MDS PREP
What is the typical timeframe for the initiation of dimensional change measurement in an amalgam?
1) At the beginning of trituration.
2) Between 5 minutes and 24 hours after the beginning of trituration.
3) At the end of trituration.
4) 40 days after the restoration.
Dimensional change measurement is typically initiated between 5 minutes and 24 hours after the beginning of trituration.
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 significance of the load deflection rate in orthodontic wires?
1) Low load deflection wires are preferred for large tooth movements.
2) High load deflection wires are preferred for large tooth movements.
3) The load deflection rate does not affect wire selection.
4) The load deflection rate determines the force applied during wire bending.
In orthodontics, wires with a low load deflection rate are typically preferred for areas requiring large tooth movements because they provide a more constant force as the tooth moves and the appliance is deactivated. This constant force is beneficial for controlling the rate of tooth movement.
What is the purity requirement for mercury in dental amalgams according to ANSI/ADA Specification No. 6?
1) It must be at least 99.9% pure.
2) It must be at least 99.0% pure.
3) It must be at least 95.0% pure.
4) It must be at least 90.0% pure.
Mercury that complies with the requirements of the United States Pharmacopoeia also meets requirements for purity in ANSI/ADA Specification No. 6, which is typically 99.9% pure.
What is the typical concentration range of phosphoric acid used for enamel etching?
1) 10-20%
2) 20-30%
3) 30-40%
4) 35-50%
Phosphoric acid concentrations between 20% and 30% are commonly used for acid etching of enamel to create a roughened surface for mechanical bonding of restorative materials.
Which of the following is NOT a type of zinc phosphate cement?
1) Type I
2) Type II
3) Type III
4) Type IV
Type IV is not a recognized classification for zinc phosphate cements.
Type of investment material used for casting of removable partial denture with base metal alloy
1) Gypsum based material
2) Phosphate based material
3) Ethyl silicate bonded
4) All of the above
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.