Dental Materials Quiz

The roughness of the finished surface is proportional to the size of abrasive particles.

The efficiency of smaller particle abrasives increases with force.

Greater force leads to more rapid removal of material and deep cuts into the surface.

<p>Lubrication has a cooling effect, carries away heat and debris, and may obscure the cutting surface.</p> Signup and view all the answers

<p>Compressive Strength, Flexural Strength, Fatigue Strength, Fracture Toughness</p> Signup and view all the answers

<p>It is important to avoid areas of stress concentration, surface defects, and notches to prevent fatigue failure. Dental materials are subjected to many moderate stresses during mastication cycles.</p> Signup and view all the answers

<p>Toughness refers to the ability of a material to absorb energy and delay fracture, while fracture toughness refers to the ability of a material with cracks to resist fracture by absorbing energy.</p> Signup and view all the answers

<p>Creep is the time-dependent deformation of an object subjected to a constant stress. Most materials undergo creep at temperatures close to their melting point, but ceramics and most metals do not undergo creep.</p> Signup and view all the answers

<p>The limit of applied force a material can withstand</p> Signup and view all the answers

<p>Maximum load in tension (or compression)</p> Signup and view all the answers

<p>The stress at which a brittle material fractures</p> Signup and view all the answers

<p>Between Yield Strength (B) and Ultimate Strength (C)</p> Signup and view all the answers

<p>Reduction in cross-sectional area, material can no longer withstand the maximum stress, strain increases, leads to fracture</p> Signup and view all the answers

<p>A measure of the rigidity of a material, defined by the ratio of stress to strain (below elastic limit)</p> Signup and view all the answers

<p>The various terms used to measure the physical and mechanical properties of dental materials are: elastic modulus, proportional limit, elastic limit, yield stress, ultimate strength, fracture strength, ductility, resilience, and toughness.</p> Signup and view all the answers

<p>Stress is the force applied to a material per unit area, while strain is the resulting deformation or change in shape of the material.</p> Signup and view all the answers

<p>The physical and mechanical properties of materials in dentistry are important for determining their suitability for specific dental applications, such as dental restorations. These properties can affect the durability, strength, and overall performance of the restorations in the oral cavity.</p> Signup and view all the answers

<p>Some of the mechanical properties of dental materials include: elastic modulus, ductility, resilience, toughness, yield strength, ultimate strength, and fracture strength.</p> Signup and view all the answers

<p>Abrasion refers to the wearing away of a surface by rubbing, cutting, or scraping. Finishing involves contouring to remove excess material and produce a smooth surface, while polishing is the final removal of material to create a smooth, highly reflective surface without scratches.</p> Signup and view all the answers

<p>Polishing tooth structures and restorations helps to improve aesthetics, minimize trauma to hard and soft tissues, improve tissue health, and increase the longevity of the restorative material.</p> Signup and view all the answers

<p>The hardness of the abrasive particles must be greater than the surface being abraded. The shape of the abrasive particles also plays a role, as objects with sharp edges have enhanced cutting efficiency. However, repeated use can dull the instrument and cause debris clogging.</p> Signup and view all the answers

<p>Some types of abrasives used in dentistry include diamonds, carbide, emery, aluminum oxide, cuttle, tin oxide, garnet, and pumice.</p> Signup and view all the answers

<p>Force is defined as one body interacting with another, generating force applied through contact of bodies or at a distance. It has three defining characteristics: point of application, magnitude (lbs, kg, N), and line of action.</p> Signup and view all the answers

<p>The range of occlusal forces in the posterior region at the mandibular hinge axis is 400-800 N for 1st and 2nd molars, 300 N for premolars, 200 N for canines, and 150 N for incisors.</p> Signup and view all the answers

<p>Facial form and muscle definition are good predictors of occlusal force. High mandibular angle is associated with lower occlusal force, while lower mandibular angle is associated with higher occlusal force.</p> Signup and view all the answers

<p>Stress (S or σ) is the force per unit cross-sectional area acting on a material. It is calculated as Stress = F/A, where F is the applied force and A is the cross-sectional area. The SI unit for stress is Pascal (Pa), which is equivalent to N/m².</p> Signup and view all the answers

<p>The properties of dental glass ionomer cements as permanent filling materials include compressive strength, tensile strength, corrosion resistance, and resistance to creep.</p> Signup and view all the answers

<p>The occlusal composite resin restoration showed signs of secondary caries because the frequent exposure to hot homemade soup and beverages with ice caused thermal cycling and microleakage, leading to the breakdown of the restoration and the development of caries.</p> Signup and view all the answers

<p>Zirconia crowns would be better suited for a patient with bruxism and a heavy bite based on just hardness. Zirconia is known for its high hardness and resistance to wear, making it more suitable for patients with heavy biting forces and a history of bruxism.</p> Signup and view all the answers

<p>The shape of the indenter used for a Vickers hardness test is a diamond square pyramid.</p> Signup and view all the answers

<p>Resilience</p> Signup and view all the answers

<p>Elastic modulus</p> Signup and view all the answers

<p>Yield strength</p> Signup and view all the answers

<p>Fracture strength</p> Signup and view all the answers

<p>Compressive strength</p> Signup and view all the answers

<p>Corrosion</p> Signup and view all the answers

<p>Zirconia crowns</p> Signup and view all the answers

<p>Diamond square pyramid</p> Signup and view all the answers

<p>Elastic region</p> Signup and view all the answers

<p>Proportional limit</p> Signup and view all the answers

<p>Stress</p> Signup and view all the answers

<p>Strain</p> Signup and view all the answers

<p>Higher speed during finishing</p> Signup and view all the answers

<p>Micrometers (µm)</p> Signup and view all the answers

<p>Reducing corrosion of metal restorations</p> Signup and view all the answers

<p>Silicas</p> Signup and view all the answers

<p>The energy required to resist the propagation of an existing crack or flaw</p> Signup and view all the answers

<p>Creep</p> Signup and view all the answers

<p>Ceramics</p> Signup and view all the answers

<p>The stress at which a material fails under repeated loading</p> Signup and view all the answers

<p>Garnet</p> Signup and view all the answers

<p>To remove excess material and produce a smooth surface</p> Signup and view all the answers

<p>Pumice</p> Signup and view all the answers

<p>Finishing involves contouring and removing excess material, while polishing involves the final removal of material to achieve a smooth and reflective surface</p> Signup and view all the answers

<p>Ultimate Strength</p> Signup and view all the answers

<p>Elastic Modulus</p> Signup and view all the answers

<p>Fracture Strength</p> Signup and view all the answers

<p>Yield Strength and Ultimate Strength</p> Signup and view all the answers

<p>All of the above</p> Signup and view all the answers

<p>Stress</p> Signup and view all the answers