Operative Final Review Flashcards
Which generation of dentin bonding agents is the gold standard?
4th Gen - Etch, prime, bond (Optibond FL)
What are shortcomings of 7th gen dentin bonding agents?
- Lower durability, Increases water sorption in HEMA rich adhesives, and phase separation of adhesive components with HEMA, increased nanoleakage, reduced shelf life
What are the benefits of wet bonding for total etch?
- Increased resin-dentin bond strengths
2. Decreased post-sensitivity
Why the addition of water for etching adhesives? (wet bonding)
Decreases the sensitivity associated with dry bonding
Why do etchants contain water?
To ionize the acidic reaction
How does the strength of an acid in self-etching adhesives affect the bond?
The stronger the acid etch component, the greater the penetration of the resin tags into the smear layer and then into dentin.
Define hybrid layer
Resin-dentin inter diffusion zone
Which generation is considered the strongest and most durable?
6th gen (self etch, etch/prime and then bond)
What are the three methods of adhesion?
- Physical (van der waals, electrostatic interaction)
- Chemical (bonds between atoms)
- Mechanical (undercuts and irregularities produce interlocking of material)
Does tubule density increase or decrease as you go from enamel to dentin to pulp
Tubule density decreases as you move away from the pulp
What is the pH and hybrid layer thickness of phosphoric acid?
pH 0.1-0.4
Depth: 5-8 um
What is the pH and hybrid layer thickness of ultra mild SE?
pH >2.5
Depth: 300 nm
pH and hybrid layer thickness of Mild SE
pH = 2
Depth: 500 nm - 1 um
pH and hybrid layer thickness of strong SE
pH < or equal to 1
Depth: 4 um
What pH is best for etchant?
Mild and 2.0
Explain “water tree formation”
Poorly hybridized resin tags are saturated with water as opposed to hybridized resin tags in etched dentin saturated with ethanol. This prevents sealing of the hybrid layer
Define microleakage
Passage of bacteria and toxins between restorative margins and tooth prep walls
Define nanoleakage
Microporosities in the hybrid layer and dentin
What is an MMP and how are they activated?
Matrix Metalloproteinase Protein - slowly degrade exposed collagen fibrils
- Activated by acid etching
Should CHX be used to inhibit MMP’s in vivo? Why is this?
No, no difference between groups in terms of sensitivity or clinical performance of composite restorations. This is because CHX is water soluble and will wash out over time.
Particle size of macro filled?
Particle size of midi
10-100 um
1-10 um
Particle size of mini
Particle size of Micro
Particle size of Nano
- 1 to 1 um
- 01 to 0.1 um
- 001 to 0.01 um
Difference between heterogenous and hybrid
Heterogenous are mixtures of cured and uncured composites that are all the same size. Hybrid has a mixture of major particle sizes
Greatest degree of conversion for composites?
65%
What is the depth of cure for A1-A2 shades?
5 mm
What is C factor?
Number of bonded vs unbounded surfaces
What is the significance of placing composite margins on dentin vs enamel?
Tredwin study concluded that all dentin margins showed significant more leakage then enamel margins in every combination. Gingival margins should be placed on enamel.
Composite contraction stress
17 MPa
Filtek bulk fill depth of cure and indications?
Depth: 4 mm
Indicated as base for Class I and II, more shrinkage, less CTE due to lower filled content
Percentages between hydrogen peroxide and carbamide peroxide
Hydrogen peroxide: 38% (in office)
Carbamide peroxide: 10% (home)
Non-vital bleaching technique
“Walking bleaching” - Uses sodium perborate (38%) - may cause cervical external resorption. Stay above CEJ
If patient is asymptomiatc, how much can you bleach?
As much as you/they want
Indications/contraindications of bleaching
Indications: Pt not happy with color esthetics
Contraindications: Hypersensitivity, pregnant and lactating women, children with large pulps, gingival recession, finances
What is in Gluma and how does it work?
Gluteraldehyde and HEMA - precipitates plasma proteins to occlude dentinal tubules . Can interfere with dentin bonding systems (because you’re occluding the tubules)
What kind of fillers are added to hybrid composites?
Surface modified zirconia/silica and surface modified silica particles
What kind of filler particles are added to Filtek supreme?
20 nm Silica filler, 4-11 nm zirconia filler, and combined 20 nm silica and 4-11 nm zirconia/silica cluster filler
What kind of filler particles to Filtek bulk fill flowable?
0.1 to 5.0 um ytterbium trifluoride filler and 0.01 to 3.5 zirconia/silica.
