MDS PREP
What is the general source of the substance used in irreversible hydrocolloid impression material?
1) Synthetic polymer
2) Plant resin
3) Brown seaweed
4) Petroleum by-product
The material is derived from the structural formula of anhydro-?-d-mannuronic acid, which is extracted from certain types of brown seaweed.
The constituent used in porcelain that fuses at high temperature to form matrix
1) Soda ash
2) Feldspar
3) Quartz
4) Koalin
Dental Materials Answer: 3
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 elastic range of a wire?
1) The maximum force a wire can withstand before permanent deformation.
2) The amount of deflection before the wire returns to its original shape.
3) The force needed to activate the wire beyond its elastic limit.
4) The difference in force between the elastic limit and ultimate tensile strength.
The elastic range of a wire is the amount of deflection it can withstand before permanent deformation occurs. It is the difference between the elastic limit and the ultimate tensile strength.
What is the typical pH of zinc polycarboxylate cement immediately after mixing?
1) Less than 2
2) Between 2 and 4
3) Between 4 and 7
4) Greater than 7
The pH is mentioned to be around 2.8 after 3 minutes, which indicates an acidic nature initially.
What is the typical setting expansion of a regular dental stone?
1) Less than 0.1%.
2) 0.1-0.2%.
3) 0.2-0.3%.
4) More than 0.3%.
Regular dental stones have a low expansion rate, usually between 0.1% and 0.2%, which is suitable for accurate model fabrication.
What is the chemical structure of Giomers?
1) They contain fluoraluminosilicate glass and silica-filled urethane resin.
2) They are purely organic ceramic-filled polymers.
3) They are a combination of glass ionomer and resin-modified glass ionomer.
4) They have a matrix of polyacrylic acid and ceramic filler particles.
Giomers are a combination of fluoraluminosilicate glass and silica-filled urethane resin. This unique composition allows for the release of fluoride and improved physical properties compared to traditional composites.
What is the elastic limit of a wire?
1) The point at which the wire returns to its original shape.
2) The point at which the wire starts to weaken.
3) The point at which the wire yields permanently.
4) The point at which the wire breaks.
The elastic limit of a wire is the point at which it yields permanently, meaning any greater force applied will result in irreversible deformation.