cavity bases Flashcards
What is a varnish?
A very thin polymer seal to the dentine surface
What is a cavity liner?
A layer of protective dentine sealer less than 0.5mm
What is a cavity base?
A dentine replacement intended to eliminate undercuts/minimise the bulk of the main restoration
What is an IRM?
Intermediate restorative material
Applied to dentine to protect pulp
What is a caveat?
A warning or proviso of specific stipulations, conditions or limitations
What is the clinical need?
Pulp- sensitive may be adversely affected by chemical/physical stimuli +/ microbial invasion
May need additional protection when placing a restoration (insulation, impermeable to noxious substances etc)
What is an ideal cavity base/liner?
Safe and biocompatible
Effective dentine seal against bacteria/stimuli
Some reparative function (dentine regeneration)
Compatible w other materials
Tooth coloured, radiopaque and easy to place
What dental materials are used as IRMS?
Varnishes (polymer solution in solvent)
CaOH cements (dycal) or MTA (Mineral trioxide aggregate, inc bio dentine) when pulp is exposed
Zinc oxide cements (ZnO/Eu, not popular)
GICs/RMGICs (resin modified)
Visible light cured resins (unfilled resins
What is a cavity varnish?
Natural/synthesis polymer dissolved in solvent
Applied to cavity floor w brush or cotton
Solvent evaporates to leave thin layer of resin, can be repeated
Acts as barrier against chem penetration and may protect against micro leakage and recurrent caries
What is a CaOH cement?
Rigid self setting material
2 pastes to mix-
1. CaOH, ZnO and others
2. Salicylate ester, titanium dioxide and calcium sulphate
Chelation reaction- forms zinc and calcium disalicylate and others
Alkaline (pH>11) due to free Ca(OH)2 which might promote tertiary dentine due to tissue irritation and has antibacterial properties
Low compressive strength (20MPa) but can withstand condensation of amalgam
Pulp cap- can be used as base or liner under restoration
Slowly soluble in water
What is Dycal?
Leading brand of CaOH Mixing time 10s Working time 2min 20s Setting time 2.5-3.5 mins Radiopaque and Ivory colour
May studies say stimulates tertiary dentine but not all studies agree- increasingly questioned
Direct antimicrobial activity unlikely (if true probably offers no clinical benefit)
What is a Zinc Oxide Euganol cement?
Wide variety of compositions
Acid-base reaction
To form metal Eugenolate chelate
Commonly used as temp
Some used as base/liner
Increasingly unpopular due to risk of pulp necrosis and inhibition of composite resin polymerisation
IRM is a name of the material
Ivory colour
Compressive strength 20MPa
What is a glass ionomer cement?
Compressive strength >50MPa Adhesive + good marginal seal Insoluble Insulating Fluoride releasing Aesthetic (also direct restorative)
Composed of basic fluoroaluminosilicate glass, a polymeric acid, water and tartaric acid
Acid-base reaction (metal cations form salt bridges w ionised carboxylic acid groups on high molecular weight polyacids)
What are resin modified GICs?
GIC w addition of water miscible monomer (HEMA) and photoinitiator
Acid-base reaction + polymerisation
Shares GIC chem bond to untreated dentine (less effective?)
Eg. Vitrebond
What is MTA?
MTA- Portland cement w bismuth oxide-
considered for pulp capping, claims to stimulate reparative dentine w good preservation of pulp
BUT slow setting (hours) so can’t be used as liner
