properties of dental materials Flashcards
what are the classifications of dental materials?
- metals & alloys
- polymers and elastomers
- ceramics
crystalline materials – metals & alloys, plus ceramics
semicrystalline = polymers and elastomers
no crystalline structure = classes&cements, waxes & organic materials
what are the four fundamental forces?
- gravity
- weak forces
- electromagnetism
- strong forces
what are fermions?
particles that join together and make up all matter; have mass, charge, spin, and obey the pauli exclusion preinciple
what are boson?
force carrier particles–
what info can you get fro mthe elastic and plastic domain on a stress-strain diagram?
elastic: stiffness or flexibility; resislience (young’s modulus – curve, rise/run)
plastic = brittleness and ductibility; toughnessq
define flexural strength
material’s ability to bend before it breaks; takes in together the tensile, compressive, and shear stresses together
how to test flexural strength
three point bending test– get a beem of material of b in width, d in thickness/height, l = distance between supports, with a force of P applied;
flexural strength = 3pl/2b(d^2)
important for denture base and long-span bridges
how to increase strength and rigidity of a bridge?
–increase the occlusal-gingival dimension
as the crack tip gets smaller in radius, the stress increases to infinity; stress at tip = (L/R)^1/2; l = length of crack, r = radius at crack tip
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in metals, they have plastic flow and ductility = blunt crack tip, never becomes really small, stress is not very big; but ceramics are not ductile and do not have plastic flow = crack tip remains sharp
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porcelain fractures are primarly related to cracking–are porous, and throughout time and cyclic loading, fatigue will develop and cracking will occur lol idk ugh
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