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Metals and their Applictions in Medical and Healthcare PowerPoint Presentation

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Description : Check out this medical presentation on Dental Abutment, which is titled "Metals", to know about the applications of metal in medical and healthcare including bone and joint replacement, dental implants, maxillo and cranio/facial reconstruction, cardiovascular devices (Titanium is regularly used for pacemaker cases and defibrillators, as the carrier structure for replacement heart valves, and for intra-vascular stents, external prostheses, and surgical instruments.

Tags : Dental Abutment, Metals, applications of metal, medical, healthcare

Published on : Jul 01, 2021 | Views : 2159 | Downloads : 1

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Slide 1-

7/4/2021 1 Metals
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7/4/2021 2 Broad Classification- Types of Biomaterials polymers, synthetic and natural metals ceramics composites
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7/4/2021 5 Metals load bearing implants and internal fixation devices; when processed suitably contribute high tensile, high fatigue and high yield strengths; low reactivity; properties depend on the processing method and purity of the metal.
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7/4/2021 6 Applications Bone and Joint Replacement Dental Implants Maxillo and Cranio/facial reconstruction Cardiovascular devices Titanium is regularly used for pacemaker cases and defibrillators, as the carrier structure for replacement heart valves, and for intra-vascular stents. External Prostheses Surgical instruments
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7/4/2021 7 Other Uses Medical Tubing Catheters Stents
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7/4/2021 8 Material Science Logic Synthesis +processing Structure Performance/Application Properties Physical Biological
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7/4/2021 9 Physical Properties of Metals: Luster (shininess) Good conductors of heat and electricity High density (heavy for their size) High melting point Ductile (most metals can be drawn out into thin wires) Malleable (most metals can be hammered into thin sheets)
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7/4/2021 10 Chemical Properties of Metals: Easily lose electrons; Surface reactive; Loss of mass; (some corrode easily) Corrosion is a gradual wearing away Change in mechanical properties
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7/4/2021 11 Periodic Table Polymeric Biomaterials
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7/4/2021 12 Metals Most elements are metals. 88 elements to the left of the stairstep line are metals or metal like elements
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7/4/2021 13 NATURE OF METALS crystalline solids composed of elemental, positively charged ions in a cloud of electrons
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7/4/2021 14 Microstructure of metals Basic atomic architecture is a crystal structure Different elements have different crystalline architectures and can combine with different partners. Iron Gold
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7/4/2021 15 Figure 2 Common Lattice Types
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7/4/2021 16 Metals Manufacturing machining" and "metal fabrication" are synonymous and refers to the activities and processes that change the shape of a metal workpiece by deforming it or removing metal from it.
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7/4/2021 17 Metals Manufacturing Casting
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7/4/2021 18 Processing: molten metal is cooled to form the solid. The solid metal is then mechanically shaped to form a particular product. How these steps are carried out is very important because heat and plastic deformation can strongly affect the mechanical properties of a metal.
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7/4/2021 19 What Happens When You Cool a Molten Metal?
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7/4/2021 20 Formation of Crystals In the free state growth proceeds simultaneously in all three axes.
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7/4/2021 21 Solidification in Casting Processes: Formation of Crystals Contained nucleation starts at edges (where coolest) and grows inward
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7/4/2021 22 Formation of Crystals Nucleation - The first unit cell solidifies Growth - New unit cells attach to existing unit cells. Where crystals meet grain boundaries are created.
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7/4/2021 23 Solidification of Metals (Grain formation) Crystal will grow naturally (along axes) until they begin to interfere. The interference point where crystal structures meet is called the grain boundary.
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7/4/2021 24 PHASES A phase is a homogeneous part or aggregation of the material that differs from another part due to a difference in structure, composition, or both; The difference in structures forms an interface between adjacent or surrounding phases; These structural defects affect mechanical performance.
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7/4/2021 25 Grains and Grain Boundaries
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7/4/2021 26 Creation of Slip Planes As crystals form, the unit cells tend to align in patterns. The alignment of these internal planes between unit cells creates slip planes.
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7/4/2021 27 Crystal Defects: Metallic crystals are not perfect. Sometimes there are empty spaces called vacancies, where an atom is missing. These and other imperfections, as well as the existence of grains and grain boundaries, determine many of the mechanical properties of metals. When a stress is applied to a metal, dislocations are generated and move, allowing the metal to deform.
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7/4/2021 28 DEFECTS IN CRYSTALLINE STRUCTURE Dislocations edge dislocation
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7/4/2021 29 PLASTIC DEFORMATIONS SLIP TWINNING
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7/4/2021 30 Fatigue Stages of Fatigue Failure no harm small cracks "clam shell" effect (note shinney area) fracture
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7/4/2021 31 COMBINATION OF SLIP LINES AND TWINNING BANDS
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7/4/2021 32 Fatigue Fatigue Limit -" The maximum stress that a metal will withstand without failure for a specified large number of cycles.” Often more important than tensile or yield strength
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7/4/2021 33 Strengthening by Grain Size Reduction Finer and more homogenous grain size results in more homogeneous packing of the crystal and impedes dislocation type motion (prevents slip); Grain-size reduction usually improves toughness. Grain size can be controlled by slowing the rate of solidification and by plastic deformation after soldification.
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7/4/2021 34 Alloys A metal comprised of two or more elements, at least one of which is metallic. Generally, metals do not like to mix. When they do they form in one of two ways: Substitution Interstitial
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7/4/2021 35 Alloys are Solid Solutions (a) substitutional and (b) interstitial More abundant element is referred to as the solvent and the less abundant element is the solute. Filling materials: Silver alloys consisting of Ag-Sn-Cu, mixed with mercury
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7/4/2021 36 Substitution Alloys Alloys formed through substitution must have similar crystal structures and atomic size.
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7/4/2021 37 Conditions for substitutional solid solutions : The atomic radii of the two elements similar Their lattice types must be the same The lower valency metal becomes the solvent
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7/4/2021 38 Crystalline Architecture Determines Mechanical Properties BCC, ductile, plastic ie more workable FCC, ductile, plastic ie workable HCP, lack plasticity
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7/4/2021 39 Dental Alloys Gold-Silver alloy (Type III for crowns & bridges: e.g. 75%Au-11%Ag-9%Cu3.5%Pd) 2.882 Å - Gold (Au) FCC : FCC (Ag) Silver - 2.888 Å Silver-Copper alloy (One of the two types of particles in 'admixed' dental amalgam alloys) 2.888 Å - Silver (Ag) FCC : FCC (Cu) Copper - 2.556 Å Silver-Tin alloy (Particles in 'low copper' dental amalgam alloys) 2.888 Å - Silver (Ag) FCC : FCC (Sn) Tin - 3.016 Å
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7/4/2021 40 Other alloys Co-Cr alloys: Co-Cr-Ni alloys: Ni-Ti alloys such as Nitinol (Ti-48Ni-2Co) are superelastic wires
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7/4/2021 41 Interstitial Size of atom becomes the major factor. Solute atoms must be small in size to fit into the spaces between the larger solvent atoms. Important interstitial solute atoms are carbon, hydrogen, boron, nitrogen, and oxygen.
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7/4/2021 42 Solid-Solution Strengthening Adding another element can increase strength. The impurity atoms redistribute lattice strain which can "anchor" dislocations. This occurs when the strain caused by the alloying element compensates that of the dislocation, thus achieving a state of low potential energy. It costs strain energy for the dislocation to move away from this state. The dissipation of energy at low temperatures is why slip is hindered. Pure metals are almost always softer than their alloys
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7/4/2021 43 Example of interstitial solid solution is steel or carbon dissolved in iron
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7/4/2021 44 Strain Hardening Ductile metals become stronger when they are deformed plastically at temperatures well below the melting point (cold working). The reason for strain hardening is that the dislocation density increases with plastic deformation (cold work). The average distance between dislocations then decreases and dislocations start blocking the motion of each one.
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7/4/2021 45 Recovery -Annealing Heating ->increased diffusion ->enhanced dislocation motion ->relieves internal strain energy and reduces the number of dislocations.
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7/4/2021 46 Titanium 2.2 million pounds of TI implanted every year hip joints, bone screws, knee joints, bone plates, dental implants, surgical devices, and pacemaker cases due to its total resistance to attack by body fluids, high strength and low modulus. dental implant
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7/4/2021 47 Commercially pure titanium (ASTM F67) Ti-6Al-4V (ASTM F136) most load bearing permanent implants due to their low density, good corrosion Poor properties in articulation
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7/4/2021 48 Titanium Alloys F67-00 Unalloyed Titanium F136-98e1 Wrought Titanium 6-Aluminum 4-Vanadium ELI Alloy F620-00 Alpha Plus Beta Titanium Alloy Forgings F1108-97a Ti6Al4V Alloy Castings F1295-97a Wrought Titanium 6-Aluminum7-Niobium Alloy F1341-99 Unalloyed Titanium Wire F1472-99 Wrought Titanium 6-Aluminum 4-Vanadium Alloy F1580-95 Titanium and Titanium 6-Aluminum 4-Vanadium Alloy Powders F1713-96 Wrought Titanium 13-Niobium 13-Zirconium Alloy F1813-97e1 Wrought Titanium 12-Molybdenum 6-Zirconium 2-Iron Alloy
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7/4/2021 49 Cobalt Alloys F75-98 Cobalt-28 Chromium-6 Molybdenum Casting Alloy F90-97 Wrought Cobalt-Chromium-15T Tungsten-10 Nickel Alloy F562-00 Wrought Cobalt-35 Nickel-20 Chromium-10 Molybdenum Alloy F563-95 Wrought Cobalt-Nickel-Chromium-Molybdenum-Tungsten-Iron Alloy F688-95 Wrought Cobalt-35 Nickel-20 Chromium-10 Molybdenum Alloy F799-99 Cobalt-28 Chromium-6 Molybdenum Alloy F961-96 Cobalt-35 Nickel-20 Chromium-10 Molybdenum Alloy F1058-97 Wrought Cobalt-Chromium-Nickel-Molybdenum-Iron Alloy F1091-91(1996) Wrought Cobalt-20 Chromium-15 Tungsten-10 Nickel Alloy F1377-98a Cobalt-28 Chromium-6 Molybdenum Powder F1466-99 Iron-Nickel-Cobalt Alloys F1537-00 Wrought Cobalt-28-Chromium-6-Molybdenum Alloy
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7/4/2021 50 Stainless Steels Types 316 and 316L, are most widely used for implant fabrication The only difference in composition between 316L and 316 stainless steel is the content of carbon. A wide range of properties exists depending on the heat treatment or cold working (for greater strength and hardness). Even the 316L stainless steels may corrode inside the body under certain circumstances in a highly stressed and oxygen depleted region, such as contact under screws or fracture plates. Thus, stainless steels are suitable to use only in temporary implant devices, such as fractures plates, screws and hip nails.
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7/4/2021 51 Stainless Steel F138-97 (316LVM) Wrought 18 Chromium-14 Nickel-2.5 Molybdenum Stainless Steel F139-96 Wrought 18 Chromium-14 Nickel-2.5 Molybdenum Stainless F621-97 Stainless Steel F745-95 18 Chromium-12.5 Nickel-2.5 Molybdenum Stainless Steel F899-95 Stainless Steel F1314-95 Wrought Nitrogen Strengthened-22 Chromium-12.5 Nickel-5 Manganese-2.5 Molybdenum Stainless Steel F1350-91(1996) Wrought 18 Chromium-14 Nickel-2.5 Molybdenum Stainless Steel F1586-95 Wrought Nitrogen Strengthened-21 Chromium-10 Nickel-3 Manganese-2.5 Molybdenum Stainless Steel
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7/4/2021 52 Metal Implant Reliability depends largely on the: corrosion, wear, and, fatigue resistance of the materials
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7/4/2021 53 Knee Replacement Therapy Primary Problem: Damaged cartilage leads to various forms of arthritis Osteoarthrites: 20.7 million Americans Symptoms: hard, bony swelling of the joints gritty feeling Immobility
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7/4/2021 54 Introduction - Background Solution: Total Knee Replacement (TKR) Nearly 250,000 Americans receive knee implants each year Results: Stops or greatly reduces joint pain Improves the strength of the leg Increases quality of life and comfort
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7/4/2021 55 Current TKR Design - Assembly Four Primary Components: 1. Femoral Component 2. Tibial Component 3. Plastic Insert 4. Patellar Component
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7/4/2021 56 Current TKR Design - Components Femoral Component Materials: Cobalt-chromium-molybdenum Ti-6Al-4V ELI Titanium Alloy Interface: Press fit, biological fixation, PMMA Patellar Component Materials: Polyethylene Cobalt-chromium-molybdenum (Ti Alloy) Interface: Press fit, biological fixation PMMA *Modular or singular design
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7/4/2021 57 Current TKR Design - Components Tibial Component Materials: Cobalt-chromium-molybdenum (cast) Ti-6Al-4V ELI Titanium Alloy Interface: Press Fit, Biological Fixation, PMMA Plastic Insert Materials: Polyethylene Interface: Press Fit
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7/4/2021 58 Current TKR Design - Problems #1 Polyethylene “The Weak Link” Articulation wear produces particulates Leading to osteolysis and bone resorption at the implant interface. loosening and eventual malfunction of the implant will occur. #2 Metal-Bone Interface Stress-shielding leads to bone degeneration Average lifespan of 10-20 years
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7/4/2021 59 Metals One complication that can occur from the use of metals in orthopedic applications is the phenomenon of stress shielding. In some situations, such as in TKR or hip replacement, the high strength of the metal in the implant induces it to assume more than its share of responsibility for the load in that region. This decreases the load born by the surrounding tissue and therefore shields it from experiencing stress. Lack of stress causes bone density to decrease as bone tissue resorbs, and causing complications in the implant/tissue interface.
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7/4/2021 60 Alternative TKR Design - The Idea #1 Wear Reduction #2 Stress Shielding
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7/4/2021 61 Alternative TKR Design - The Idea 510(k) status preferred Hip replacement surgery is a close relative to Total Knee Replacement Metasul has had success with metal-metal interface system 100,000 Implanted Worldwide
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7/4/2021 62 Alternative TKR Design - Materials Alternative Design: Metal-Metal Interface using a three-material system Material: Wrought cobalt-chromium- molybdenum alloy (forged) Polyethylene Insert Porous Titanium alloy bone bond
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7/4/2021 63 ENDOSSEOUS IMPLANT
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7/4/2021 64 Classification of implants
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7/4/2021 65 The implant system Drilled and placed into the jawbone. Dental implant post or abutment is usually screwed into the top of the dental implant. An artificial dental crown can be made to precisely fit onto the implant post.
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7/4/2021 66 The implant process
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7/4/2021 67 The leap 1952 - Per Ingvar Branemark, Discovered the titanium screw. Introduced the concept of Osseointegration All existing designs based on Branemark Titanium Screw
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7/4/2021 68 Osseointegration – The Divine Mantra A fixture is osseointegrated if it provides a stable and apparently immobile support of prosthesis under functional loads, without pain, inflammation, or loosening.
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7/4/2021 69 Titanium Easily available. Lightweight, corrosion resistant, easily milled into different shapes, while maintaining its strength. Forms layer of titanium oxide, which is a stable and reactive interface that becomes coated with plasma proteins. Ti-6Al-4V was alloyed to create a biocompatible material with added strength.
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7/4/2021 70 HA coating – surface improvement Rapid osseointegration Biointegration in 4 weeks – 90% of implant-bone contact at 10 months. In contrast, Titanium - 10 weeks in to osseointegrate – 50% implant-bone contact at 10 months Demerits Unstable, susceptible to bacterial infection
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7/4/2021 71 Osteopontin – a novel surface Osteopontin (OPN) is an extracellular glycosylated bone phosphoprotein with a polypeptide backbone of about 32,000. It binds calcium and interacts with the vitronectin receptor. Binds covalently to fibronectin. In bone it is produced by matrix-producing osteoblasts, at the mineralization front, and by bone resorbing osteoclasts.
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7/4/2021 72 How it enhances osseointegration Makes dead metal “come alive”. Surrounding cells “don’t see an inert piece of metal, they see a protein and it’s a protein they know”. OPN is expressed prior to mineralization and regulated by osteotropic hormones, binds to hydroxyapatite, and enhances osteoclast and osteoblast adhesion. Protection against bacterial infection. Maintains overall tissue integrity and biomechanical strength during bone remodeling.
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7/4/2021 73 Future of implants Manufacture "designer implants", which could carry different types of proteins, one set to spur soft tissue healing, another to encourage hard tissue growth on another front. Given that dental implants are fixed in the jawbone and inserted through gum tissue, this two-pronged approach would be essential.