5 Written questions
5 Matching questions
- The ability of a material to sustain considerable permanent deformation without rupture under <b>compression</b>, as in hammering or rolling into a sheet, is termed ____________.
- Materials with a high elastic modulus have:
a. high strength values.
b. low strength values.
- A value of 0.3 for Poisson's ratio is typical. Thus, the shear modulus is usually about ___% of the elastic modulus.
- A low elastic modulus and a low tensile strength suggest ___________ resistance.
a. low impact
b. high impact
- Three types of stress in dentistry:
- a mealibility
- b 1. tensile stress
2. shear stress
3. compressive stress
- c 38%
- d they could have either. they are independent of each other.
- e a. low impact
5 Multiple choice questions
• The <b>stress</b> at which a test specimen exhibits a specific amount of plastic strain (0.2%)
• The YS at 0.2% strain offset from the origin is 1536 MPa in this case.
- Ultimate strength
a test for tensile strength that is only used for materials that exhibit predominantly elastic deformation and little or no plastic deformation (brittle).
- of enamel rod orientation.
- b. tensile
5 True/False questions
Change in length per unit initial length.
Units are in %
Units of Modulus of elasticity → Giganewtons per square meter (GN/m²), or gigapascals (<b>GPa</b>)
(T/F) Stiffness of a dental prosthesis can increase by increasing its thickness. → Toughness increases with increases in strength and ductility.
From mechanical property point of view, why isn't it a good idea to burnish amalgam, composites, ceramics and nonresin luting agents? → Stress and/or strain
Tensile strength for:
a. Dental porcelain
c. Resin-based composite
e. Alumnia ceramic → a. Dental porcelain → 50-100 MPa
b. Amalgam → 27-55 MPa
c. Resin-based composite → 30-90 MPa
d. Poly → 60 MPa
e. Alumnia ceramic → 120 MPa