Dental Materials Science Flashcards
7 cards from real DMD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Dental Materials Science flashcards as text
The Vickers hardness test measures dental material hardness using which type of indenter?
Answer: A square-based diamond pyramid
The Vickers hardness test uses a square-based diamond pyramid indenter pressed into the surface under a specific load, and hardness is calculated from the diagonal length of the indentation.
Which metal restorative system is most likely to cause galvanic corrosion when placed adjacent to existing dental amalgam restorations?
Answer: Base metal alloy containing nickel and chromium
Base metal alloys create an electrochemical couple with amalgam due to their different electrode potentials, resulting in galvanic corrosion and potential sensitivity.
Water sorption by dental composite resins results in which dimensional change?
Answer: Hygroscopic expansion that partially offsets polymerization shrinkage
Water sorption causes hygroscopic expansion of composite resins, which can partially compensate for the polymerization shrinkage that occurs during initial curing.
A low contact angle (θ approaching 0°) of an adhesive resin on a conditioned tooth surface indicates:
Answer: Good wettability and favorable adhesion potential
A low contact angle indicates good wettability, meaning the adhesive spreads readily over the surface and can penetrate microporosities to form a strong mechanical bond.
According to ADA classification, which type of gold casting alloy has the highest strength and is indicated for long-span fixed partial dentures and removable partial denture frameworks?
Answer: Type IV (extra hard)
Type IV (extra hard) gold alloys have the highest strength and hardness due to the highest proportion of platinum-group metals, making them suitable for thin, high-stress restorations.
The diametral tensile strength test is used to evaluate brittle dental materials because:
Answer: Direct uniaxial tensile testing of brittle specimens is technically problematic and unreliable
Brittle dental materials like porcelain and gypsum are difficult to grip without fracture during direct tensile testing, so compressive loading of a disk specimen (diametral test) induces predictable tensile stress.
Which mechanical property describes a dental material's ability to fully recover its original dimensions after removal of the deforming force?
Answer: Elasticity
Elasticity is the property by which a material returns completely to its original size and shape after the deforming stress is removed, with no permanent deformation.