MDS PREP
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.
What is the typical refractive index range of bis-GMA and TEGDMA, and what happens when they are mixed in equal proportions?
1) 1.50 to 1.60 and increases.
2) 1.40 to 1.60 and decreases.
3) 1.55 for bis-GMA and 1.46 for TEGDMA, and a mixture yields approximately 1.50.
4) 1.50 for bis-GMA and 1.60 for TEGDMA, and a mixture yields approximately 1.55.
The refractive indices of bis-GMA and TEGDMA are approximately 1.55 and 1.46, respectively, and when mixed in equal proportions, they provide a refractive index of around 1.50.
Purpose of adding indium to metal alloy in porcelain fused to metal is
1) To improve bonding
2) To increase strength
3) To decrease porosity
4) To match the thermal expansion of metal and procelain
Dental Materials Answer: 1
What is the primary mechanism of adhesion for resin cements?
1) Micromechanical retention
2) Chemical bonding
3) Physical adsorption
4) Ionic bonding
Resin cements primarily achieve adhesion through micromechanical retention and chemical bonding.
What is the primary difference between Class I and Class II gypsum products?
1) Setting time.
2) Compressive strength.
3) Expansion.
4) Both A and B.
Class II (dental stone) has a higher compressive strength compared to Class I (dental plaster), making it suitable for model making and other applications requiring higher durability.
What is the recommended thickness of the luting agent film for optimal effectiveness?
1) 50 µm
2) 25 µm
3) 15 µm
4) 5 µm
According to the text, a luting agent must be sufficiently fluid to flow into a continuous film of 25 µm thickness or less without fragmentation.
What is the primary component of zinc polycarboxylate cement?
1) Zinc oxide
2) Polyacrylic acid
3) Titanium dioxide
4) Calcium hydroxide
Zinc polycarboxylate cement primarily consists of zinc oxide and polyacrylic acid.
Which of the following statements about the dimensional change of amalgams is correct?
1) The low-copper, lathe-cut alloy has the highest dimensional change.
2) The high-copper admixed alloy has the lowest dimensional change.
3) All amalgams have a dimensional change of -19.7 µm/cm.
4) All amalgams have a dimensional change of -1.9 µm/cm.
The lowest change of -1.9 µm/cm was for the high-copper admixed alloy.