MDS PREP
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.
What is the main component of zinc oxide-eugenol cement?
1) Zinc oxide
2) Silica
3) Phosphoric acid
4) Polycarboxylate acid
Zinc oxide-eugenol cement is primarily composed of zinc oxide and eugenol.
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.
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 happens to acrylic resin when it absorbs water?
1) It expands linearly
2) It contracts linearly
3) It remains the same dimensionally
4) It swells in volume
When acrylic resin absorbs water, it expands linearly by approximately 0.23%, which can affect the fit and function of the denture.
Which of the following denture base materials has the highest linear shrinkage?
1) High-impact acrylic resin
2) Vinyl acrylic resin
3) Conventional acrylic resin
4) Rapid heat-cured acrylic resin
Rapid heat-cured acrylic resin has the highest linear shrinkage at 0.97%, which can affect the fit and stability of the denture.
What is the typical range of water to powder ratio for dental stone?
1) 0.28-0.30.
2) 0.40-0.45.
3) 0.45-0.50.
4) 0.50-0.60.
Dental stone typically has a lower water to powder ratio compared to other gypsum products, which gives it higher strength and durability suitable for making dental models.
What type of dental cement is used in cases of rampant caries and unhygienic oral conditions?
1) Zinc polyacrylate
2) Calcium sulfate
3) Zinc oxide-eugenol
4) Calcium hydroxide
Calcium hydroxide is used in cases of rampant caries and unhygienic oral conditions due to its antibacterial and tissue-dissolving properties.