Dental Ceramics

~ Exam ~

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This test has 20 questions.

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1. Which of the following is NOT an essential constituent of potters clays?
  a. Feldspar
  b. Glass
  c. Quartz
  d. Kaolinite
2. Water’s main function in clays is to:
  a. Hydrate feldspathic substances
  b. Break down kaolinite into gibbsite and silica
  c. Reduce friction between clay particles
  d. Create alkaline metal oxides from the non hydrous fluxes
3. Sintering means:
  a. Shock cooling of molten glass to make frits
  b. The molecular bonding of ceramic particles below their melting

  c. Melting of non refractory clay constituents
  d. Condensation of constituent particles to form greenware
4. Which of the statements is false?
  a. Stoneware is harder than earthenware because it contains more feldspar
  b. Earthenware is so porous that vessels made from it requires a glaze to make them waterproof

  c. Domestic porcelain is made from a short clay
  d. Dental porcelains contain no aluminum oxide
5. Which of the following metal oxides is NOT a glass former?
  a. Iron oxide
  b. Boron oxide
  c. Antimony oxide
  d. Phosphorous oxide
6. Glass is a supercooled liquid, and thus:
  a. It flows very slowly at room temperature

  b. It expands slightly when it solidifies

  c. Its crystalline structure varies depending on temperature
  d. It has a solidus instead of a melting temperature
  e. A and C above
7. Borosilicate glass
  a. Was used to build the mirror of the Hale telescope
  b. Is water soluble
  c. Is used on the space shuttle outer windows
  d. Is used to make windows in x-ray operatories
  e. A and C above
8. Fluxes in glass:
  a. Are alkaline metallic oxides
  b. In the raw state are chemically bonded covalently
  c. Are eutectics
  d. Disrupt the crystalline structure of silica
  e. A and D above
9. Glass ceramics
  a. Are glasses made with the addition of aluminous crystals prior to fusing
  b. Do not require feldspathic veneers for esthetics
  c. Start as glasses but end up filled with internally seeded crystals
  d. Are always transparent due to the refractive index of the crystals
10. Ceramming
  a. Is the process of controlled melting of the glass ceramic
  b. Is a process of controlled devitrification of the glass

  c. Is the result of powder condensation of a glass ceramic
  d. Is a process of controlled, but rapid cooling of the glass ceramic
11. Opacity in glass results from
  a. Particle sizes larger than the wavelength of the ambient light
  b. A difference between the refractive indexes of the glass and the particles
  c. Pigmentation within the molecular structure of the glass former
  d. Rapid cooling producing internal crazes which reflect light
  e. A and B above
12. Leucite crystals
  a. Are always added to glass ceramics to reduce tensile stresses
  b. Form in nearly all feldspathic glasses when held at a specific temperature
  c. Have a very small coefficient of thermal expansion
  d. Are not used in PFM porcelain formulations
13. Vitrification means
  a. The process of turning crystalline silica into glass

  b. The formation of crystalline silica in a glass matrix
  c. The sintering of silica crystals in a glass matrix
  d. The fusing of amorphous glass into crystalline silica
14. Which of the following statements is not true?
  a. Porcelain is a highly vitrified ceramic body
  b. Refractory materials in porcelain do not melt at normal kiln temperatures
  c. The purpose of quartz crystals in dental porcelains is to act as crack stoppers
  d. The best crack stoppers in a porcelain body are quartz particles
15. Aluminum oxide
  a. Always causes opacity
  b. Is used as a crack stopper
  c. Is used as a glass stabilizer
  d. Is rarely used in modern dental porcelains due to its optical properties
  e. B and C above
16. Feldspathic porcelain is inherently weak due to:
  a. Its inherently low coefficient of elasticity
  b. Uneven cooling causes microcracking on the internal surfaces of concave/convex bodies
  c. The concentration of stress in tiny surface defects
  d. The presence of crystalline particles in the glass matrix
  e. A, B, and C above
17. Which is NOT always true of a core?
  a. A core fits the tooth or teeth
  b. A core is rigid
  c. A core is translucent
  d. A core supports an esthetic porcelain veneer
18. In-Ceram all-alumina cores are:
  a. Used to make bridge frameworks
  b. Made using a slip casting technique
  c. Made using milling techniques
  d. Nearly solid sintered alumina
19. Zirconium Dioxide cores
  a. Are milled from fully sintered zirconium dioxide
  b. Are stabilized with yttrium
  c. Are made by dry pressing pure zirconia against an oversized die
  d. Are unsuitable for making posterior bridges
  e. B and C above
20. Silane
  a. Is made by bonding methyl chloride to a silicone atom
  b. Is a multi sided molecule
  c. Bonds to both silica and organic molecules
  d. All of the above