MDS PREP
Which phase in high-copper amalgams is associated with the formation of CuCl23Cu(OH)2 as a corrosion product?
1) The ? (delt1) phase.
2) The ? (gamm1) phase.
3) The ? (epsilon) phase.
4) The ? (zet1) phase.
The n' phase in high-copper amalgams is associated with the formation of CuCl23Cu(OH)2.
What happens if the water temperature exceeds 50°C during the mixing of gypsum products?
1) The setting reaction is accelerated.
2) The setting reaction is retarded.
3) No reaction occurs.
4) The material becomes less soluble.
If the temperature of the water used to mix gypsum products exceeds 50°C, it can slow down the setting reaction due to the reversible nature of the gypsum crystal formation at higher temperatures.
What is the function of benzoyl peroxide in the composition of denture base resin powder?
1) It acts as a filler
2) It acts as a cross-linking agent
3) It acts as an initiator
4) It acts as an inhibitor
Benzoyl peroxide in the powder of denture base resin is responsible for initiating the polymerization process when it reacts with the monomer in the liquid component.
What is the relationship between the concentration of zinc and the setting expansion of an amalgam alloy?
1) A higher zinc concentration results in greater setting expansion.
2) A lower zinc concentration results in greater setting expansion.
3) There is no relationship between zinc concentration and setting expansion.
4) The relationship is not specified in the given text.
The relationship between zinc concentration and setting expansion is not specified in the given text. However, the presence of zinc in amalgams can affect the rate and extent of setting.
What is the difference between type I and type II glass ionomer cements?
1) Type I has a higher fluoride release
2) Type II has a higher compressive strength
3) Type I sets faster
4) Type II has better aesthetic properties
Type II glass ionomer cements have a higher compressive strength, while Type I is often used for better aesthetics.
What is the primary function of a light-curing unit in the polymerization of resin-based materials?
1) To generate heat for setting.
2) To activate the photosensitizer and initiate the polymerization reaction.
3) To accelerate the chemical reaction.
4) To increase the viscosity of the material.
Light-curing units emit light at specific wavelengths that are absorbed by the photosensitizer in the resin, triggering the free radical polymerization process and setting the material.
The sprue former should be attached to the wax pattern
1) At the thinnest point
2) At the point of greatest bulk
3) At the junction of proximal and
4) None of the above occulsal surfaces
Dental Materials Answer: 2
The sprue former should be attached to the wax pattern at the area of more bulk
What are microfilled composites known for?
1) Their high wear resistance.
2) Their high translucency.
3) Their ease of manipulation.
4) Both A and B.
Microfilled composites contain very fine silica particles (0.04 to 0.2 µm in diameter), which give them excellent translucency and a high surface area for better filling of small restorations.