This document provides an overview of implant biomaterials. It begins with definitions of key terms like implant, biomaterial, and biocompatibility. It then discusses the history of biomaterials dating back to ancient times. The document classifies biomaterials and discusses properties like biocompatibility, corrosion resistance, and bone-implant interactions. Specific materials are covered like metals (titanium, cobalt-chromium alloys), ceramics, and polymers. The document emphasizes that titanium and its alloys are the most commonly used dental implant materials due to their biocompatibility and ability to osseointegrate. Surface modifications are also discussed to enhance integration with bone.

1. Implant biomaterials
Presented by
Dr Arunima Upendran
1st MDS
1

2. CONTENTS
• Introduction
• Terminologies
• History
• Classification of biomaterials
• Biocompatibility
• Biofunctionability
• Individual materials
– Metals and alloys
– Ceramics and carbon
– Polymers and composite polymers
• Surface modifications
• Conclusion
• References 2

3. Introduction
3

4. DEFINITIONS
Implant (1890): to graft or insert a material such as an
alloplastic substance, an encapsulated drug, or tissue into the
body of a recipient
Implant (1809): any object or material, such as an alloplastic
substance or other tissue, which is partially or completely
inserted or grafted into the body for therapeutic, diagnostic,
prosthetic, or experimental purposes.
4
GPT 9

5. Biomaterial (1966): any substance other than a drug that can
be used for any period of time as part of a system that treats,
augments, or replaces any tissue, organ, or function of the
body
Biocompatible: capable of existing in harmony with the
surrounding biologic environment
Biotolerant – Material that is not necessairly rejected but are
surrounded by fibrous layer in the form of a capsule
5

6. • Bio inert – Material that allow close apposition of bone
on their surface
• Bioactive - Materials that allow formation of new bone
on their surface and ion exchange with host tissue
• Osteoconductive – the materials that forms scaffolding
that allows the formation of bone
• Osteoinductive – materials that have capacity to induce
bone formation.
6

7. HISTORY
7

8. 8
• 600 AD - Mayan
population -
implantation of pieces of
Shell

9. • Ancient Egyptians used tooth shaped shells and ivory to
replace teeth
• The Etruscans, living in what is now modern Italy, replaced
missing teeth with artificial teeth carved from the bones of
oxen.
9

10. • In the 1700s John Linter and Pierre Fauchard suggested the
possibility of transplanting teeth of one human into another
10

11. In 1809, Maggiolo fabricated a gold implant which was
placed into fresh extraction sockets to which he attached a
tooth after a certain healing period.
In 1886 Edmunds was the first in the US to implant a
platinum disc into the jawbone, to which a porcelain
crown was fixated.
In 1887, a physician named Harris attempted the same
procedure with a platinum post, instead of a gold post
11

12. In the early 1990s Lambotte fabricated implants of aluminum,
silver,brass,red copper, magnesium,gold and soft steel plated
with gold and nickel.
Greenfield in 1909 made a lattice cage design of iridoplatinum
12

13. •Early pioneers in this field include Dr. A.E. Strock, who, in 1931
suggested using Vitallium r, a metal alloy, for dental implants.
•Surgical cobalt chromium molybdenum alloy was introduced to
oral implantology in 1938 by Strock.
•In 1947, Manlio Formiggini of Italy developed an implant made
of tantalum. At the same time, Raphael Chercheve designed a
double delinked spiral implants made of a chrome-cobalt alloy.
13

14. •By 1964, commercially pure titanium was accepted as the
material of choice for dental implants, and since that time,
almost all dental implants are made of titanium. The body does
not recognize titanium as a foreign material, resulting in less
host rejection of the implant.
14

15. In the 1960s, emphasis was placed on making the biomaterials
more inert and chemically stable within biologic environments.
The high purity ceramics of aluminum oxide, carbon, and
carbon – silicon compounds and extra low interstitial (ELI)
grade alloys are classic examples of these trends.
15

16. In 1975 the first synthodont aluminium oxide implant
was placed in a human
Vitreous carbon implants were first placed in early 1970
by Grenoble
In early 1980s Tatum introduced Omni R implant made
of titanium alloy root form implant with horizontal fins.
16

17. Niznick in 1980 introduced Core-vent, an endosseous screw
implant manufactured with a hydroxyapatite coating. Calcitek
corporation began manufacturing and marketing its synthetic
polycrystalline ceramic hydroxyapatite coated cylindrical post
titanium alloy implant.
17

18. In 1985, Straumann Company designed plasma sprayed
cylinders and screws to be inserted in a one stage operation.
Brane mark devoted 13 years conducting animal studies to
determine the parameters under which osseointegration would
occur. Based on his study titanium was made the material of
choice.
18

19. Osseointegration
osseointegration: 1. the apparent direct
attachment or connection of osseous tissue to
an inert, alloplastic material without intervening
fibrous connective tissue; 2. the process and
resultant apparent direct connection of an
exogenous material’s surface and the host bone
tissues, without intervening fibrous connective
tissue present; 3. the interface between
alloplastic materials and bone;
19

20. Osseointegration
20

21. 21

22. 22

23. Classification of implant materials
23

24. 24

25. Requirements of an ideal implant material
25

26.  meet 2 basic criteria
– Biocompatibility with living tissue
– Biofunctionality with regard to force transfer
 Implant properties can be studied under
– Bulk properties
– Surface properties
26

27. Bulk properties
27

28. Modulus of elasticity (E)
 Measure of change in dimension (strain) with respect to
stress
• comparable to bone (18GPa )should be selected
 more uniform distribution of stress at implant bone interface
as under stress both of them will deform similarly.
 relative movement at implant bone interface is minimized.
28

29. Tensile, Compressive, Shear, Strength
• High tensile, compressive, shear strength to prevent
fractures and improve functional stability.
29

30. Yield strength and Fatigue strength
• Yield strength is magnitude of stress at which a
material shows initial permanent deformation
• Fatigue strength is stress at which material fractures
under repeated loading
• An implant material should have high yield strength
and fatigue strength to prevent brittle fracture under
cyclic loading
30

31. Ductility
• Refers to relative ability of a material to deform
plastically under a tensile stress before it fractures
• ADA demands a minimum ductility of 8% for dental
implant
• Required for fabrication of optimal implant
configurations
• Safeguards against brittle fractures of implant
31

32. Hardness and Toughness
Hardness – resistance to permanent surface
indentation or penetration
• Increase hardness decreases the incidence of wear of
implant material
Toughness – amount of energy required to cause
fracture.
• Increased toughness prevents fracture of the
implants.
32

33. Electrical and Thermal conductivity
• Should be minimum to prevent thermal expansion,
contraction, and oral galvanism.
33

34. 34

35. Surface properties
35

36. Surface tension and surface energy
• Determines
– Wettability of implant by wetting fluid (blood)
– Cleanliness of implant surface
• Surface energy of > 40 dyne / cm
• Surface tension of 40 dyne/cm or more
• Characterstics of very clean surface
• Results in good tissue integration with load carrying
capacity
36

37. Biocompatibility
• Not total inertness
• Ability of a material to perform with an appropriate
biological response in a specific application
• Mainly a surface phenomenon
• Most important requirement for a biomaterial
• Depends on
– Corrosion resistance
– Cytotoxicity of corrosion products
37

38. Corrosion resistance
• Corrosion is deterioration of a metal caused by
reaction with its environment
• Following types of corrosion are seen
38

39. Williams suggested that three types of
corrosion were most relevant to dental
implants:
• Stress corrosion cracking
• Galvanic corrosion
• Fretting corrosion
39

40. Stress corrosion cracking (SCC)
 The combination of high magnitudes of applied mechanical
stress plus simultaneous exposure to a corrosive environment
can result in the failure of metal materials by cracking, where
neither condition alone would cause the failure.
40
William presented this phenomenon of SCC in multicomponent orthopedic
implants.

41. • Lemons et al Hypothesized that it may be responsible for
some implant failures in view of high concentrations of forces
in the area of the abutment-to-implant body interface.
41

42. • Most traditional implant body designs under three-
dimensional finite element stress analysis show a
concentration of stresses at the crest of the bone support and
cervical one-third of the implant.
42

43. • This tends to support potential SCC at the implant interface
area (i.e. a transition zone for altered chemical and
mechanical environmental conditions).
• This has also been described in terms of corrosion fatigue (i.e.,
cyclic load cycle failures accelerated by locally aggressive
medium).
43

44. Galvanic corrosion (GC)
• GC occurs when two dissimilar metallic materials are in
contact and are within an common electrolyte medium,
resulting in current to flow between the two.
44

45. Galvanic Corrosion
• The metallic materials with the dissimilar potentials can have
their corrosion currents altered, thereby resulting in a greater
corrosion rate..
45

46. Fretting corrosion (FC)
• FC occurs when there is a micromotion and rubbing contact
within a corrosive environment such as the perforation of the
passive layers and shear-directed loading along adjacent
contact surface.
46

47. • Normally, the passive oxide layers on metallic substrates
dissolve at such slower rates that the resultant loss of mass is
of no mechanical consequence to the implants.
47

48. Pitting Corrosion
• A more critical problem is irreversible local perforation of the
passive layer that is often caused by chloride ions, which may
result in localized pitting corrosion.
48

49. Crevice corrosion
• Occurs in narrow region eg implant screw – bone
interface
49

50. Electrochemical corrosion
• In this anodic oxidation and cathodic reduction takes
place resulting in metal deterioration as well as
charge transfer via electrons.
• All these types of corrosion and charge transfer can
be prevented by presence of passive oxide layer on
metal surface.
• The inertness of this oxide layers imparts
biocompatibility to biomaterials
50

51. PROTECTION AGAINST CORROSION
•Passivation
•Increasing the noble metal content
•Polishing the surface
•Avoid dissimilar metal contact
51

52. Cytotoxicity of corrosion products
• Toxicity of implant materials depends on toxicity of corrosion
products which depends on
– Amount of material dissolved by corrosion per unit time
– Amount of corroded material removed by metabolic activity in
same unit time
– Amount of corrosion particles deposited in the tissue
• Both increased corrosion resistance and decreased toxicity of
corrosion products contribute to biocompatibility
52

53. METAL CONTAMINATION
• Two different metals in the saline solutions or body fluids may
result in a localized difference of electrochemical potential
and cause galvanic corrosion. So the instruments that contact
titanium implant during insertion procedures either be solid
titanium, titanium tipped or treated to prevent metallic
transfer.
• During storage, sterilization and surgical set up no other type
of metal should contact the implant surface.
53

54. Bone and implant surface interaction
• The implant material should have an ability to form
direct contact or interaction with bone
( osseointergration)
• This is largely dependent on biocompatibility and
surface composition of biomaterial ( presence of
passivating oxide layer).
54

55. Biomaterials
55

56. Titanium
• Gold standard in implant materials
• Composition of Commercially pure titanium
– Titanium 99.75%
– Iron 0.05%
– Oxygen 0.1%
– Nitrogen 0.03%
– Hydrogen 0.012%
– Carbon 0.05%
56

57. The American Society for Testing and Materials(ASTM)
committee F-4 on materials for surgical implants recognizes
four grades of commercially pure Titanium and two Titanium
alloys:
• Cp titanium grade I (0.18% Oxygen)
• Cp titanium grade II (0.25% Oxygen)
• Cp titanium grade III (0.35% Oxygen)
• Cp titanium grade IV (0.40% Oxygen)
57

58. • Consists of 2 phases α and β phase
• manufactured - controlled machining ( lathing , threading ,
milling )
• Configuration like cylinders ,screws and blade forms etc are
used
• Casting of titanium alloy is difficult due to high melting points
(1700°C)
• Also Ti readily absorbs nitrogen ,hydrogen and oxygen from air
during casting which makes it brittle
58

59. Properties
Biocompatibility
• Titanium is one of the most biocompatible material due to its
excellent corrosion resistance
• The corrosion resistance is due to formation of biologically
inert oxide layer
Oxide layer
• Titanium spontaneously forms tenacious surface oxide on
exposure to the air or physiologic saline
• Three different oxides are
– TiO Anastase
– TiO2 Rutile
– Ti2 O3 Brookite
59

60. • TiO2 is the most stable and mostly formed on titanium surface
• self healing i.e. if surface is scratched or abraded during
implant placement it repassivates instantaneously
• Also Ti oxide layer inhibits low level of charge transfer, lowest
among all metals ;main reason for its excellent
biocompatibility
60

61. • Good yield strength , tensile strength , fatigue strength .
• Modulus of elasticity (110 GPa) is half of other alloys and 5
times greater than bone; helps in uniform stress distribution
• Good strength ,but less than Ti alloys.
• Ductile enough to be shaped into implant by machining
• Low density 4.5g/cm3 , light weight
61

62. • Ti allows bone growth directly adjacent to oxide surface
• Inspite of excellent corrosion resistance peri-implant
accumulation and also accumulation in lung, liver, spleen of Ti
ions is seen, however in trace amount it is not harmful
• Increased level of titanium ions can result in titanium
metallosis.
62

63. Titanium alloys Ti6Al4V
• Consists of
- Titanium
– 6% Aluminium – alpha stabilizer
– 4% Vanadium – beta stabilizer
63

64. Properties
• corrosion resistance - Excellent
• Oxide layer - resistant to charge transfer -biocompatibility
• Modulus of elasticity is 5.6 times that of the bone ,more
uniform distribution of stress
• Strength of titanium alloy is greater than pure titanium – 6
times that of bone hence thinner sections can be made
• Ductility is sufficient
• Exhibits osseointergration
64

65. Uses
• Extensively used as implant material due to excellent
biocompatibility ,strength ,osseointegration
65

66. Disadvantages
• Its high cost (although the cost has been reduced over the past
few years).
• Titanium is difficult and dangerous to cast. The metal forms
oxides so rapidly that an explosive reaction may occur.
(So it is used either in machined or plastic form)
66

67. Ti Ore (Carbon and Chlorine)
TiCl
Ti Sponge
Ti Ingots
67
Heated
Reduced in presence of molten Na
Fused under Vacuum

68. 68
Original Branemark
fixture
Titanium screw
Cp Ti screw implant

69. Cobalt , Chromium , Molybdenum
alloy
• Composed of same elements as vitallium
• Vitallium introduced in 1937 by Venable Strock and Beach
• Composition
– 63% Cobalt
– 30% Chromium (CrO provides corrosion resistance)
– 5% Molybdenum(strength)
69

70. Properties
• High mechanical strength
• Good corrosion resistance
• Low ductility
• Direct apposition of bone to implant though seen ,it is
interspersed with fibrous tissue
70

71. Uses
• most often used in cast-and-annealed metallurgic condition.
• Limited for fabrication of custom designs for subperiosteal
frames due to ease of castability and low cost.
Precautions:
• As cast cobalt alloys are the least ductile of the alloy systems
used for dental surgical implants, and bending of finished
implants should be avoided.
71

72. Iron , Chromium, Nickel based alloy
• These are Surgical steel alloys or Austenitic steel
• Have a long history of use as orthopedic and dental implant
devices
Composition
– Iron
– Chromium – 18% - corrosion resistance
– Nickel – 8% - stabilize austenitic steel
72

73. Properties
• High mechanical strength
• High ductility
• Pitting and crevice corrosion.
• Hypersensitivity to nickel has been seen
• Galvanic potential
• Bone implant interface shows fibrous encapsulation and
ongoing foreign body reactions
• Use is limited
73

74. Precious metals
• Gold , Platinum , Palladium
• They are noble metals unaffected by air , moisture , heat and
most solvents
• Do not depend on surface oxides for their inertness
• Low mechanical strength
• Very high ductility
• More cost per unit weight
• Do not demonstrate osseointegration
• Not used
74

75. Ceramics
• Ceramics are inorganic , non metallic materials manufactured
by compacting and sintering at elevated temperature
• Consist of
• Bioinert ceramics
– Aluminium oxide
– Titanium oxide
– Zirconium oxide
• Bioactive ceramics
– Calcium phosphate ceramics – (CPC)
hydroxyapatite (HA)
tricalcium phosphate (TCP)
– Glass ceramics 75

76. Bioinert Ceramics
• direct bone apposition at implant surface but do not show
chemical bonding to bone
Properties
• Bioinert ceramics are full oxides i.e. bulk and surface thus
excellent bio compatibility
• Good mechanical strength
• Low ductility which results in brittleneSS
• Color similar to hard tissue
76

77. Uses
• Though initially thought to be suitable for load bearing dental
implants but to due inferior mechanical properties
• Used as surface coatings over metals
– to enhance their biocompatibility
– to increase the surface area for stronger bone to implant
interface
77

78. DISADVANTAGES
• Exposure to steam sterilization results in measurable
decrease in strength of some ceramics
• So dry heat sterilization is recommended
• Scratches or notches may induce fracture initiating sites
• Although initial testing showed adequate mechanical
strengths long term clinical results clearly demonstrate a
functional design and material related limitations.
78

79. Bioactive ceramics
Calcium phosphate ceramics
• These ceramics have evoked greatest interest in present times
• Mainly consists of
– Hydroxyapatite( HA)
– Tricalcium phosphate( TCP)
79

80. Properties
Biocompatibility
• CPC have biochemical composition similar to natural bone
• CPC form direct chemical bonding with surrounding bone due
to presence of free calcium and phosphate compounds as
implant surface
• Excellent biocompatibility
• No local or systemic toxicity
• No alteration to natural mineralization process of bone
80

81. • Lower mechanical tensile and shear strength
• Lower fatigue strength
• Brittle, low ductility
• Exists in amorphous or crystalline form
• Exists in dense or porous form
– Macro porous - > 50 μm
– Micro porous - < 50 μm
81

82. • The pores though decrease the strength they increase the
surface area providing additional region for tissue ingrowth
• Ideal pore size is around 150μm, same diameter as shown by
inter trabecular spaces in bone
82

83. Solubility of CPC
• CPC show varied degree of resorption or solubility in
physiologic fluids
• The resoption depends on
Crystallinity
– High crystallinity is more resistant to resorption
Particle size
– Large particles size requires longer time to resorb
83

84. Porosity
– Greater the porosity, more rapid is the resorption.
Local environment
– Resorption is more at low pH eg in case of infection or
inflammation
Purity
– presence of impurities accelerate resorption
It has been seen that HA resorb less readily than TCP
84

85. Uses
• Due to lack of mechanical strength, not used as load bearing
implants
• Used as Bone grafts material for augmentation of bone
• As bioactive surface coating for various implant material to
increase
– biocompatibility
– strength of tissue integration
85

86. DISADVANTAGES
• Low mechanical tensile and shear strengths under fatigue
loading
• Low attachment strength on some substrates
• Variable solubility depending on the product and their clinical
applications
86

87. Glass ceramics
• They are bioactive ceramics
• Bioglass or Ceravital
• Silica based glass with additions of calcium and phosphate
produced by controlled crystallization
Properties
• High mechanical strength
• Less resistant to tensile and bending stresses
• Extremely brittle
• They chemically bond to the bone due to formation of calcium
phosphate surface layer
87

88. Mechanism of action
Ca p gel crystalises – entraping collagen fibrils
Collagen fibrils develop and gets in corporated in the ca and P gel
Osteoblasts proliferates- collagen fibrils
Ca and P migrates to silica gel surface
Silica gel forms
Hydrogen ions from tissues replaces sodium ions
Calcium , sodium & phosphorous ions to get dissolved
Change in ph near bioglass surface
88

89. Uses
• Inferior mechanical properties – not used as load bearing
implant
• Used more often as bone graft material
• When used as coating bond between coating and metal
substrates is weak and subject to dissolution
89

90. Carbon and carbon silicon compounds
• Vitreous Carbon and Carbon compounds (SiC)were introduced
in 1960 for use in implantology
Properties
• Inert
• Biocompatible
• Modulus of elasticity is close to that of bone
• Bone implant interface shows osseointegration
• Brittle
• Susceptible to fracture under tensile stress
90

91. Uses
• Used mainly as surface coatings for implants Materials
• Extensive applications for cardiovascular devices
91

92. ADVANTAGES
• Tissue attachment
• Thermal and electrical
insulation
• Color control.
• Provides opportunities for
attachment of active
biomolecules
LIMITATIONS
• Poor Mechanical strength.
• Time dependent changes
in the physical
characteristics.
• Biodegradation could
adversely affect Stability.
• Minimal resistance to
scratching or scraping.
92

93. Polymers
• Polymeric implants were first introduced in 1930s
• However they have not found extensive use in implant due to
• Low mechanical strength
• Lack of osseointegration
93

94. • These can be designed to match tissue properties and can be
fabricated at relatively low cost.
• These include polytetraflouroethylene (PTFE),
polyethyleneterephthalate (PET), polymethylmethacrylate
(PMMA), polypropylene (PP), polysulfone (PSF), silicon rubber
(SR), polyetheretherketone (PEEK)
94

95. • Used currently to provide shock absorbing qualities in load
bearing metallic implants.
E.g. in IMZ system (kirsch 1974) a polyoxymethylene intra mobile
element (IME) is placed between prosthesis and implant body
which
– Ensures more uniform stress distribution
– Acts as internal shock absorber
95

96. Properties
• Polymers have low strengths and elastic moduli and higher
elongation to fracture compared with other class of
biomaterials.
• Thermal and electric insulators
• Relatively resistant to biodegradation compared to bone
• Most uses have been for internal force distribution connectors
intended to better simulate biomechanical conditions for
normal tooth functions
• Some are porous where as others are constituted as solid
structural forms
96

97. DISADVANTAGES
• Sensitive to sterilization and handling techniques.
• Electrostatic surface properties and tend to gather dust or
other particulate if exposed to semi clean oral environments
• Cleaning the contaminated porous polymers is not possible
without a laboratory environment
• So the talc on the gloves or contact with towel or gauze pad or
any such contamination must be avoided.
97

98. Polyetheretherketone (PEEK)
• synthetic, tooth colored polymeric material
• The monomer unit of etheretherketone monomer
polymerizes via step-growth dialkylation reaction of bis-
phenolates to form polyetherether- ketone.
98

99. • lower Young’s (elastic) modulus (3– 4 GPa) being close to
human bone
• modified easily by incorporation of other materials
 For example; incorporation of carbon fibers can increase the
elastic modulus up to 18 GPa
• very limited inherent osteoconductive properties
• methods to improve the bioactivity of PEEK including
 coating PEEK with synthetic osteoconductive hydroxyl apatite
 increasing its surface roughness and chemical modifications
 incorporating bioactive particles
99

100. 100

101. Composites
• Combination of polymer and other synthetic biomaterial.
• They have advantages that properties can be altered to suit
clinical application
• Have a promising future
101

102. Surface characterization and
preparation of implants
102

103. SURFACE TOPOGRAPHY
• Surface topography relates to the degree of roughness of the
surface and the orientation of surface irregularities.
 Types of Surface Roughness
2) Microsurface Roughness.
a) Abraded
TiO2
Al203
b) Acid Etched
HCl
H2SO4
c) Coating
TPS
HA
103
1) Macrosurface
Roughness.
Screw
Hollow basket
Core Vent

104. • Wennerberg and co workers
1.Roughness
a.Smooth; <0.5μm
b. Rough: 0.5-3 μm
1. minimally rough: 0.5-1 μm
2. Intermediately rough: 1-2 μm
3. Rough: 2-3 μm
2. Texture
a.Concave : HA coating & ti plasma sprayed
b.Convex : Etching & blasting
104

105. ADVANTAGES OF INCREASED
SURFACE ROUGHNESS
1) Increased surface areas of the implant adjacent to bone.
2) Improved cell attachment to the bone.
3) Increased bone present at implant surface.
4) Increased biomechanical interaction of the implant with bone.
105

106. Passivation
• Refers to enhancement and stabilization of oxide layer to
prevent corrosion
• Performed by immersion in 40% nitric acid
• Used for Co Cr implant
106

107. Acid etching
• In this the surface is treated with strong acids like
hydrochloric acid, sulfuric acid and nitric acid.
• Results in clean surface with roughened texture for increased
tissue adhesion
• Sa – 0.3-1 μm
• Amorphous oxide layer - 10 μm thick.
107

108. Sand blasting
• Sand particles are used to get a roughened surface texture
which
– increases the surface area
– increases the attachment strength at the bone implant
interface
 In this approach, the implant surface is bombarded with
particles of aluminum oxide (Al2O3) or titanium oxide (TiO2),
and by abrasion, a rough surface is produced with irregular
pits and depressions .
108

109. • Roughness depends on particle size, time of blasting,
pressure, and distance from the source of particles to the
implant surface.
• Blasting a smooth Ti surface with Al2 O3 particles of 25 μm,
75 μm, or 250 μm produces surfaces with roughness values of
1.16 to 1.20, 1.43, and 1.94 to 2.20, respectively.
109

110. SANDBLASTED AND ACID ETCHED
(SLA)
• Recently, a new surface was introduced that was sandblasted
with large grit and acid-etched (SLA, Straumann).
• This surface is produced by a large grit (250 to 500 μm)
blasting process, followed by etching with hydrochloric-
sulfuric acid.
• The average ra for the acid-etched surface is 1.3 μm, and the
sandblasted and acid-etched surface, ra= 2.0 μm.
110

111. 111
SAND BLASTED IMPLANT
SAND BLASTED AND ACID ETCHED
IMPLANT

112. • Wennerberg et al 1996. superior bone fixation and bone
adaptation
• Orsini Z et al (2000)
 Acid etching with NaOH, Aq. Nitric acid, hydrofluoric acid.
Decrease in contact angle by 10⁰ – better cell attachment.
 increase in osseointegration by removal of aluminium
particles (cleaning).
112

113. POROUS
• Porous sintered surfaces are produced when spherical
powders of metallic or ceramic material becomes a coherent
mass with the metallic core of the implant body.
• Lack of sharp edges is what distinguishes these from rough
surfaces.
• Porous surfaces are characterized by pore size, pore shape,
pore volume, and pore depth, which are affected by the size
of spherical particles and the temperature and pressure
conditions of the sintering chamber.
113

114. 114

115. POROUS SURFACE: ADVANTAGES
1. A secure, 3-D interlocking interface with bone.
2. Predictable and minimal crestal bone remodelling.
3. Greater surgical options with shorter implant lengths.
4. Shorter initial healing times and
5. Porous coating implants provide the space, volume for cell
migration and attachment, thus support contact osteogenesis.
115

116. 116
SURFACE OF A POROUS
TITANIUM ALLOY IMPLANT
FIBROBLASTS CULTURED
FOR 24 HOURS ON THE
SURFACE OF A POROUS
TITANIUM ALLOY
IMPLANT.

117. Surface coatings
• Implant surface may be covered with porous
coatings which increases
• Surface area and roughness
• Attachment strength at bone implant interface
• Biocompatibility
• Several coating techniques exist .
• Plasma sprayed technique is used most commonly
• Two types
– Plasma sprayed titanium
– Plasma sprayed hydroxyapatite
117

118. Plasma sprayed Titanium
• Described by Schroeder et al ( 1976)
• Titanium particles with mean size of 0.05 to 0.1 are heated in
plasma flame
• Plasma flame consists of electric arc through which argon gas
stream passes
• A magnetic coil directs the stream of molten titanium particles,
which is then sprayed on the titanium surface
118

119. • Thickness of coating 0.04 to 0.05 mm
• Sprayed coating exhibits round pores that are interconnected
,pore diameter(150-400μm)
119

120. Advantages
• Increases the surface area by 600%
• Increases attachment of implant to bone
• Increase load bearing capacity
Disadvantages
• Cracking and exfoliation of the coating due to stresses
,sterilization and insertion.
• Metallic particles found in perimplant tissue
120

121. 121

122. Titanium Plasma Sprayed Coating (TPS)
122
Steinemann 1988, Tetsch 1991- 6-10 times increase surface area.
Roughness Depth profile of about 15mm

123. Plasma sprayed hydroxyapatite
• Herman 1988
• Crystalline HA powder is heated to a temperature of 12000 to
16000 °C in a plasma flame formed by a electric arc through
which an argon gas stream passes .
• HA particle size is approximately 0.04mm
• The particles melt and are sprayed on to the substrate ,they fall
as drops and solidify
• Round interconnected pores are formed
123

124. • Coating bonds to substrate by mechanical interlocking
• Coating of 0.05 mm is formed
• There is a lot of controversy regarding the ideal coating
thickness
• Studies have shown that:
• Fracture occurred in coatings more than 0.1mm in thickness
• Whereas bioresorption was unacceptably rapid with coatings
less than 0.03mm in diameter
• Ideal coating thickness of 0.05 mm is recommended
124

125. Advantages
• Permits direct chemical bonding of the bone to implant surface
• Increases surface area
• Stronger bone to implant interface
• Increases corrosion resistance and biocompatibility
• Decreases healing period of implants
• Bone adjacent to coated implant is better organized and
mineralized ,thus increased load bearing capacity
125

126. Disadvantages
• Studies have shown that coatings exhibit several drawbacks:
• Coatings have shown to undergo gradual resorption over time
and subsequent replacement with bone (creeping
substitution)
• Studies have shown that this resorption results in decreased %
of bone implant contact area over time
• Due to resorption of the coating ,biocompatibility of exposed
and altered core substrate becomes questionable
126

127. • Bond strength between coating and the substrate seems to be
inadequate to resist shear stresses
• Due to this weak bond ,coating is susceptible to removal or
fracture during
– sterilization
– insertion in dense bone
• Due to roughened surface, coating often shows adherence of
microorganisms on their surface
127

128. Indications
• HA coated implants can be used in
• D3 and D4 bone which show poor bone density and structure
as they
– Increase bone contact levels
– Forms stronger bone implant interface
– Increases survival rates
• Fresh extraction sites as they promote
– Faster healing
– Greater initial stability
• Newly grafted sites where implants are to be placed eg sinus
lifts 128

129. 129

130. Electrophoretic deposition
• Mineral ions that need to be coated on the implant surface are
dissolved in the electrolytic bath
• Current flows through electrolyte leading to formation of
surface coating
130

131. Sol gel deposition ( Dip Coating )
• Coating is applied on substrate by dipping into a solution HA
powder and ethanol in dip coating apparatus and finally
sintering it
131

132. 132
SEM micrographs of HA coatings (via SOL 2) on Ti-6Al-4V substrates after heating at 840°C
((a) macroscopic appearance, (b) porous microstructure of the HA coat layer, and (c) cross-
sectional view of the HA coating layer).

133. Alternative surface coating
techniques
133

134. Hot isostatic pressing
• In this the HA powder is mixed with water and sprayed on the
substrate
• It is then hot pressed at 850°C
• The coating produced is dense
having increased shear strength
134

135. Pulsed laser deposition
• Alternative procedure to obtain HA coating
• Nd YAG laser beam is used to spray HA on the preheated
substrate in a vacuum chamber
• HA coating of greater crystallinity is obtained that shows
decreased resorption
135

136. 136
SEM x 70 SEM x 300
SEM x 300

137. Other methods of calcium phosphate
deposition
1. Sputter deposition
 Deposition of bioceramic thin films (based on ca p systems)
 Advantages ; improves adhesion bw substrate and the
coating;Higher removal torque compared to uncoated
 Disadvantage: time consuming
137

138. 2. Biomimetic precipitation
 Calcium phosphate – biomimetically ppt – surface of implant-
early ingrowth of bone into porous surfaces
 20-25 μm thick coating
 Advang ; early bone ingrowth
 Failure due to debris coating, macrophage infiltration and
fibrous tissue encapsulation – wont occur as with plasma
sprayed HA coating
138

139. 3. Bioactive glass coating
 Made on alumina,SS, Co Cr Mo alloy, fiber reinforced
composite, titanium and ti-6Al-4Va
 Created with infrared lasers and reactive plasma spraying
 Higher osseointegration
 Higher removal torque
139

140. Recent advances in surface coatings
Zi unite: metal free ceramic; porous surface based on
zirconia
Bioactive glass coated: bioactive silicate glass particles
are sprayed over the implants by enameling procedure
Protein coated: recombinant human bone
morphogenic protein is coated over implants
140

141. Corundum blasting: creates deep pits in the
implant surface that can act as retentive pockets
for new bone
PVD coating: physical vapor deposition such as
titanium nitride / zirconium nitride are applied
for cosmetic reasons on implant collar and
abudment for wear protection
141

142. Regenerating periodontal ligament
• Kawaguchi et al (2004) used autologous bone marrow (MSC)
in combination with allocollagen to regenerate periodontal
ligament in experimental grade III defects in dogs.
• One month after implantation, there was regeneration of
cementum, periodontal ligament, and alveolar bone.
142

143. Bio- Tooth Generation
• Murine stem cells when transferred into renal capsules
resulted in development of tooth structure and associated
bone.
• Teeth have also been engineered ectopically and transplanted
into the jaw with some success
• Recently some researchers developed a bioroot into which a
post and crown were placed.
143

144. • Complete tooth regeneration can also be accomplished by
placing the stem cells into a mold of tooth crown which is
made of enamel-like substance with a scaffold material
• The stem cells then start looping blood vessels through this
scaffold to enable its implantation elsewhere in the body until
mature teeth are formed, following which these teeth will be
extracted and implanted in the oral cavity
144

145. Sterilization
145

146. • Today in most cases manufacturers guarantees precleaned and
presterilized implants ,ready to be inserted
• In case the implants needs to be resterilized conventional
sterilization techniques are not satisfactory
• Steam sterilization
– should not be used as it results in contamination of surfaces
with organic substances
• Dry heat sterilization
– Also leaves organic and inorganic surface residues
146

147. Radio frequency glow discharge technique (RFGDT) or Plasma
cleaning
• Most frequently used methods
• In this, material to be cleaned is bombarded by high energetic
ions formed in gas plasma in a vacuum chamber
• Removes both organic and inorganic contaminants
147

148. UV light sterilization
– Recently UV light sterilization is also being used
– It cleans the surface and also increase the surface energy
Gamma radiation
• Method used to sterilize pre packaged dental implants.
• Radiation dose exceeding 2.5 megavolts is given
• Components remain protected, clean and sterile until
packaging is opened, within sterile field of surgical procedure
148

149. Conclusion
149

150. • Various implant alter response of surrounding tissue to its
placement – osseointegration
• More importantly the surface characteristics determines the
predictability and success of osseointegration
150

151. References
• Implant Dentistry -Carl E Misch.
• Sciences of dental materials - Anusavise.
• Materials used in dentistry – S Mahalekshmi
151

152. Cross references
• Cells and Materials Vol. 9, No. 1, 1999 (pages 1-19)
• Int J Oral Maxillofac Implants 2000;15:779–784
• Int J Biomed Sci 2015; 11 (3): 113-120
• J Int Clin Dent Res Organ 2015;7:148-59
• Journal of Prosthodontics 17 (2008) 357–364
• Int J Oral Maxillofac Implants 2016;31:555–562.
152

153. 153