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Biomaterials.ppt
- 1. Evolution of BiomaterialScience & Technology • 1st generation (since 1950s) Goal: Bioinertness • 2nd generation (since 1980s) Goal: Bioactivity • 3rd generation (since 2000s) Goal: Regenerate functional tissue
- 2. Some application ofbiomaterials • Skeletel system • Joint replacement(Hip, knee) • Bone plate • Bone cement • Artificial tendon and ligment • Dental implant • Cardiovascalar sysem • Blood vessel prosthesis • Heart valve • Catheter • Organs • Artificial heart • Skin repair template • Artificial kidney • Heart-lung machine • Senses • Cochlear replacement • Intraocular lens • Contact lens • Corneal bandage • Titanium , Stainless steel, PE • Stainless steel, Co-Cr alloy • PMMA • Hydroxylapatie Teflon, Dacron • Titanium, alumina, calcium phosphate • Dacron, Teflon, Polyurethane • Reprocessed tissue, Stainless steel, Carbon • Silicone rubber, teflon, polyurethane • Polyurethane • Silicone-collage composite • Cellulose, polyacrylonitrile • Silicone rubber • Platium electrodes • PMMA, Silicone rubber, hydrogel • Silicone-acrylate. Hydrogel • Collagen, hydrogel Application Types of Materials
- 3. What is aBiomaterial? A material intented to interface with biological systems to evaluate, treat, augment or replace any tissue, organ or function of the body.
- 4. Biomaterials • Polymeric biomaterials •Bioceramics • Metallic biomaterials • Biocomposite • Biologically based (derived) biomaterials
- 5. Biocompatibility • Biocompatibility: Theability of a material to perform with an appropriate host response in a specific application. • Host response: the reaction of a living system to the presence of a material
- 6. Biocompatibility • B=f(X1,X2......Xn) • WhereX: material, design, application etc.
- 7. Medical Device • Itdoes not achieve its principal intended action in or on the human body by pharmacological, immunological or metabolic means, but it may be assisted in its function by such means.
- 8. Polymerization • Condensation: Areaction occurs between two molecules to form a larger molecule with the elimination of a smaller molecule. • Addition: A reaction occurs between two molecules to form a larger molecule without the elimination of a smaller molecule.
- 9. Polymeric Biomaterials: Adv& Disadv • Easy to make complicated items • Tailorable physical & mechanical properties • Surface modification • Immobilize cell etc. • Biodegradable • Leachable compounds • Absorb water & proteins etc. • Surface contamination • Wear & breakdown • Biodegradation • Difficult to sterilize
- 10. Polymeric Biomaterials • PMMA •PVC • PLA/PGA • PE • PP • PA • PTFE • PET • PUR • Silicones
- 11. Bioceramic: Advantages and disadvantage •High compression strength • Wear & corrosion resistance • Can be highly polished • Bioactive/inert • High modulus (mismatched with bone) • Low strength in tension • Low fracture toughness • Difficult to fabricate
- 12. Bioceramics • Alumina • Zirconia(partially stabilized) • Silicate glass • Calcium phosphate (apatite) • Calcium carbonate
- 13. Metallic Biomaterials:Advantages &Disadvantages • High strength • Fatigue resistance • Wear resistance • Easy fabrication • Easy to sterilize • Shape memory • High moduls • Corrosion • Metal ion sensitivity and toxicity • Metallic looking
- 14. Metallic biomaterials • Stainlesssteel (316L) • Co-Cr alloys • Ti6Al4V • Au-Ag-Cu-Pd alloys • Amalgam (AgSnCuZnHg) • Ni-Ti • Titanium
- 15. Surface modification (treatment) •Physical and mechanical treatment • Chemical treatment • Biological treatment
- 16. Surface Properties ofMaterials • Contact angle (Hydrophilic & Hydrophobic) • ESCA & SIMS (surface chemical analysis) • SEM (Surface morphology)
- 17. Deterioration of Biomaterials •Corrossion • Degradation • Calcification • Mechanical loading • Combined
- 18. General Criteria formaterials selection • Mechanical and chemicals properties • No undersirable biological effects carcinogenic, toxic, allergenic or immunogenic • Possible to process, fabricate and sterilize with a godd reproducibility • Acceptable cost/benefit ratio
- 19. Material Properties • Compresssivestrength • Tensile strength • Bending strength • E-Modulus • Coefficient of thermal expansion • Coefficient of thermal coductivity • Surface tension • Hardness and density • Hydrophobic/philic • Water sorption/solubility • Surface friction • Creep • Bonding properties
- 20. Cell/tissue reaction toimplant • Soft tissue • Hard tissue • Blood cells
- 21. The biological milieu •Atomic scale • Molecular scale • Cellular level • Tissue • Organ • System • Organism
- 22. pH in humans •Gastric content 1.0 • Urine 4.5-6.0 • Intracellular 6.8 • Interstitial 7.0 • Blood 7.17-7.35
- 23. Sequence of localevents following implantation in soft tissue • Injury • Actute inflammation • Granulation tissue • Foreign body reaction • fibrosis
- 24. Soft tissue responseto an implant • Actut (mins to hrs) Cell type: Leukocytes Function: Recognition, engulfment and degradation (killing) • Chronic (days to months) Cell types: Macrophages, monocytes and lymphocytes. • Granulation tissue formation (3-5 days) Cell types: Endothelial cells (forming blood vesssels), fibeoflasts (forming connnective tissue) • Foreign body reaction (days to life time) Cell types: Foreign body giant cells, Macrophages, fibroblasts • Fibrosis & Fibrous encapsulation Cell type: Fibroblasts
- 25. Bioactive and Osteointegration •A chemical bonding between bone and material will be formed. (Bioactive, Hydroxylapatite) • A direct contact between bone and impant under light microscope. (Osterintegration, titanium)
- 26. Blood material interaction •Hemolysis (red cells) • Coagulation (Platelets)
- 27. Test Hierarchies (forblood-contacting device) • Cell culture, cytotoxicity (Mouse L929 cell line) • Hemolysis (rabbit or human blood) • Mutagenicity (Ames test) • Systemic injection, acute toxicity (Mouse) • Sensitization (Guinea pig) • Pyrogenicity (Rabbit) • Intramuscular implnatation (Rat, rabbit) • Blood compatibility • Long-term implatation.
- 28. Standards • Test methods •Materials standards • Device standards • Procedure standards
- 29. ISO 10993 andEN 30993 • ISO 10993-1: guidance on selection of tests • ISO 10993-2: Animal welfare requirements • ISO 10993-3: Test for genotoxicity, carcinogenicity and reproductive toxicity • ISO 10993-4: Selection of tests for interactions with blood • ISO 10993-5: Tests for cytotoxicity: In vitro methods • ISO 10993-6: Test for local effects after implantation • ISO 10993-7: Ethylene oxide sterilization residuals • ISO 10993-8: Clinical investigation • ISO 10993-9: Degradation of materials related to biological testing • ISO 10993-10: Tests for irritation and sensitization • ISO 10993-11: Tests for systemic toxicity • ISO 10993-12: Sample preparation and reference materials • ........
- 30. Testing of Biomaterials •Physical and mechanical • Biological In vitro assessment in vivo assessment Functional assessment Clincal assessment
- 31. Biomaterials applications • Dentalimplant • Tooth fillings • Vascular implants • Drug delivery, bone fixing pine, suture • Bone defect fillings • Hip joint prosthesis bone plate • Scaffolds for tissue engineering • Contanct lens
- 32. 3-principles in dentalimplant design • Initial retention • Anti-rotation mechanics • No sharp-edges
- 33. Tooth fillings materials •Amalgam • Dental composite • Ceramics • Other metals
- 34. General criteria fortooth filling materials • Non-irritation to pulp and gingival • Low systemic toxicity • Cariostatic • Bonding to tooth substance without marginal leakage (20 u) • Not dissolved or erode in saliva • Mechanical strength, wear resistance, modules matching. • Good aesthetic properties • Thermal propertiesy (expansion & conductivity) • Minimal dimensional changes on setting and adequate working time and radio opacity
- 35. Textile structure andvascular implant • Weaving • Braiding • knitting
- 36. Calcium phosphate-based bioceramic • Bone(ACP, DCPD, OCP &HA) • Ca-P compounds • Applications: Bone fillers/HA-coatings/HA-PLA/In situ setting cement/tooth paste/drug tablets
- 37. Hip joint prosthesis •Ceramic head • Metallic stem • Polymeric socket • Composite bone cement
- 38. Tissue engineering • Theapplication of engineering disciplines to either maintain existing tissue structures or ti enable tissue growth. • From a material engineering pint of view, tissues are considered to be cellular composites representing mltiphase system: Three main structural components: 1. Cells organised into functional units 2. The extracellular matrix 3. Scaffolding architecture
- 39. Polymer concepts intissue engineering • Fabrication procedures of a porous polymer 3D scaffold: PLGA dissolved in chloroform and mixed with NaCl particles, evaporation of the chloroform, dissoltion of NaCl in water, resulting a polymer sponge with over 96% porosity.
- 40. Requirements for SoftTissue Adhesive • Biodegradable • Fast spread on wet (wound) surface • Adequate working time • Adequate bonding strength • Hemostasis • Biocompatible
- 41. Contact lens • Opticalproperties • Chemical stability • Oxygen transmissibility • Tear film wettability • Resistance to lipid/protein deposition • Easy to clean
- 42. Drug delivery (Slow/Controlled release) •Most effective and low toxi dose • A constant dosage over a long period • Local treatment • Easy to handle and cost-effective
- 43. Classification of slowrelease system • Diffusion controlled • Water penetration controlled • Chemically controlled • Pendant chain systems • Regulated system (Magnetic or ultrasound)
- 44. Leading medical devicecompany • Johnson & Johnson (www.jnj.com) • Biomet INC (www.biomed.com) • Strycker Howmedica Osteonics (www.osteonis.com) • Sulzer Orthopedics Ltd (www.sulzerotho.com) • Zimmer (www.zimmer.com) • Merck & Co Inc (www.merck.com) • Nobel biocare/AstraZeneca/Pacesetter AB/Q-med/Artimplant/Doxa
- 45. Sterilization Methods •Moist heat(121-125oC, 15-30 min) •EO (CH2CH2O) •Radiation (60Co & Electron Beam) •Dry heat > 140oC •Others (UV, Ozone X-ray etc)
- 46. •Orthopedics (small joints) •Catheters,Drains •Extracorpreal Equipment (Dialysis, heart bypass manchines, blood oxygenator) •Aesthetic implant •Spine •HIP ? Silicone Applications
- 47. Calcium phosphate cement(CPC) is a synthetic bone graft material that was invented in 1986 by L. C. Chow and W. E. Brown, scientists at the American Dental Association. The cement is a white powder consisting of equimolar amounts of ground Ca4(PO4)2O (tetracalcium phosphate, TTCP) and CaHPO4 (dicalcium phosphate anhydrous, DCPA). When mixed with water, the material forms a workable paste which can be shaped during surgery to fit the contours of a wound. The cement hardens within 20 min allowing rapid closure of the wound. The hardening reaction, which forms nanocrystalline hydroxyapatite (HA) as the product, is isothermic and occurs at physiologic pH so tissue damage does not occur during the setting reaction. CPC was FDA approved for the treatment of non-load-bearing bone defects in 1996. HA is the primary inorganic component of natural bone which makes the hardened cement biocompatible and osteoconductive. Over time, CPC is gradually resorbed and replaced with new bone. Because CPC is brittle, it is used for non-load-bearing applications such as dental and cranio-facial applications. CPC has two significant advantages over pre-formed, sintered ceramics. First, the CPC paste can be sculpted during surgery to fit the contours of the wound. Second, the nanocrystalline hydroxyapatite structure of the CPC makes it osteoconductive causing it to be gradually resorbed and replaced with new bone. Recent work with CPC has focused on improving mechanical properties, making premixed cements, making the cement macroporous and seeding cells and growth factors into the cement. Invention of CPC: Brown WE, Chow LC (1986) A new calcium phosphate water setting cement. Brown PW, ed. Cements Research Progress. Westerville, OH: American Ceramic Society; 352–379. CPC Review: Friedman CD, Costantino PD, Takagi S, Chow LC. (1998) BoneSourceTM hydroxyapatite cement: a novel biomaterial for craniofacial skeletal tissue engineering and reconstruction. J Biomed Mater Res (Appl Biomater) 43:428- 432, 1998. Image Copyright 2007 by Wright Medical Technology, Inc. Used with permission.
- 48. Requirements of aScaffold used for tissue engineering • Easy cell penetration, distribution, proliferation • Permeability of culture medium • In vivo vascularization (once implanted) • Maintenance of cell phenotypes • Adequate mechanical properties • Controlled biodegradation • Ease of fabrication