14. Composite Flashcards
a mixture of silicate glass particles with an acrylic monomer that is polymerized during the application
DENTAL COMPOSITES
DENTAL COMPOSITES has (3) phases, what are those?
o Organic Resin Matrix
o Inorganic Fillers
o Coupling Agent
High Molecular Weight Resin
A. Organic Resin Matrix
B. Inorganic Fillers
C. Coupling Agent
A
Low Molecular Weight Resin
A. Organic Resin Matrix
B. Inorganic Fillers
C. Coupling Agent
A
Bisphenol A=glycidyl methacrylate (Bis-GMA)
High Molecular Weight Resin
Urethane dimethacrylate (UEDMA)
High Molecular Weight Resin
Low Molecular Weight Resin
Triethylene Glycol dimethacrylate (TEGDMA)
MONOMER
A. Organic Resin Matrix
B. Inorganic Fillers
C. Coupling Agent
A
makes the initial mixture fluid and moldable for placement into a cavity preparation
MONOMER
→ quartz
→ lithium aluminum silicate
→ barium aluminum silicate
→ barium, strontium, zinc glas
A. Organic Resin Matrix
B. Inorganic Fillers
C. Coupling Agent
B
colloidal silica
A. Organic Resin Matrix
B. Inorganic Fillers
C. Coupling Agent
B
SILICATE PARTICLES (FILLER)
A. Organic Resin Matrix
B. Inorganic Fillers
C. Coupling Agent
B
→ mechanical reinforcement of the mixture
SILICATE PARTICLES (FILLER)
→ produce light transmission and light scattering that add
enamel-like translucency to the mixture
SILICATE PARTICLES (FILLER)
T or f
EFFECTS OF FILLERS:
decrease in coefficient of thermal expansion
T
T or f
EFFECTS OF FILLERS:
→ decrease in polymerization shrinkage
→ increase in compressive strength
T or f
EFFECTS OF FILLERS:
decrease in water sorption
T
T or f
EFFECTS OF FILLERS:
→ improved aesthetics
→ radiopacity
T
Gamma-methacryloxy propyltrimethoxysilane
ORGANOSILANES
provides a good bond between the inorganic fillers and resin
matrix
ORGANOSILANES
silane has groups that reacts with inorganic filler and other
groups that reacts with the organic matrix
ORGANOSILANES
hydroquinone
POLYMERIZATION INHIBITOR
butylated hydroxytoluene
POLYMERIZATION INHIBITOR
INITIATOR/ACTIVATOR SYSTEM
→ self-cured/auto-cured
→ light-cured
POLYMERIZATION INHIBITOR
→ filler content
o high filler levels = decrease in fluidity
→ filler particle size
→ method of filler addition
→ matrix composition
→ polymerization method
CLASSIFICATION
.005 to .01 micron
Nanofillers
.01 to .1 micron
Microfillers
1 to 10 microns
Midfillers
10 to 100 microns
Macrofillers
very large particles
Megafillers
→ mixed ranges of fillers
→ largest particle size defines the hybrid
HYBRIDS
(FILLER SIZE)
Self-Cured
Initiator?
Benzoyl Peroxide
Self-Cured
Activator?
Tertiary Amine
UV Light Activated
Initiator?
Benzoin Methyl Ether
Visible Light Activated
Initiator
Diketones and Aromatic Ketones (Camphoroquinone and Biacetyl with Tertiary Amines)
→ color matching
→ wear
→ marginal integrity
→ post-operative sensitivity
CLINICAL CONSIDERATION
smear layer
DENTAL ADHESIVES
any debris, calcific in nature, produced by reduction or instrumentation of enamel, dentin, and cementum that precludes interaction with underlying tooth tissue
smear layer
→ 37% phosphoric acid
→ createst micro-porosities
ETCHANT
→ aids bonding to enamel by:
o removal of surface debris
o producing micro-porosities into which resin can penetrate
o causing exposure of greater surface area
→ reduces microleakage
EFFECTS OF ETCHING
hydrophilic monomers dissolved in organic solvents such as ethanol and acetone
PRIMER
solvents can displace H2O in the dentinal tubules and the moit collagen network
PRIMER
hydrophobic properties for copolymerization with adhesive resin
PRIMER
objective:
o transform the hydrophilic dentin into hydrophobic and spongy state that allows the adhesive resin to wet and penetrate the exposed collagen network
PRIMER
stabilize the hybrid layer and to form resin extensions into the dentinal tubules called resin tags
ADHESIVE/BONDING
zone in which the resin adhesive micromechanically interlocks with dentinal collagen
HYBRID LAYER
- rate of dimensional change of a material per unit
change in temperature
Linear Coefficient of Thermal Expansion (LCTE)
- amount of water that the composite absorbs over a period of time per unit of surface area
- higher filler content have lower water absorption value
Water Absorption
- shrinkage of the material while hardening
- hybrid shrinks less than microfilled
Polymerization Shrinkage
- ability to resist surface loss as a result of rubbing
contact with tooth structure, restorative material,
food - hybrid have higher resistance to wear
Wear Resistance
- smoothness of the surface of restorative material
- size of the filler determines the smoothness
Surface Texture
PROPERTIES OF COMPOSITE
(1) Linear Coefficient of Thermal Expansion (LCTE)
(2) Water Absorption
(3) Polymerization Shrinkage
(4) Wear Resistance
5) Surface Texture
(6) Radiopacity
(7) High Bond Strength to Enamel and Dentin
(8) Good Color Match to Tooth Structure
(9) Ease of Manipulation
(10) Ease of Finishing and Polishing
(11) Modulus of Elasticity
(12) Solubility
loss of weight per unit of surface area due to the disintegration in oral fluids of a material over a period of time at a given temperature
Solubility
pulpal inflammatory or degenerative changes
PROBLEMS DUE TO MICROLEAKAGE
detrimental effect on the property of materials
PROBLEMS DUE TO MICROLEAKAGE
→ recurrent caries
→ hypersensitivity of exposed dentin
→ longevity and service-ability of restoration may be compromised
PROBLEMS DUE TO MICROLEAKAGE
