Dental Materials Properties PDF

1 SYLLABUS  2 ▪ Introduction to Dental Materials and its Physical, Mechanical and Chemical Properties ▪ Gypsum Products ▪ Impression Materials and CONTENT Compounds ▪ Synthetic Resin...

1 SYLLABUS  2 ▪ Introduction to Dental Materials and its Physical, Mechanical and Chemical Properties ▪ Gypsum Products ▪ Impression Materials and CONTENT Compounds ▪ Synthetic Resin ▪ Denture Base Resin ▪ Denture Cleanser  3 ▪ Restorative Resin ▪ Dental Cements ▪ Dental Amalgam and Direct CONTENT Filling Gold ▪ Dental Casting Alloys  4 ▪ Dental Waxes ▪ Dental Ceramic CONTENT ▪ Dental Abrasives and Polishing Agent  5 Properties of Dental Materials  6 At the end of the session, the learners should be able to: 1. Describe the various classifications of material properties. 2. Differentiate between mechanical, Properties of physical and biological properties. Dental 3. Relate the properties of materials to its Materials clinical requirements and performance.  7 ▪ Interatomic bonds ▪ Primary bonds (Chemical bonds) ▪ Share electrons (Strong bond) Areas to be ▪ Ionic bonds reviewed ▪ Covalent bonds ▪ Metallic bonds ▪ Combination of primary bonds  8 ▪ Interatomic bonds ▪ Secondary bonds ▪ Charge variations among atomic groups of molecule induce dipole Areas to be forces that attract adjacent reviewed molecules or parts of a large molecule ▪ van der Waals forces ▪ Hydrogen bond  9 ▪ Atomic arrangement ▪ Crystalline structure ▪ Space lattice ▪ Metals Areas to be ▪ Non-crystalline structure reviewed ▪ Amorphous ▪ Non-repeating units ▪ Glass  10 ▪ Interatomic bond distance and thermal energy Areas to be ▪ Bond distance reviewed ▪ Bonding energy ▪ Thermal energy  11 ▪ Diffusion ▪ Adhesion and bonding Areas to be ▪ Surface and surface energy reviewed ▪ Wetting ▪ Contact angle and wetting angle  12 Areas to be reviewed ▪ Surface and surface energy  13 Areas to be reviewed ▪ Surface tension  14 Areas to be reviewed ▪ Wetting  Wettability Measure of the affinity of a liquid for a solid as indicated by spreading of a drop. Degree of wetting depends on the relative surface energies of the solids and the liquids and on their intermolecular attraction.  17 ▪ Adhesion and bonding ▪ Adhesion Areas to be ▪ Cohesion reviewed ▪ Adhesive ▪ Adherend  18 ▪ Adhesion: An attraction between two contacting surfaces promoted by the interfacial force of attraction between the molecules or atoms of two different species; adhesion may occur as chemical adhesion, mechanical adhesion (structural interlocking),or a combination of both. ▪ Adherend and adhesive: Substance that promotes adhesion of one substance or material to another. An adherend is a material substrate bonded to another material by means of an adhesive.  19 Adhesive Adherend  20 ▪ Bonding: The action of joining objects or particles together by means of adhesive or force of attraction. ▪ Cohesion: Bonding between molecules or atoms of the same species. ▪ Contact angle: Angle of intersection between a liquid and a surface of a solid that is measured from the solid surface through the liquid to the liquid/vapor tangent line originating at the terminus of the liquid/solid interface; used as a measure of wettability, whereby no wetting occurs at a contact angle of 180, and complete wetting occurs at an angle of 0.  21 Areas to be reviewed ▪ Contact angle and wetting angle  22 ▪ Micromechanical bonding: Retention associated with an adhesive penetrating a roughened adherend surface. ▪ Surface energy: ▪ The excess energy of attraction that the surface of a material (liquid and solid) as compared with the bulk of the material because molecules or atoms at the surface are not surrounded by their fellows as those in the bulk. ▪ It can be treated as the work (energy) required to build an area of a particular surface and has the unit of mN/m2.  23 ▪ Surface tension: ▪ The tendency of fluid surfaces to contract to the smallest surface area by an inward force caused by the imbalance of mutual attraction between molecules on the liquid surface. ▪ The very inward force also keeps the molecules of the surface constantly under tension. ▪ The cohesive force keeping molecules bonded on the surface is known as the surface tension of the liquid, with the unit of mN/m.  24 ▪ Wetting and wetting agent: ▪ Wetting is the ability of a liquid to maintain contact with a solid surface; it reflects the intermolecular interactions when the two are brought in intimate contact. ▪ A wetting agent is a surface-active substance that can be applied to a solid substrate to reduce the surface tension of the liquid to be placed on the solid; the purpose is to promote wetting or adhesion.  25 At the end of the session, the learners should be able to: 1. Describe the various classifications of material properties. 2. Differentiate between mechanical, Properties of physical and biological properties. Dental 3. Relate the properties of materials to its Materials clinical requirements and performance.  26 ▪ Properties ▪ “A characteristic or trait that you can use to describe matter by observation, measurement, or combination.” ▪ “An essential or distinctive attribute or Rational quality of a thing.” ▪ Why do we study properties? ▪ Why do dental materials evolve?  27 1. Rheology/viscosity 2. Physical properties 3. Mechanical properties Properties of 4. Thermal behavior Dental 5. Adhesion/adherend Materials 6. Working time/setting time 7. Biological Properties/ Biocompatibilty  28 ▪ Study of deformation and flow characteristics of matter, whether liquid or solid RHEOLOGY ▪ Viscosity ▪ Resistance to fluid flow  29 ▪ Stress ▪ Force per unit area that develops within a material when an external force is applied TERMINOLOGY ▪ Strain ▪ Calculated change in length divided by the initial reference length  30 ▪ Shear stress: τ = F/A ▪ σ (sigma) ▪ τ (tau) TERMINOLOGY ▪ Shear strain: ε = l/l0 ▪ γ (gamma) ▪ ε (epsilon)  31 Greek Alphabet  32 TERMINOLOGY ▪ Shear stress  Time-dependent plastic strain 33 of a solid under a static or constant load TERMINOLOGY  34 ▪ Stress Strain Curve ▪ Used to characterize the viscous behavior of fluid ▪ Viscous ▪ Having high viscosity RHEOLOGY ▪ Viscosity: h = τ/ε ▪ 𝜂(𝛾̇ ) ▪ 𝜂(eta) ▪ Shear rate 𝛾̇  35 RHEOLOGY ▪ Stress Strain Curve  36 ▪ Newtonian ▪ Viscosity does not change ▪ Dilatant ▪ Rate of flow decreases with increasing strain until it reaches a RHEOLOGY nearly constant value ▪ Pseudoplastic ▪ Rate of flow increases with increasing strain  37 ▪ Plastic ▪ Behave like rigid material until some minimum amount of strain is applied ▪ Thixotropic RHEOLOGY ▪ Viscosity depend on previous deformation of the liquid. ▪ Material becomes less viscous and more flowable upon repeated applications of pressure  38 RHEOLOGY  39 RHEOLOGY  40 ▪ Shear rate ▪ The rate at which a fluid is sheared or “worked” during RHEOLOGY flow. ▪ 1/s = 1 hertz ▪ Cycle per seconds  41 ▪ Creep ▪ Time-dependent plastic strain of a solid under a static or constant load STRESS ▪ Sag RELAXATION ▪ Irreversible deformation of metal frameworks of fixed dental prostheses in the firing temperature range of ceramic veneers  42 STRESS RELAXATION  43 ▪ “Any property that is measurable, whose value describes a state of a physical system.” ▪ “...properties that can be measured PHYSICAL or observed without changing the PROPERTIES chemical nature of the substance.” ▪ “.. characteristic of matter that is not associated with a change in its chemical composition.”  44 ▪Based on laws of ▪ Mechanics ▪ Acoustics ▪ Optics ▪ Thermodynamics PHYSICAL ▪ Electricity PROPERTIES ▪ Magnetism ▪ Radiation ▪ Atomic structure ▪ Nuclear phenomenon  45 Color Density Volume Physical Mass Properties Boiling point Melting point  46 ▪ Esthetics (Aesthetics) Physical ▪ Principles and techniques Properties associated with development of color and appearance COLOR required to produce a natural, pleasing effect in the dentition  47 ▪ Three dimensions of color space ▪ Hue ▪ Dominant color of an object Physical Properties ▪ Value ▪ Relative lightness or darkness COLOR of a color (grey scale) ▪ Chroma ▪ Degree of saturation of a particular color  48 Physical Properties COLOR 3D Munsell Color Space  49 Physical Properties COLOR ▪ L*a*b* Color Chart  50 ▪ L*a*b* Color Chart Physical ▪ L – Hue Properties ▪ a – red-green axis COLOR ▪ b – yellow-blue axis  51 Physical Properties COLOR ▪ L*a*b* Color Chart  52 Physical Properties COLOR ▪ Metamerism  53 ▪ Nature of light Physical ▪ Visible light Properties ▪ 400 nm - 700 nm COLOR ▪ Protanopia ▪ Color blindness  54 ▪ Reflection ▪ Specular reflectance (Mirror- Physical like Properties ▪ Diffuse reflectance (Dull) ▪ Absorption COLOR ▪ Refraction ▪ Transmission  55 ▪ Refraction ▪ A change of direction that light undergoes when it enters a Physical medium with a different density Properties from the one through which it has COLOR been traveling ▪ Transmission ▪ Passing through unchanged  56 Physical Properties COLOR ▪ Refraction  57 ▪ Opacity ▪ Related to amount of light it can absorb and or scatter. Absorbes more light. Physical ▪ Translucency Properties ▪ Absorbs less light ▪ Transparency COLOR ▪ Absorbs no light ▪ Transparent material transmit 100% of the light  58 ▪ Refractive index ▪ Measure of the bending of a ray of light when passing from Physical one medium into another. Properties ▪ Enamel: 1.65 COLOR ▪ Reflect some light ▪ Absorb some light ▪ Refract some light ▪ Transmits some light  59 Physical Properties COLOR  60 Physical Properties COLOR ▪ Fluorescence  61 ▪ Fluorescence ▪ Natural tooth absorbs light of short wavelength too short to be visible Physical to human eye. Properties ▪ 300 nm – 400 nm (ultraviolet radiation) COLOR ▪ Energy tooth absorb becomes light with longer wavelength ▪ The tooth becomes a light source  62 Physical Properties COLOR ▪ Fluorescence  63 Physical Properties COLOR ▪ Radiopacity ▪ Opacity to the radio wave and x-ray portion of the electromagnetic spectrum  64 Physical Properties COLOR ▪ Radiolucency  65 ▪ Please review this lecture and look up terms that you did not understand. Assignment ▪ Read rest of properties presented in the list of dental materials properties.  66 Properties of Dental Materials Part II  67 ENAMEL DENTIN 2%Organic 10% Water 25% Water 50% Mineral 88% Mineral 25%Organic  68 ▪ ADA Specification Program ▪ Council of Scientific Affairs ▪ US Food and Drug Administration Standards for ▪ FDI: Specifications Dental (Fèdèration Dentaire Internationale) Materials ▪ ISO (TC 106 –Dentistry) (International Organization of Standardization)  69 ▪ ADA Specification Program ▪ Specification number ▪ US Food and Drug Administration Standards for ▪ FDI & ISO worked together Dental ▪ TC 106 responsible to standardize Materials terminology, test methods, develop standards for dental materials, instruments, appliances and equipment  ▪Heat Transmission 70 ▪ Thermal Conductivity ▪ Quantity of heat in calories per second passing through a material 1 cm thick with a cross section of 1 THERMAL cm2 having temperature difference PROPERTIES of 1K (10C) and is measured under steady-state conditions in which the temperature gradient does not change  71 ▪ KELVIN ▪ The kelvin (K) temperature scale extends the degree Celsius scale such that zero degrees K is defined as absolute zero (0 K = -273.15 0C). DEFINITION ▪ Temperatures on this scale are called “kelvins”. ▪ K = 0C + 273.15 ▪ Celsius to Kelvin: K = 0C + 273.15 72  73 ▪Heat Transmission ▪ Thermal Conductivity (𝛋) ▪ Physical property that governs THERMAL heat transfer through a material PROPERTIES by conductive flow ▪ watt/meter/K ▪ W x m-1 x K-1 (W m-1 K-1 )  74 ▪ Thermal Conductors ▪ Materials with high thermal conductivity include metals Thermal Conductivity  75 ▪ Thermal Insulators ▪ Materials with low thermal conductivity include resins Thermal Conductivity  ▪ Water = 0.44 ▪ Enamel= 0.93 ▪ Dentin= 0.57 Thermal Conductivity ▪ Amalgam= 22.6 (W m-1 K-1) ▪ Composite= 1.09-1.37 ▪ Pure gold= 297.00 ▪ Zn Phosphate= 1.05  77 ▪ Heat Transmission ▪ Thermal diffusivity (h) ▪ Measure of the speed with which a temperature change will spread through an object THERMAL when one surface is heated PROPERTIES ▪ Grams per cm3 ▪ cm2 s-1 ▪ h = ___𝜿___ c𝝆 x 𝝆  78 h= ___𝜿___ c𝝆 x 𝝆 ▪ 𝜿 thermal conductivity ▪ c𝝆 equal to specific heat Thermal ▪ 𝝆 temperature-dependent density in grams per cm3 Diffusivity Specific Heat Quantity of heat needed to raise the temperature of a unit mass by 10C  ▪ Water = 0.0014 ▪ Enamel= 0.0047 ▪ Dentin= 0.0018-0.0026 Thermal Diffusivity ▪ Amalgam= 0.96 (cm2 s-1) ▪ Composite=0.0019-0.0073 ▪ Pure gold= 1.18 ▪ Zinc Phosphate=0.0030  80 ▪ Coefficient of Thermal Expansion ▪ A change per unit length per THERMAL unit of the original length of a PROPERTIES material when its temperature is raised 10C (1 K) 𝜶 = __ΔL__ L x ΔT  ▪ Coefficient of Thermal Expansion- ▪ Enamel= 11.4 X 10-6/C Thermal ▪ Gold= 14 X 10-6/C Properties ▪ Amalgam= 25 X 10-6/C ▪ Composite= 14-50 X 10-6/C When you drink something warm When you drink something cold  84 ▪ Tarnish ▪ Surface discoloration on a metal or a slight loss or alteration of the surface finish or luster ▪ Usually forerunner of corrosion Electrochemical PROPERTIES  85 ▪ Corrosion ▪ Electrochemical process and is dependent on the ability to conduct electrical current, either by means of free electrons in Electrochemical metals or via ions in solution PROPERTIES  86 ▪ CHEMICAL CORROSION (Dry Corrosion) ▪ Direct combination metallic and non-metallic elements to yield a chemical compound Electrochemical PROPERTIES  87 ▪ ELECTROCHEMICAL CORROSION (Galvanic corrosion, Wet corrosion) Electrochemical ▪ Anode PROPERTIES ▪ Cathode ▪ Electrolyte  88 ▪ ELECTROCHEMICAL CORROSION (Galvanic corrosion, Wet corrosion) Electrochemical ▪ Anode PROPERTIES ▪ Surface or site on a surface where positive ions (M+) are formed with production of free electrons  89 ▪ ELECTROCHEMICAL CORROSION (Galvanic corrosion, Wet corrosion) ▪ Cathode Electrochemical ▪ Surface or site where metal ions are PROPERTIES deposited from saturated solution and consume free electrons produced at the anode  90 Electrochemical PROPERTIES  91 ▪ ELECTROCHEMICAL CORROSION (Galvanic corrosion, Wet corrosion) ▪ Electrolyte Electrochemical PROPERTIES ▪ A substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water.  92 Electrochemical PROPERTIES  93 Electrochemical PROPERTIES  94 ▪ ELECTROCHEMICAL CORROSION (Galvanic corrosion, Wet corrosion) Electrochemical PROPERTIES https://www.sciencedirect.com/topics/chemistry/pitting-corrosion  95 ▪ ELECTROCHEMICAL CORROSION (Galvanic corrosion, Wet corrosion) Electrochemical PROPERTIES ▪  96 ▪ Pitting Corrosion ▪ Metal ions at base of pit oxidizes Electrochemical PROPERTIES  97 Electrochemical PROPERTIES https://www.ddcoatings.co.uk/2276/what-is-pitting-corrosion  98 Electrochemical PROPERTIES  99 ▪ Crevice corrosion ▪ Corrosion occurring in confined spaces to which the access of the working fluid from the environment is limited. These spaces are Electrochemical generally called crevices. PROPERTIES ▪ Pitting corrosion occurs across the surface of a component, crevice corrosion is associated with a crevice  100 Electrochemical PROPERTIES  101 Electrochemical PROPERTIES  102 Electrochemical PROPERTIES https://www.researchgate.net/publication/51110972_El ectrical_Implications_of_Corrosion_for_Osseointegratio n_of_Titanium_Implants/figures?lo=1  103 ▪Galvanic Shock ▪ Combination of dissimilar metals are in direct physical contact ▪ May produce galvanic corrosion Electrochemical PROPERTIES https://dentagama.com/news/oral-galvanism  104 Electrochemical PROPERTIES  105 Electrochemical PROPERTIES  ▪ Protection Against Corrosion 106 ▪ Protective covering ▪ Passivating metal ex. Chromium ▪ These can be disrupted Electrochemical PROPERTIES Mechanical Properties  109 ▪ Clenching force (Gibbs et al. (2002) ▪ With loss of posterior teeth: Clenching and ▪ 426 N (98 to 1031 N) between Mastication age of 26-78 Forces ▪ Complete dentition ▪ 720 N (244-1242 N)  ▪ Mechanical properties are the measured responses: ▪ Both elastic (reversible upon force reduction) and plastic DEFINITION (irreversible or nonelastic), ▪ Of materials under an applied force, distribution of forces, or pressure.  ▪ Defined by the laws of mechanics—that is, the physical science dealing with forces that act on bodies and DEFINITION the resultant motion, deformation, or stresses that those bodies experience.  112 ▪ Stress ▪ Force per unit area that develops within a material when an external force is TERMINOLOGY applied ▪ Strain ▪ Calculated change in length divided by the initial reference length  113 ▪ Shear stress: τ = F/A ▪ σ (sigma) ▪ τ (tau) TERMINOLOGY ▪ Shear strain: ε = l/l0 ▪ γ (gamma) ▪ ε (epsilon)  ▪ Stress-Strain Curve Mechanical Properties  115 Elevation Depression Open Close Mechanical Protrusion Retraction Properties Lateral (Side to side)  ▪ TYPES OF STRESS 116 ▪ Compressive ▪ Tensile ▪ Shear ▪ Twisting moment/ Torsion ▪ Bending moment / Flexural Mechanical Properties  117 Compressive stress ▪ When the body is subjected to two sets of forces in the same straight line but directed towards each other Mechanical Properties  118 Mechanical Properties  119 Tensile stress ▪ When it is subjected to two sets of forces that are directed away from each other in the same straight line. Mechanical Properties  120 Mechanical Properties https://www.scielo.br/j/jaos/a/cYnhXdLSR4cSmDVBPrXwqrC/?lang=en#ModalFigf1  121 Shear stress ▪ result of two forces directed parallel to each other Bending moment / Flexural ▪ force per unit area of a Mechanical material that is subjected to Properties flexural loading Twisting moment/ Torsion ▪ result of two rotational forces directed towards/away to each other  122 ▪ Shear Stress ▪ Bending Moment/Flexural ▪ Twisting moment/Torsion Mechanical Properties  123 Mechanical Properties  124 FLEXURAL STRENGTH  125 TORSIONAL STRENGTH  126 ▪ Young’s Modulus or Modulus of Elasticity ▪ Relative stiffness or rigidity of a Mechanical material Properties ▪ Ratio of the stress to the strain of a material within its elastic behavior  127 Elastic Modulus  ▪ Elastic Modulus 128 Mechanical Properties  129 Poisson’s Ratio  130 ▪ Elastic Modulus Mechanical Properties  Elastic Deformation  Elastic Deformation  Elastic Deformation Plastic/Permanent Deformation Plastic/Permanent Deformation Plastic/Permanent Deformation Plastic/Permanent Deformation Plastic/Permanent Deformation  ▪ Elastic strain (reversible) 140 ▪ Plastic strain (irreversible) Mechanical Properties Which material has a higher elastic modulus? ` Material A Material B  143 ▪ Elastic limit - the maximum stress a material can withstand before it becomes plastically deformed ▪ Maximum flexibility - is defined as the flexural strain that occurs when the material is stressed to its proportional Mechanical limit Properties  144 ▪ Law of elasticity ▪ For relatively small deformations of an object, the displacement or size of the deformation is directly Hooke’s Law proportional to the deforming force or load. ▪ Under these conditions the object returns to its original shape and size upon removal of the load. https://www.britannica.com/science/Hookes-law  145 ▪ Elastic behavior of solids according to Hooke’s law can be explained by the fact that small displacements of Hooke’s Law their constituent molecules, atoms or ions from normal positions is also proportional to the force that causes the displacement. https://www.britannica.com/science/Hookes-law  146 Proportional limit - the stress above which stress is no longer proportional to strain. Yield strength/ Proof stress - the Mechanical stress required to produce a given Properties amount of plastic strain Ultimate strength - measure of stress required to fracture a material  147 Mechanical Properties  Stress-Strain Curve S YS Fracture Point t EL r PL e s s Strain Elastic limit- maximum stress which a material can endure without undergoing plastic/permanent deformation S YS Fracture Point t EL r e PL s s Strain Proportional limit- maximum stress at which stress is proportional to strain S YS Fracture Point t EL r e PL s s Strain Yield strength- stress value just above proportional limit in which there is already a permanent strain S YS Fracture Point t EL r e PL s s Strain  152 ▪ Resilience (springiness) - the amount of energy absorbed within a unit volume of a structure when it is stressed to its proportional limit. Mechanical Properties  ▪ Maximum amount of energy that the material can absorb without undergoing permanent deformation ▪ Measured by area under straight line portion of curve Resilience  154 ▪ Toughness - the amount of elastic and plastic deformation energy required to fracture a material. Mechanical Properties  ▪ Amount of energy required to fracture a material ▪ Resistance to fracture Toughness  156 ▪ Flexural strength/ transverse strength/ modulus of rupture Mechanical ▪ Force per unit area at the instant of fracture in a test Properties specimen subjected to flexural loading  Flexural Strength Testing  158 Mechanical Properties  ▪ Brittleness - is the relative 159 inability of a material to sustain plastic deformation before fracture of a material occurs. Mechanical Properties  ▪ Ductility - ability of a material to 160 be stretched plastically at room temperature without fracturing. Percent elongation. Mechanical Properties  ▪Malleability - the ability of a material to 161 sustain considerable permanent deformation without rupture under compression, as in hammering or rolling into a sheet. Percent compression. Mechanical Properties  162 ▪ Dental Materials ▪ Ductile 1. Gold 2. Silver Mechanical 3. Platinum Properties ▪ Malleable 1. Gold 2. Silver 3. Copper  Hardness Tests ▪ Brinell (BHN)- not for brittle materials or plastics that exhibit elastic recovery. - For metals Hardness - ▪ Rockwell - not for brittle materials or plastics that exhibit elastic recovery. resistance of a -For metals material ▪ Knoop (KHN)- for hard and soft, brittle to indentation materials ▪ Enamel ▪ Dental  Hardness Tests ▪ Vickers (VHN)- for brittle Hardness - materials resistance of a ▪ Enamel 270-360 VHN material ▪ Dentin 50-60 VHN to indentation ▪ Shore- for rubbers and plastics ▪ Barcol- for rubbers and plastics  ▪ Hardness Testing (Indentation) 165 Mechanical Properties Hardness Testing BRINELL Brinell Hardness Number (kgf/mm2) BRINELL & VICKERS HARDNESS TEST Hardness Testing VICKERS Vickers number (HV)  168 ▪ Teeth bonding is a procedure in which a tooth-colored resin material (a durable plastic material) is applied and Bonding hardened with a special light, which ultimately "bonds" the material to the tooth to restore or improve a person's smile.  169 ▪ A molecular or atomic attraction between two contacting surfaces promoted by interfacial forces of Adhesion attraction between the molecules or atoms of two different species ▪ Chemical, mechanical or a combination of both.  170 ▪Material properties Success of ▪Design of dental device Dental Materials ▪Biocompatibility of component materials  171 ▪ Non-toxic ▪ Non-irritant ▪ No carcinogenic or allergic potential Biological ▪ Bioinert Properties ▪ Remains unchanged from activity of biologic organisms and does not elicit biologic activity ▪ No adverse event  ▪ The ability of a biomaterial to 172 perform its desired function with respect to a medical (or dental) therapy ▪ Without eliciting any undesirable local or systemic effects in recipient or beneficiary of that Biocompatibilty therapy ▪ Generating the most appropriate beneficial cellular or tissue response in that specific situation ▪ Optimizing the clinically relevant performance of that therapy (Williams 2008)  173 ▪ “the ability of a material to function in a specific application in the presence of an appropriate host response” Biocompatibilty  174 ▪ The chemical nature of its components ▪ The physical nature of its components ▪ Types and locations of patient tissues that will be exposed to the device ▪ Duration of exposure ▪ Surface Characteristics of the material Biocompatibilty ▪ Amount and nature of substances eluted depends on: from the material  175 Biocompatibilty  176 Biocompatibilty  177 ▪ Define intended use and indications of dental materials ▪ Identify the main components Selecting of dental materials Biocompatible ▪ Read on clinical Materials performance/published literature from independent sources