Operative: Composite & Glass Ionomer Flashcards
Enamel Bonding vs Dentin Bonding
Enamel Bonding
* Reliable
* Predictable
* Shear bond strength=20+ MPa
* Etching: Turns low surface energy surfaces to rough high surface energy surfaces w/Increased wetting
Dentin Bonding:
* Just as strong
* Not as reliable or predictable
Why is it hard to bond to dentin?
Composition:
* dentin has more organic and water (not affected by acid) & Less mineral
Structure:
* enamel rod’s= parallel
* Dentin: collagen=bowl of spaghetti
Depth:
* The Deeper you go= Larger & more number dentin Tubules= Decreased bond strength
Smear Layer:
* decreses dentin permeability
Etch
30-40% phosphoric acid
* 15 seconds
* Rinse w/water for 10 seconds
Removes smear layer
* Cleans surface debris
- Etched Enamel: Chalky, creates microporosities
- Etched Dentin: exposes collagen layer; widens dentin tubules
Primer:
HEMA: (Hydroxymethyl methacrylate)
* Amphipathic molecule: hydrophobic & hyrdrophillic end
* Monomer + Solvent
* allergic contact dermatitis
* Prevents collagen collapse
Solvent:
* Acetone, Ethanol, or water
Bond
Aka Adhesive
Bis-GMA
* MMA Bond: chemical bond to primer and composite resin
Hybrid Layer
Hybrid Layer
Mechanical interface b/w tooth and adhesive
* Micromechanical Bond=Key to great bond strength
resin tags:
* adhesive resins lock into the microporosities of etched enamel and intertubular dentin
Etch and Rinse Systems
Etch in own syringe
4th Gen: Gold Standard
* Etch
* Prime
* Bond
5th Gen:
* Etch
* Prime/Bond
Self Etch Systems
Less powerful etch
* Decreased Post-op sensitivity
* weaker bond= doesn’t completely remove smear layer
* Recommend: Carbide burs only-leave less smear layer
6th Gen:
* Etch/Primer
* Bond
7th Gen
* Etch/Prime/Bond
Composite Resins
Resin Matrix: Bis-GMA
* leach bisphenol A (BPA)–> wear of composite or uncured resin
* Negligible side effects
Filler Particles: Silica
* radiopaque
* affect composite properties
Coupling Agent: Silane
* adhesion b/w Filler & Resin
What are the different types of composite?
Macrofill
Microfill
Hybrid
NanoFill
Nanohybrid
Flowable
Packable
Larger Fillers vs Higher Filler content
Larger Fillers:
* more strength
* Don’t polish or wear (rougher) as well
Higher Filler Content= Less water absorption
Self Cure vs Light Cure Composite
Self Cure Composite: 2 paste system
Benzoyl peroxide=intiator
Tertiary Amine: activator
Light Cure Composite: 1 Paste System
* Camphorquinone=initiator
* 468 nm light initiates polymerization
Polymerization shrinkage
Composites shrinks 2-3% as they polymerize
C-Factor=Configuration factor
* =ratio of bound to unbound surfaces
GV Black class is inversely related to C factor
* The higher the class, the lower the C factor
What does a High C-Factor have a higher chance of?
- shrinkage
- microleakage
- post-op sensitivity
Glass Ionomer
Acid base rxn
* Acid: Polyacrylic acid
* Base: FA glass
Retention: Chemical bond to tooth (Calcium Chelation)
* Self adhesive (no prime and bond)
Strength: weaker vs composite
* Fl release
Compare Glass Ionomer & Composite Resin
Glass Ionomer
* Acid: Polyacrylic acid
* Base: FA Glass
Retention: Chemical Bond (Calcium Chelation)
* Self Adhesive (no prime or bond)
Strength: Weaker vs composite:
* FL release
Composite Resin:
* Matrix: Bis-GMA
* Filler: Barium silicate glass
* Light cure or self cure
Retention: Micromechanical bond
Strength: Stronger vs GI
* No Fl release
Resin-Modified Glass Ionomers (RMGI)
Sets by:
* acid-base rxn
* Free-radical addition polymerization (Light &/or chemical cure)
More rapid polymerization bc of free radical initiation
Releases FL
Stronger than Glass Ionomer
Compomers
Aka: Polyacid-Modified Resin Composites
Anhydrous (Water free) Single pastes
* contains the major ingredients of Composite resin and Glass Ionomer
* EXCEPT WATER
Used in ortho
* slower polymerization (more time to clean up excess)
* Releases fluoride
Ionomer-Modified Composites
Sets only by Polymerization
But contain ion-leachable glasses (=Fl release)
Macrofill Composite
80% Filler
* particle size: 8 um
Very Strong
* Rough
* Increased Wear
Microfill Composite
40% Filler
* Particle Size: .04 um
Weak
* Good polish
* Good Wear Resistance
Hybrid Fill Composite
80% Filler
* particle size: 1 um
Best of both worlds: (Marco vs Micro)
Nanofill Composite
Particle size: 0.005-0.01 um
Conglomerate to form spectrum of sizes
Nanohybrid Composite
Most Popular (Ex: Filltrek)
Incorporates the conglomerate sizes of 0.05-0.01 um particles
Flowable vs Packable Composite
Flowable:
* Very low filler amount
* Decreased wear resistance
Packable:
* High filler amount
* very viscous
