MDS PREP
What is the optimal force applied during condensation of a 1 mm diameter condenser nib?
1) 3.75 pounds
2) 8.43 pounds
3) 15 pounds
4) 0.04-0.4 µm
The optimal force for condensing a composite resin using a 1 mm diameter condenser nib is 15 pounds, which is within the physiologic limits of the tooth and provides effective condensation.
What is the minimum compressive strength required for lining materials?
1) 1.0 MPa
2) 3.0 MPa
3) 5.0 MPa
4) 10 MPa
Lining materials must have a minimum compressive strength of 5 MPa to withstand the forces in the oral cavity.
What is the typical force applied with a condenser during restorative procedures?
1) 0.04-0.4 µm
2) 1-5 µm
3) 3.75 pounds
4) 8.43 pounds
The typical force applied with a condenser during restorative procedures is 3.75 pounds for a 0.5 mm diameter nib, 8.43 pounds for a 0.75 mm diameter, and 15 pounds for a 1 mm diameter nib. The force is applied parallel to the long axis of the instrument shaft.
What does ORMOCER stand for in the context of dental filling materials?
1) Organically Modified Resin-ceramic Opportunistic
2) Organically Modified Resin-ceramic Material
3) Organically Modified Ceramic
4) Optimized Resin-ceramic Matrix
ORMOCER stands for Organically Modified Ceramic. These materials are advanced filling options in dentistry with a unique matrix technology and filler particles that result in high biocompatibility and aesthetics.
How does the degree of polymerization affect the strength of resin?
1) There is no correlation between the two
2) Higher degree of polymerization results in increased strength
3) Lower degree of polymerization results in increased strength
4) The strength is unaffected by the degree of polymerization
A higher degree of polymerization in resins generally correlates with greater strength, as more polymer chains are formed and cross-linked.
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.
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 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.