MDS PREP
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.
What are the two primary components of the liquid phase of a denture base resin?
1) Nonpolymerized methyl methacrylate and a cross-linking agent
2) Prepolymerized beads and benzoyl peroxide
3) Hydroquinone and glycol dimethacrylate
4) Monomer and initiator
The liquid phase of a denture base resin primarily consists of nonpolymerized methyl methacrylate (monomer) and a cross-linking agent like glycol dimethacrylate.
What is the effect of temperature on the setting time of gypsum products?
1) Increased temperature accelerates the setting reaction.
2) Increased temperature has no effect on the setting reaction.
3) Increased temperature retards the setting reaction.
4) Temperature has an inconsistent effect on the setting reaction.
Higher temperatures generally speed up the chemical reactions involved in the setting of gypsum products, leading to a shorter setting time.
What is the typical range of Charpy impact strength for a heat-activated denture resin?
1) 0.48 to 0.78 joules
2) 0.98 to 1.27 joules
3) There is no typical range provided
4) The information is not relevant to heat-activated resins
Heat-activated denture resins typically have a Charpy impact strength range of 0.98 to 1.27 joules, which is higher than that of chemically activated resins.
What are the main advantages of using light-cured resins over chemically cured resins?
1) Less shrinkage, better aesthetics, and improved bond strength.
2) Lower cost and less sensitivity to moisture.
3) Faster setting and less technique sensitive.
4) Both A and C.
Light-cured resins generally have less shrinkage and are more aesthetically pleasing due to their ability to be polymerized to a higher degree. They also offer improved bond strength compared to chemically cured resins.
Austenite is an alloy of iron and carbon with the iron in
1) Alpha form
2) Beta form
3) Gamma form
4) None of the above
Dental Materials
Answer: 3
The first light-activated systems were formulated for UV light to initiate free radicals. Today the UV light-cured composites have been replaced by visible blue-light-activated systems with greatly improved depth of cure, a controllable working time, and other advantages.
Because of these advantages, visibly light-activated composites are more widely used than are chemically acti wited materials.
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.
What is the typical pH of zinc polycarboxylate cement immediately after mixing?
1) Less than 2
2) Between 2 and 4
3) Between 4 and 7
4) Greater than 7
The pH is mentioned to be around 2.8 after 3 minutes, which indicates an acidic nature initially.