Website navigation tips: All the links in following pages are marked in Blue. When the cursor is passed on the links the colour changes in relation to the grade of difficulty of the topic discussed in the linked page. Green colour means that the related topic is easy and no specific mathematical or physical knowledge is needed in order to understand it. Orange colour indicates an average difficulty topic. Black colour indicates the most advanced topics that require a higher knowledge of mathematics and physics.

 

Biomaterials used in prosthetic devices are designed in order to be used in contact with biological tissues for a long period of time minimizing any adverse tissue reaction. Biomaterials must be chemically and mechanically biocompatible and their mechanical strength must be appropriate for the specific structural function. Titanium and its alloys are the most common metallic materials used in dental implantology because of their high biocompatibility, low density, mechanical resistance and resistance to corrosion.
Titanium has a low density compared to other metals: ρ = 4.5 g/cm³. Its Young's modulus E has a value of about 100-110 GPa and it's ultimate strength σ_m is of about 300 MPa. The low density of titanium is such that its mechanical properties specific to density are much higher than those of other metals such as steel or aluminium.
Titanium is often used in form of alloy. Alloy elements modify the microstructure of the material and thus its mechanical properties. Table 1 reports the mechanical characteristics of pure Titanium and of its most common alloys.

 

Alloy	Young's modulus [GPa]	Yield strength [Mpa]	Ultimate strength [Mpa]	Ultimate strain [%]
Ti pure - Grade 1 Ti pure - Grade 2 Ti pure - Grade 3 Ti pure - Grade 4	102.7 102.7 103.4 104.1	170 275 380 485	240 345 450 550	24 20 18 15
Ti-6Al-4V (Annealed)	110 - 114	825-869	895-930	6-10
Ti-6Al-7Nb Ti-5Al-2.5Fe Ti-5Al-1.5B Ti-15Zr-4Nb-4Ta-0.2Pd (Annealed) Ti-15Zr-4Nb-4Ta-0.2Pd (Aged)	114 112 110 99 94	880-950 895 820-930 693 806	900-1050 1020 925-1080 715 919	8-15 15 15-17 28 18
Ti-13Nb-13Zr (Aged) Ti-12Mo-6Zr-2Fe (Annealed) Ti-15Mo (Annealed) Ti-15Mo-5Zr-3Al (Solubilized) Ti-15Mo-5Zr-3Al (Aged) Ti-15Mo-2.8Nb-0.2Si (Annealed) Ti-35.3Nb-5.1Ta-7.1Zr Ti-29Nb-13Ta-4.6Zr (Aged)	79-84 74-85 78 80 80 83 55 80	836-908 1000-1060 544 838 1000-1060 945-987 547 864	973-1037 1060-1100 874 852 1060-1100 979-999 597 911	10-16 18-22 21 25 18-22 16-18 19 13.2

Table 1: Mechanical characteristics of pure titanium and titanium alloys

 

In specific applications a Young's modulus closer to that of bone may be required so that stress and strain distributions in the adjacent tissues are not excessively altered. Table 2 shows the Young's modulus of pure titanium and titanium alloys compared to the Young's modulus of cortical bone whose range is shown in red.

 

Table 2: Young's modulus of pure titanium and titanium alloys in GPa. The red box indicates the range of values for the Young's modulus in cortical bone.