Resin-based restorative materials Flashcards
What is the most used restorative material?
composite
What is organic resin matrix disperesed by?
inorganic fillers bound to the resin by a silane coupling agent and an initiator-accelerator system
What are the different resin matrixes?
- Bis-GMA
- UDMA
- TEGDMA
What are the benefits of filler particles?
- Reinforcement of resin matrix
- DECREASED polymerization shrinkage
- DECREASED thermal expansion and contraction
- Viscosity control
- DECREASED water sorption
- INCREASED radiopacity
What in the filler increases the radiopacity?
Barium
Strontium
Zirconium
________ filler amount reduces the thermal expansion and contraction coefficients
Higher
The reduced shrinkage is proportional to the filler ________
volume
What is the coupling agent?
silane
The interfacial bridge forms between what?
the resin matrix and the filler
What is the point of the coupling agent/interfacial bridge?
✓ Better stress distribution between resin matrix and filler particles
✓ Improvesthe mechanical properties
✓ Decreased watersorption along filler-resin interface
Composites require that monomers to coverted into
polymers
What triggers the composite convertion from monomers to polymers?
free radicals
What is the activator for chemical/self-cure composite?
tertiary amine
What is the initiator for chemical/self-cure composite?
Benzoyl peroxide
What is the reaction for a chemical/self-cure composite?
What is the activator for light-cured composite?
blue light (465 nm)
What is the initator for light-cured composite?
- camphoroquinone (photosensitizer)
- DMAEMA (amine)
What are the characteristics of regular (conventional/packable) composite?
- 80-85% filler
- many applications, versatile, laying technique, more esthetic
What are the characteristics of flowable composite?
- 40-60% filler
- polymerization shrinkage
- under regular comp class II
What are the three classification by handling characteristics?
- regular
- flowable
- bulk fill
What are the characteristics of bulk fill composite?
✓ Developed to enable restoration in single increment built up to 4-5 mm
✓ Increased depth of cure
✓ Reduced polymerization shrinkage stress
✓ Improved adaptation to the surface of the cavity
✓ Simplified placement technique compared to regular composites (incremental)
How do bulk fill composites achieve a depth of cure (polymerization)?
- Reduced filler amount
- Increased filler particle size
- Alternative photoinitiators
How do bulk fill composites achieve modulate the polymerization reaction?
- Altered filler particles
- Presence of stress-relieving monomer
What are the filler particles for bulk fill composites like?
- Lower amount of filler particles
- Pre-polymerized filler particles (similarly to microparticules comp)
- Low elastic modulus = help to absorb stresses
- Added larger filler size particles
What are the monomers for bulk fill composites?
- UDMA
- Modified UDMA (adding aromatic groups)
- Fragmentation dimethacrylate monomers