DENTAL MATERIAL

DENTAL MATERIAL

1. DENTAL COMPOSITES: fill material and sp tray

   • Consits of: RESIN, FILLER, COUPLING AGENT

2. FIBRE REINFORCED MATERIALS:type of composite

3. consits of: FIBRES OF HIGH STRENGTH AND MODULUS

4. EMBEDDED IN A BONDED MATRIX

5. TESTS USED TO CHARACTERISE MATERIALS

   • TENSILE = for applied to elongate rod
   • COMPRESSIVE = force applied, not recommended for brittle materials
   • DIAMETRAL TENSILE STRENGTH = for brittle mat where conventional tensile n/a
   • FLEXURAL = determines how material bends (3points)
   • VICKERS,BRINELL,KNOOP = surface hardness test
   • Large num - low hardness, small num - high hardness
   • SHEAR BOND STRENGTH = adhesive failure. Pebdulum swing #'s specimen
   • SURFACE ROUGHNESS = Profilometer asses surface characteristics
   • THERMAL PROPERTIES = thermal conductivity (K) rate of heat transfer

6. RHEOLOGICAL PROPERTIES

   • Study of the flow of materials
   • ie Luting cement , flowable comp
   • Study of VISCOSITY and how it vaaries with rate of shear and time
   • DILATANT: viscosity INCREASES with applied pressure
   • NEWTONIAN: viscosity remains CONSTANT with applied pressure
   • PSEUDOPLASTIC= viscosity DECREASES with applied pressure

7. CHEMICAL PROPERTIES - CORROSION

   • Chemical reactivity of metals and alloys
   • An electrolytic property
   • Should dispaly good corrosion resistance

8. BIOLOGICAL PROPERTIES

   • lab screening, in vivo test, human randomised cotrolled trial
   • Ideal material - non toxic, non irritant to the pulp, non cariogenic