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Lecture no 2 introduction to dental material
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Lecture no 2 introduction to dental material

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  • 1. U L F A T
  • 2. INTRODUCTION TO CHEMISTRY OF DENTAL MATERIALS DR. YAWAR HAYAT KHAN BDS, M.Sc. (London) Assistant Professor/ Head of Department (Dental Materials) Islamic International Medical College (Dental Section)
  • 3. Topics/ Lectures
    • General Introduction to Dentistry
    • Introduction to Dental Materials
    • Physical properties of materials:
      • Characterisation of solid surfaces
      • Adsorption, absorption, and sorption
      • Surface tension, wetting, capillary rise
      • Forces involved in Denture retention
    • Thermal, Electrical and other related properties of dental materials
    • Mechanical properties i.e. stress, stain, stress/ strain relationship and other related properties.
  • 4. Topics/ Lectures
    • Classification of dental materials on their basis of chemistry e.g., example Polymers, Ceramics, Metals, Alloy and Composites.
    • Impression materials in all respects and duplicating materials.
    • Adhesion: Enamel and Dentine bonding agents and bonding system.
    • Dental Cements.
      • Zinc Phosphate Cement.
      • Zinc Oxide/ Eugenol, Modified Zinc Oxide/ Eugenol, Ethoxy Benzoic Acid Cement, Zinc Polycarboxylate, Zinc Polyacrylate Cement, Silico Phosphate Cement.
      • Glass Ionomer Cement and Hybrid Ionomer Cement
      • Compomers, Cavity Varnish, Cavity Liners, Calcium Hydroxide and Gutta purcha.
  • 5. Topics/ Lectures
    • Composite Restorative Materials and properties of composites
    • Dental amalgam
    • Abrasion and polishing materials
  • 6.
    • Science of Dental Materials is an applied basic science dealing with the physical, chemical, biological properties and interaction with oral tissues of the materials used in clinical dentistry
    • This subject also deals with the manipulative techniques, applications and uses of dental materials
    • Every dental procedure requires the use of materials so a variety of materials are available which requires proper selection and evaluation
    • Subject is approached with the view of determining:
      • Chemical nature of material
      • Physical & mechanical functions
      • Manipulative techniques
      • Applications
      • Biological considerations
    • To conclude it is relevant to say that the subject of dental materials is a basic science in itself with its own tenets and principles
    Introduction to Dental Materials
  • 7. AIM OF THE SUBJECT
    • Since dentistry is considered both as an art and science subject therefore, the aim of science of dental materials is to stress upon the principles involved in the use of dental materials. The main requirements for dental materials in general are as under:
      • Why materials react and behave as they do?
      • What manipulative techniques are used?
      • How variation in techniques effect their properties?
      • What is the effect of material on its environment?
      • What is the nature of the interface between the synthetic material and oral tissues?
      • What is the effect of oral environment on the material?
      • What is the appearance of materials?
      • What other properties are important?
      • Is the material easy and convenient to use?
  • 8. HISTORICAL BACKGROUND
    • Early History
      • Related to Phoenicians, Greeks & Romans
      • Gold is one of the oldest materials used (prosthetic dental purposes for at least 2500 years)
    • Medieval & Early Modern Period
      • Dental historians doubt that beginning of Christian era to 1500 AD was a “DARK AGE” of inactivity
      • Shift of practice from prosthetic restoration to restoration of carious teeth which were filled with alum, honey and other substances during the period of 1050 – 1122 AD (Al Razi)
      • First book to treat dentistry independently was written in German in 1548 AD by Walter Herman Ryff
    • Beginning of Dental Science
      • 1600 – 1840 AD
    • Period of Mechanical Improvement
      • 1840 – 1900 AD
  • 9. HISTORICAL BACKGROUND
    • Advances Since 1900 AD
      • Establishment of Dental institutes
      • Establishment of standard organizations
        • American Dental Association (ADA)
        • National Bureau of Standards
    • Future Development in Biomaterials
      • Specific Stress on bio-compatibility of materials
  • 10. DENTAL MATERIALS
    • Requirements of Materials
    • Selection of Materials
    • Handling of Materials
    • Evaluation of Materials
    • Application of Materials
    • Classification of Materials
  • 11. REQUIREMENTS of Materials
      • Why materials react and behave as they do?
      • What manipulative techniques are used?
      • How variation in techniques effect their properties?
      • What is the effect of material on its environment?
      • What is the nature of the interface between the synthetic material and oral tissues?
      • What is the effect of oral environment on the material?
      • What is the appearance of materials?
      • What other properties are important?
      • Is the material easy and convenient to use?
  • 12. SELECTION of Materials
    • Since variety of materials are available, so they require proper selection
    • Good selection leads to success of restoration
    • Selection is subjected to the need and type of restoration
  • 13. HANDLING of materials
    • Direct materials (filling materials)
    • Indirect materials (impression materials)
  • 14. EVALUATION of Materials
    • Proper evaluation & testing of the material is required before application
    • It is emphasized that most manufacturers of dental materials should operate appropriate quality assurance programs so that the materials are thoroughly tested and evaluated before release into the market
    • Steps for evaluation:
        • Standard specification
        • Laboratory evaluation
        • Clinical trials
  • 15.
    • Criteria for Selection
    • Analysis of problem
    • Consideration of requirement
    • Consideration of available material &
    • their properties
    • Choice of material
  • 16.
    • Standard Specification
      • Many standard specification tests of both national & international standards are available which effectively maintained quality level of most of the dental materials
    • Laboratory Evaluations
      • Certain lab tests some of which are used in standard specifications, can be used to indicate the suitability of materials
      • For e.g., simple solubility test can indicate the stability of a material in aqueous media – a very important property for filling materials
      • The methods used to evaluate materials in lab give results which can be correlated with the clinical experiences
    • Clinical trials
      • Ultimate test is clinical trial although lab tests provides suitable information and useful data regarding materials
      • Many materials provides good results in laboratory, but found lacking when subjected to clinical use
      • Majority of manufacturers perform clinical trials on materials in cooperation with a hospital or university before finally releasing a product
  • 17. APPLICATION of Materials
    • Varies from material to material
    • Also depends upon the requirement and oral conditions
  • 18. CLASSIFICATION OF MATERIALS
    • Ceramics
    • Metals
    • Polymers
    • Composites
  • 19.
    • They are simple or complex combinations of metallic or non-metallic elements of periodic table
    • Characteristically they are hard & abrasive
    • Examples are Alumina, Tungsten Carbide & Silica
    CERAMICS
  • 20.
    • Metals are usually:
      • Hard
      • Lustrous
      • Dense
      • Good conductors of heat & electricity
      • Ductile & malleable
    • They are electropositive i.e., they give positive ions in solutions
    • Of over 100 elements in the PERIODIC table, some 68 are metals
    METALS
  • 21.
    • Metals can occur either as pure elements, or in compounds with other elements in ores. For example:
      • Gold occurs as pure metal
      • Silver occurs as pure metal
      • Copper seldom occurs as pure metal
    • Metals can be produced by the following methods
      • Thermal methods
      • Hydrometallurgical methods
      • Thermo-electrolytic methods
    METALS
  • 22.
    • Polymers are long-chain molecules consisting of many repeating units. A monomer is the smallest repeating unit in the polymer chain.
    • Polymers are prepared from monomers and the process is known as polymerization.
    • They are classified as natural materials and synthetic materials
    • Natural materials include proteins, polysaccharides (agar, alginate & starch), polyisoprenes (gutta percha and rubber), polynucleic acids (DNA & RNA)
    POLYMERS
  • 23.
    • Synthetic materials includes polythene, nylon and bakelite
    • Organic compounds found in fossil fuels, as gas, oil, coal. Other natural polymers are wood pulp & cotton (cellulose), nucleic acids & collagen (structural building blocks of all living things)
    • Polymers have;
        • Low melting points
        • Fairly soft & not stiff
        • Can be synthetically produced
    POLYMERS
  • 24.
    • Are combinations of basic ceramic, metallic & polymeric materials
    • Composites are prepared to improve properties of individual components & enhance their clinical service
    • Examples are
      • Ceramic – metallic
      • composites ----- Tungsten
      • Carbide – Cobalt burs
    COMPOSITES
  • 25. Materials in use
  • 26. THANK YOU

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