MDS PREP
What is the ideal consistency of a luting agent according to ANSI/ADA Specification No. 96 (ISO 9917)?
1) Thixotropic
2) Plastic
3) Thin film
4) Putty
The ideal luting agent consistency is not explicitly mentioned in the text, but it should be able to flow into a film less than 25 µm thick without fragmentation.
What is the typical composition of the mica crystals in a fluoromica glass ceramic like Dicor?
1) SiO2 · K2O · MgO · Al2O3 · ZrO2
2) Al2O3 · K2O · Na2O · MgO · ZrO2
3) SiO2 · CaO · Al2O3 · ZrO2
4) Al2O3 · Na2O · MgO · CaO
Fluoromica glass ceramics like Dicor have a composition based on mica crystals consisting of silica, potassium oxide (K2O), magnesium oxide (MgO), and aluminum oxide (Al2O3), with zirconium oxide (ZrO2) added for stability. Fluorides are included in the mixture to achieve fluorescence in the finished prosthesis. The material is castable and shares some similarities with traditional dental ceramics but with unique properties derived from its crystalline structure.
What is the primary cause of delayed expansion in zinc-containing low-copper or high-copper amalgams?
1) Contamination by oxygen during trituration.
2) Contamination by water during trituration or condensation.
3) Over-trituration.
4) The presence of the ?2 phase.
A large expansion can take place if the amalgam is contaminated by moisture during trituration or condensation, known as delayed expansion or secondary expansion.
What are the typical operating speeds for low-, medium-, and high-speed amalgamators?
1) 3000 to 3200 cpm for low-speed, 3500 to 3700 cpm for medium-speed, and 4000 to 4400 cpm for high-speed.
2) 3200 to 3400 cpm for low-speed, 3700 to 3800 cpm for medium-speed, and 4000 to 4400 cpm for high-speed.
3) 3000 to 3200 cpm for medium-speed, 3500 to 3700 cpm for high-speed, and 4000 to 4400 cpm for low-speed.
4) 3200 cpm for low-speed, 3700 cpm for medium-speed, and 4400 cpm for high-speed.
Low-speed amalgamators operate at 3200 to 3400 cpm, medium-speed at 3700 to 3800 cpm, and high-speed at 4000 to 4400 cpm.
What is the structural formula of the substance found in irreversible hydrocolloid?
1) Anhydro-?-d-mannuronic acid
2) Anhydro-?-d-glucuronic acid
3) Anhydro-?-d-glucuronic acid
4) Anhydro-?-d-mannuronic acid
Irreversible hydrocolloid, such as alginate, is based on the structure of anhydro-?-d-mannuronic acid.
What is the effect of acid etching on dentin bond strength?
1) It decreases bond strength.
2) It has no effect on bond strength.
3) It increases bond strength.
4) It is unpredictable.
Acid etching of dentin creates a micro porous surface that allows for better infiltration and mechanical interlocking of the bonding agent, leading to improved bond strength between the restorative material and the tooth structure.
What is the modified form of zinc oxide-eugenol used for temporary cementation?
1) Type I
2) Type II
3) Type III
4) Type IV
The modified form of zinc oxide-eugenol used for temporary cementation is commonly known as Type II due to its lower compressive strength and ease of removal.
What is the main component of zinc oxide-eugenol cement?
1) Zinc oxide
2) Silica
3) Phosphoric acid
4) Polycarboxylate acid
Zinc oxide-eugenol cement is primarily composed of zinc oxide and eugenol.