L6: Dental Cements Flashcards
how are dental cements usually formed ?
mixing powdered metallic oxide or glass with a liquid
what are the types of cements ?
type 1 luting cement: used in temporary and permanent fillings
type 2 restorative cements : used in temporary and permanent fillings
type 3 :liner and base application
what are luting cements used for ?
sealing space between 2 substance
what film thickness should luting cements have ?
less then 25um
what do type 3 cements ( base and liner ) do?
provide thermal and galvanic insulation . they contain ceramic powdered which allows them to have lower thermal and electrical conductivity then metals
what type of cement is zinc phosphate and what reaction does it involve?
type 1 luting cement (25um)
or type 2 restorative cement if thickness is 25-40um
acid-base reaction that is exothermic
what technique is used to combat rise in temperature ( exothermic reaction) when mixing zinc phosphate ?
incremental mixing
controlling the ratio of liquid to powder also affects the temperature
low viscosity cements are known as?
luting agents
what powder is the key powder?
zinc oxide
what mechanism is responsible for mechanical retention of zinc phosphate ?
interlocking
how does zinc polycarboxylate bind to tooth?
chemical bonding
What mineral leeches from zinc polycarboxylate ?
fluoride which acts as an anti-caries agent
which type of cement is zinc polycarboxylate ?
type 1 luting cement , base , and temporary restorative cement
what is the only cement does that not involve an acid-base reaction? ( oil-based)
zinc oxide eugenol (chemically neutral) (other cements are acidic)
which cement has a obtundent effect ?
zinc oxide eugenol
what is the most commonly used temporary cement?
zinc oxide eugenol , it is also used as temporary luting cement , and to seal exposed dental tubules, as well as a lining cement but not with resin based composite
what cement is often used alongside amalgam ?
zinc phosphate
zinc oxide eugenol does not form a chemical bond
:D
why to zinc oxide eugenol cements usually disintegrate?
free eugenol from the cement leaches out and is replaced by water
why cant zinc oxide euganol be used with resin composites ?
because it interferes with the polymerization process
what is calcium hydroxide used for “?
pulp capping ( as protective barrier beneath amalgam and resin composites)
provides alkaline environment
baase-liner
DYCAL is an example of which dental cement ?
calcium hydroxide
what form does calcium hydroxide come in ?
paste
setting reaction of calcium hydroxide and glycol-salicylate results in formation of ____
calcium-disalicylate
why does calcium hydroxide have anti-bacterial effects ?
because it provides an alkaline environment
how is calcium hydroxide applied ?
in thin sections not exceeding 0.5mm
calcium hydroxise is applied in deep cavities near pulp with potential formation of secondary dentine
they do not provide thermal insulation and are weakened by moisture
:D
non-setting calcium hydroxide is widely used in____
pulp therapies
what is cavity varnish used for ?
protect glass ionomer filling
prevention of corrosion of amalgam
it is insoluable in oral fluid which reduces microleakage between restoration margins and walls of tooth cavity
what is pulp capping ?>
A procedure to treat pulp that has been exposed
through caries removal or trauma, by the application of a medicament;
