Filling Materials

Filling Materials

1. Requirements

   • Aesthetic
   • Adhesive bond with tooth
   • Radiopaque
   • Decreased thermal conductivity & diffusivity
     • Protect pulp
   • Similar coefficient of thermal expansion to enamel & dentine
   • Long WT & short ST
   • Mechanical properties
     • Strong (less creep)
     • Tough
     • Reduced wear
     • Hard

2. Amalgam

   • Setting reaction = y + Hg --> y1 + y2 + y + Hg
   • Composition
     • Powder = Silver, Tin, Copper, Zinc
     • Liquid = Mercury
   • Advantages
     • Least moisture sensitive
     • Most durable
   • Disadvantages
     • Brittle in thin sections
     • Thermal diffusivity > tooth tissue
       • Need cavity liner for deep cavity e.g. setting CaOH
     • Creep -> ditching
     • Galvanic corrosion
     • No tooth adhesion
       • Needs mechanical retention added to cavity prep -> more destructive

3. Composite

   • Composition
     • Resin
       • Bis-GMA
       • Large vol. -> reduces shrinkage
     • Filler
       • Higher filler content -> reduced shrinkage & thermal expansion + increased mechanical properties
       • Radiopaque
     • Coupling agent
       • Joins filler to polymer
       • Silane coupling agent
       • Increases mechanical properties
   • Types
     • Handling characteristics
       • Packable
       • Flowable
         • Reduced filler content
           • Lower viscosity
         • Use
           • Fissure sealant
           • Cavity liner
           • Non-carious cavity
     • Activation
       • Chemical
         • 2 pastes - requires mixing
       • Light
         • 1 paste + blue light source
         • Depth of cure
         • Unlimited WT (command set)
       • Dual
         • Both light & chemical
   • Setting reaction = exothermic free-radical polymerisation
   • Advantages
     • Tooth coloured
     • Durable
     • Adhesion to tooth with bond
   • Disadvantages
     • Shrinkage
       • Debonding in cavity
       • Post-op sensitivity
       • Marginal staining & microleakage -> secondary caries
       • Enamel microcracks
     • Most moisture sensitive

4. GIC

   • Setting reaction = Acid-base
     • Dissolution, gelation, hardening
   • Composition
     • Powder = Sodium aluminosilicate glass
       • Contains Fluoride
     • Liquid = Acrylic/Maleic acid
   • Use
     • Cervical restorations (poor moisture control)
     • Cavity liner
     • (luting cement - different material)
   • Advantages
     • Adhesion to tooth
     • Radiopaque
     • Similar thermal properties to dentine
     • Slightly moisture sensitive (1st hour)
     • Fluoride release
   • Disadvantages
     • Brittle/reduced flexural strength
     • Dissolves in acid
     • Least durable