cavity bases and liners Flashcards
(35 cards)
what are intermediate restorative materisals
materials applied to dentine to protect the pulp prior to placing the main restorative material
types of itermediate restorative materials
varnish
cavity liner
cavity base
varnihs
thin polymer seal to the dentine surface
cavity liner
layer of protective dentine sealer less than 0.5mm thick
cavity bas
dentine replacement intend to eliminate undercuts or minimise bulk of main restorative materail
thicker than 0.5mm
clinical need of IRMs
dental pulp chamber sensitive
may need additional protection for the pulp when placing direct restorative material
prevents heat or chemical diffusion to pilp
what might adversely affect the pulp
physical stimuli e.g. temp or mechanical forces
chemical stimuli e.g. acids
which may relate to
caries, microbial ingress or contamination
n
n
an ideal cavity base or liner properties
1) safe and biocompatible
2) form effective dentine seal against chemicals, bacteria and other stimuli
3) may encourage dentine generation in pulp chamber (reparative dentine, 2 or 3)
4) chemically and mechanically compatible with other restorative materials
5) tooth coloured, radiopaque and easy to place
dental materials used as IRMs
1) Varnishes (polymer solution in solvent)
2) calcium hydroxide cemenets (dycal)*
3) MTA (biotentine)*
4) Zinc oxide cements commonly zinc oxide-eugenol or ZOE
5) Glass ionomer cements
6) Resin modified glass ionomer cements
7) visible light cured resins
* used where pulp exposed
cavity varnishes material and how it works
natural or synthetic polymer resins dissolved in solvent and applied to cavity floor with brush of cotton
solvent evaporates to leave a thin layer of resin
acts as a barrier against chemical penetration of tooth tissue and may protect against micro leakage and secondary caries
calcium hydroxide cements
rigid self setting material
presented as two pastes for mixing
two paste material used in calcium hydroxide cements
1) calcium hydroxide, zinc oxide
2) salicylate ester, titanium oxide, calcium sulphate
chemical reaction forms zinc and calcium dislylate and other compounds
properties of calcium hydroxide
- Alkaline nature due to free Ca(OH)2 may promote tertiary dentine formation (due to slight irritation) and provide antibacterial properties (may help heal cavity)
- low compressive strength but sufficient to withstand condensation of amalgam
- initial pH greater than 11, alkalinity associated with local tissue irritation that later mineralise (reparative dentine once dentine like in appearance)
- may be used as a protective base or liner under primary restorative, acts primarily as a pulp camp
- slowly soluble in water
what is the leading brand of CaOH cement in Uk
dycal
radiopaque and ivory colour
how is zinc oxide eugenol formed
acid base reaction between a metal oxide and eugenol (forms metal eugenolate chelate)
what zinc oxide eugenol used for most commonly
tempoarary restoration
can be used for base/liner
why is zinc oxide eugenol unpopular
due to risk of pulpal necrosis and inhibition of composite rein polymerisation( stops setting reaction)
why should zinc oxide eugenol not be used with compostie
due to inhibition of composite resin polymerisation
what is IRM
zinc oxide eugenol material
what is IRM designed fro
to remain in place for 12 montths
uses underneath a non resin restoraion
glass ionomer cements properties
- Relatively robust (compressive strength >50 Mpa)
- adhesive
- insoluble
- insulating
- fluoride releasing
- aesthetic (can be used as a direct restorative material)
what is glass ionomer cements composed of
basic fluoaluminsilicate glass
polymermic acid
water
tartaric acid
how is GIC formed
mixing via acid base reaction
- metal cations form salt bridges with ionised carboxylate acid groups on high molecular weight polyacids
