intro to dental material science Flashcards
what is the dental procedure
- examination
- diagnosis
- treatment plan (which material is suitable, how to use material, explain options to patient, select material)
what is the effect of dental materials
- selection = adequate, best type
- preparation = cavity design, tooth surface
- placement = technique, increments, curing
- performance = quality of fit, longevity
- patient expectations = aesthetics, durability
what does the dental material need to have to be safe
- a CE mark = an essential requirement, show material is safe
why just you not assume new materials are good
manufactures are constantly making new materials, but art doesn’t mean that they are better
- should read about material before using it
what are different types of restorative materials
- amalgam
- composite
- glass ionomer cements
- compomers
- porcelain
what are different types of impression materials
- impression compound
- impression paste
- hydrocolloids = alginate mainly
- elastomers = polysulphides, polyethers, silicones
what are different types of metals/alloys
- amalgam
- cobalt chromium
- titanium
- gold
- stainless steel
what are challenges in choosing materials
- so many materials to choose form
- constant changes to products and names
- range of brands
what is porcelain used for
veneers
what is composite resin
used for restorations
- can come in cartridge or nozzle
- low to high viscosities available
how do impression materials work
- record dentition in negative replica
- flows into trays at low viscosity
- undergoes setting reaction - becomes firm, stable
- gypsum (dental stone) = gives positive replica
what is PMMA
a denture base material
what are the mechanical properties of the materials
- force applied to material
- stress
- strain
- elastic modulus
what are some mechanical forces materials are subjected to
- biting, chewing, grinding
what may happen to the material from the force applied to it
- stretch/compress = depends on how force is applied
- deform/ change shape = temporarily (during application) or permanently
- fracture = failure
what types of force can be applied to the material
- compressive = squeeze material
- tensile = stretch
- shear = object bonded to another surface and apply force along parallel line of object
what is stress
force acting on an area
what is strain
change in length/original length
what is the stress-strain curve
- most materials have one
- FS = fracture stress
- star = proportional limit (up to here stress and strain are proportional)
- elastic modulus is in mega pascals (its the slope)
what is the elastic modulus
- also called Young/s modulus
- is the rigidity/stiffness of the material
what are the 4 mechanical properties and their opposites
- hard / soft
- strong / weak
- rigid / flexible
- ductile / brittle
what mechanical properties does enamel have
- hard
- strong
- rigid
- brittle
what is the typical biting force
- is a compressive force applied to upper tooth when biting
- typical biting force = 500 to 700N
what type of forces are grinding/chewing
- shear forces
- tooth slides along surface of another
- frictional forces are applied
- shear forces can remove restorations (material needs to adhere to enamel or it will be removed by masticatory forces)