Tooth coloured filling material Flashcards
Give examples of tooth coloured filling material
- Composite
- GIC
- RMGI
What is dental composite made up of
Inorganic filler and an organic binder
What are the advantages of composite
- Aesthetic
- Conserves tooth structure
- Chemically bonds to tooth
- Has a low thermal conductivity
What are the disadvantages of composite
- Technique sensitive
- Polymerisation shrinkage
- Has a decreased wear resistance
What can polymerisation shrinkage lead to
- Marginal leakage
- Secondary caries
- Post op sensitivity
How does composite set
Via a free radical addition polymerisation
Talk through the stages of a composite free radical addition polymerisation
- Activation: chemical and light
- Initiation
- Propagation
- Termination
What causes polymerisation shrinkage
Poor body to dentine
What can polymerisation shrinkage lead to
- Poor retention
- Staining
- Sensitivity
- Secondary caries
How far can the blue composite setting light travel effectively
2mm
Why are filler placed in dental composite
To reduce shrinkage upon curing
What do inorganic fillers reduce
- Polymerisation shrinkage
- Water absorption
- Thermal expansion
What do inorganic fillers increase
- Compressive tensile strength
- Modulus of elasticity
- Abrasion resistance
Why are coupling agents added to compsite
- Improve adherence of resin to filler surface
- Chemically coat filler surface and increase strength
When is flowable composite indicated
- Class V restoration
- Micro preparations
- Extended fissure sealings
- Adhesive cementation of ceramic restoration
- Blocking out cavity undercuts
- Initial base later
What are the disadvantages of flowable composite
Has a lower filler volume and so exhibit increased shrinkage and wear with decreased strength
What does etch do to enamel
Decalcifies the enamel rods exposing the dentinal tubules
Why do we etch enamel before composite placement
- Remove debris and surface enamel
- Increase surface area
- Increase wetting
What does acid etching do to enamel
- Improves retention of the restoration
- Increases the surface area of the dentine
- Remices the smear layer from prep
4,Allowes for penetration of bonding agents into dentine
