Test on Resin-Bonded Fixed Partial Dentures
Dental Ceramics: History, Strength & Types for Students
Test: Dental ceramics
20 questions
Question 1: The mechanical properties of zirconia ceramics are improved by increasing the yttrium oxide stabilizer content beyond 3 mol% due to enhanced stress-induced transformation in the retained cubic phase.
A. Ano
B. Ne
Explanation: Higher amounts of yttrium oxide stabilizer lead to the retention of the cubic phase at room temperature. The cubic phase is fully stabilized and does not exhibit a stress-induced transformation, meaning its mechanical properties are not as high as those of 3Y-TZP.
Question 2: The evolution of CAD-CAM systems for machined restorations primarily led to the development of ceramics requiring only a single, uniform sintering stage for all types of restorations.
A. Ano
B. Ne
Explanation: The study materials indicate that the evolution of CAD-CAM systems led to the development of new machinable ceramics in two stages: a fully sintered stage for hard machining and a presintered green stage for easier, soft machining. This contradicts the idea of a single, uniform sintering stage for all types of restorations.
Question 3: Is the microstructure of heat-pressed lithium disilicate ceramics composed of randomly oriented interlocked crystals forming a "house of cards" microstructure?
A. Ano
B. Ne
Explanation: The study materials state that the microstructure of lithium disilicate, a heat-pressed ceramic, consists of randomly oriented interlocked crystals in a "house of cards" microstructure.
Question 4: The strengthening of partially stabilized tetragonal zirconia is achieved through a martensitic stress-induced transformation.
A. Ano
B. Ne
Explanation: The study materials state that strengthening in highly crystalline ceramic materials like partially stabilized tetragonal zirconia is obtained through a martensitic stress-induced transformation.
Question 5: Brittle dental ceramics are susceptible to fracture, but they typically contain only one primary type of flaw from which fracture can initiate.
A. Ano
B. Ne
Explanation: Brittle materials such as ceramics always contain at least two types of flaws from which fracture can initiate: fabrication defects and surface cracks.