MDS PREP
What is the typical mixing ratio for zinc polycarboxylate cement?
1) 1:1
2) 1:2
3) 2:1
4) 3:1
The typical mixing ratio for zinc polycarboxylate cement is 1:2 (powder to liquid).
How many grams of high-density noble metal alloy is required for casting of a molar?
1) 3 gms
2) 6 gms
3) 9 gms
4) 12 gms
Dental Materials Answer: 3
With high-density noble metal alloy 6 grams is adequate for premolar and anterior castings, 9 grams is adequate for molar casting and 12 grams is adequate for pontics.
What is the primary use of sodium chloride as an accelerator in gypsum-based materials?
1) To increase the setting temperature.
2) To accelerate the setting reaction.
3) To improve the mechanical properties.
4) To prolong the working time.
Sodium chloride acts as an accelerator in gypsum-based materials by increasing the solubility of the hemihydrate, thereby speeding up the conversion to dihydrate and the overall setting process.
What is the water sorption value of poly (methyl methacrylate) according to the provided information?
1) 0.69 mg/cm²
2) 0.85 mg/cm²
3) 1.05 mg/cm²
4) There is no information provided on water sorption value
The text states that poly (methyl methacrylate) has a water sorption value of 0.69 mg/cm², which affects its dimensional stability and physical properties.
What is the effect of adding potassium sulfate to gypsum-based materials?
1) It accelerates the setting reaction.
2) It retards the setting reaction.
3) It increases the porosity.
4) It has no effect on the setting reaction.
Potassium sulfate acts as an accelerator by increasing the solubility of the hemihydrate and promoting the formation of dihydrate, which speeds up the setting process.
What is the typical film thickness required for a luting material?
1) 50 µm
2) 25 µm
3) 15 µm
4) 5 µm
For effective luting, the material should form a thin film, typically around 25 µm.
Which type of amalgam alloy has the lowest compressive strength at 1 hour?
1) High-copper lathe-cut alloy
2) Low-copper lathe-cut alloy
3) High-copper spherical alloy
4) Low-copper spherical alloy
The compressive strength at 1 hour is lowest for the low-copper lathe-cut alloy, which is 45 MPa.
What is the primary difference in polymerization between heat-activated and chemically activated resins?
1) Heat-activated resins have a lower degree of polymerization
2) Chemically activated resins have a higher degree of polymerization
3) There is no difference in the degree of polymerization
4) The polymerization process is the same for both types of resins
Heat-activated resins typically have a higher degree of polymerization, resulting in less residual monomer and greater strength compared to chemically activated resins.