All Free Dental Materials MCQs with Answers

• A. 90
• B. 343
• C. 67
• D. 450

Explanation: Dental amalgam has a Knoop hardness of approximately 90 KHN in commonly cited dental-materials tables.

• A. 50 - 60 KHN
• B. 40 - 48 KHN
• C. 15 - 20 KHN
• D. 25 - 35 KHN

Explanation: Microfilled composites contain smaller and less heavily loaded filler particles, giving them a lower Knoop hardness than hybrid…

• A. Investment
• B. Models
• C. Casts
• D. Dies

Explanation: Investment expansion is useful because it compensates for the solidification shrinkage of the casting alloy.

• A. Using asbestos linear
• B. Placing the sprue at least one quarter inch away form the end of casting ring
• C. Preventing rapid heating the investment in burnout oven
• D. Using a short and wide sprue

Explanation: Back-pressure porosity results when air or gases cannot escape from the mold as molten alloy enters it.

• A. Produce a smoother casting
• B. Increase setting expansion
• C. Decrease setting expansion
• D. Increase thermal expansion

Explanation: A thinner gypsum investment mix contains more water, which increases porosity after drying and reduces the effective gypsum concentration.

• A. Gypsum
• B. Silica content
• C. Carbon content
• D. Copper

Explanation: The gypsum binder is the principal source of strength in a gypsum-bonded investment, while silica mainly provides refractory behaviour and…

• A. Type 1
• B. Type 2
• C. Type 3
• D. Type 4

Explanation: Type I inlay wax is intended for the direct technique, where the wax pattern is formed directly in the prepared tooth.

• A. Gypsum bonded
• B. Phosphate bonded
• C. Silica bonded
• D. None of the above

Explanation: Cobalt-chromium alloys melt at high temperatures, so gypsum-bonded investments cannot withstand casting temperatures reliably.

• A. Utility wax
• B. Inlay wax
• C. Carding wax
• D. Sticky wax

Explanation: Boxing wax is also called carding wax because it is used to form the wax wall around an impression before pouring the cast.

• A. Paraffin
• B. Carnauba
• C. Canadelila
• D. Gum dammar

Explanation: Gum dammar improves the toughness of inlay wax and reduces its tendency to flake or crumble during carving.

• A. Galvanic current caused by gold onlay occluding with a large restoration
• B. Retained cement in gingival sulcus
• C. Excess acid in mix
• D. Supracocclusion of restoration

Explanation: A sharp shooting pain whenever dissimilar metallic restorations contact can result from galvanic current, with saliva acting as the…

• A. Candellila wax
• B. Paraffin wax
• C. Carnauba wax
• D. Gum dammar

Explanation: Paraffin wax forms the major portion of inlay wax, while harder waxes such as carnauba and candelilla modify its hardness and softening…

• A. Bowen
• B. Buonocore
• C. G.V. Black
• D. William H Taggart

Explanation: William H. Taggart introduced the lost-wax casting technique for cast inlay restorations in 1907.

• A. Make inlay wax patterns
• B. Temporarily cement inlays:
• C. Invest inlay patterns
• D. Box models

Explanation: Inlay wax is a pattern material that is shaped directly or indirectly into the form of the restoration and then invested for casting.

• A. Strength
• B. Expansion components for casting shrinkage
• C. Decrease strength
• D. Contraction

Explanation: Quartz is a refractory component of dental investment and undergoes thermal expansion when heated.

• A. More porous investment in the mould
• B. Hollow sprue pin
• C. Narrow sprue diameter
• D. Large reservoir

Explanation: A narrow sprue restricts the flow of molten alloy and may prevent the mould from filling completely, producing an incomplete casting.

• A. Shrinkage of alloy on cooling
• B. Investment breakdown
• C. Incomplete gas elimination
• D. Incomplete wax elimination

Explanation: Incomplete wax elimination can leave carbon or wax residues that produce a shiny, glossy casting surface and smooth margins.

• A. 700°C
• B. 1,300°C
• C. 1,063°C
• D. 900°C

Explanation: Gypsum-bonded investments should generally not be heated above about 700°C because the gypsum binder decomposes at higher temperatures and…

• A. Decrease flow
• B. Continuous expansion
• C. Relaxation of the internal stresses
• D. Water loss

Explanation: Wax patterns contain internal stresses that gradually relax, causing distortion if investing is delayed.

• A. Impressions
• B. Casts
• C. Die
• D. Casts and Dies

Explanation: Gypsum products are mainly used to make positive replicas of oral structures, including study casts, working casts and dies.