MDS PREP
Before restoring a tooth with composite, the area is etched. Accidental contamination occurs with saliva, Therefore
1) the area is re-etched before restoration
2) the area is air-dried using an air spray and continue with restoring
3) wipe the saliva with cotton and continue to restore.
4) add excess composie material and cure it
Dental Materials Answer: 1
Etching of tooth surface with 37% phosphoric acid creates microporosities in the enamel and dentin. This is the main method of adhesion of composite resin to tooth surface.
After etching the surface energy of the enamel will increase. This will make it very sticky to any kind of contaminants. If salivary contamination will occur, the salivary proteins will precipitate in the microporosities. This will prevent the adequate penetration of the bonding agent, therby reducing the micotag formation. Hence, complete isolation is essential.
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.
During crown cementation, complete filling of crown with cement is not advisable due to :
1) Increased risk of bubble entrapment
2) Increased seating time
3) Increased pressure required for seating crown
4) All of the above
Dental Materials Answer: 4
It is not advisable to fill the crown completely with cement due to following 4 reasons:
1. the time for removal of excess cement elevates.
2. the risk for bubble entrapment increases
3. increased pressure may be needed
4. the time for seating increases
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.
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 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.
How do resin teeth typically bond with denture base resins?
1) Through mechanical undercuts.
2) Through silanization.
3) By forming chemical bonds.
4) Both A and B.
Resin teeth are capable of forming chemical bonds with commonly used denture base resins, which allows for a stronger and more durable bond compared to porcelain teeth.
What is the typical composition of Resin-Modified Glass Ionomer Cement (RMGI)?
1) Glass ionomer and polyacrylic acid
2) Glass ionomer, HEMA, and tartaric acid
3) Glass ionomer and polycarboxylate acid
4) Glass ionomer and zinc oxide
RMGI contains glass ionomer along with 2-hydroxyethylmethacrylate (HEMA) and tartaric acid to improve its properties.