Cavity lining materials Flashcards
cavity base
thick layer used to minimise amount of restorative needed and amount of undercut required - often used when restorative is a metal
what is and what is the purpose of a cavity lining
thin layer at the base of a cavity, offers pulpal protection from
- thermal stimuli - e.g exothermic setting reactions, heat conduction
- microleakage
- chemical stimuli - common in composites for some unreacted chemicals to be present
thermal conductivity
how well heat is transferred through a material - ideally restoratives should be as low as possible whereas denture bases should be high
thermal expansion coefficient
change in length per unit length for a temperature rise of 1 degrees , restoratives and liners should ideally match the coefficient of tooth surfaces
thermal diffusivity
similar to conductivity , measured in cm^2 / sec, restoratives should be low
cariostatic
inhibits formation of dental caries
what is setting calcium hydroxide used for
cavity linings
what are zinc oxide based cements used for
cavity bases
name a popular modern cavity liner
(RM)GIC’s
pros and cons of setting calcium hydroxide
easy to use, good setting time, alkaline pH that may kill caries bacteria, radiopaque
low compressive strength, soluble, unstable, cement can cause necrosis of pulp ondontoblast layer
what type of zinc oxide based cements are still used today and name the 3 types
ZOE
zinc oxide eugenol
ZOE cement
resin modified ZOE cement
ethoxybenzoic acid cement (EBA - EBA replaces some eugenol)
resin modified and EBA are less soluble and stronger than original ZOE cement
why cant ZOE products be used under composite
eugenol inhibits composite resin setting and may cause discolouration
