Sweep 1 Flashcards
Facebow needed for multiple restorations because
you need to have the original arc of rotation in order to properly make occlusion in multiple restorations.
Internal space
Uniform space of
25 μ to 35 μ for the luting agent
Cement spreads evenly
• Reduced marginal gap width
Most accurate way to adjust
proximal contact with
shim stock
Metal proximal contact adjustment
DO NOT USE
COARSE DIMOND BURS since they leave a rough finish that is hard to polish.
Check
2. Marginal Integrity
§ Disclosing wax
§ Rouge in turpentine
§ Powdered spray (Occlude)
§ Water soluble marking agents (Liqua-Mark) § Elastomeric detection pastes
Use a small bur (1⁄2 round or 330) to
adjust the internal surface
- Stability
The restoration should not rock or rotate when force is applied.
Causes:
Nodules, distortion during impression making or distortion of a poured cast. In FPD: Parallelism between abutments, Undercuts, Pontic.
Occlusion adjustment
Use for porcelain the
porcelain adjustment kit and for Metal, carbide finishing burs, white or green stones
Metal crown occlusal surfaces are best finished with a
carbide finishing burs and white or green small stones.
A small football shape bur helps
enhance and maintain the anatomy of grooves and triangular
The gold polishing kit contains
Coarse Brown points and discs, dark green Medium and lighter green Fine points and discs
FINISHING AND POLISHING METAL
Start with a Moore’s fine white sand paper disc to remove imperfections on the axial walls and continue with abrasive silicone wheels
Contouring Porcelain Armamentarium:
- Flexible diamond disk
- Porcelain grinding wheel • Diamonds
- Porcelain adjustment Kit abrasive wheels and points.
Today gold solders are given a fineness designation to indicate the
proportion of pure gold contained in 1000 parts.
Group I
Traditional gold containing solder
Group II
Special solders which have the
brand name with a pre or post designation.
Don’t use a coarse or reg diamond bur for proximal contacts, because
If you use in high speed, and grind any ceramic, you can cause microcracks in porcelain/zirconia. Feldspathic procelain may correct if put back in oven.
Pre-ceramic solders
Are high fusing alloys that slightly
melt beneath the softening point of the parent alloy to be joined.
This solders ideally should flow well above the fusion range of the subsequent applied porcelain
Porcelain fuses about
1800o F
Steps in seating a crown:
- Proximal contact
- Mariginal integrity (intaglio)
- Stability
- Occlusion
- Contouring (contacts, embrasures, pontic)
Shimstock tells you exactly how
a contact will be. Floss will give you contact, but it is an acquired feel. Tightness is the thing to learn here.
Shimstock -
slide in between teeth and pull. IF you push and it holds shimstock, it is too tight. If you push and it drags, you’re good. If you push and it pulls through, check again with floss.
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 solders
Are low fusing alloys that
melt bellow the pyroplastic range of the porcelain
Post ceramic soldering:
Less chance of
sag or deformation of the framework
Post ceramic soldering:
• Slightlyweaker andmorebrittle
solder joint since framework can’t be quenched
Post ceramic soldering:
• Large gap space for solder =
decreases
strength, higher porosity, higher meniscus, more difficult to solder
Post ceramic soldering:
• Small gap space for solder =
incomplete
joint
Note: Excessive soldering gap space will cause
undersized mesiodistal FDP widths
• 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
LASER WELDING
• Uses laser energy to
joint two pieces of metal
LASER WELDING• Used in dentistry since
1970
LASER WELDING• Used for welding
FDP’s, RDP’s
components
LASER WELDING
• ——– equipment
• Higher ——- and reduced
——— than soldering
Expensive
strength
corrosion
ANTIFLUX
Used to
limit the spreading of solder
Antiflux Is placed in areas of the
casting before the flux to prevent the flow of molten solder.
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.
FLux 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.
650 fine gold use dfor
ceramics
Ideal gap for solder should be
GAP .25 mm
The bigger the gap, the more distortion - solder shrinks as it cools.
Metamerism
colors changing in different conditions (between two objects
CHROMA (saturation) Adjustment:
Yellow increases chroma on yellow shade Orange has same effect on yellow-red shade
HUE (color) Adjustment:
Pink-purple moves yellow toward yellow-red Yellow decreases the red of a yellow-red shade.
A restoration with a high ———- is difficult to modify
CHROMA
§ Using a complementary color of the shade reduces its
CHROMA
yellow requires violet
Blue requires green
§ Adding stains lowers the
VALUE (dark or
light) of the restoration and increases the metameric effect.
VALUE adjustment:
Attempting to increase value is difficult, but can be increased if the
dominant color added has a higher lightness ranking.
white stain can be used but will
increase opacity
A:
red brown
B
red yellow
C
grey
D
red-grey
§ No vacuum when
glazing mcc retorations
§ Polished porcelain is no more abrasive
than
glazed porcelain
Canines tend to be a bit
darker in shade
Emergence profile of margin better for
metal margin porcelain crowns. Otherwise, this will be overcontoured
