MDS PREP
What is the primary function of a base material in dental restoration?
1) To seal the tooth from microleakage
2) To provide insulation from thermal changes
3) To reinforce the tooth structure
4) To enhance the aesthetics of the restoration
A base material in dental restoration is primarily used to provide a seal against microleakage.
Apart from composites and ceramics, another material that could be copy milled easily and inexpensively is:
1) Molybdenum
2) Germanium
3) Titanium
4) Chromium
Dental Materials Answer: 3
Fabrication of ceramics and metals like titanium that are difficult to cast, is done by CAD-CAM process and copy milling.
How do resin teeth typically bond with denture base resins?
1) Through mechanical undercuts.
2) Through silanization.
3) By forming chemical bonds.
4) Both A and B.
Resin teeth are capable of forming chemical bonds with commonly used denture base resins, which allows for a stronger and more durable bond compared to porcelain teeth.
What is the maximum allowable creep for a 1-day-old amalgam specimen under a 36 MPa stress at 37°C according to ANSI/ADA Specification No. 1 (ISO 24234)?
1) 0.5%
2) 1%
3) 2%
4) 3%
The maximum allowable creep is 1% for amalgam quality according to the specification.
What is the typical film thickness for a resin cement?
1) 50 µm
2) 25 µm
3) 15 µm
4) 5 µm
Resin cements are generally applied in a film thickness of 25 µm or less for optimal performance.
What is the primary chemical bonding mechanism between etched enamel and restorative materials?
1) Formation of a smear layer.
2) Ionic bonding.
3) Covalent bonding.
4) Mechanical interlocking.
Acid etching creates microscopic tags and fissures on the enamel surface, allowing the restorative material to flow in and mechanically interlock, enhancing the bond strength.
What is the difference between type I and type II glass ionomer cements?
1) Type I has a higher fluoride release
2) Type II has a higher compressive strength
3) Type I sets faster
4) Type II has better aesthetic properties
Type II glass ionomer cements have a higher compressive strength, while Type I is often used for better aesthetics.
What is the typical particle size range of the fillers in conventional, microfilled, and hybrid composites?
1) Conventional: 8-12 µm, Microfilled: 0.04-0.4 µm, Hybrid: 0.1-0.01 µm
2) Conventional: 1-5 µm, Microfilled: 0.04-0.4 µm, Hybrid: 0.01-0.1 µm
3) Conventional: 8-12 µm, Microfilled: 0.01-0.05 µm, Hybrid: 0.5-1 µm
4) Conventional: 0.01-0.1 µm, Microfilled: 0.1-0.5 µm, Hybrid: 0.5-1 µm
The particle size of the fillers in composite materials affects their physical and handling properties. Conventional composites have larger filler particles, while microfilled and hybrid composites have smaller ones. The text provides the typical ranges for each type of composite.