DENTAL MATERIALS Flashcards
What are 2 examples of materials with micromechanical adhesion?
- composite
- compomer
What are the 3 main methods of adhesion?
- micromechanical adhesion: acid etch technique of resins to enamel
- chemical adhesion: to either enamel or dentine using coupling agents/cements
- adhesion through wetting, penetration and formation of a hybrid, layer of a material at the interface between between the restorative and the substrate - modern dentine bonding agent
What are 2 examples of materials with chemical adhesion?
- GI
- amalgam
How long does GI take for almost near completion of set and how long for final set?
24 hours for near completion
3 months for final setting
Application of a barrier for how long will protect the GI?
(vaseline, fissure sealant or GI varnish)
1 hour
What are the effects of dehydration and excess moisture on GI?
dehydration will cause it to crack
excess moisture may make the GI swell
What are 5 advantages of GI?
- fluoride releasing
- good marginal seal
- adhesive in its own right
- bonds to moist tooth
- thermal expansion is similar to that of a tooth
What are 3 disadvantages of GI?
- easy to dissolve away (although some ability to dissolve is necessary in order to release fluoride) not ideal in acidic mouths
- matte and dull in appearance, the particles are relatively large and therefore scatter light, low wear resistance
- low fracture and flexural strength
What are 8 advantages of amalgam?
- good compressive strength
- good wear resistance
- kind to opposing teeth
- easy to use
- antibacterial
- chemical setting
- cheap
- radiopaque
What are 4 disadvantages of amalgam?
- none adhesive
- weak in thin sections
- thermal conductor
- not tooth coloured
Which base lining is the following?
- soluble in water
- not strong: low compressive strength
- not adhesive
- pH 11-12
- bacteriostatic
- promotes tertiary reactionary dentine
uses:
- place in deepest part of the cavity only
- dont place all over dentine surface
- thin layer of 0.5mm
calcium hydroxide
Which base lining is the following?
- obundant (sedative) effect - neutral pH
- not to be used under resin bases restorations
- not very strong compared to other base cements
- non adhesive
zinc oxide and eugenol cements
Which base lining is the following?
- low set solubility
- higher fracture toughness
- fluoride release
- strongest of all materials used for bases
uses:
- lining (not near pulp)
- base
- temp dressing
resin modified GI (fuji) (vitrebond)
Which base lining is the following?
- chemical bond to tooth tissue
- high early solubility
- anti caries
- releases fluoride
- acts as fluoride reservoir
- low solubility
traditional GI cement
What are 8 properties of the ideal base/liner?
- perfect insulator of pulp
- infinite compressive strength
- perfect biocompatability
- cheap
- adheres to tooth: perfect seal
- expands and contracts in harmony with tooth
- does not degrade or corrode in the oral environment
- not technique sensitive
