Cavity Lining Materials Flashcards
lining materials are
a protective barrier, prevents gaps between tooth and filling
cavity base
thick mix, used to minimise bulk of material or block out undercuts [metal restorations]
cavity lining
placed voer dentine, protects and promotes pulpal health
cavity LM provide pulpal protection from
chemical stimulin
thermal stimuli
bacteria and endotoxins [microleakage]
CLM have therapeutic and palliative effects;
calms down inflammaiton and promotes pulpal healing
reduces px symptoms
properties of CLM
ease of use, thermal conductivity low, thermal expansion coefficient matching tooth, thermal diffusity matching tooth, high compressive strength, radiopaque, cariostatic
thermal expansion coefficient
change in length per unit length for a temperature rise of 1*C
types of material used as CLM
calcium hydroxide [liner]
zinc oxide cements [base]
GIC/RMGIC [liner]
CaOH liner
CaOH, zinc oxide filler, plasticiser
butylene glycol disalicyte catalyst
pH12 in reaction
CaOH MOA
irritates odontoblast layer, forms reparative dentine, calcium from pulp helps form a bridge in pulp/dentine, high alkaline content in bactericidal
used when cavity approaches pulp, covered with RMGIC
CaOH properties
quick setting time, radiopaque, easy to use
BUT
low compressive strength, unstable, soluble
ZnO as cavity base
zinc oxide eugenol (ZOE), root canal sealer, PD dressings
not used under composite resin, will not set
ZnO properties
adequate working time, rapid setting, low thermal conductivity
bUT
low strength 20MPa, weak hydrogen bond, high solubility
resin modified ZOE
adds resin to mixture, reduces solubility, increases compressiver strength to >40MPa, making suitable liner
GIC as lining material
only liner able to bond to restorative materials, bond and seal dentine, bond to composite over