MDS PREP
What is the purpose of using a temporary cement?
1) To provide a permanent seal
2) To allow for temporary fixation before the final restoration is placed
3) To strengthen the tooth structure
4) To fill gaps caused by caries
Temporary cements are used to hold a temporary restoration in place until the final restoration can be placed, and they should have a lower compressive strength to allow for easy removal.
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.
What is the primary function of a retarder in gypsum-based dental materials?
1) To accelerate the setting reaction.
2) To enhance the mechanical properties.
3) To prolong the working time.
4) To improve the dimensional stability.
Retarders in gypsum-based materials slow down the setting reaction by forming an adsorbed layer on hemihydrates, allowing more time for manipulation and placement before the material sets.
What is the optimal force applied during condensation of a 1 mm diameter condenser nib?
1) 3.75 pounds
2) 8.43 pounds
3) 15 pounds
4) 0.04-0.4 µm
The optimal force for condensing a composite resin using a 1 mm diameter condenser nib is 15 pounds, which is within the physiologic limits of the tooth and provides effective condensation.
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 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 dough-forming time for denture base resin according to ANSI/ADA Specification No. 12?
1) Less than 10 minutes
2) Less than 5 minutes
3) Less than 20 minutes
4) Less than 30 minutes
ANSI/ADA Specification No. 12 requires that the material should reach a doughlike consistency in less than 10 minutes from the start of the mixing process.
What are the main properties of Compomers?
1) High elasticity and high load deflection rate.
2) High modulus of elasticity and low shrinkage.
3) Easy to inject, shape, and polish with good aesthetics.
4) High thermal conductivity and good radiopacity.
Compomers are known for their ease of use, being non-sticky, and simple to place and shape. They are a hybrid of glass ionomer and composite resin properties, offering good aesthetics and user-friendly handling.