Exists in nature as 2 ore forms  Rutile ( TiO2 )  Ilmenite ( FeTiO3 ) www.indiandentalacademy.com
  30. 30. Titanium Extraction from ore forms Kroll process Reduction of TiCl4 by magnesium Iodide process  Involves formation of titanium iodide through reaction of raw titanium with iodine  Titanium iodide is later decomposed on a heated titanium wire www.indiandentalacademy.com
  31. 31. Properties Oxidizes or passivates upon contact with room temp air or normal tissue fluids Tensile strength Wrought soft(root form) and ductile metallurgic (plate form implants) tensile strength is 1.5 times greater than that of bone Fatigue strength Usually 50% less than tensile strength Density 4.5g/cm3 www.indiandentalacademy.com
  32. 32. Properties Modulous of elasticity  5 times greater than that of compact bone  Hence enables uniform stress distribution at bone implant interphase www.indiandentalacademy.com
  33. 33. Advantages Biologically inert and biocompatible Excellent resistance to corrosion Low specific gravity High heat resistance High strength comparable to that of stainless steel www.indiandentalacademy.com
  34. 34. Advantages Lowenberg et al (1987) Titanium & zirconium alloy discs are biocompatible with gingival fibroblasts J Dent Rest 1987 : 66 : 1000 www.indiandentalacademy.com
  35. 35. Biocompatibility of Ti Titanium oxide surface Brookite oxide layer • Amorphous in atomic structure • Formed in normal temperature or tissue fluid environment • Usually very adherent and thin in dimension (less than 20 nm) • Found in case of surgical implants Rutile or Anatase oxide layer • Crystalline atomic structure • Formed by processing Ti at elevated temp or anodizing it in organic acids at high voltages • Oxide layer formed is hetrogenous and thick(10 to 100 times thicker) • More likely to exhibit porosity such as scale www.indiandentalacademy.com
  36. 36. Tissue interactions with Ti Oxide Highest oxide growth area : bone marrow site Lowest oxide growth area : cortical regions Active exchange of ions at the surface exhibited by increased levels of Ca & P on oxide surface www.indiandentalacademy.com
  37. 37. Tissue interactions with Ti Oxide Ti Gel conditions Hydrogen peroxide environment has been shown to interact with Ti and form a complex gel Such Ti gel conditions are credited with  Low apparent toxicity  Low inflammation  Bone modelling  Bactericidal charecteristics www.indiandentalacademy.com
  38. 38. Tissue interactions with Ti Oxide Local and systemic release of ions has been reported with Ti & Ti alloy implants  Ion release results in an increase in oxide layer thickness with inclusions of Ca , P & S  Free Ti ions have shown to inhibit growth of hydroxyapatite crystals www.indiandentalacademy.com
  39. 39. Advantages of TiO2  Minimizes biocorrosion in absence of interfacial motion or adverse environmental conditions  In vivo repassivation areas scratched or abraded during placement repassivate in vivo  Solar RJ , Pellack SR , Korostoff F (1979) Oxide layer tends to increase in thickness under corrosion testing www.indiandentalacademy.com
  40. 40. Advantages of TiO2 Hoar TP , Meals DC (1966) Breakdown of this oxide layer is unlikely in altered solutions such as chlorine solution Both et al Ti allows bone growth directly adjacent to the oxide surfaces www.indiandentalacademy.com
  41. 41. limitations High cost www.indiandentalacademy.com
  42. 42. limitations Difficult & dangerous casting  A high vacuum or ultrapure gas atmosphere is needed  Metal has a high melting point  Metallic embrittlement may occur due to propensity to absorption of O , N , & H  Metal fumes and oxidises rapidly at elevated temp.  almost explosive reaction may occur www.indiandentalacademy.com
  43. 43. Titanium alloys 3 forms of alloys used in dentistry  Alpha  Beta  Alpha-beta Most commonly used for dental implants : alpha-beta variety .e.g Ti -6Al-4V, Ti- 6Al-7Nb www.indiandentalacademy.com
  44. 44. Advantages Strength  wrought alloy condition is about 6 times stronger than compact bone  Can be fabricated in thinner sections MOE slightly greater than that of Ti  5.6 times of compact bone Demonstrates oxide formation like Ti Demonstrates osseointegrated surfaces Highly resistant to fatigue & corrosion www.indiandentalacademy.com
  45. 45. limitations Ductility considerably less than Ti Adverse effects of Al & V biodegradation on local & systemic tissues Difficult to cast www.indiandentalacademy.com
  46. 46. Co – Cr – Mo based alloys Most often used as  As cast  Cast & annealed metallurgic condition High strength permits custom designing www.indiandentalacademy.com
  47. 47. Co – Cr – Mo based alloys Composition Co Cr Mo Ni C Continuous phase for basic properties Corrosion resistance Strength & bulk corrosion resistance Provides strength ductility www.indiandentalacademy.com
  48. 48. advantages high strength  4 times that of compact bone Excellent biocompatibility profile www.indiandentalacademy.com
  49. 49. disadvantages Less ductile  bending of finished implants shhould be avoided www.indiandentalacademy.com
  50. 50. Fe – Cr – Ni based alloys Surgical stainless steel alloys e.g. 316 low C Used for orthopedic and dental implant devices Used in wrought and heat treated metallurgic condition www.indiandentalacademy.com
  51. 51. Advantages High strength High ductility Cost effective www.indiandentalacademy.com
  52. 52. Disadvantages Most subject to crevice and biocorrosion Ni allergy Galvanic coupling and biocorrosion with Ti , Co , Zr and C www.indiandentalacademy.com
  53. 53. Noble metals Most commonly used noble metals  Tantalum  Platinum  Irridium  Gold  Palladium  Alloys of these metals www.indiandentalacademy.com
  54. 54. Advantages Inert electrochemically Easily available esp. gold Do not depend on surface oxides www.indiandentalacademy.com
  55. 55. Disadvantages Low strength Cost per unit weight is high Weight per unit volume (density) is less www.indiandentalacademy.com
  56. 56. Ceramics & carbon Ceramics are inorganic , non metallic , non polymeric materials manufactured by compacting and sintering at elevated temperatures. 2 types Bioinert ceramics Bioactive & biodegradable ceramics www.indiandentalacademy.com
  57. 57. Bioinert ceramics Ceramics from Al , Ti , & Zr oxides Used as  root form  endosteal plate form  pin type dental implants www.indiandentalacademy.com
  58. 58. properties www.indiandentalacademy.com
  59. 59. Indications Anterior root form devices www.indiandentalacademy.com
  60. 60. Contraindications Subperiosteal devices as they have low fracture resistance and high relative cost of manufacturing www.indiandentalacademy.com
  61. 61. Advantages Minimal thermal and electrical conductivity Minimal biodegradation Minimal reactions with bone , soft tissue and oral environment In certain lab animal and human studies exhibit direct interfaces with bone like osseointegrated Ti implants Gingival attachment zones along sapphire root form implants in lab animals have demonstrated localized bonding www.indiandentalacademy.com
  62. 62. Disadvantages Exposure to steam sterlization------> measurable decrease in strength Scratches or notches may introduce fracture initiation sites Chemical solutions may leave residues May abrade other materials www.indiandentalacademy.com
  63. 63. Bioactive & biodegradable ceramics Consist of solid or porous particles with compositions relatively similar to the mineral phase of bone Inernal reinforcement through Mechanical ( central metallic rods ) Physiochemical (coating over another substrate ) techniques www.indiandentalacademy.com
  64. 64. Indications Ridge retainers : rods and cones for filling tooth extraction sites Structural support under high magnitude loading conditions :  rods  Cones  Blocks  H- bars Used in combination with organic compounds such as  Collagen  Drugs  Bone morphogenic protein www.indiandentalacademy.com
  65. 65. Physical properties Factors affecting :  Surface area or form of the product  Porosity  crystallinity www.indiandentalacademy.com
  66. 66. Chemical properties Factors affecting  Ca – P ratio  Composition  Elemental impurities such as carbonate  Ionic substitutions in atomic structure  PH of surrounding region www.indiandentalacademy.com
  67. 67. Chemical properties General formula M1O 2+ (XO4 3- ) 6 Z2 -1 standard apatite products  Crystalline monolythic hydroxyapatite  Crystalline tri calcium phosphate Indicated for  Bone augmentation & replacement  Carriers for organic products  Coatings for endosteal and subperiosteal implants www.indiandentalacademy.com
  68. 68. Advantages Chemistry mimics normal biologic tissue Excellent biocompatibility Attachment between CPC and hard and soft tissues Minimal thermal and electrical conductivity MOE closer to bone Colour similar to hard tissues www.indiandentalacademy.com
  69. 69. Disadvantages Variable chemical and structural charecteristics Low mechanical tensile & shear strengths under fatigue loading Low attachment between coating and substrate Variable solubility Variable mechanical stability of coatings under load bearing conditions Overuse Incompatible with steam or water sterilization www.indiandentalacademy.com
  70. 70. Disadvantages S.C. Guy , M. J. Quade , M. J Schiedt (1993) Porous hydroxyapatite has demonstrated the least fibroblast attachment. Epithelium and gingival fibres forming an attachment to implant materials has been reported in the following order Titanium > non porous HA > porous HA J Periodontology (1993: 64 : 542 – 546 ) www.indiandentalacademy.com
  71. 71. Carbon compounds Similar to ceramics  Chemical inertness  Absence of ductility Differenence from ceramics  Electrical & thermal conductivity A two stage implant system  vitredent : popular in 1970 Design and material limitations significant clinical failures  withdrawl from clinical use Used as coatings on metallic & ceramic implants www.indiandentalacademy.com
  72. 72. Polymers Common polymeric materials  PTFE  PET  PMMA  UHMW-PE  PP  PSF  PDS  SR  Can be combined with  Particulate or fibres of carbon  Aluminium oxide  HA  Glass ceramics  Biodegradable calcium phosphate www.indiandentalacademy.com
  73. 73. limitations Low strength Low MOE compared to bone Higher elongation to fractures High cold flow charecteristics , creep and fatigue strength Low resistance to abrasion and wear Sensitive to sterilization and handling techniques Electrostatic surface properties , hence tend to gather dust www.indiandentalacademy.com
  74. 74. Indications Tissue attachment , replacement & augmentation Coatings for force transfer to soft tissue and hard tissue regions Internal force distribution connectors for O.I implants Structural scaffolds , plates & screws www.indiandentalacademy.com
  75. 75. Surface charecteristics Surface coatings Passivation Surface texturing Ion implantation www.indiandentalacademy.com
  76. 76. Surface coatings Titanium coating Hydroxyapatite coating www.indiandentalacademy.com
  77. 77. Titanium coating Introduced by Hahn & Palich Reported bone in growth in Ti hybrid powder plasma sprayed implants inserted in animals www.indiandentalacademy.com
  78. 78. Procedure Porous or rough Ti surfaces have been fabricated by plasma spraying a powder form of molten droplets at high temp. At temp in the order of 15,000 degree celsius , an argon plasma is assosciated with a nozzle to provide very high velocity ( 600 m/ sec ) partially molten particles of Ti powder (0.05 to 0.1 mm diameter) projected onto a metal or alloy substrate Thickness of plasmas sprayed layer : 0.04 to 0.05 mm www.indiandentalacademy.com
  79. 79. Microscopic structure Round or irregular pores that can be connected to each other www.indiandentalacademy.com
  80. 80. Advantages Increases the total surface area upto several times Produce attachment by osteoformation Enhances attachment by increasing ionic interactions Dual physical & chemical anchor system Increase in tensile strength through growth of bony tissues into 3-D features Improved force transfer to periimplant area www.indiandentalacademy.com
  81. 81. Disadvantages Cracking & scaling because of stresses produced by processing at elevated temp. Risk of accumulation of abraded material in the interfacial zone during implanting of Ti plasma sprayed implants www.indiandentalacademy.com
  82. 82. Hydroxyapatite coating Introduced to dental profession by de Groot Procedure Majority of commercially available HA coated implant systems use a plasma spray technique www.indiandentalacademy.com
  83. 83. procedure A powdered crystalline HA is introduced and melted by the hot , high velocity region of a plasma gun and propelled onto the metal implant as a partially melted ceramic www.indiandentalacademy.com
  84. 84. Limitation of plasma spraying It can alter the nature of crystalline ceramic powder and can result in the deposition of a variable % of a resorbable amorphous phase Ion beam Sputtering coating technique Expected to produce dense , more tennacious and thinner coatings www.indiandentalacademy.com
  85. 85. Advantages Better organization & mineralization of adjacent bone Better biomechanics & initial load bearing capacity Improved bone to implant attachment Increase in bone penetrations Protective shield Enhanced coating substrate bond www.indiandentalacademy.com
  86. 86. Disadvantages Partial resorption of CPC may occur due to remodelling of the osseous interphase Resorption of coating in infected & chronic inflammation areas www.indiandentalacademy.com
  87. 87. Recent advances in HA coatings Fluorapatite Heat treated hydroxyapatite coatings ( HA-HT) Harry et al (1996) Remaining coating thickness at the end of 24 months:- HA 38% FA 95% HA-HT 97% Int J Prosthodont 1996 :9 142-148 www.indiandentalacademy.com
  88. 88. Passivation Refers to enhancement of oxide layer to  Prevent release of metallic ions  Enhance biocompatibility 2 procedures  Immersion in 40 % nitric acid  results in a thin oxide layer  Anodization electric current is passed through the metal www.indiandentalacademy.com
  89. 89. Surface texturing Enhances surface area by upto 6 times Methods  Plasma spraying with Ti  Acid etching  Particulate Blasting www.indiandentalacademy.com
  90. 90. Acid etching Ti implants can be etched with  Nitric acid  HF acid Chemically alters the surface Eliminates some type of contaminants www.indiandentalacademy.com
  91. 91. Particulate blasting Can be done with various media such as  Silica  Alumina  Glass beads Provides irregular rough surfacing less than 10 micron scales Limitation osteolysis caused by foreign debris Resorbable blast media www.indiandentalacademy.com
  92. 92. Ion implantation Done by bombarding the surface of implant with high energy ions upto a surface depth of 0.1 micron Increases corrosion resistance of Ti through formation of TiN layer Increases hardness and abrasion & wear resistance Nitrogen implantation & carbon doped layer deposition recommended for stainless steel www.indiandentalacademy.com
  93. 93. Selection of implant material Strength of implant material Quality of bone Bone height  8 mm bone  Ti implant failure rate was 70% while HA was 4%  12 mm bone  no significant difference www.indiandentalacademy.com
  94. 94. Selection of implant material Fresh extraction sites better initial stability of HA Newly grafted sites HA preferred  Greater implant bone interphase  Higher shear bond strength  Higher torsional strength www.indiandentalacademy.com
  95. 95. Surface cleanliness & sterlization Alberkston et al (1985) Implants that seem functional may fail even after years of function and the cause may be attributed to improper ultrasonic cleaning , sterlization or handling during the surgical placement www.indiandentalacademy.com
  96. 96. Cases of surface contamination Lausmaa et al showed large variations in C contamination loads of Ti implants (20% to 60%) in the 0.1 to 3 nm thickness range Trace amounts of Ca , P , N , Si , S , Cl , Na Residues of F due to passivation & etching treatments Ca , Na & Cl may be incorporated during autoclaving Si may be present due to sand & glass bead blasting procedures www.indiandentalacademy.com
  97. 97. Sterlization Conventional steam sterlization Radio frequency glow discharge technique (RFGDT) U.V Light sterlization Gamma radiation procedures www.indiandentalacademy.com
  98. 98. Radio frequency glow discharge technique Sterlization under a controlled noble gas discharge at very low pressure Gas ions bombard the surface & remove surface atoms and molecules which are adsorbed or are its constituents www.indiandentalacademy.com
  99. 99. Advantages Baier et al Provides a clean surface as well as a high surface energy state Thinner , more stable oxide films Improved wettability & tissue adhesion Principle oxide unchanged Decrease in bacetrial contamination on HA coated implants reported May enhance Ca & P affinity due to an increase in elemental zone at the surface www.indiandentalacademy.com
  100. 100. U. V light sterlization Effective on spores Enhances bioreactivity Cleans the surface safely & rapidly Grants high surface energy www.indiandentalacademy.com
  101. 101. Gamma radiation sterlization Most metallic systems exposed to radiation doses exceeding 2.5 mega – rads Advantages Packaging & all internal parts of assembly sterlized Components remain protected , clean & sterile until inner containers are opened within the sterile field of surgical procedure www.indiandentalacademy.com
  102. 102. Disadvantages Some ceramics can get discoloured Polymers may be degraded by gamma radiation exposures www.indiandentalacademy.com
  103. 103. Hartman et al (1989) RFGDT & UV sterlizedimplants show rapid bone ingrowth and maturation while steam sterlized implants seem to favour thicker collagen fibres at the surface Carlsson et al (1989)  Reported similar healing responses with RFGDT & conventionally treated implants  Cautioned that RFGDT produces much thinner oxide layer at the surface and may deposit silica oxide from the glass envelope www.indiandentalacademy.com
  104. 104. Biocompatibility Boca , Raton , Fla (1981) An appropriate response to a material (biomaterial) within a device (design) for a specific clinical application www.indiandentalacademy.com
  105. 105. History 1960 Emphasis on inert & chemically stable materials Classic e.g  High purity ceramics of aluminium oxide  Carbon & carbon silicon compounds  Extra low interstitial grade alloys www.indiandentalacademy.com
  106. 106. History 1970s Biocompatibility of implants was defined in terms of minimal harm to the host or to the biomaterial Stable interaction - central focus of B.C. www.indiandentalacademy.com
  107. 107. History 1980s Focus transferred to bioactive substrates Substances which tended to positively influence tissue response  considered to be biocompatible www.indiandentalacademy.com
  108. 108. History 1990s Emphasis is on chemically & mechanically anisotropic substances Growth (mitogenic) & inductive ( morphogenic ) traits of material are given importance while defining biocompatibility www.indiandentalacademy.com
  109. 109. Analysing biocompatibility Individual constituents :  Implant materials  Tissues Effect on local & systemic tissues Interfacial zone www.indiandentalacademy.com
  110. 110. ADA criteria Evaluation of physical properties that ensure sufficient strength Demonstration of ease of fabrication & sterlization potential without material degradation Cytotoxicity testing Freedom from defects A minimum of 2 clinical trials , each with a minimum of 50 human subjects conducted for three years  for provisional acceptance Clinical trial of 5 years to earn acceptance www.indiandentalacademy.com
  111. 111. Biocompatibility concerns Titanium  Normal Ti levels in humans 50ppm  May reach upto 300 ppm in tissues surrounding Ti implants  Tissue discolouration may be visible but is still well tolerated Hydroxyapatite  Disintegration particles (esp smaller than 5 microns) formed due to dissolution of amorphous substance  toxic to fibroblasts  Direct interaction with cells results in irreversible cell membrane demage www.indiandentalacademy.com
  112. 112. Biocompatibility concerns Co-Cr alloys & stainless steel  Potential electrolytic action  galvanic corrosion  Release of nickle & beryllium ions Polymers  Chronic irritation of surrounding tissue with fibrous encapsulation  Reported to cause some allergenic and carcinogenic reactions  Bone loss gingival recession peri-implantitis www.indiandentalacademy.com
  113. 113. www.indiandentalacademy.com
  114. 114. References Contemperory implant dentistry : Carl E Misch 3rd edition Philips science of dental materials 11 edition Craig dental materials DCNA vol 36 no1 JADA dec 1990 vol121 Periodontology 2000 : 1998 vol 17 IJP 1996 vol 9 no.2 JPD sep 1992 vol68 no.3 J Periodontology 1993 vol 64 no.6 JPD 1985 vol 54 no.3 www.indiandentalacademy.com
  115. 115. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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