MDS PREP
Hardness number which does not depend on the ductility of metal
1) KHN
2) VHN
3) RHN
4) BHN
Dental Materials Answer: 1
Knoop hardness test - Diamond of rhombic shape (The long axis of indentotion is measured)
Vickers (Diamond pyramid test) - Diamond of square base shape (The diagonal length of the indentation is measured)
Rockwell - Diamond of conical shape (The penetration depth is measured)
Brinells - Steel ball (The diameter of indentation is measured)
The Knoop hardness test is used to obtain the values for both exceedingly hard and soft materials. The
hardness value is independent of the ductility of the material.
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.
What is the typical range of pH for acidic dental cements?
1) pH > 7
2) pH 7-10
3) pH 4-7
4) pH < 4
Acidic dental cements typically have a pH less than 7.
What is the primary function of gold foil in a direct gold restoration?
1) To provide a rigid framework for the powdered gold
2) To enhance the aesthetic appeal of the restoration
3) To improve the adhesion of the gold to the tooth structure
4) To act as a barrier between the gold and the oral environment
Gold foil is used in direct gold restorations to create a three-dimensional structure that can hold the loosely bound powdered gold in place. The foil acts as a container and facilitates the condensation of the gold particles into a cohesive mass, which is then adapted to the prepared cavity.
What happens to the strength of irregularly shaped amalgam alloys when they are over-triturated?
1) It significantly increases.
2) It significantly decreases.
3) It remains the same.
4) It first increases and then decreases.
The strength of irregularly shaped amalgam alloys increases with over-trituration.
What is the purity requirement for mercury in dental amalgams according to ANSI/ADA Specification No. 6?
1) It must be at least 99.9% pure.
2) It must be at least 99.0% pure.
3) It must be at least 95.0% pure.
4) It must be at least 90.0% pure.
Mercury that complies with the requirements of the United States Pharmacopoeia also meets requirements for purity in ANSI/ADA Specification No. 6, which is typically 99.9% pure.
What is the role of camphorquinone in photocuring of resin composites?
1) It emits blue light for curing.
2) It absorbs blue light and initiates polymerization.
3) It enhances the color stability of the composite.
4) It is a filler material for increasing strength.
Camphorquinone is a photosensitizer that absorbs blue light and initiates the free radical polymerization of the resin when irradiated, leading to cross-linking and setting of the composite.
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.