MDS PREP
What is the effect of pH on the bond strength of zinc polycarboxylate cement?
1) High pH increases bond strength.
2) Low pH increases bond strength.
3) pH has no effect on bond strength.
4) High pH decreases bond strength.
The bond strength is influenced by the acidity; a lower pH can enhance the bond strength.
Which phase in high-copper amalgams is associated with the formation of CuCl23Cu(OH)2 as a corrosion product?
1) The ? (delt1) phase.
2) The ? (gamm1) phase.
3) The ? (epsilon) phase.
4) The ? (zet1) phase.
The n' phase in high-copper amalgams is associated with the formation of CuCl23Cu(OH)2.
What is the typical concentration range for an amine initiator like DMAEMA in a dental composite resin?
1) 0.1-0.2 wt%.
2) 0.5-1.0 wt%.
3) 1-2 wt%.
4) 2-5 wt%.
An aliphatic amine like DMAEMA is used at low concentrations (around 0.15 wt%) in composite resins to initiate the free radical polymerization in the presence of the light-sensitive initiator, such as camphorquinone.
What is the typical bond strength of etched enamel with restorative materials?
1) 5-10 MPa.
2) 15-25 MPa.
3) 5-10 MPa.
4) 30-50 MPa.
Properly etched enamel surfaces can achieve bond strengths of approximately 15 to 25 MPa when using suitable restorative materials.
The elastomeric impression material commonly supplied as a base paste & a liquid catalyst is :
1) Polysulfide
2) Condensation silicone
3) Addition silicone
4) Polyether
Dental Materials Answer: 2
The condensation silicone impression materials are supplied as a base paste and a low-viscosity liquid catalyst (or a paste catalyst).
Putty is a high-viscosity material that has been developed in order to overcome the large polymerization shrinkage of the condensation silicone impression materials.
All the other impression materials are generally supplied as catalyst paste & base paste.
What is the typical average particle size of powered gold used in dental restorations?
1) 15 ?ms
2) 10 ?ms
3) 5 ?ms
4) 20 ?ms
The average particle size of powered gold used in dental restorations is 15 ?ms. This size allows for the gold to be manipulated and condensed properly within the cavity preparation to achieve the desired restorative outcome.
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 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.