dental material science Flashcards
what determines the type of restorative material to be used?
shape of cavity
what holds an amalgam filling in place?
shape of cavity
what holds an composite filling in place?
bonding agent
what is amalgam creep?
deformation of amalgam due to constant stress
what technique is used to bond composite to the tooth?
acid etch technique
how is acid-etching carried out?
- 30% phosphoric acid is applied to tooth for 20 secs, this creates grooved surface
- after 20 secs etch is rinsed away
- bonding agent is then applied to tooth, this seeps into the grooves
- bonding agent is then cured using light, locking it onto the surface of the tooth
- composite can then be built up on the tooth
what does composite renin consist of?
mostly resin with small amounts of glass filler particles (composite)
what is the function of the glass filler particles (composite) in composite resin?
give flexibility
(resin-modified) glass ionomer cement is a type of composite, what are the benefits of this?
contains fluoride which increases enamel resistance to caries
what causes enamel and dentin to contract?
cold stimuli
contraction of the restorative material may cause what?
microleakage as saliva and bacteria can ingress the tooth
what is the benefit of low viscosity impression material?
provides the most accurate record of tooth surface detail
what is the benefit of high viscosity impression material?
most dimensionally stable after setting and removing
how is low viscosity impression material applied?
placed around the individuals teeth then tray is inserted
how is high viscosity impression material applied?
placed in tray, tray inserted and patient bites
