Sweep 2 Flashcards
Delivery sequence
prox contacts Marginal integrity Stability Occlusion Contouring (gingival third, etc)
Pre-ceramic soldering
DISADVANTAGES
Difficult (narrow melting range) • Volatilization of base metal (overheating)
• Microporosity or pitting
• Not good bond with porcelain • Color
• Corrosion
POST-CERAMIC SOLDERING
advantages
Less chance of sag or deformation of the framework
• Slightlyweaker andmorebrittlesolder joint since framework can’t be quenched • Small gap space for solder = incomplete
joint
• Large gap space for solder = decreases
strength, higher porosity, higher meniscus, more difficult to solder
• TORCH SOLDERING
Use for pre-ceramic soldering mc FDP soldering full gold FDP s
Difficult for post-ceramic soldering
OVEN SOLDERING
Use for pre and post-ceramic soldering
Can use vacuum Visualization is more difficult
INFRARED SOLDERING
Can be used for low-fusing connectors and pre-ceramic soldered joints
Uses special unit with an infrared light
Graphite or iron oxide (rouge) with turpentine as a solvent are often used as
antiflux
SOLDERING FLUX
A substance applied to the metal surface to be soldered to remove oxides or prevent their formation.
Borax Glass (Na2B4O7) used with Au alloys. Other fluxes available for non Au alloys are available, some of their formulas are not published.
SOLDERING INVESTMENTS
• Are similar to regular casting investments. • Contain fused quartz (lowest expanding
form of silica) as a refractory component.
POST-CERAMIC SOLDERING HEATING SCHEDULE
- Burn-out Duralay in burnout oven 15-20 minutes at 300 oF
- Place in porcelain oven at 1200 oF and allow all carbon residue to be eliminated.
- Coat piece of solder with small amount of flux (do not allow the flux to contact porcelain).
- After a few minutes (3 min) raise temperature to 1620 oF and watch through the furnace door until solder melts.
- Remove immediately and lower furnace temperature and evaluate solder joint.
In order to ensure contact with the ridge intra-orally, the ——– should be scraped smooth to a depth no more than ——-mm (Technician usually does this
cast ridge
0.25
Mand pontics
Mod ridge lap = low resorption
Ovoid- med resorption
Sanitary - lots of resorption
Mod ridge lap
T contact
Metal connectors:
2mm x 2mm ideally
Connector shape
heart shaped
Most acrylics react with eugenol, but
normally not enough to create a problem. Allows for eugenol cements. Composites don’t work with eugenol, all ceramic crowns don’t either. Problem is that you need to clean later.
PMM Advantages:
- Best abrasion resistance • Best color stability
- Good polishability
- Good marginal finish
PMM Disadvantages:
- High heat polymerization (165o) • High shrinkage
- Monomer irritant to pulp
- Eugenol deteriorates resin
PMM Indications:
- Indirect techniques
* Long-term provisionals • Conventional provisionals • Long span provisionals
PEM Advantages:
- Low shrinkage
- Rubber stage to set
- Longer working time
- Lower polymerization time • 125oF
PEM Disadvantages:
- Poor hardness
- Poor abrasion resistance • Poor color stability
- Poor finishability
- Eugenol deteriorates resin
Hybrids Advantages:
- Low shrinkage
* Corrected by additions • Can be radiopaque
Hybrids Disadvantages:
• Brittle
• Repairsandmixingaremore
difficult • Expensive
Hybrids Indications:
• Long span restorations • Long term provisionals
CHROMA (———–) Adjustment:
Yellow increases chroma on yellow shade Orange has same effect on yellow-red shade
saturation
HUE (——) Adjustment:
Pink-purple moves yellow toward yellow-red Yellow decreases the red of a yellow-red shade.
color
§ A restoration with a high ——– is difficult to modify
CHROMA
§ Choosing a shade with a lower CHROMA is always better since is
easier to alter.
§ Using a complementary color of the shade reduces its
CHROMA
yellow requires violet
Blue requires green
Adding stains lowers the ——— (dark or
light) of the restoration and increases the metameric effect.
VALUE
VALUE adjustment:
Attempting to increase value is difficult, but can be increased if the dominant color added has a higher lightness ranking.
For example white stain can be used but will increase opacity.
