L1 Introduction to dental materials Flashcards
physical and chemical properties of materials generally depend on?
energetic interaction between valance electrons
what is a primary bond ?
chemical bond that occurs due to sharing of electrons (ionic , covalent , and metallic)
what is a secondary bond ?
bond with no sharing of electrons , instead it is reliant on dipole forces (van der waals forces and hydrogen bonds0
what is a crystal ?
regularly spaced configuration with long repetitive space lattice
what is the simplest shape of a lattice ?
cube
describe the melting point of non-crystalline structures .
doesn’t have a definite melting point , instead it gradually softens as temperatures rise
noncrystalline formation is also known as ?
amorphous structure ( dental waxes)
is glass a crystalline structure ?
no because its atoms tend to be arranged in non-repeating units
what is glass-transition temperature ?
temperature at which there is an abrupt increase in molecular mobility in none crystalline materials.
what is the difference between direct and indirect restorative dental materials ?
direct restorative materials are used to directly fill up cavities while indirect materials are fabricated in a dental lab first
what is the difference between direct and indirect restorative dental materials ?
direct restorative materials are used to directly fill up cavities while indirect materials are fabricated in a dental lab first
why do metals have a limited role in dentistry ?
because they are too soft to resist deformation from external forces
what are eutectic alloys ?
alloys that have a lower melting point than any of it components
describe the physical properties of ceramics .
brittle , considered non-metallic with inorganic structure
describe the physical properties of polymers .
composed of very high molecular weight molecules with repeating units called macromolecules
