MDS PREP
What are the main components of a typical dental composite resin?
1) Monomers, fillers, initiators, and accelerators.
2) Resins, fillers, catalysts, and diluents.
3) Polymers, pigments, and plasticizers.
4) Monomers, fillers, and cross-linking agents.
Dental composite resins typically consist of a resin matrix (monomers), filler particles (such as silica or glass), initiators (like camphorquinone), and accelerators (such as amines) to control the setting process.
What is the relationship between the concentration of zinc and the setting expansion of an amalgam alloy?
1) A higher zinc concentration results in greater setting expansion.
2) A lower zinc concentration results in greater setting expansion.
3) There is no relationship between zinc concentration and setting expansion.
4) The relationship is not specified in the given text.
The relationship between zinc concentration and setting expansion is not specified in the given text. However, the presence of zinc in amalgams can affect the rate and extent of setting.
What is the typical composition of the mica crystals in a fluoromica glass ceramic like Dicor?
1) SiO2 · K2O · MgO · Al2O3 · ZrO2
2) Al2O3 · K2O · Na2O · MgO · ZrO2
3) SiO2 · CaO · Al2O3 · ZrO2
4) Al2O3 · Na2O · MgO · CaO
Fluoromica glass ceramics like Dicor have a composition based on mica crystals consisting of silica, potassium oxide (K2O), magnesium oxide (MgO), and aluminum oxide (Al2O3), with zirconium oxide (ZrO2) added for stability. Fluorides are included in the mixture to achieve fluorescence in the finished prosthesis. The material is castable and shares some similarities with traditional dental ceramics but with unique properties derived from its crystalline structure.
What are the two primary purposes of using a luting agent in the placement of a single crown?
1) To achieve a tight seal and to enhance esthetics
2) To provide insulation against thermal changes and to reduce sensitivity
3) To bond the crown to the tooth and to protect the pulp
4) To disinfect the tooth and to provide a base for the crown
Luting agents are used to create a tight seal between the crown and the tooth and to enhance the retention of the restoration.
What is the most corrodible phase in the low-copper amalgam system?
1) Sn7. Hg
2) ? (gamm1) phase
3) Cu3Sn phase
4) ? (delt1) phase
The Sn7. Hg or ? (gamm1) phase is the most corrodible in the low-copper amalgam system.
What is the chemical structure of Giomers?
1) They contain fluoraluminosilicate glass and silica-filled urethane resin.
2) They are purely organic ceramic-filled polymers.
3) They are a combination of glass ionomer and resin-modified glass ionomer.
4) They have a matrix of polyacrylic acid and ceramic filler particles.
Giomers are a combination of fluoraluminosilicate glass and silica-filled urethane resin. This unique composition allows for the release of fluoride and improved physical properties compared to traditional composites.
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 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.