MDS PREP
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.
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 Today the UV light-cured composites have been replaced by visible blue-light-activated systems with greatly improved depth of cure, a controllable working time, and other advantages.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 primary difference between the setting mechanism of light-cured and chemically cured composite resins?
1) Light-cured resins shrink towards the external surface, while chemically cured resins shrink towards the center.
2) Chemically cured resins require light activation.
3) Light-cured resins require a chemical catalyst.
4) There is no significant difference in the setting mechanism.
The setting mechanism of light-cured resins involves free radical polymerization initiated by light, which causes the material to contract away from the light source (typically the external surface).
What is the maximum allowable level of mercury in the blood according to the given information?
1) 1 µg/L
2) 3 µg/L
3) 5 µg/L
4) 10 µg/L
The maximum allowable level of mercury in the blood is specifically mentioned as 3 µg/L in the provided text.
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.
What are the primary advantages of Ormocers over conventional composites?
1) Outstanding biocompatibility and minimal shrinkage.
2) High elasticity and superior resistance to masticatory forces.
3) Enhanced wear resistance and fluoride release.
4) All of the above.
Ormocers offer several advantages over conventional composites. They have excellent biocompatibility, minimal shrinkage, and their chemical structure allows for high resistance to masticatory forces. Additionally, they are aesthetically pleasing and can be polished to resemble natural teeth.
What are the stoichiometric formulas for the gamma (?), epsilon (?), and zeta (?) phases in dental amalgams?
1) ?: Ag3Sn, ?: Cu3Sn8, ?: Cu3Sn
2) ?: Ag3Sn, ?: AgSn, ?: CuSn
3) ?: AgSn, ?: Cu3Sn, ?: Ag3Sn8
4) ?: AgSn, ?: CuSn, ?: Ag3Sn.
?: Ag3Sn, ?: Cu3Sn8, ?: Cu3Sn
Which of the following is not a type of temporary cementing material?
1) Zinc oxide-eugenol (type III)
2) Calcium hydroxide
3) Glass ionomer cement (type 1)
4) Resin-modified glass ionomer cement
Resin-modified glass ionomer cement is not listed as a type of temporary cementing material in the text.