MDS PREP
What is the primary function of the eugenol in zinc oxide-eugenol cement?
1) To provide antimicrobial properties
2) To act as a plasticizer
3) To initiate the setting reaction
4) To increase the compressive strength
The eugenol in zinc oxide-eugenol cement acts as a plasticizer, providing temporary softness for easier manipulation.
What is the ANSI/ADA Specification No. 96 (ISO 9917) minimum compressive strength for luting cement?
1) 50 MPa
2) 70 MPa
3) 100 MPa
4) 150 MPa
The ANSI/ADA Specification No. 96 (ISO 9917) stipulates a minimum 24-hour compressive strength of 70 MPa for standard luting consistency dental cement.
What is the role of camphorquinone in photocuring of resin composites?
1) It emits blue light for curing.
2) It absorbs blue light and initiates polymerization.
3) It enhances the color stability of the composite.
4) It is a filler material for increasing strength.
Camphorquinone is a photosensitizer that absorbs blue light and initiates the free radical polymerization of the resin when irradiated, leading to cross-linking and setting of the composite.
What are the three physical properties controlled by the ANSUADA Specification No. 1 (ISO 24234) for dental amalgam?
1) Creep, tensile strength, and thermal expansion.
2) Compressive strength, hardness, and density.
3) Creep, compressive strength, and dimensional change.
4) Tensile strength, modulus of elasticity, and corrosion resistance.
The specification controls the qualities of dental amalgam by listing requirements for creep, compressive strength, and dimensional change.
What is the effect of adding potassium sulfate to gypsum-based materials?
1) It accelerates the setting reaction.
2) It retards the setting reaction.
3) It increases the porosity.
4) It has no effect on the setting reaction.
Potassium sulfate acts as an accelerator by increasing the solubility of the hemihydrate and promoting the formation of dihydrate, which speeds up the setting process.
What is the preferred method of degassing for powered gold restorations?
1) An alcohol flame
2) An oxygen-acetylene flame
3) A butane flame
4) A nitrogen-hydrogen flame
The preferred method for degassing powered gold restorations is the use of an alcohol flame, specifically one that is a clean blue flame from absolute or 90% ethyl/methyl alcohol. The material is held in the flame until it reaches a dull red glow, which typically takes 15-20 seconds. This process removes any trapped air or volatile components that could compromise the integrity of the restoration.
What is the effect of trituration time on the dimensional change of spherical amalgam alloys?
1) It increases with increased trituration time.
2) It decreases with increased trituration time.
3) It is not affected by trituration time.
4) It is greatest at normal trituration time.
Compressive and tensile strengths of spherical alloys are greatest at normal trituration time.
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.