MDS PREP
Apart from composites and ceramics, another material that could be copy milled easily and inexpensively is:
1) Molybdenum
2) Germanium
3) Titanium
4) Chromium
Dental Materials Answer: 3
Fabrication of ceramics and metals like titanium that are difficult to cast, is done by CAD-CAM process and copy milling.
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 typical composition of Resin-Modified Glass Ionomer Cement (RMGI)?
1) Glass ionomer and polyacrylic acid
2) Glass ionomer, HEMA, and tartaric acid
3) Glass ionomer and polycarboxylate acid
4) Glass ionomer and zinc oxide
RMGI contains glass ionomer along with 2-hydroxyethylmethacrylate (HEMA) and tartaric acid to improve its properties.
What is the classification of amalgam alloys based on zinc content?
1) Alloys with more than 0.01% zinc are classified as zinc-free, and those with less than 0.01% as zinc-containing.
2) Alloys with more than 0.01% zinc are classified as zinc-containing, and those with less than 0.01% as uno-zinc.
3) Alloys with more than 0.01% zinc are classified as high-zinc, and those with less than 0.01% as low-zinc.
4) Alloys with more than 0.01% zinc are classified as uno-zinc, and those with less than 0.01% as zinc-containing.
Alloys with more than 0.01% zinc are classified as zinc-containing, and those with less than 0.01% as uno-zinc.
What is the typical setting expansion of a high expansion dental stone?
1) Less than 0.1%.
2) 0.1-0.2%.
3) 0.2-0.3%.
4) More than 0.3%.
High expansion dental stones are designed to expand more than typical dental stones to compensate for the contraction of other materials and ensure a precise fit for restorations.
What is the liquefaction temperature of agar hydrocolloid?
1) 37°C - 50°C
2) 60°C - 70°C
3) 70°C - 100°C
4) 50°C - 65°C
Agar hydrocolloid must be heated to a liquefaction temperature between 70°C and 100°C to be suitable for impression taking.
How does the concentration of mercury in urine relate to neurological changes?
1) Neurological changes are detected at urine mercury levels of 1 µg/L.
2) Neurological changes are detected at urine mercury levels of 10 µg/L.
3) Neurological changes are detected at urine mercury levels of 500 µg/L.
4) There is no established link between mercury concentration in urine and neurological changes.
Neurological changes are not detected until urine mercury levels exceed 500 µg/L, which is significantly higher than the levels associated with amalgam placement.
What is the typical peak wavelength for light-activated dental composite resins?
1) 300-400 nm.
2) 400-500 nm.
3) 500-600 nm.
4) 600-700 nm.
Light-activated dental composite resins are usually cured with blue light at a peak wavelength of about 470 nm, which is absorbed by the photoinitiator, such as camphorquinone.