TITANIUM AND ITS ALLOYS in prosthodontics

Titanium and it's alloys

1. TITANIUM AND ITS ALLOYS SHREYA SHASTRY DEPT OF PROSTHODONTICS COLLEGE OF DENTAL SCIENCES DAVANGERE GUIDED BY: Dr. PRASANNA SIR DEPARTMENT OF PROSTHODONTICS COLLEGE OF DENTAL SCIENCES

2. CONTENTS INTRODUCTION HISTORY MANUFACTURING OF TITANIUM CLASSIFICATION OF TITANIUM GRADES OF TITANIUM APPLICATIONS CRYSTILLINE FORMS OF TITANIUM PROPERTIES OF TITANIUM TITANIUM CASTING TITATIUM MACHINING SURFACE MODIFICATIONS TITANIUM IN PROSTHODONTICS TITANIUM IN IMPLANT CONCLUSION REFERENCES

3. INTRODUCTION Titanium is a pure element listed in periodic table with atomic no. 22 and an atomic mass of 47.9. It is the 9 th most abundant element and 4th most abundant structural metallic element in earth’s crust. Of the total amount of titanium mined, majority is titanium dioxide which is used as a pigment in paint. Only 5 to 10% is used in its metal form. The evolution of titanium applications to medical and dental field has dramatically increased in the past few years because of titanium’s excellent biocompatibility ,corrosion resistance and desirable physical and mechanical properties In recent years it has been used for fixed and removable prosthesis, implants and files etc.. Titanium can form several oxides- TiO , TiO2O3, TiO2-of which TiO2 is the most common TiO2 can have three different crystal forms-rutile ,anatase and brookite.But also can be amorphous

4. HISTORY Titanium was first discovered by Williams Gregor,aBritish minerologist in 1791who found the metal in a black magnetic sand in Cornwall and named it MENACHITE. Martin H Klaproth, a German chemist and minerologist rediscovered it in 1795 to be known as TITANIUM named after the Titans of Greek mythology. Dr. Wilhelm Kroll, from Luxembourg is considered as the father of titanium industry He invented usefull metallurgical processes for commercial production of titanium metal, the kroll process

5. MANUFACTURING OF TITANIUM Titanuim is produced by heating titanium ore[rutile ,ilmenite] with petroleum derived coke in a reactor at 100 degree c. The mixture is then treated with chlorine gas ,forming titanium tetrachlorideTiCl4 and other volatile compounds,which are subsequently separated by continuous fractional distillation in the presence of carbon and chlorine and then reducing the resultant TiCl with molten sodium to produce titanium sponge. This sponge is then fused under vacuum or in an argon atmosphere into titanium ignots . It is often remelted to remove inclusions and ensure uniformity

6. CLASSIFICATION OF TITANIUM AND ITS ALLOYS 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 ASTM 1 to 1V - based on the incorporation of small amounts of oxygen, nitrogen, hydrogen, iron, and carbon during purification procedure. cp grade 1 cp grade 11 cp grade111 cp grade 1V

7. 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.

8. GRADES OF TITANIUM ALPHA ALLOYS • Contain neutral alloying elements (such as tin) and/ or alpha stabilisers (such as aluminium or oxygen) only •Not heat treatable •Examples:Ti-5AL-2SN- ELI, Ti-8AL-1MO-1V NEAR-ALPHA ALLOYS • Contain small amount of ductile beta-phase •Alloyed with 1–2% of beta phase stabilizers such as molybdenum, silicon or vanadium •Examples: Ti-6Al-2Sn- 4Zr-2Mo, Ti-5Al-5Sn- 2Zr-2Mo, IMI 685, Ti 1100

9. BETA AND NEAR BETA ALLOYS •Metastable and which contain sufficient beta stabilisers •Examples : Ti-10V- 2Fe-3Al, Ti-13V-11Cr- 3Al, Ti-8Mo-8V-2Fe- 3Al, Beta C, Ti-15-3 ALPHA AND BETA ALLOYS •Metastable and generally include some combination of both alpha and beta stabilisers •Can be heat treated •Examples:Ti-6Al-4V, Ti-6Al-4V-ELI, Ti-6Al- 6V-2Sn

10. Ti-6AL-4V Most widely used titanium alloy. Has greater strength than CP Ti . Health hazards from the slow release of aluminium and vanadium. Hence, replacing vanadium with the same atomic percentage of niobium yields Ti-6Al-7Nb The mechanical properties of the two alloys are similar and their corrosion resistance is similar to that of CP Ti . At room temperature, Ti-6Al-4V is a two-phase (α + β) alloy. 975° C, single-phase BCC β alloy. 700° C produce recrystallized microstructures having fine equiaxed α grains. The mechanical properties of (α + β) titanium alloys are dictated by the amount, size, shape, and morphology of the α phase and the density of α/β interfaces.

11. WROUGHT NICKEL-TITANIUM ALLOY Known as NITINOL , used as a wire for orthodontic appliances. Nitinol is characterized by its high resiliency, limited formability, and thermal memory. COMPOSITION 55% nickel 45% titanium Possesses a temperature transition range (TTR). PROPERTIES Lowest elastic modulus and yield strength but the highest spring back (maximum elastic deflection Shape memory alloy, below TTR it can be deformed plastically above TTR will return to its original shape

12. Clinically, the low elastic modulus and high resiliency mean that lower and more constant forces can be applied with activations and an increased working range. The High spring back is important if large deflections are needed, such as with poorly aligned teeth. The alloy is brittle and therefore cannot be soldered or welded, so wires must be joined mechanically APPLICATIONS

13. WROUGHT BETA-TITANIUM ALLOY Titanium –molybdenum alloy known as beta-titanium is used as wrought orthodontic wire COMPOSITION AND MICROSTRUCTURE 78% titanium 11.5% molybdenum 6% zirconium 4.5% tin PROPERTIES Beta-titanium alloy has values of yield strength, modulus of elasticity, and springback intermediate to those of stainless steel and Nitinol. Its formability and weldability are advantages over Nitinol, and it has a larger working range than do stainless steel wires

14. CRYSTYLINE FORMS OF TITANIUM O'Brien W.J.: Dental Materials and Their Selection, Fourth Edition Titanium can exist in two crystal forms. The first is alpha which has a hexagonal close-packed crystal structure. The second is beta which has a body-centered cubic structure.

15. Chemistry of Titanium

16. Disintegration of the metal may occur due to action of moisture, atmospheric acid and alkaline other chemical agents. Titanium is a thermodynamically reactive metal, gets readily oxidized during exposure to air and electrolytes to form oxides, hydrated complexes, and aqueous cationic species. (PASSIVATION) Oral Cavity shows wide changes in the pH and fluctuation in the temperature .

17. The oxides and hydrated complexes act as barrier layers between the titanium surface and the surrounding environment and suppress the subsequent oxidation of titanium across the metal/barrier layer/solution interface. 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. Palladium was chosen among the platinum group metals, as it prevents corrosion of titanium by the addition of only a small amount (0.15%).

18. Physical properties There are three general types of titanium base alloys, such as alpha alloys, alpha-beta alloys, and beta alloys 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 hexagonal close-packed atomic strAt temperatures up to 882°C, pure titanium exists as ucture (alpha phase).

19. 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 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

20. MECHANICAL PROPERTIES 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 Modulus of elasticity of cp grade I titanium to cp grade IV titanium ranges from 102 to 104 GPa (a change of only 2%) The modulous of elasticity is 5 times greater than that of compact bone.

21. The yield strength increases from 170 to 483 MPa (a gain of 180%). These changes are related chiefly to oxygen residuals in the metal 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.

22. BIOLOGICAL PROPERTIES 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 . Bone formation at the implant site

23. 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 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

24. 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

25. C0RROSION RESISTANCE Corrosion : the action, process, or effect of corroding; a product of corroding; the loss of elemental constituents to the adjacent environment. GPT-8 The most noted chemical property of titanium is its excellent resistance to corrosion; It is almost as resistant as platinum, capable of withstanding attack by acids, moist chlorine in water but is soluble in concentrated acids. Titanium oxidizes (passivates) upon contact with room temperature air or normal tissue fluids.

26. This passivated condition minimizes biocorrosion phenomenon. In situations where implant would be placed within a closely fitting receptor site in bone, areas scratched or abraded during placement would repassivate in vivo. This characteristic is one important property consideration related to the use of titanium for dental implants.

27. BIOCOMPATIBILITY GPT 8 defines “ biocompatible ” as capable of existing in harmony with the surrounding biologic environment Attempts to use titanium for implant fabrication dates to the late 1930s. It was found that titanium was tolerated as was stainless steels and cobalt alloys. Titanium’s lightness and good mechano-chemical properties are salient features for implant application. Titanium was found the only metal biomaterial to osseointegrate (Van Noort , 1987). Also, there were even assumptions on a possible bioactive behaviour (Li et al., 1994) due to the slow growth of hydrated titanium oxide on the surface of the titanium implant that leads to the incorporation of calcium and phosphorous.

28. Commercially pure titanium ( Ti CP) and extra low interstitial Ti-6Al-4V (ELI) are the two most common titanium base implant biomaterials. These materials are classified as biologically inert biomaterials. As such, they remain essentially unchanged when implanted into human bodies Its very good biocompatibility is due the formation of an oxide film (TiO2) over its surface. This oxide is a strong and stable layer that grows spontaneously in contact with air and prevents the diffusion of the oxygen from the environment providing corrosion resistance. It is a biomaterial with a high superficial energy and after implantation it provides a favourable body reaction that leads to direct apposition of minerals on the bone-titanium interface and titanium osseointegration ( Acero et al., 1999)

29. It is immune to attack from body fluids , Compatible with the bone growth Strong and flexible Low thermal conductivity prevents irritation of the pulp Capability of bonding to resin cements and to porcelain. Absolutely inert in the human body

30. NON MAGNETIC Commercially pure titanium and all the titanium alloys are non magnetic . Benefit to titanium for use in medicine is its non-ferromagnetic property, patients with titanium implants can be safely examined with magnetic resonance imaging (convenient for long-term implants).

31. FLEXIBILITY PROSTHODONTIC APPLICATIONS Retention of a partial denture depends on the amount of undercut engaged on an abutment tooth and the flexibility of the clasp. Flexibility is influenced by clasp length and the denture base material. Titanium clasps are purported to have greater flexibility than cobalt-chromium cast clasps which should enable them to engage deeper undercuts or be used where shorter clasp arms are needed such as on premolar teeth

32. OSSEOINTEGRATION The apparent direct attachment or connection of osseous tissue to an inert, alloplastic material without intervening connective tissue. GPT-8 The two most widely used titanium alloys, cpTi and Ti-6A1-4v can both readily osseointegrate . Osseointegration is considered to occur when direct contact develops between living bone and the metal, without any intervening layer of fibrous capsule. Both cpTi and Ti-6A1-4v are bioactive and able to promote formation of bone in direct contact with the metal surface

33. The interfacial zone (20-50 nm) is crucial for osseointegration.it is the region in to which growth factors are released from bone cells and this initiates bone formation Deposition of proteins on surface oxide layer Formation of fibrin matrix Laying down of osteoblasts which fill the interfacial region The oxide layer on the surface plays a major role in success of osseointegration.Thicker and rougher oxide layer encourages osseointegration It has the effect of passivating metal so that the corrosion is inhibited and release of titanium ions is minimised They have surfaces with appropriate surface energy and charge which attracts layer of proteins subsequently leading to deposition of extracellular matrix which stimulate osteoblasts

34. CASTING Casting is major problem in titanium High melting temperature Low density High affinity of titanium to oxygen, nitrogen, hydrogen Reaction between titanium and investment material

35. Titanium casting systems 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 ) . A pressure /vacuum system with one chamber for melting and casting ( Cyclare , J Morita) vacuum / centrifuge casting system ( Tycast . Jeneric / Penetron , and Titaniumer , Ohara) 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.

36. MANIPULATION OF TITANIUM ALLOYS An argon/arc with a non-consumable tungsten electrode or high-frequency induction is used for melting titanium alloys in an argon or helium atmosphere Crucibles: Copper, magnesia, or carbon Centrifugal force, casting pressure difference, and gas pressure have been used to force the molten-metal flow into the mold

37. The two most important factors in casting titanium-based materials are its HIGH MELTING POINT (1700° C for CP Ti ) Special melting procedures, cooling cycles, mold material, and casting equipment to prevent metal contamination CHEMICAL REACTIVITY Reacts with H2, O2, N2. Manipulation of titanium at elevated temperatures must be performed in a well-controlled vacuum or inert atmosphere. Else, titanium surfaces can be contaminated with oxygen surface layer, which can be as thick as 100 μm . This reduces strength and ductility and promote cracking.

38. POROSITY OF CAST TITANIUM It was reported that sprue design commonly used for co- cr alloy not suitable for titanium Large and multiple sprues found to reduce porosity. Direction of sprues: lowest porosity in titanium circumfrential clasp was obtained when was sprue attached perpendicular to minor connector

39. TITANIUM MACHINING The initial application of titanium to dentistry was machined Ti dental implants. titanium machining has been developed by Andersson et al for the fabrication of unalloyed titanium crowns and fixed partial dentures 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.

40. ADDITIVE MANUFACTURING/3D PRINTING OF Ti DENTAL IMPLANTS In additive method softening of metal powder layer by layer under the influence of an electron or laser is done Power based cycles such as laser power bed combination (LPBF) and electron beam melting and laser metal deposition are being extensively used for manufacturing of dental prosthesis 3DP/AM the most attractive methods for production of implants Swiftness Precisely controlled Exact shape and dimension

41. The yield strength, tensile strength and hardness were compared under ti alloy Ti -64 for 3D printing and metallurgical process Mechanical properties are higher for additive manufacturing than conventional methods

42. Titanium welding Greater affinity to oxygen Rapid reaction rate at high temperature-----so conventional method that uses oxygen flame---not used. So laser is suitable for titanium becausehigher rate of laser beam absorption low thermal conductivity Advantages of laser welding: Heat affected area is small No direct contact is required with weld area Provide precise well defined weld Its possible to repair combustable acrylic resin with lasers

43. COMMERCIAL LASER WELDING UNITS

44. SURFACE MODIFICATIONS OF TI IMPLANTS There are also many ways to intentionally modify the surface of the implant. They include conventional mechanical treatment (sand blasting), wet or gas chemical reaction treatment electroplating or vapor plating, and ion-beam processing, which leaves bulk properties intact and has been newly adapted to dentistry from thin film technology. A general rule has been that cleaner is better. Contact angles are also greatly modified by acid treatment or water rinsing

45. Titanium implants may be etched with a solution of nitric and hydrofluoric acids to chemically alter the surface and eliminate some types of contaminant products. The acids very rapidly attack metals other than titanium, and these processes are electrochemical in nature. Proponents of this technique argue that implants treated by sandblasting and acid etch provide superior radiographic bone densities along implant interfaces compared with titanium plasma-sprayed surfaces

46. ALTERNATIVE METHODS FOR SURFACE PREPARATION anodic oxidation, plasma oxidation, plasma cleaning, and vapor deposition

47. Anodic oxidation Anodic oxidation is an electrochemical method of treatment. The sample to be treated is made an anode in an electrolytic bath, and when a potential is applied on the sample, a current will flow through the electrolyte due to ion transport. The transport of oxygen ions through the electrolyte builds up a passivating oxide layer on the surface of the sample. The thickness of the surface oxide formed depends, often linearly, on the applied potential Plasma oxidation In plasma oxidation, an oxygen plasma is used instead of a liquid electrolyte. Plasma oxidation offers essentially the same possibilities to control

48. Plasma cleaning is technically identical to plasma oxidation, but used in order to increase the surface cleanliness, which usually results in an increase in the surface energy . Vapor deposition Vapor deposition can be used to deposit desirable atoms or continuous films on surfaces. As the name implies, the method is based on the principle that the material to be deposited is heated until it evaporates.. The vapor is then allowed to condense on the material to be coveredThese techniques are often referred to as physical vapor deposition (PVD). Deposition can also be made by chemical reactions and is then called chemical vapor deposition (CVD).

49. Surface Coatings Hydroxyapatite Coatings (HA) Tricalcium phosphate (TCP) Calcium aluminate. Titanium plasma Spray (TPS) Tricalcium phosphate (TCP) Calcium aluminate.

50. Hydroxyapatite Coating 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. Block and Thomas showed an accelerated bone formation and maturation around HA-coated implants in dogs when compared with noncoated implants

51. Beyond an increase in surface area as compared to smooth surface implants, this surface has also shown to have an accelerated initial integration, which makes it ideal for quick initial post-surgical stabilization in weak bone. HA coating can also lower the corrosion rate of the same substrate alloys Titanium Screw Implant with a Hydroxylapatite (HA) coating

52. 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.

53. HA coating has been credited with enabling HA-coated Ti or Ti alloy implants to obtain improved bone-to-implant attachment compared with metallic surfaces HA coated machined collar cylinder implant

54. Titanium Plasma Sprayed Screw Implant It consists of fine grain titanium particles applied to the cylinder in an argon environment under extremely high temp., pressure and velocity. It offers an increase in surface area over the smooth surface and, thus also more retention in the bone. Some research has also shown that initial integration into the host bone is somewhat accelerated through that.

55. Porous or rough titanium surfaces have been fabricated by plasma spraying a powder form of molten droplets at high temperatures. At temperatures in the order of 15,000C, An argon plasma is associated with a nozzle to provide very high velocity 600 m/sec partially molten particles of titanium powder (0.05 to 0.1 mm diameter) projected onto a metal or alloy substrate. The plasma sprayed layer after solidification (fusion) is often provided with a 0.04 to 0.05 mm thickness.

56. The optimum pore size ranged from 150 to 400  m and coincidentally correspond to surface feature dimensions obtained by some plasma spraying processes. In addition, porous surfaces can result in an increase in tensile strength through in growth of bony tissues into three dimensional features .

57. Additional advantages of HA over TPS include the following: Faster healing bone interface Increased gap healing between bone and HA Stronger interface than TPS Less corrosion of metal The clinical advantages of TPS or HA coatings may be summarized as the following : Increased surface area ( can be up to 600%) Increased roughness for initial stability Stronger bone-to-implant interface

58. Titanium and complete denture frameworks 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 HOW TO OVERCOME 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.

59. 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

60. Titanium and Partial denture frameworks Cp titanium and titanium alloys containing aluminium and vanadium, or palladium ( Ti -O Pd), should be considered potential future materials for RPD frameworks Their versatility and well-known biocompatibility are promising; however, long-term clinical studies are needed to validate their potential usefulness

61. Titanium and FPD Porcelains manufactured to bond to titanium are currently commercially available. The Procera porcelain ( Procera , Nobelpharma : Goteborg, Sweden) was formulated for machine-milled crowns 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

62. TITANIUM AND IMPLANTS Titanium and its alloys are important in dental and surgical implants because of their high degree of biocompatibility, strength and corrosion resistance. Gold standard in implant materials Pure titanium, theoretically may form several oxides. TiO ,  TiO 2,   Ti 2 O 3   Among these TiO 2 is the most stable and most commonly used under physiologic conditions. These oxides form spontaneously on exposure of Ti to air

63. Titanium both as a pure metal and and as an alloy is easily passivated forming a stable 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 The rate of dissolution is one of the lowest of all passivated implant metals and seems to be well tolerated by the body.

64. 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

65. 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. 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.

66. 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 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.

67. Titanium and its alloys exhibit moderate yield strengths. When the yield strength is exceeded, the shape of the implant is altered . Elongation is directly related to malleability. Low elongation can result in implant fracture during processing or manipulation at the time of insertion. Finally, the tensile strengths, should be sufficiently high for functional stability of a properly designed dental implant Commercially pure (cp) titanium and alloys of titanium exhibit good elongation properties

68. TITANIUM FOAM August 8th, 2008 Canadian researchers at the NRC Industrial Materials Institute have developed a porous titanium foam implant said to mimic a metallic version of bone The titanium foam is made by saturating polyurethane foam with a solution of titanium powder and binding agents . The titanium clings to the polyurethane matrix, which is then vaporised away along with the binding agents. This results in a titanium lattice which is finally heat-treated to harden it. .

69. Later, through a high-temperature heat treatment, the polymer is removed and the titanium particles are consolidated to provide mechanical strength to the porous structure. The rough surface creates friction between the implant and the bone, and also allows bone growth into the pores to help fix the implant in place. Among its potential benefits, titanium foam could make dental implants less invasive.

70. Selecting an Implant All commercially available dental implant biomaterials exhibit excellent biocompatibility, tissue response, and predictability none of the titanium-based materials have proven to be more biocompatible than any other group. Recognizing that some implant materials are stronger than others, clinicians must treatment plan implant selection accordingly If a patient has a history of parafunctional habits and implant fracture , for example, the clinician should choose an implant made of titanium alloy, rather than cp grade I titanium.

71. Titanium and maxillofacial prosthesis 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-counter die 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. 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 

72. 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 .

73. Titanium implants are used for retention of bone anchored Hearing Aid (BAHA) .

74. CONCLUSION Both titanium and titanium alloys, based on their physical and chemical properties, appear to be especially suitable for dental implants and prostheses. Processing difficulties, however, have limited titanium’s usefulness in fixed and removable prostheses. For the construction of endosseous implants, titanium and its alloys have become well-accepted and can be considered the materials of choice.

75. REFERENCES Carl E. Misch: contemporary implant dentistry, second edition,1999 Philips Science of Dentla Materials, Kenneth J. Anusavice ; 11 th Edition O'Brien W.J.: Dental Materials and Their Selection, Fourth Edition Contemporary Fixed Prosthodontics, Fourth edition, Stephen F. Rosenstiel. Fundamentals of Fixed Prosthodontics, 3 rd edition, Shillingburg Titanium and Titanium Alloys: Fundamentals and Applications, by Dr. Christoph Leyens , Dr. Manfred Peters Esthetic dentistry and ceramic restorations  By Bernard Touati, Paul Miara , Dan Nathanson Titanium alloys, by Vydehi Arun Joshi Titanium applications in dentistry, J Am Dent Assoc, 2003 Vol 134, No 3, 347-349.