MDS PREP
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.
What is the function of ZnO in Gutta Percha?
1) To increase flexibility
2) To improve thermal insulation
3) To enhance radio-opaque properties
4) To form the matrix of Gutta Percha
ZnO is a filler in Gutta Percha, and it improves the strength and flexibility of the material.
What is the typical setting time for zinc oxide-eugenol temporary cement?
1) Less than 5 minutes
2) 5-10 minutes
3) 10-15 minutes
4) More than 15 minutes
Zinc oxide-eugenol temporary cement typically sets in about 5-10 minutes.
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.
A wax pattern made in the mouth will shrink appreciably as it is cooled to room temperature because :
1) The thermal expansion coefficient of wax is very high
2) The thermal expansion coefficient of wax is very low
3) Melting temperature is very high
4) Melting temperature is very low
Dental Materials Answer: 1
A wax pattern made in the mouth will shrink appreciably as it is cooled to room temperature because the coefficient of thermal expansion of wax is very high.(This is the property which describes the thermal energy transport in watts per second through a specimen 1cm thick with a cross sectional area of 1 cm2 when the temperature differential between the surfaces of the specimen perpendicular to the heat flow 10 K) Co efficient of thermal expansion is defined as the change in length per unit of the original length of a material when its temperature is raised 10K.
The opacity in ceramics is achieved by adding
1) Boric oxide
2) Copper oxide
3) Silica
4) Titanium oxide
What is the elastic limit of a wire, and what happens when a wire is deflected beyond this point?
1) The elastic limit is the point at which the wire begins to deform plastically.
2) The elastic limit is the force needed to permanently deform a wire.
3) The elastic limit is the maximum force a wire can withstand before fracture.
4) The elastic limit is the point at which a wire will always return to its original shape regardless of the force applied.
The elastic limit, also known as the yield strength, is the point at which a wire starts to undergo permanent deformation. When a wire is deflected beyond this point, it does not return to its original shape completely.
What is the primary advantage of using resin cements over other types of cements?
1) Higher compressive strength
2) Improved adhesion to the tooth structure
3) Lower film thickness requirement
4) Faster setting time
Resin cements are known for their excellent adhesion, providing a strong bond to tooth structure and restorative materials.