All Free Dental Materials MCQs with Answers

• A. linear coefficient of thermal expansion less than but close to that of metal
• B. high fusion temperature
• C. high fusion expansion
• D. Linear coefficient of thermal expansion greater than, but close to that of the metal

Explanation: The porcelain should have a slightly lower, but closely matching, coefficient of thermal expansion than the metal.

• A. Surface diffusion of silver from the marginal metal
• B. Vaporization of silver from the walls of contaminated furnaces
• C. More rapid silver diffusion in sodium containing glass
• D. Silver ionization by porcelains with high oxygen potential

Explanation: Green discoloration can result from silver contamination released from the walls of a furnace previously used with silver-containing…

• A. Exchange of aluminium and sodium ions
• B. Exchange of aluminium and potassium ions
• C. Exchange of sodium and potassium ions
• D. None of the above

Explanation: Chemical strengthening uses ion exchange, replacing smaller sodium ions at the porcelain surface with larger potassium ions.

• A. McClean
• B. Ash
• C. Plateau
• D. DeChemant

Explanation: De Chemant introduced the first porcelain tooth material in the late eighteenth century, establishing porcelain as an alternative to…

• A. Diamond but for porcelain and carbide bur for metal
• B. Diamond bur
• C. Stainless steel bur
• D. Carbide bur

Explanation: A diamond instrument is used to cut or adjust porcelain, whereas a carbide bur is more suitable for cutting the metal substructure.

• A. Binder
• B. Strengthener
• C. Pigment
• D. Crack minimzer

Explanation: Quartz is crystalline silica, and its dispersed particles reinforce the porcelain body and limit deformation during firing.

• A. Two coloured restorations
• B. Castabel ceramic
• C. Heat pressed ceramics
• D. None of the above

Explanation: Dicor is a castable glass-ceramic system: the restoration is cast from glass and then cerammed by controlled heat treatment.

• A. Is Feldspathic glass
• B. Not used to mask the colour of the cement used in placing of restoration
• C. Contains opacifier like zirconium and titanium oxide
• D. Used to produce the characteristic translucence, which is an inherent aspect of the incisal edge in natural teeth

Explanation: Opaque porcelain masks the dark metal substructure and contains opacifying oxides such as zirconium oxide and titanium oxide.

• A. Alumina
• B. Silica
• C. Kaolin
• D. Boric oxide

Explanation: Boric oxide acts as a flux by lowering the softening and fusion temperature of the ceramic mixture.

• A. Decor MGC
• B. Cerestore
• C. Infusium
• D. Leucite

Explanation: D·C·MGC, or Dicor machineable glass ceramic, is a machinable glass ceramic used for restorations.

• A. Translucency
• B. Metamerism
• C. Refractive optics
• D. Opacification

Explanation: Metamerism is the change in apparent colour when an object is viewed under different light sources.

• A. Rubber matrix
• B. Plastic
• C. Glass
• D. Resin matrix

Explanation: Dental porcelain is a glass-based ceramic, so its metallic or colouring elements are incorporated into a glass matrix.

• A. Shape and size of particle
• B. Uniform distribution of particle size
• C. Number of particles
• D. None of the above

Explanation: During condensation, particle shape and size determine how closely porcelain particles pack and therefore how much pore space remains.

• A. Titanium oxide
• B. Copper oxide
• C. Silica
• D. Boric oxide

Explanation: Titanium oxide is an effective opacifier because its high refractive index scatters light within the ceramic.

• A. Have a higher coefficient of thermal expansion than acrylic teeth:
• B. Have a lower abrasion resistance than enamel
• C. Have a higher abrasion resistance than gold
• D. Should be used where the inter dental clearance is small

Explanation: Porcelain denture teeth are very hard and highly abrasion resistant, even more so than gold, although this hardness can abrade opposing…

• A. Primary impression
• B. None of the above
• C. Impression of single tooth
• D. Corrective impressions

Explanation: Impression waxes are used mainly for corrective or relining impressions because they can be softened and adapted over an existing…

• A. Utility wax
• B. Base plate wax
• C. Beading wax
• D. Boxing wax

Explanation: Utility wax can be added to the borders of a stock tray to extend and adapt its contour around the arch.

• A. Modeling wax
• B. Iowa wax
• C. Green stick wax
• D. None of the above

Explanation: Iowa wax is a mouth-temperature impression wax that softens at intraoral temperature and can record tissues with minimal discomfort.

• A. It should be rapidly displaced from the mouth
• B. It will take up water and expand if kept wet
• C. It may exhibit fluid exudates on the surface as a result of imbibition of water
• D. It will shrink as a result of syneresis

Explanation: Surface fluid exudation is caused by syneresis, the loss of water from an alginate gel, not imbibition.

• A. Their hardness after setting
• B. Their use
• C. Water content
• D. Eugenol content

Explanation: Type I zinc oxide eugenol impression paste sets harder, whereas Type II sets softer and is easier to remove from undercut areas.