MDS PREP
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 typical setting expansion of a high expansion dental stone?
1) Less than 0.1%.
2) 0.1-0.2%.
3) 0.2-0.3%.
4) More than 0.3%.
High expansion dental stones are designed to expand more than typical dental stones to compensate for the contraction of other materials and ensure a precise fit for restorations.
What is the typical pH of a resin cement immediately after mixing?
1) Less than 2
2) Between 2 and 4
3) Between 4 and 7
4) Greater than 7
The pH of resin cements is usually slightly acidic after mixing, subject to variation in formulation.
What is the ADA specification for the gelation temperature of agar-agar hydrocolloids?
1) It should not be less than 32°C
2) It should be exactly 32°C
3) It should be more than 32°C
4) There is no specific ADA specification for gelation temperature
The American Dental Association (ADA) Specification-11 states that the gelation temperature should not be less than 32°C to ensure proper setting and avoid distortion of the impression.
The point at which a stress of a material exhibits a specific limited deviation P Is called
1) Proportional limit
2) Tensile strength
3) Ultimate strength
4) Yield strength
Dental Materials Answer: 4
Yield strength is the stress required to produce plastic deformation.
In orthodontic wire selection, what is the benefit of using a wire with a high load deflection rate?
1) It provides a constant force over a wider range of tooth movements.
2) It is more suitable for areas requiring minimal tooth movement.
3) It is less prone to permanent deformation during activation.
4) It has a steeper force-deflection curve.
In orthodontics, wires with a high load deflection rate are beneficial in areas where minimal tooth movement is desired, such as in maximum anchorage extraction cases or during finishing.
What is the structural formula of the substance found in irreversible hydrocolloid?
1) Anhydro-?-d-mannuronic acid
2) Anhydro-?-d-glucuronic acid
3) Anhydro-?-d-glucuronic acid
4) Anhydro-?-d-mannuronic acid
Irreversible hydrocolloid, such as alginate, is based on the structure of anhydro-?-d-mannuronic acid.
Ability of an orthodontic wire to spring back to Its original shape is evaluated by
1) Brittleness
2) Resilience
3) Tensile strength
4) Toughness
Dental Materials Answer: 2
Resilience is the amount of energy absorbed by a structure when it is stressed to proportional Limit.
The elastic area of the stress-strain graph gives resilience; entire area up to breaking point is a measure of toughness.
The slope of straight Line gives Young’s modulus.