MDS PREP
What type of dental cement is used in cases of rampant caries and unhygienic oral conditions?
1) Zinc polyacrylate
2) Calcium sulfate
3) Zinc oxide-eugenol
4) Calcium hydroxide
Calcium hydroxide is used in cases of rampant caries and unhygienic oral conditions due to its antibacterial and tissue-dissolving properties.
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 function of ZnO in Gutta Percha?
1) To increase flexibility
2) To improve thermal insulation
3) To enhance radio-opaque properties
4) To form the matrix of Gutta Percha
ZnO is a filler in Gutta Percha, and it improves the strength and flexibility of the material.
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 range for dimensional change between 5 minutes and 124 hours for an amalgam specimen according to ANSI/ADA Specification No. 1 (ISO 24234)?
1) -5 to +10 ?m/cm
2) -10 to +15 ?m/cm
3) -15 to +20 ?m/cm
4) -20 to +25 ?m/cm
The specification requires that the dimensional change for a cylindrical specimen must fall within the range of -15 to +20 ?m/cm for 5 minutes to 124 hours after setting.
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 the liquefaction temperature of agar hydrocolloid?
1) 37°C - 50°C
2) 60°C - 70°C
3) 70°C - 100°C
4) 50°C - 65°C
Agar hydrocolloid must be heated to a liquefaction temperature between 70°C and 100°C to be suitable for impression taking.
What is the classification of amalgam alloys based on zinc content?
1) Alloys with more than 0.01% zinc are classified as zinc-free, and those with less than 0.01% as zinc-containing.
2) Alloys with more than 0.01% zinc are classified as zinc-containing, and those with less than 0.01% as uno-zinc.
3) Alloys with more than 0.01% zinc are classified as high-zinc, and those with less than 0.01% as low-zinc.
4) Alloys with more than 0.01% zinc are classified as uno-zinc, and those with less than 0.01% as zinc-containing.
Alloys with more than 0.01% zinc are classified as zinc-containing, and those with less than 0.01% as uno-zinc.