MDS PREP
Bonding of GIC to tooth structure is brought about by
1) metal ions
2) hydroxyl bond
3) carboxyl bond
4) ionic bond
Dental Materials Answer: 3
one ot the main adanhtges of GIC as a restoratie material was its ability to form chemical bonds with the tooth structure.
Bonding in GIC primarily invokes chelation of carboxyl groups of the polyacids sith the calcium in the apatite of enamel and dentin. Bond rength of enamel is always greater than that of dentin due to higher mineral content. The bonding is improved by the removal of the debris layer called smear layer’ by a process called conditioning.
What is Goldent, and how is it used in dental restorations?
1) A brand of gold alloy used for inlays and onlays
2) A form of gold foil with a high platinum content
3) A combination of powdered gold and gold foil in a pellet form
4) A gold-plated stainless steel mesh used for subgingival retention
Goldent is a form of direct gold restoration where pellets of powdered gold are wrapped in a No. 3 gold foil. The foil acts as a container for the gold particles and allows for better handling and condensation during placement. Each pellet contains approximately 95% powdered gold and 5% gold foil, making it more economical than using gold foil alone for restorations.
What is the typical range of pH for acidic dental cements?
1) pH > 7
2) pH 7-10
3) pH 4-7
4) pH < 4
Acidic dental cements typically have a pH less than 7.
What is the typical pH of a resin cement immediately after mixing?
1) Less than 2
2) Between 2 and 4
3) Between 4 and 7
4) Greater than 7
The pH of resin cements is usually slightly acidic after mixing, subject to variation in formulation.
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
What are the typical mixing and setting times for zinc phosphate cement?
1) Mixing time: 1-2 minutes, Setting time: 5 minutes
2) Mixing time: 5-10 minutes, Setting time: 20 minutes
3) Mixing time: 1-15 minutes, Setting time: 1-2 minutes
4) Mixing time: 3-5 minutes, Setting time: 5-10 minutes
According to the text, the mixing time for zinc phosphate cement is about 1-15 minutes.
What is the thermal property of GIC similar to?
1) Enamel
2) Dentin
3) Glass Ionomer
4) Zinc Oxide-Eugenol Cement
GIC has a thermal expansion coefficient of 13-16 PPM/�C which is quite close to the values of dentin (8-11 PPM/�C). This similarity helps in reducing marginal leakage.
What is the typical composition of Zinc Oxide-Eugenol Cement?
1) Zinc oxide and polyacrylic acid
2) Zinc oxide and eugenol
3) Zinc phosphate and polyacrylic acid
4) Zinc oxide and sodium silicate
Zinc Oxide-Eugenol Cement is primarily composed of zinc oxide and eugenol, with a pH of approximately 7, making it less irritating to pulpal tissues.