Ceramics

What is used to calibrate the muffles

Pure metals such as silver

What margin style is not recommended for ceramic restorations

Knife/Feather

Best margin style for ceramic crowns

Deep/Heavy Chamfer

Next best answer is Shoulder

What has low fusing porcelain

Feldspathic

Lithium disilicate

Pressed ceramic using phosphate bond

Subtractive CAM wet mill

Presintered blocks milled down to a crown

Zirconia

Slow heat, slow cool

Subtractive CAM
Dry miling

PFG needs to contain a base metal such as

Porcelain Fused Gold

Indium, zinc, and tin to provide the oxide layer for porcelain bonding.

Gold itself doesn’t produce oxides

PFM Material thickness for incisal

1.5 - 2 mm

PFM Material thickness for metal

0.3 - 0.4 mm

PFM Material thickness for opaque

0.1 - 0.2 mm

Silver in metal coping or metal substructure will cause

greening

For metal ceramic restorations, phosphate bonded investments must be used. The cast arm needs to be wound how many times

4.5 to 5 times

Investment Ring, place patterns in what zone of investment ring

cold zone

Investment Ring - runner bar should be in the ____ of the mass

Heat center

Finishing coping / framework to receive opaque - do not finish with ____ wheels

rubber

Steam clean and air abrade to create a ___ retention

micromechanical

Oxidation aka

Degassing

Compression bond

cooling metal shrinks to draw porcelain together

Strongest under compression

Weakest under tension

Chemical bond primarily uses what kind of oxide

tin

Van der Waals Forces

Positive and negative molecules attract

What causes a bond to fail

Too much oxide layer

Remember to airbrade surface and steam clean

What causes dark metal oxides

Copper

Surface contaminates will cause

bubble formation during porcelain firing

PFM requirements for contact

1.5-2mm away from contact

PFM requirements for porcelain build up

max of 2mm

PFM requirements for coping

min of 0.3mm

Porcelain shrinkage percentage

14%, shrinks towards the greatest bulk

PFM requirements framework must be rigid with a min of

0.5mm

Condensing

process of packing particles together and removing water

Condensing methods

Vibration - tapping
Capillary action - blotting to draw moisture together

Pressure packing - smoothing with tissue

Whipping brush - brush to remove loose particles

What prep is used best for butt joint margin

Shoulder

Natural teeth appear more translucent at ___
*What color stain?

mesial and distal incisal edges
blue/gray stain

Calibrating the porcelain oven is measured by the

pyrometer or thermocouple

During firing sequence, porcelain starts to Vitrify - (what is this term)

becomes glasslike

Properly fired body bake should have what kind of appearance

pebbly/orange peel appearance

Porcelain is strongest/weakest when

strongest under compression

weakest under tension

Never place metal ceramic junction at MI contact point, should be min of

1.5-2mm away from contact

E.max

Lithium disilicate = glass ceramic = pressed ceramic

wet mill / subtractive CAM

Burnout lithium discilicate can emit

carbon monoxide

Name the colors visible to human eye / hue

red

orange

yellow

green

blue

violet

chroma

sautration of hue

ex: deep red has more chroma than light pink

color value

relative to white or black

primary colors

red

yellow

blue

secondary colors

green

orange

violet

complementary colors for red, yellow, blue?
This will neutralize the color

red = green (strawberry)

yellow = violet (Lakers)

blue = orange (OCC)

Metamerism

when stimuli reaching the eye causes two objects to match in color under certain lightning conditions. To avoid this, compare things in the same light

Vita Shade colors

A = Yellow/Red

B = Yellow

C = Yello/Gray

D = Yellow/Gray/Red

Welding vs Soldering

Welding = joining of parent metals

Soldering = filler metal

Acid etch

Use hydrofluoric acid to etch porcelain

1.     Adding violet to a yellow hue would

increase its value

1.     When polishing a metal ceramic restoration, an extremely high luster is achieved by using

BBC on a bristle brush and rouge on a felt wheel

Laser welding

Is accomplished using a pencil-like tip that is electrically charged

1.     For post-soldering, which wax should be used to prevent porcelain from contacting soldering investment?

ivory

1.     If complementary hues of equal chroma are blended together, which of the following will result?

neutral gray

1.     The external stains used with dental porcelain to attain proper shades are made from

metallic oxides

1.     The advantage of porcelain shoulder margins is

improved aesthetics

1.     The type of spruing that uses a runner bar is

indirect

1.     What stain will minimize the appearance of green in a porcelain crown?

pink

1.     When preforming the first body fire, the vacuum pump should be started

before increasing the furnace temperature

1.     During the final die preparation, applying a thin surface hardener over the margins

Prevents the marked line from smudging and maintains marginal integrity

1.     The oxide layer formed during casting can be removed by

aluminum oxide blasting

The function of a runner bar is to serve as a

reservoir

1.     When the shade of a completed porcelain restoration appears too gray, the most likely cause is insufficient

opaque

A ceramic stain made from an oxide of indium is what color?

yellow

1.     Multiple cracks in a finished porcelain restoration are the likely result of

thermal shock

1.     The portion of the wax pattern that should be placed in the thermal zone of the heat center of the ring is the

reservoir

1.     A cloudy appearance in body porcelain is due to:

insufficient vacuum

1.     According to most manufacturers at what thickness will porcelain most nearly match the shade guide?

1.5mm

1.     Mounted stones which are vitrified are used to finish metal substructures because they

do not contaminate the metal

1.     Wetting agents are used on wax patterns to

a.     Reduce surface nodules on the metal casting

1.     The reason for vacuum firing porcelain is to

a.     Eliminate air space and enhance shade

1.     What would be the BEST instrument to use for creating an enamel check line using an external staining technique?

a.     A #0 sable hair brush

1.     Narrow cracks which may appear in tooth enamel are called

check lines

1.     Which preparation is most desirable for a porcelain jacket crown?

shoulder

1.     Which of the following is NOT a purpose of opaque porcelain?

a.     It simulates the enamel of a natural tooth

1.     The broken-arm principle of casting has which of the following advantages?

a.     Increases the speed of the entering alloy

1.     The junction between exposed metal and porcelain on a porcelain fused to metal crown is the ____ line

finish

1.     Which porcelain is NOT intended to be fused to metal?

incisal