MDS PREP
What is the maximum allowable creep for a 1-day-old amalgam specimen under a 36 MPa stress at 37°C according to ANSI/ADA Specification No. 1 (ISO 24234)?
1) 0.5%
2) 1%
3) 2%
4) 3%
The maximum allowable creep is 1% for amalgam quality according to the specification.
What is the typical force applied with a condenser during restorative procedures?
1) 0.04-0.4 µm
2) 1-5 µm
3) 3.75 pounds
4) 8.43 pounds
The typical force applied with a condenser during restorative procedures is 3.75 pounds for a 0.5 mm diameter nib, 8.43 pounds for a 0.75 mm diameter, and 15 pounds for a 1 mm diameter nib. The force is applied parallel to the long axis of the instrument shaft.
Modern dental noble metal casting alloys generally have equiaxed fine grain structures because of the incorporation of small amounts of
1) Chromium
2) Indium
3) Iridium
4) Palladium
Dental Materials Answer: 3
The term equiaxed refers to the fact that three dimensions of each grain are similar. In dendritic structure, grains are elongated. Dendritic micro structures are not desirable for cast dental alloys, reason being the inter dendritic regions can serve as sites for
crack propagation.
Addition of about 1 wt% of ruthenium, Iridium or rhenium as grain refiners makes modern dental noble metal casting alloys as equiaxed microstructures.
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 is the maximum weight loss allowed for a specimen surface according to the specification?
1) 0.04 mg/cm³
2) 0.69 mg/cm²
3) 0.23 mg/cm²
4) There is no maximum weight loss mentioned
The specification mentions that the weight loss must not be greater than 0.04 mg/cm³ from the specimen surface, which is considered negligible from a clinical standpoint.
Which of the following is not a type of oil-based cement?
1) Zinc oxide-eugenol
2) Zinc phosphate
3) Nano-eugenol-zinc oxide
4) All of the above are oil-based cements
Zinc oxide-eugenol is the only oil-based cement mentioned in the text.
Which of the following is NOT a type of zinc phosphate cement?
1) Type I
2) Type II
3) Type III
4) Type IV
Type IV is not a recognized classification for zinc phosphate cements.
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.