MDS PREP
What is the typical range of pH for almost neutral cements?
1) pH 4-7
2) pH 7-10
3) pH > 10
4) pH 4-10
Almost neutral cements have a pH range of 7-10, with zinc oxide-eugenol being an example.
What are the common types of water-based dental cements?
1) Zinc polycarboxylate
2) Calcium sulfate
3) Zinc oxide-eugenol
4) All of the above
Water-based cements include zinc polycarboxylate and calcium sulfate.
What is the typical setting time range for Type II (Normal set) alginate impression material?
1) 1-2 minutes
2) 2-4 minutes
3) 4-6 minutes
4) 6-8 minutes
Type II (Normal set) alginate impression material has a setting time of 2-4 minutes, which is longer than the fast-setting Type I material.
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.
What is the chemical composition of Giomers?
1) They are made of fluoride-releasing resin with ceramic filler.
2) They are a combination of glass ionomer and composite resin.
3) They contain fluoraluminosilicate glass and polyalkenoic acid.
4) They are composed of a polymethacrylate matrix with silica fillers.
Giomers are hybrid aesthetic restorative materials that employ PRG technology. The chemical composition includes fluoraluminosilicate glass reacted with polyalkenoic acid, which is then included in a silica-filled urethane resin matrix.
What is the typical composition of Resin-Modified Glass Ionomer Cement (RMGI)?
1) Glass ionomer and polyacrylic acid
2) Glass ionomer, HEMA, and tartaric acid
3) Glass ionomer and polycarboxylate acid
4) Glass ionomer and zinc oxide
RMGI contains glass ionomer along with 2-hydroxyethylmethacrylate (HEMA) and tartaric acid to improve its properties.
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.
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