titanium and titanium alloys. / academy of fixed orthodontics


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  • titanium and titanium alloys. / academy of fixed orthodontics

    1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
    2. 2. www.indiandentalacademy.com
    3. 3. Metals have been used as Biomaterials for many centuries. Around 1565 gold plate was reported to be used to repair cleft palate defects. Gold alloys and their substitutes are formed by a casting process developed by Taggart in 1907. Since then, cast gold restorations have been routinely used in clinical dentistry. www.indiandentalacademy.com
    4. 4. With advances in dental porcelain in the 1960s and the significant increase in the price of gold in the 1970s, alternative alloys such as palladium alloys and base metal alloys, were developed. The allergenic and carcinogenic properties of base metal alloys used in dentistry especially nickel and beryllium-based alloys, have fueled controversy. www.indiandentalacademy.com
    5. 5. The evolution of titanium (Ti) applications to medical and dental implants has dramatically increased in the past few years because of titanium’s excellent biocompatibility corrosion resistance and desirable physical and mechanical properties. www.indiandentalacademy.com
    6. 6. Titanium has become a material of great interest in prosthodontics in recent years. A growing trend involves the use of titanium as an economical and biocompatible replacement for existing alloys for fixed and removable prostheses. However, long term of titanium casting, joining, and porcelain bonding have to be evaluated before this wonder metal can be used routinely in clinical dentistry. www.indiandentalacademy.com
    7. 7. www.indiandentalacademy.com
    8. 8. www.indiandentalacademy.com
    9. 9. www.indiandentalacademy.com
    10. 10. Most important deterrent to the use of Ti in dental application is the fact that it is difficult and dangerous to cast, The metal oxidizes so rapidly at elevated temperature that an almost explosive reaction may occur. So that it needs to cast titanium alloy in oxygen atmosphere (vacuum or argon) to prevent excessive oxidation. www.indiandentalacademy.com
    11. 11. www.indiandentalacademy.com
    12. 12. The physical and mechanical properties of pure Ti and Ti alloys can be greatly varied with the addition of small traces of other elements such as oxygen, iron, and nitrogen. Commercially pure titanium, is available in four different grades www.indiandentalacademy.com
    13. 13. ASTM 1 to 1V - based on the incorporation of small amounts of oxygen, nitrogen, hydrogen, iron, and carbon during purification procedure. ASTM committee on materials for surgical implants recognizes four grades of commercially pure titanium and two titanium alloys. www.indiandentalacademy.com
    14. 14. www.indiandentalacademy.com
    15. 15. The two alloys are Ti-6Al-4V and Ti-6A1-4V extra low interstitial (ELI). Commercially pure titanium is also referred to as unalloyed titanium. All six of these materials are commercially available as dental implants. www.indiandentalacademy.com
    16. 16. Ti-6A1-4V Several alloys of titanium are used in dentistry. Of these alloys, Ti 6Al-4V is the most widely used. At room temperature, Ti-6A1-4V is a two- phase α+β alloy. At approximately 975°C, an allotropic phase transformation takes place, transforming the microstructure to a single phase BCC β-alloy. www.indiandentalacademy.com
    17. 17. www.indiandentalacademy.com
    18. 18. Thermal treatments dictate the relative amounts of the α and β phases and the phase morphologies and yield a variety of microstructures and a range of mechanical properties. www.indiandentalacademy.com
    19. 19. www.indiandentalacademy.com
    20. 20. www.indiandentalacademy.com
    21. 21. An extremely reactive metal, titanium forms a tenacious oxide layer that contributes to its biocompatibility and electro chemical passivity. This stable oxide with a thickness on the order of nanoseconds, and it repassivates in a time on the order of nanoseconds. www.indiandentalacademy.com
    22. 22. However, titanium-based alloys and alloys containing titanium are prone to gap corrosion and discoloration in the oral cavity. Therefore titanium is electrochemically inactivated by the addition of small percentage of a metal of platinum group to improve the anticorrosion properties of the alloys by inducing a firm passive coating. www.indiandentalacademy.com
    23. 23. Palladium was chosen among the platinum group metals, as it prevents corrosion of titanium by the addition of only a small amount (0.15%). www.indiandentalacademy.com
    24. 24. www.indiandentalacademy.com
    25. 25. The lightly held 3d² and 4s² electrons are highly reactive and rapidly form a tenacious oxide that is responsible for the metal’s biocompatibility. The remaining electrons are relatively stable and tightly bound. www.indiandentalacademy.com
    26. 26. There are three general types of titanium base alloys, such as alpha alloys, alpha-beta alloys, and beta alloys, according to the predominant room temperature phases present in the microstructure. At temperatures upto 882°C, pure titanium exists as hexagonal close- packed atomic structure (alpha phase). www.indiandentalacademy.com
    27. 27. Above that temperature, pure titanium undergoes a transition from hexagonal close- packed structure (alpha) to a body-centered cubic structure (beta). The metal melts at 1665°C. A component with a predominantly β-phase is stronger than a component with an α-phase microstructure. www.indiandentalacademy.com
    28. 28. Alloying elements are added to stabilize one or the other of these phases by either raising or lowering the transformation temperatures. The elements oxygen. aluminium, carbon, and nitrogen stabilize the alpha phase of titanium because of their increased solubility in the hexagonal close-packed structure. www.indiandentalacademy.com
    29. 29. For example, in Ti-6A1-4V aluminium is an a stabilizer, which expands the a phase field by increasing the (α+β) to β transformation temperature. Elements that stabilize the beta phase, include manganese, chromium. iron and vanadium. They expand the β -phase field by decreasing the (α+β ) to β transformation temperatures. www.indiandentalacademy.com
    30. 30. Vanadium stabilizes the beta phase of Ti-6A1-4V alloy, so that it exists as a combination of alpha and beta phases. The combination of phases gives the alloy strength. www.indiandentalacademy.com
    31. 31. The ELI alloys are sometimes used. “Extra low interstitial” describes the low levels of oxygen dissolved in interstitial sites in metal. With lower amounts of oxygen and iron residuals in the ELI alloy, ductility is improved slightly. www.indiandentalacademy.com
    32. 32. In general, alpha titanium is weldable, but difficult to form or work with at room temperature. Beta titanium, however, is malleable at room temperature and is thus used in orthodontics. The (α+β) alloys are strong and formable but difficult to weld. www.indiandentalacademy.com
    33. 33. Thermal and thermo chemical treatments can refine the post cast microstructures and improve properties. www.indiandentalacademy.com
    34. 34. Density 4.5g/cm³ (considerably less than gold or Ni-Cr or Co-C r alloys) Because of the light weight of the titanium and its strength-to-weight ratio, high ductility, and low thermal conductivity would permit design modifications in Ti restorations and removable prostheses, resulting in more functional and comfortable use. www.indiandentalacademy.com
    35. 35. The low cost of titanium raw material (USD 22 to 27 per kg) makes titanium material attractive for dental prostheses. www.indiandentalacademy.com
    36. 36. The environmental resistance of titanium depends primarily on a thin, tenacious, and highly protective surface oxide film which is about 2O - 50 A°. Titanium and its alloys develop stable surface oxides with high integrity, tenacity and good adherence. www.indiandentalacademy.com
    37. 37. The surface oxide of titanium will, if scratched or damaged, immediately reheal and restore itself in the presence of air or water. The protective oxide film on titanium mainly Ti02 (rutile), is stable over a wide range of pHs, potentials, and temperatures, and is specially favoured as the oxidizing character of the environment increases. www.indiandentalacademy.com
    38. 38. For this reason, titanium generally resists mild reducing, neutral, and highly oxidizing environments upto reasonably high temperatures. It is only under highly reducing conditions that oxide film breakdown and resultant corrosion may occur. These conditions are not normally found in the mouth. www.indiandentalacademy.com
    39. 39. The Coefficient of thermal expansion is a most important factor in bonding of an alloy to porcelain. The difference in the coefficient of the expansion between the alloy and porcelain should be within ±1x10-6 /°C to obtain sufficient bonding strength. www.indiandentalacademy.com
    40. 40. Coefficients of thermal expansion of pure titanium and Ti-6A1-4V are 10.37 x 10-6 and 12.43 x 10-6 /ºC, respectively, which are considerably smaller than those of commercial porcelain materials which is about 14 x l0-6 /°C. www.indiandentalacademy.com
    41. 41. Titanium is the most corrosion resistant metallic material for implants in present use, but, paradoxically, the self formed protective oxide film on titanium can be affected by excessive use of the commonest preventive agents in dentistry, prophylactic polishing and topical fluoride app1ications. www.indiandentalacademy.com
    42. 42. Adhesion of titanium to methacrylate based polymer materials can be increased by plasma treatment. www.indiandentalacademy.com
    43. 43. MECHANICAL PROPERTIES www.indiandentalacademy.com
    44. 44. The mechanical properties of titanium and its alloys surpass the requirements for an implant material. Orthopaedic and dental implants require strength levels greater than that of bone and an elastic modulus close to that of bone. www.indiandentalacademy.com
    45. 45. The most commonly used and important titanium alloy is Ti-6A1-4V, because of its desirable proportion and predictable producibility. The ultimate tensile strength of spongeous bone is about 83 MPa and cortical bone is about 117 MPa. www.indiandentalacademy.com
    46. 46. www.indiandentalacademy.com
    47. 47. www.indiandentalacademy.com
    48. 48. It is important to note that while the modulus of elasticity of cp grade 1 titanium to cp grade 1V titanium ranges from 102 to 104 GPa (a change of only 2%), the yield strength increases from 170 to 483 MPa (a gain of 180%). Reasons for the changes are related chiefly to oxygen residuals in the metal. www.indiandentalacademy.com
    49. 49. The characteristic trend of increasing strength with relatively constant modulus continues when comparing cp titanium with titanium alloys. The elastic modulus of the alloys is slightly higher (113 MPa compared with 104 MPa of cp grade 1V titanium), but the yield strength increases over 60% to 795 MPa for ELI alloys and 860 MPa for Ti-6A1-4V alloys. www.indiandentalacademy.com
    50. 50. Titanium has poor shear strength and wear resistance, however making it unsuitable for articulating surface or bone screw applications. www.indiandentalacademy.com
    51. 51. Compared with Co-Cr-Mo alloys, titanium alloy is almost twice as strong and has half the elastic modulus. Compared with 316L stainless steel, the Ti-6A1-4V alloy is roughly equal in strength, but again, it has half the modulus. www.indiandentalacademy.com
    52. 52. Strength is beneficial because materials better resist occlusal forces without fracture or failure, Lower modulus is desirable because the implant biomaterial better transmits forces to the bone. www.indiandentalacademy.com
    53. 53. www.indiandentalacademy.com
    54. 54. Titanium and its alloys are inert, have excellent biocompatibility and predictability. The non-alloyed titanium elicits an acute inflammatory response with an increased number of leukocytes around the implant. However, the number of inflammatory cells decrease during the first week and fibroblasts become the major cells in the interfacial tissue. www.indiandentalacademy.com
    55. 55. During the first week the implant is surrounded by a fluid space that contains proteins, erythrocytes. inflammatory cells and cell debris. One week after insertion of implants, the size of the fluid space reduces in non-alloyed titanium, for example, ion implanted titanium. www.indiandentalacademy.com
    56. 56. The inflammatory cells present in this space seldom adhere to the surface of the non- alloyed titanium and do not appear activated. Non-alloyed titanium implants are surrounded by a thin layer of orderly arranged collagen and elongated fibroblasts. www.indiandentalacademy.com
    57. 57. Titanium also provides a surface suitable for the proliferation of several differentiating tissues. Non-alloyed titanium fixtures which are inserted in knee-joints after drilling through the cartilage or synovial tissue heal within the joints and a direct contact with the subchondral bone is established 4 to 6 weeks after insertion. www.indiandentalacademy.com
    58. 58. Non-alloyed titanium can also be used intra- articularly as it causes no inflammation in the synovial tissue. Plaque accumulation of titanium or hydroxylapatite (HA) coated titanium is less than on natural teeth because of its high surface energy. www.indiandentalacademy.com
    59. 59. Bone formation and its maturation occurs faster on HA coated Ti implants than on non- coated Ti implants. Since enhanced bone growth preceedes by rapid clotting, so the clotting occurs faster on the HA-coated Ti implants than on non-coated titanium implants. www.indiandentalacademy.com
    60. 60. www.indiandentalacademy.com
    61. 61. Lost wax casting www.indiandentalacademy.com
    62. 62. www.indiandentalacademy.com
    63. 63. This is a the recently developed investment for casting titanium inlay, crown and bridge. Binder - calcia Refractory -Zirconia www.indiandentalacademy.com
    64. 64. There are 2 types of Calcia and mixing liquid. 1. Saturation type (total expansion 2 ± 3%) 2. Delayed expansion type Properties 1. Total thermal and setting expansion found was -1 .5 - 2.5% 2. The maximum thermal expansion is found at - 900 - 1200°c www.indiandentalacademy.com
    65. 65. www.indiandentalacademy.com
    66. 66. Cp titanium - vacuum casting www.indiandentalacademy.com
    67. 67. Pure titanium melts at 3,035°F (1,668°C) and reacts readily with conventional investments and gases like oxygen, nitrogen and carbon. In addition because of its low specific gravity, titanium flows less easily that gold alloy when cast in centrifugal casting machine. Therefore, it must be cast and soldered with special equipment in oxygen free environment. www.indiandentalacademy.com
    68. 68. New alloys of titanium with nickel that can be cast by more conventional. methods are being developed. They release verity little ionic nickel and bond well to porcelain. New methods of forming titanium crowns and copings by CAD/CAM technology avoids the problem of casting altogether. www.indiandentalacademy.com
    69. 69. Lost-wax casting is one of the most widely used methods for the fabrication of metallic restorations outside of the mouth. www.indiandentalacademy.com
    70. 70. Three different types of specially designed Ti casting systems are presently available namely A pressure / vacuum casting system with separate melting and casting chamber (Castmatic, Dentaurum) . www.indiandentalacademy.com
    71. 71. A pressure /vacuum system with one chamber for melting and casting (Cyclare, J Morita) and vacuum / centrifuge casting system (Tycast. Jeneric / Penetron, and Titaniumer, Ohara) www.indiandentalacademy.com
    72. 72. The market price for each system ranges from USD 20,000 to 30,000. www.indiandentalacademy.com
    73. 73. A new casting machine for casting of titanium and Ni-Ti alloys was developed by H.Hamanaka et al in 1989. The machine consists of an upper melting chamber and a lower casting chamber with an argon arc vacuum pressure system. www.indiandentalacademy.com
    74. 74. www.indiandentalacademy.com
    75. 75. The main features that have been developed are as follows: 1) The melting and casting chambers are evacuated to a higher degree by means of an oil diffusion pump. 2) In the casting chamber, a heater has been placed to control the mold temperature; it may be moved up and down with use of the lever outside the chamber. www.indiandentalacademy.com
    76. 76. 3) Two types of copper crucibles have been developed - one a split type and the other a tilting type that are changeable. 4) A device for direct suction has been placed at the bottom of the mold for improved castability. 5) The vaccum tank and the compressed argon gas tank have been set to operate more efficiently. www.indiandentalacademy.com
    77. 77. 6) With use of the water-cooled electrode and double D.C. electric sources, the capacity for melting alloy is about 100g. 7) A new control system was developed. In this system, after a mold and metal are set on the machine, the upper and lower chambers are evacuated. www.indiandentalacademy.com
    78. 78. Then, argon gas is fed into the upper chamber when the “start” button is pushed, and an electric arc begun automatically at the given pressure. After the alloy melts down, the new control system can be started when the “cast” button is pushed. www.indiandentalacademy.com
    79. 79. At first. the upper chamber is exhausted for 0 to 1.0 seconds , and then the copper crucible splits or tilts to drop the molten metal. From 0.01 to 0.05 seconds later, the compressed argon gas is injected into the upper chamber. This control system works automatically in accordance with a given program. www.indiandentalacademy.com
    80. 80. Advantages of this machine are: As gas in the mold is removed by the mold being heated under a high vacuum, the reaction between the molten metal and the mold decreases. www.indiandentalacademy.com
    81. 81. The new control system and the two types of crucibles developed proved very useful for prevention of internal macro-defects in castings and for improvement of castability. Mechanical properties and castability of pure titanium are improved. www.indiandentalacademy.com
    82. 82. www.indiandentalacademy.com
    83. 83. The initial application of titanium to dentistry was machined Ti dental implants. As an alternative to lost-wax casting, the Procera system (Nobelpharma) with titanium machining has been developed by Andersson et al for the fabrication of unalloyed titanium crowns and fixed partial dentures. www.indiandentalacademy.com
    84. 84. The external contour of a titanium crown or coping can be shaped out of a solid piece of titanium by a milling machine, while the internal contour of the titanium crown is spark eroded with a carbon electrode. Single titanium crowns can be fabricated with this method, and multiple unit fixed prostheses can be made by laser welding individual units together. www.indiandentalacademy.com
    85. 85. www.indiandentalacademy.com
    86. 86. Information on the marginal fit of titanium crowns was unavailable until quite recently. Meyer and Schafers evaluated cast titanium inlay and partial veneer crowns. Heterogeneous results did not satisfactorily withstand comparison to conventional methods. The authors questioned the clinical application of titanium casting. www.indiandentalacademy.com
    87. 87. Ida et al reported that, in more than 100 cast titanium crowns made, the fit was inferior to that of silver-palladium crowns but superior to that of nickel-chromium crowns. The criteria used to determine fit were not described. www.indiandentalacademy.com
    88. 88. Blackman et al examined the fit of 20 cast titanium copings divided into two equal groups with 45 and 90 degree shoulders. The surface of marginal discrepancy was greatest with the 90 degree configuration. Casting shrinkage occurred particularly along the horizontal axis in the plane of the shoulder. It was concluded that Ti crown copings can be cast with acceptable fitting accuracy. www.indiandentalacademy.com
    89. 89. www.indiandentalacademy.com
    90. 90. Different methods to join titanium have been investigated. Yamagishi et al examined the mechanical properties of Nd:YAG laser welds of titanium plates (1mm thick) and found that there is a significant relationship between three-point bending strength and the irradiation atmosphere, the irradiation intensity, and the combination of atmosphere and intensity. www.indiandentalacademy.com
    91. 91. Laser welding is effective when performed in an argon environment. At the same time, the results are markedly different with various intensities of irradiation. www.indiandentalacademy.com
    92. 92. Roggensack et al studied the bending fatigue behavior of titanium joined by laser and plasma welding. No significant differences in fatigue strength could be found between the two methods of welding. Extreme loads led to earlier fatigue in the plasma welded specimens. www.indiandentalacademy.com
    93. 93. www.indiandentalacademy.com
    94. 94. Even after the recent developments and improvements in casting technology, the challenge of using titanium casting for prosthesis still presents major difficulties. The mechanical properties of cast titanium differ significantly from those of the parent metal. www.indiandentalacademy.com
    95. 95. Also, the outer 100 to 200 micro meter of the surface has greater hardness and reduced ductility than the core material. Titanium’s high-fusing temperature and chemical activity are considered primarily responsible for these casting problems. www.indiandentalacademy.com
    96. 96. So new techniques like spark erosion (electro erosion) and machine duplication termed “copymilling” have been introduced. Ti-6A1-4V is one of the superplastic alloys that exhibits excellent elongation (more than 1,000%) at a temperature of 800°C to 900°C. www.indiandentalacademy.com
    97. 97. This super plasticity deformation is obtained by grain-boundary sliding or dislocation with a fine-grain structure (diameter 4 to 10 micro meters). Ti-6A1-4V is applied to denture framework fabrication. www.indiandentalacademy.com
    98. 98. The retention of acrylic resin to the titanium base is an important consideration. Noriyuki Wakabayashi et al confirmed that bond strength between a denture-base resin containing an adhesion-promoting monomer and Ti-6Al-4V alloy that had been airborne particle abraded using aluminum oxide particles was statistically equivalent to that between the same resin and a cobalt- chromium alloy casting. www.indiandentalacademy.com
    99. 99. www.indiandentalacademy.com
    100. 100. www.indiandentalacademy.com
    101. 101. Commercially pure (cp) titanium and titanium alloys containing aluminum and vanadium, or palladium (Ti-O Pd), should be considered potential future materials for removable partial denture frameworks. www.indiandentalacademy.com
    102. 102. Their versatility and well-known biocompatibility are promising; however, long-term clinical studies are needed to validate their potential usefulness. Currently, when cp titanium is cast under dental conditions, the material properties change dramatically. www.indiandentalacademy.com
    103. 103. During the casting procedure, the high affinity of the liquid metal for elements such as oxygen, nitrogen, and hydrogen results in their incorporation from the atmosphere. www.indiandentalacademy.com
    104. 104. The usefulness of Ti as a metal for removable partial denture (RPD) and complete-denture frameworks has been evaluated. Removable partial denture frameworks that were 0.70 mm thick had better castability than did 0.35 mm thick RPD frameworks, suggesting that if Ti is used for RPD frameworks, a thicker wax pattern is needed than is used in casting of a conventional denture framework with Co-Cr alloys. www.indiandentalacademy.com
    105. 105. In the same study, Ti commonly failed to cast perfect mesh specimens, but Co-Cr alloys did not have this problem. www.indiandentalacademy.com
    106. 106. www.indiandentalacademy.com
    107. 107. The biocompatibility of titanium is well known in its clinical application in dental and craniofacial implants. Its use has been recently extended to include metal ceramic crowns. Titanium copings can be fabricated by casting or by machine milling. www.indiandentalacademy.com
    108. 108. The low coefficient of thermal expansion (CTE) of titanium (about 9 x 10-6 /ºC) compared to those of the conventional low- fusing porcelains (about 13 x 10-6 /°C) raised the concern of thermal compatibility. www.indiandentalacademy.com
    109. 109. Porcelains manufactured to bond to titanium are currently commercially available. The Procera porcelain (Procera, Nobelpharma: Goteborg, Sweden) was formulated for machine-milled crowns processed through the Procera technique, while the Duceratin porcelain (Degussa, South Plainfield NJ) was formulated for cast titanium crowns. www.indiandentalacademy.com
    110. 110. The strength of porcelain-fused-to-metal structures is related to mechanical properties of the metal framework, the veneering porcelain, the porcelain-metal interface, and their interactions. www.indiandentalacademy.com
    111. 111. www.indiandentalacademy.com
    112. 112. There is abundant literature on the adherence of oxides formed at high temperatures on gold alloys, Ni-Cr, and Co-Cr alloys. The oxidation mechanisms and reasons for development of a non-adherent oxide layer while not perfectly understood, are well characterized for Ti and its alloys. www.indiandentalacademy.com
    113. 113. Kirmura et al reported the oxidation effects of the porcelain-titanium interface reaction. They concluded that the conventional degassing procedure is not suitable for porcelain-titanium restorations and that the cycle should be below 800°C to minimize the metallic oxide formation on the Ti surface. www.indiandentalacademy.com
    114. 114. www.indiandentalacademy.com
    115. 115. The use of metals for implants dates back to ancient times. It was not until the 1930s, however, that improvements in metal technology led to an era of expanded surgical use of metallic implants. www.indiandentalacademy.com
    116. 116. www.indiandentalacademy.com
    117. 117. A successful long-term implant requires biocompatibility, toughness, strength, corrosion resistance, wear resistance, and fracture resistance. Titanium alloys of interest to dentistry exist in three forms: alpha, beta, and alpha-beta. These types originate when pure titanium is heated, mixed with elements such as aluminium and vanadium in certain Concentration and cooled. www.indiandentalacademy.com
    118. 118. Titanium and its alloys are important in dental and surgical implants because of their high degree of biocompatibility, their strength. and their corrosion resistance. www.indiandentalacademy.com
    119. 119. Pure titanium, theoretically, may form several oxides. Among these . TiO, Ti02 and Ti2 03. Of these, TiO2 is the most stable and therefore the most commonly used under physiologic conditions. These oxides form spontaneously on exposure of Ti to air. www.indiandentalacademy.com
    120. 120. When an implant is introduced into the body, complex reactions begin to take place at the oxide/bio environment interface. The oxide film grows as ions diffuse outward from the metal and inward from the environment. The oxide that forms in the body may therefore, be somewhat different than that which forms in air. www.indiandentalacademy.com
    121. 121. The rate of formation and composition of this film is important. Titanium, both as a pure metal and as an alloy, is easily passivated, forming a stable Ti02 surface oxide that makes the metal corrosion resistant. This oxide will repair itself instantaneously on damage such as might occur during insertion of an implant. www.indiandentalacademy.com
    122. 122. The normal level of Ti in human tissue is 50 ppm. Values of 100 to 300 ppm are frequently observed in soft tissues surrounding Ti implants. At these levels, tissue discoloration with Ti pigments can be seen. www.indiandentalacademy.com
    123. 123. This rate of dissolution is one of the lowest of all passivated implant metals and seems to be well tolerated by the body. The clinical significance of this data is substantiated by more than 20 years of clinical experience with pure Ti and Ti 6A1 4V alloys. www.indiandentalacademy.com
    124. 124. www.indiandentalacademy.com
    125. 125. This reactive group of metals and alloys (with primary elements from reactive group metallic substances) form tenacious oxides in air or oxygenated solutions. Titanium (Ti) oxidizes (passivates) upon contact with room temperature air and normal tissue fluids. www.indiandentalacademy.com
    126. 126. This reactivity is favourable for dental implant devices. In the absence of interfacial motion or adverse environmental conditions, this passivated (oxidized) surface condition minimizes biocorrosion phenomena. In situations where the implant would be placed within a closely fitting receptor site in bone, areas scratched or abraded during placement would repassivate in vivo. www.indiandentalacademy.com
    127. 127. This characteristic is one important property in vivo. This characteristic is one important property consideration related to the use of titanium for dental implants. Some reports show that the oxide layer tends to increase in thickness under corrosion testing and that breakdown of this layer is unlikely in aerated solutions. www.indiandentalacademy.com
    128. 128. Bothe et al. studied the reaction of rabbit bone to 54 different implanted metals and alloys and showed that titanium allowed bone growth directly adjacent to the oxide surface. Leventhal further studied the application of titanium for implantation. Beder et al., Cross et al., Clarke et al., and Brettle were able to expand indications of these materials. In all cases titanium was selected as the material of choice because of its inert and biocompatible nature paired with excellent resistance to corrosion. www.indiandentalacademy.com
    129. 129. www.indiandentalacademy.com
    130. 130. Proper implant configuration can help effectively control or alter force transmission to remain within physiologic limits of health. The basic metallurgic properties of titanium, particularly its ductility, allow it to be strong and malleable, permitting fabrication of optimal dental implant configurations with little compromise. www.indiandentalacademy.com
    131. 131. Relatively high strength is required in a prosthetic metal so it can withstand the mechanical forces and stresses placed on it during short-and long-term function without undergoing unintended permanent deformation or fracture. www.indiandentalacademy.com
    132. 132. However, a lower toughness specific to deformation is desired so that one can shape the implant during the manufacturing process, and when appropriate, bend it to accommodate the anatomic conditions found at the host site. These conditions vary, system by system. www.indiandentalacademy.com
    133. 133. The strength values for the wrought soft and ductile metallurgic condition (normal root forms and plate form implants) are approximately 1.5 times greater than the strength of compact bone. In most designs where the bulk dimensions and shapes are simple, strength of this magnitude is adequate. www.indiandentalacademy.com
    134. 134. Commercially pure (cp) titanium and alloys of titanium exhibit good elongation properties. Elongation is directly related to malleability. Low elongation can result in implant fracture during processing or manipulation at the time of insertion. www.indiandentalacademy.com
    135. 135. Titanium and its alloys exhibit moderate yield strengths. Yield strength relates to the magnitude of stress at which a metallic material shows initial permanent deformation. When the yield strength is exceeded, the shape of the implant is altered. www.indiandentalacademy.com
    136. 136. Finally, the tensile strengths, the point at which metallic material can fracture in response to an applied load, should be sufficiently high for functional stability of a properly designed dental implant. www.indiandentalacademy.com
    137. 137. In general, titanium and its alloys have outstanding strength-to-weight ratios; good yield, tensile, and fatigue strength; and adequate toughness for dental implant systems. www.indiandentalacademy.com
    138. 138. The alloy of titanium most often used is titanium- aluminum-vanadium. The wrought alloy condition is approximately 6 times stronger than compact bone and thereby affords more opportunities for designs with thinner sections (e.g., plateaus, thin interconnecting regions, implant-to-abutment connection screw housing, irregular scaffolds, porosities). www.indiandentalacademy.com
    139. 139. The modulus of elasticity of the alloy is slightly greater than that of titanium, being about 5.6 times that of compact bone. The alloy and the primary element (Ti) both have titanium oxide (passivated) surfaces. Information has been developed on the oxide thickness, purity, and stability as related to implant biocompatibilities. www.indiandentalacademy.com
    140. 140. In general, titanium and alloys of titanium have demonstrated interfaces described as “osseointegrated” for implants in humans. Also, surface conditions where the oxide thickness has varied from hundreds of angstroms of amorphous oxide surface films to 100% titania (Ti02 rutile-form ceramic) have demonstrated osseointegration. www.indiandentalacademy.com
    141. 141. www.indiandentalacademy.com
    142. 142. www.indiandentalacademy.com
    143. 143. Titanium plasma sprayed coating (TPS) The first rough titanium surface introduced Coated with titanium powder particles in the form of titanium hydridePlasma flame spraying technique www.indiandentalacademy.com
    144. 144. Porous or rough titanium surfaces have been fabricated by plasma spraying a powder form of molten droplets at high temperatures in the order of 15,000 ºC, an argon plasma is associated with nozzle to provide very high velocity 600 m/sec partially molten particle c titanium powder (0.05 to 0.1mm diameter) projected onto a metal or alloy substrate. www.indiandentalacademy.com
    145. 145. The plasma sprayed layer after solidification (fusion) is often provided with a 0.04 to 0.05mm thickness. www.indiandentalacademy.com
    146. 146. When examined microscopically, the coatings show round or irregular pores that can be connected to each other. These types of surfaces were first developed by Hahn and Palich, who reported bone ingrowth in plasma spray titanium hybrid powder and plasma spray-coated implants inserted in animals. www.indiandentalacademy.com
    147. 147. In addition, porous surfaces can result in an increase in tensile strength through ingrowth of bony tissues into three dimensional features, High shear forces determined by the torque testing methods and improved force transfer into the periimplant area have also been reported. www.indiandentalacademy.com
    148. 148. www.indiandentalacademy.com
    149. 149. www.indiandentalacademy.com
    150. 150. Hydroxyapatite coating by plasma spraying was brought to the dental profession by deGroot. Kay et al. showed with scanning electron microscopy (SEM) and spectrographic analyses that the plasma-sprayed HA coating could be crystalline and could offer chemical and mechanical properties compatible with dental implant applications. www.indiandentalacademy.com
    151. 151. Thomas showed an accelerated bone formation and maturation around HA-coated implants in dogs when compared with non-coated implants. HA coating can also lower the corrosion rate of the same substrate alloys. Cook et al. measured the HA coating thickness after retrieval from specimens inserted in animals for 32 weeks and showed a consistent thickness of 50micrometer, which is in the range advocated for manufacturing. www.indiandentalacademy.com
    152. 152. The bone adjacent to the implant has been reported to be better organized than with other implant materials and with a higher degree of mineralization. In addition, numerous histologic studies have documented the greater surface area of bone apposition to the implant in comparison to uncoated implants, which may enhance the biomechanics and initial load-bearing capacity of the system. www.indiandentalacademy.com
    153. 153. HA coating has been credited with enabling HA-coated Ti or Ti alloy implants to obtain improved bone-to-implant attachment compared with machined surfaces. www.indiandentalacademy.com
    154. 154. Implants of solid sintered hydroxyapatite have been shown to he susceptible to fatigue failure. This situation can be altered by the use of a CPC (calcium phosphate coating) along metallic substrates. Although several methods may be used to apply CPC coatings, the majority of commercially available implant systems are coated by a plasma spray technique. www.indiandentalacademy.com
    155. 155. A powdered crystalline hydroxyapatite is introduced and melted by a hot, high- velocity region of a plasma gun and propelled onto the metal implant as a partially incited ceramic. www.indiandentalacademy.com
    156. 156. One advantage of CPC coatings is that they can act as a protective shield to reduce potential slow ion release from the Ti-6A1-4V substrate. Also, the interdiffusion between titanium and calcium, and phosphorus and other elements may enhance the coating substrate bond by adding a chemical component to the mechanical bond. www.indiandentalacademy.com
    157. 157. www.indiandentalacademy.com
    158. 158. www.indiandentalacademy.com
    159. 159. Cranial prosthesis: Titanium has been recently used in fashioning cranial prostheses (Gordon and Blair, 1974) This metal is a strong but light material that is soft enough to be swaged in a die-counterdie system. Moreover it can be strain hardened and thus become stronger with manipulation. Sheets that are 0.6 1mm thick are adequate and its radiodensity permits most radiographic studies. www.indiandentalacademy.com
    160. 160. After the metal prosthesis is shaped, trimmed, and polished, tissue acceptance of the implant is enhanced by anodizing it in a solution of 80% phosphoric acid, 10% sulphuric acid, and 10% water (Gordon and Blair, 1974). www.indiandentalacademy.com
    161. 161. Titanium trays offer the best combination of strength and rigidity with the least bulk of any implant material currently available for restoration of mandibular defects. Titanium frameworks are also used for rehabilitation of maxillary and mandibular defects like cleft palate. www.indiandentalacademy.com
    162. 162. The osseointegration technique allows the placement of titanium implants in to the orbital bony resin that are capable of supporting a facial prosthesis. The osseointegration procedure, allows titanium implants in to bone to project through the skin, providing points of attachment for prosthetic devices . www.indiandentalacademy.com
    163. 163. Titanium implants are used for retention of bone anchored Hearing Aid (BAHA) . www.indiandentalacademy.com
    164. 164. www.indiandentalacademy.com
    165. 165. Based on their physical properties and biocompatibility, titanium and its alloys have emerged as the metals of choice in dental implant industry. The application of titanium to fixed and removable prostheses is still in the developmental stages. Concerns regarding castability, porcelain bonding, and joining have been reported. www.indiandentalacademy.com
    166. 166. Some reports in the literature have indicated problems with castability and porosity. Others have shown that clinically acceptable titanium castings can be produced. Problems associated with porcelain bonding and titanium joining need to be resolved. www.indiandentalacademy.com
    167. 167. Attempts to substitute gold alloys with titanium for dental prostheses by the dental industry, laboratories and clinicians, have been a slow process. At present time, use of titanium restorations or prostheses is low because of lack of knowledge of the material among dentists and long-term c1inic follow-up. www.indiandentalacademy.com
    168. 168. Titanium is a useful biomaterial. It will probably continue to dominate the implant market in the future. Titanium is economical an readily available, but the technologies of machining, casting, welding and veneering it for dental prostheses are new. www.indiandentalacademy.com
    169. 169. Increased use of titanium in prosthodontics depends on research and clinical trials to compare its effectiveness, as an equivalent or superior metal, to existing metals. The future of titanium in dentistry looks promising. www.indiandentalacademy.com
    170. 170. www.indiandentalacademy.com
    171. 171. William J. 0’Brien: Dental materials and their selection Robert G. Craig: Restorative dental materials. John F McCabe: Applied dental materials. E.C.Coombe: Notes on dental materials. Kenneth J Anusavice: Science of dental materials. E.H. Greener: Material science in dentistry. Bernard G. N. Smith: The clinical handling of dental material. Carl. F Misch :Contemporary implant Dentistry. Charles. M. Weiss, Adam Weiss: Principles and practice of implant Dentistry. www.indiandentalacademy.com
    172. 172. AKAGI. K, OKAMOTO. y, MATSUURA. T, HORIBE. T “Properties of test metal ceramic titanium alloys”, J Prosthet Dent 1992; 68: 462-7. ANDERSSON.M, BERGMAN. B, BESSING. C, ERICSON. G, LUNDQUIST. P, NILSON. H “Clinical results with titanium crown fabricated with machine duplication and spark erosion”, Acta Odontol Scand 1989 ; 47 : 279-286. www.indiandentalacademy.com
    173. 173. BALTAG. 1. WATANABE. K. KUSAKARI. H., MIYAKAWA. 0, “Internal porosity in circumferential clasps of a clinical framework design”, J Prosthet Dent 2002: 88: 15 1-8. BERG. E, DAVIK.G, HEGDAHL.T, “Hardness, strength, and ductility of prefabricated titanium rods used in the manufacture of spark erosion crowns”, J Prosthet Dent 1996; 75: 419-425. BERG. F. WAGNER.W,C. Davik. G, Dootz. E.R, “Mechanical properties of laser-welded cast and wrought titanium”, J Prosthet Dent 1995; 74: 250-7. www.indiandentalacademy.com
    174. 174. BLACKMAN. R, BARGHI. N. TRAN. C, “Dimensional changes in casting titanium removable partial denture frameworks”, J Prosthet Dent 1991: 65: 309-15. B. Kasemo, Biocompatibility of titanium implants: Surface science aspects J Prosthet Dent June 1983 volume 49 number 6. www.indiandentalacademy.com
    175. 175. Gregory R. Parr , Richard W. Toth, et al Titanium: The mystery metal of implant dentistry. Dental materials aspects J Prosthet Dent 1985,Vol54,No.3,410-414. www.indiandentalacademy.com
    176. 176. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com