MDS PREP
What does ORMOCER stand for in dental materials?
1) Organically Modified Resin Monomer Ceramic
2) Organically Modified Resin Matrix Composite
3) Organically Modified Ceramic Resin
4) Ormocer is not an acronym.
ORMOCER stands for Organically Modified Ceramic, which is a type of advanced filling material that combines the properties of ceramics and resins for superior performance in dental restorations.
What is the primary advantage of using the frozen slab technique with zinc phosphate cement?
1) It increases the working time.
2) It decreases the setting time.
3) It increases the mechanical properties.
4) It changes the pH of the cement.
The frozen slab technique increases the working time of zinc phosphate cement by allowing more moisture to condense on the cool glass slab.
Gypsum Bonded Investment should NOT be heated above
1) 700°C
2) 750°C
3) 800°C
4) 900°C
Dental Materials Answer: 1
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.
Porcelain binds to metal in PFM crown by:
1) Metallic bind
2) Mechanical bond
3) Chemical bond
4) Both 2 and 3
Dental Materials Answer: 4
Porcelain binds to metal in metal ceramic restorations by mechanical interlocking and chemical bonding. Mechanical interlocking is provided by proper wetting of the metal surface by porcelain.
The adherent metallic oxides, which are formed during the degassing cycle form a good chemical bond with porcelain.
Tin oxide and Indium oxide are formed from precious metal alloys while chromium oxide is formed from base metal alloys.
What is the primary function of a dental sealer in restorative procedures?
1) To prevent microleakage
2) To desensitize the tooth
3) To enhance the aesthetics of the restoration
4) To reinforce the tooth structure
A dental sealer is used to fill the microscopic spaces between the restorative material and the tooth structure, primarily to prevent microleakage.
During crown cementation, complete filling of crown with cement is not advisable due to :
1) Increased risk of bubble entrapment
2) Increased seating time
3) Increased pressure required for seating crown
4) All of the above
Dental Materials Answer: 4
It is not advisable to fill the crown completely with cement due to following 4 reasons:
1. the time for removal of excess cement elevates.
2. the risk for bubble entrapment increases
3. increased pressure may be needed
4. the time for seating increases
What is the typical mixing time for temporary cementing materials?
1) 1-5 minutes
2) 5-15 minutes
3) 15-30 minutes
4) 1-15 minutes
The text does not specify the exact mixing time for temporary cements, but it states that the mixing time for all three varieties is approximately 1-15 minutes.