Implant:
Is a material or device placed in and or on oral tissue to support oral prostheses. Implant materials: 2 basic classes of materials 1- ceramic 2- metalمادة سنية / د . زينةثاني اسنان موصل12 / 4 / 2016 *
Implant properties
Implant material can be classified according to: - Physical, mechanical, chemical and biological properties. These properties include elastic modulus, tensile strength and ductility to determine optimal clinical application. - metal posses high strength and ductility. - ceramic and Carbone are brittle materials.*
A- metallic implant
1- Titanium is the most implant material used The American society for testing and materials (ASTM) For surgical implants recognizes four grades of commercially pure titanium and two titanium alloy 1- Cp titanium grade I ( 0.18 oxygen) 2- Cp titanium grade II ( 0.25 oxygen) 3- Cp titanium grade III( 0.35 oxygen) 4- Cp titanium grade IV ( 0.40 oxygen)*
metallic implant:
Ti and Titanium alloys most commonly used named Ti-6Al-4V and Ti-6Al-4V extra. Ti-6Al-4V most commonly used. Modula of elasticity of it is closer to the bone than any other material. This produce most uniform distribution of stress along the bone implant surface.*
Advantages
1- high degree of compatibility 2- high strength 3- high corrosion resistance Disadvantages 1- high cost 2- difficult and dangerous to cast*
2- Cobalt chromium molybedinium alloy
Composition of this alloy consist of 1- cobalt 63% 2- Chromium 30% 3- Molybedenium 5 % 4- carbon ,manganese and nickel traces
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Advantages
1- low cost and easy fabrication 2- when properly fabricated show good biocompatibility Disadvantages 1-poor ductility*
Stainless steel : composition
1- chromium for corrosion resistance 2- nickel to stabilize structure 3- iron 4- carbon Properties 1- high strength and ducility so resist brittle fracture, Easy fabrication and high tensile strength.*
disadvantages
1- galvanic potential 2- susceptible to pit and crevice corrosion B- ceramic and ceramic coated implant materials: Ceramic implant are of two types 1- bio inert aluminum oxide 2- bio active hydroxy appetite*
General properties of ceramic
1- high compressive strength up to 500 mpa 2- less resistance to shear and tensile strength 3- brittle*
Advantages:
1- excellent biocompatibility. 2- color is similar to bone, enamel and dentine. 3- minimal electrical and thermal conductivity. Disadvantages: 1- low tensile ,shearing and mechanical strength under fatigue. 2- low attachment strength for some coating with substrates.
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Polymer:
First used in 1930 s. Not used now a day, because of low mechanical strength And susceptibility to fracture during function. Sterilization by only gamma radiation. Contamination of polymer.*
Selection of implant material
1- important consideration is strength of material and type of bone to be placed. 2- anterior implant designated for use in narrow space have smaller diameter. 3- single implant in posterior area have larger diameter.*