Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
101 Cards in this Set
- Front
- Back
What is a dental amalgam? |
The powdered metal is predominately silver with a little tin (made of silver and mercury) |
|
Name two kinds of amalgam alloy |
1) Lathe cut-from grinding an ignot 2) Spherical alloys-from spraying molten metal into an inert atmosphere |
|
When was amalgam initially developed? |
Developed in France in the 1800's Not in the USA until 1933 |
|
What is the composition of low copper amalgam? |
65% silver 25% tin less than 6% copper 1% zinc |
|
What is the function of silver in amalgam? |
Silver: causes setting expansion and increases strength and corrosion resistance
|
|
What is the function of tin in amalgam? |
Tin: causes setting contraction and decreases strength and corrosion resistance |
|
What is the function of copper in amalgam? |
Copper: functions much the same as silver |
|
What is the function of zinc in amalgam? |
Zinc: reduces oxidation of other metals |
|
What is the weakest and most corrosion prone phase of low copper? |
Sn-Hg (tin-mercury), the gamma two phase |
|
What % copper is in high copper amalgams? |
10-30% copper |
|
What two factors affect the handling and performance of amalgam? |
1) Manufacturer 2) Dentist |
|
Amalgam has high _________ strength |
Compressive |
|
Amalgam has low ___________ strength |
Shear **Don't want this in a class IV filling |
|
What is creep? |
A slow change in shape caused by compression |
|
Dental amalgam is not recommended for what class restoration? |
Class IV |
|
Why can zinc cause an amalgam to expand? |
Zinc reacts with water to produce hydrogen gas which causes the amalgam to expand. |
|
What percent of patients have mercury toxicity? |
0.1% of patients |
|
Gold foil restorations are limited to what class restoration? |
Small restorations like class V because of low strength |
|
What are luting agents? |
Luting agents glue things together (crown to tooth) |
|
Name two things that provide pulp protection |
1) Liners-may stimulate secondary dentin formation (calcium hydroxide) 2) Bases-provide thermal insulation |
|
What protects the pulp from an irritating base or cement? |
Varnish |
|
Name 3 liquids used in dental cements |
1) Eugenol 2) Phosphoric Acid 3) Polyacrylic Acid |
|
What are the components of Eugenol? |
Oil and cloves |
|
What liquid used in dental cements may be irritating to the pulp? |
Phosphoric Acid |
|
Name 5 kinds of dental cements |
1) ZOE cement 2) Zinc phosphate cement 3) Polycarboxylate cement 4) Glass-ionomer cement 5) Composite cement |
|
The 2 disadvantages of ZOE cement are..? |
1) Inadequate strength 2) High solubility |
|
A disadvantage of zinc phosphate cement is..? |
It irritates the pulp (creates a low pH) |
|
Why is a cooled glass slab used when mixing zinc phosphate cement? |
Because the setting reaction is exothermic
EXOTHERMIC REACTION |
|
What are 2 advantages of glass-ionomer cements? |
1) Releases fluoride 2) Bonds to tooth structure, stainless steel and alloys |
|
What is the cement of choice for luting metal or ceramometal crowns? |
Resin modified glass ionomer |
|
A MAJOR disadvantage of polycarboxylate cement is..? |
It is NOT strong |
|
The 3 advantages of polycarboxylate cements are..? |
1) Bonds to tooth structure 2) Very biocompatible 3) Releases fluoride |
|
What liner promotes the formation of secondary dentin? |
Calcium hydroxide liners (Dycal) |
|
What is the composition of Temp Bond, a temporary cement? |
Zinc oxide and vegetable oil |
|
Name 3 types of impression trays |
1) Stock trays 2) Custom trays 3) Special use trays--Triple trays |
|
Name 3 types of impression materials |
1) Inelastic 2) Aqueous elastomeric 3) Nonaqueous elastomeric |
|
What are the 3 types of inelastic impression materials? |
Plaster Wax ZOE |
|
How many types of inelastic impression materials are there? |
3 |
|
How many types of aqueous elastomeric impression materials are there? |
2 |
|
How many types of nonaqueous elastomeric impression materials are there? |
4 |
|
What are the 2 types of aqueous elastomeric impression materials? |
Alginate and Agar |
|
The 4 types of nonaqueous elastomeric impression materials are..? |
Polysulfides Condensation silicones Polyethers Addition silicones |
|
Which type of impression material returns to its original form after deformation? |
Elastomeric |
|
What will not reverse to a sol once it is set as a gel |
Alginate |
|
Warm water ____________ the setting rate of alginate |
Increases |
|
Used for study models and casts |
Alginate |
|
Requires special impression trays that circulate cooling water |
Agar (reversible hydrocolloid) |
|
What is a by product of condensation silicones? |
Alcohol |
|
What are the most popular type of elastomeric impression materials? |
Addition silicones |
|
Name 3 disadvantages of polysulfides |
1) Odor 2) Stains clothing 3) Long working time |
|
Hydrocolloids will absorb water and distort. What is this called? |
Inbibition |
|
What is the calcination process? |
CaSO4 2H2O + heat ---> (CaSO4)2 + H2O |
|
What are the 3 types of gypsum products? |
1) Plaster 2) Stone 3) Improved Stone |
|
Which gypsum product is the weakest and least expensive? |
Plaster |
|
Which type of gypsum product is yellow and referred to as alpha-hemihydrate? |
Stone
|
|
What color is plaster? |
White
|
|
What color is stone? |
Yellow |
|
What color is high strength, or improved stone? |
Pink |
|
Which type of gypsum product is used to make dies? |
Improved Stone |
|
What is the setting reaction when hemihydrate is mixed with water? |
Exothermic |
|
What is the water/powder ratio for plaster? |
45-50 ml/100g |
|
What is the water/powder ratio for stone? |
28-30 ml/100g |
|
What is the water/powder ratio for improved stone? |
19-24 ml/100g |
|
The final setting time for gypsum products is..? |
30-45 minutes |
|
A retarder used to increase the setting time is? |
Borax (sets slower) |
|
Product used to accelerate the setting time..? |
Calcium sulfide |
|
A ________ water powder ratio decreases the setting time (sets faster) |
Lower (makes a thicker mix) |
|
Which has the most expansion: plaster or stone? |
Plaster |
|
Dry strength is measured when? |
When there is no excess water in the sample |
|
Dry strength may be ________ times stronger than wet strength |
2 to 3 times stronger |
|
What is placed in the mixing bowl first: water or powder? |
Water |
|
Indirect restoration are constructed where? |
Outside the mouth Usually in the lab |
|
Onlays restore what? |
One or more cusps |
|
Crowns restore what? |
Teeth that have lost a significant amount of tooth structure Teeth that have had a RCT |
|
Dental bridges replace what? |
Missing teeth |
|
Veneers are placed where? |
On the facial surfaces of anterior teeth |
|
Ceramic materials lack what? |
Toughness & fracture resistance
**this is not true nowadays |
|
Another name for a temporary restoration..? |
Provisional restoration |
|
The name of the wax used for crowns |
Inlay casting wax
|
|
The name of the wax used in the fabrication of dentures |
Baseplate wax |
|
Attached to the wax pattern to create an opening for the mold |
Sprue |
|
What color are inlay casting waxes? |
Dark blue |
|
What color is sticky wax? |
Yellow |
|
What color is baseplate wax? |
Pink |
|
What color is boxing wax? |
Red |
|
The mold must expand to compensate for what? |
The shrinkage of the metal |
|
What is a refractory? |
It improves the investments resistance to heat (Usually silica) |
|
What is burnishing? |
Pushing metal against the tooth to close any gap |
|
What are the noble metals? |
1) Gold 2) Platinum 3) Palladium |
|
How many noble metals are there? |
3 |
|
What are the precious metals? |
Noble metals + Silver |
|
Carat is parts per ______? |
24 |
|
Fineness is parts per _________? |
1000 |
|
Twelve carats is ______ fineness? |
500 |
|
High noble is _____% gold or noble elements |
68%
**Will be on test |
|
Base metals are less than ____% noble elements |
25% |
|
What is sintering porcelain? |
Taking a powder and heating it up.
Firing the porcelain causes the powders to be sintered, which changes the porcelain from powder to solid. |
|
What is the material of choice for dental implants? |
Titanium |
|
What metal is commonly used now in partial dentures? |
Either nickel-chromium or cobalt-chromium |
|
What is a PFM crown? |
PFM stands for: Porcelain fused to metal |
|
What does CAD/CAM mean? |
computer-aided design/computer-aided manufacturing |