Linings and bases Flashcards
what do linings and bases protect the pulp from?
an overlying restorative material
phosphoric acid based cements are composed of a powder containing what?
zinc oxide and other metallic oxides
phosphoric acid based cements are composed of a liquid containing what?
aqueous phosphoric acid
is the setting reaction of phosphoric acid based cements endo or exothermic?
exothermic
how do you delay the set and increase the working time of phosphoric acid cement?
introduce the powder incrementally into the liquid
why is phosphoric acid based cements highly irritating to the pulp?
low pH
low molecular weight so can penetrate deep into tubules
positives of using phosphoric acid based cements 3
thermal and electrical insulator
strength to withstand condensation
radiopaque
silicophosphate cements contain a liquid of aqueous phosphoric acid and buffers. what does the powder contain?
zinc oxide and aluminosilicate glass
advantages of silicophosphate cements 3
great strength
less solubility
leach fluoride
copper cements contain a liquid of aqueous phosphoric acid and buffers. what does the powder contain?
zinc oxide and black copper oxide
zinc oxide eugenol cements are composed of a liquid containing what?
eugenol plus olive oil to control viscosity
zinc oxide eugenol cements are composed of a powder containing what?
zinc oxide
hydrogenated resin/polystyrene for reinforcement
positives of using zinc oxide eugenol cements
obtundant affect - soothing
bactericidal - zinc
thermal and electrical insulator
resin reinforcements can withstand condensation
when should you not use zinc oxide eugenol cements?
not compatible with resin composites
what are the two types of calcium hydroxide cement?
chemical activated
VLC - visible light cured activated
chemical activated calcium hydroxide cement consists of a 2 pastes containing what?
paste 1: glycol salicylate
paste 2: zinc oxide with calcium hydroxide
what is the setting reaction for calcium hydroxide cements?
VLC activated polymerisation of methacrylate monomer
monomer mixed with hydroxyethylmethacrylate
what increases the rate of set of calcium hydroxide cements?
moisture
visible light cured materials are endo or exothermic?
exothermic
positives of using calcium hydroxide cements
high pH so beneficial irritancy and bactericidal
thermal and electrical insulators
good restorative material compatibility
negatives of using calcium hydroxide cements
insufficient strength to withstand amalgam condensation/packing
not adhesive so no coronal seal
polycarboxylates consist of a powder and liquid containing what?
powder - zinc oxide (or freeze dried)
liquid - aqueous solution of polyacrylic acid
polycarboxylates have a strong bond to ?, weak bond to ? and non existant bond to ?
gold
stainless steel
porcelain
polycarboxylates are mildly irritant. why?
acidic but have a high molecular weight reducing penetration
positives of polycarboxylates
fluoride renders them bacteriostatic
thermal and electrical insulator
strength for amalgam condensation
good restorative material combatibility
adhesive to coronal seal
what does RMGIC stand for?
resin modified glass ionomer cement
positives of glass ionomers
bacteriostatic due to fluoride release
thermal and electrical insulator
strength to withstand restoration placement
adhesive
good restorative materials compatibility
what is composite bulk fill
flowable composite with delayed/reduced shrinkage
allows you to fill cavity in 4mm increments rather than 2mm like standard composite
what does bulk dentine replacement biodentine consist of?
tricalcium silicate
calcium carbonate
zirconium oxide
water
super plasticising agent
what does biodentine claim to do?
foster formation of reparative dentine
