MDS PREP
What is the typical average particle size of powered gold used in dental restorations?
1) 15 ?ms
2) 10 ?ms
3) 5 ?ms
4) 20 ?ms
The average particle size of powered gold used in dental restorations is 15 ?ms. This size allows for the gold to be manipulated and condensed properly within the cavity preparation to achieve the desired restorative outcome.
What is the primary function of a luting agent in the context of dental restorations?
1) To bond the restoration to the tooth
2) To provide a protective barrier against bacteria
3) To insulate the tooth from thermal changes
4) To fill in gaps caused by tooth decay
A luting agent's primary function is to bond the restoration to the tooth and enhance its retention.
What is the typical range of Charpy impact strength for a heat-activated denture resin?
1) 0.48 to 0.78 joules
2) 0.98 to 1.27 joules
3) There is no typical range provided
4) The information is not relevant to heat-activated resins
Heat-activated denture resins typically have a Charpy impact strength range of 0.98 to 1.27 joules, which is higher than that of chemically activated resins.
The essential ingredient of dental inlay investment are :
1) Quartz, cristobalite
2) β hemihydrate
3) α hemihydrate
4) Ammonium phosphate
Dental Materials Answer: 3
The essential ingredients of the dental inlay investment employed with the conventional gold casting alloys are a-hemihydrate of gypsum, quartz, or cristobalite, which are allotropic forms of silica.
Nitinol has the disadvantage of which of the following?
1) It cannot be formed into desired shapes
2) It lacks elastic properties
3) Its strength is not suited for orthodontic purposes
4) It lacks stiffness
Dental Materials Answer: 1
Nitinol is a metal alloy – or mixture – of nickel and titanium. This type of wire is also known as “memory wire” or “smart wire,” and it can be used for braces.
Which of the following is NOT a component of dental amalgam?
1) Finely ground silver/tin metal powder
2) Mercury
3) Hydrophilic polymer
4) Zirconia
Dental amalgam is a mixture of metallic elements consisting of silver, tin, copper, and sometimes zinc, combined with liquid mercury to form an amalgamated alloy. The mercury acts as a matrix that bonds the metal particles together. It does not contain hydrophilic polymers, which are typically found in resin-based composite materials used for tooth-colored restorations.
What is the typical film thickness required for zinc polycarboxylate cement?
1) 50 µm
2) 25 µm
3) 15 µm
4) 5 µm
As a luting material, zinc polycarboxylate should form a film of less than 25 µm.
What is the significance of the line of force during the condensation of dental amalgam?
1) The line of force determines the speed at which the amalgam is condensed.
2) The line of force is the amount of force applied to the condenser during condensation.
3) The line of force describes the direction of force applied with a condenser.
4) The line of force is the amount of force needed to cause the amalgam to flow into the preparation.
The line of force refers to the direction in which the force is applied during condensation. It is crucial to apply the force in a controlled and precise manner to avoid causing damage to the tooth or the restoration. The text mentions that the force applied with a condenser parallels the long axis of the instrument shaft, with specific angles recommended for different areas of the cavity.