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Cavity varnish

• It is a natural gum (copal resin) or a synthetic resin dissolved in a solvent such as chloroform, alcohol, and acetone. The solvents evaporate leaving the resin behind.
• Applied in thin layers - 2-5 microns
• Varnish should be confined to dentin
• It has been used under amalgam and before cementation of indirect restorations with zinc phosphate cement
• To seal the dentinal tubules, which will reduce the effects of micro leakage.
• It is not thick enough to provide thermal insulation

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Contraindications

• Composite – free monomer layer dissolves the varnish
• Ca (OH) 2 & ZOE – beneficial effects are lost
• Polycarboxylates – interferes with adhesion
• GIC –blocks fluoride production

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Cavity sealers

• A materials provide sealing as well as bonding at the interface between cavity preparation walls and restoration
• Examples include: Adhesive bonding systems, resin luting cements and glass ionomer luting cement.
• The film thickness 20-50 µm

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Cavity liners

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• Minimum thickness -0.2- 1 mm
• To provide barrier against the ingress of bacteria
• To provide Therapeutic effect and applied only to the dentin Cavity walls that are nearer to the pulp.
• Suspension of calcium hydroxide in volatile solvents such as methyl ethyl ketone or ethyl alcohol.

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Other types of liners

• Type III GIC

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• Type IV ZOE

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Cavity bases

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A material of minimal thickness (1 to 2mm) to replace missing dentin used for
Provide thermal protection and mechanical Support for the restoration.
Examples of Cavity Bases:-
Glass ionomer and Resin-modified glass ionomer cement
Zinc phosphate cements
Zinc polycarboxylate cement
Zinc-oxide Eugenol Cement

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Glass Ionomer Cement:

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Advantages

• Anti-cariogenic effect due to fluoride release
• Chemically bonded to tooth structure
• Good physical properties
• Biocompatible to dentin/pulp complex

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Zinc Eugenol Oxide

• They are cements of low strength
• They are the least irritating of all dental
• They have an obtudant effect on exposed dentin

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Classification

• Type I ZOE : For temporary cementation
• Type II ZOE : Permanent cementation
• Type III ZOE : For temporary filling and cement base
• Type IV ZOE : Cavity liners

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Modified ZOE Cements:

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The modified ZOE cements are as follows

• EBA – alumina modified cement
• Polymer reinforced ZOE cement

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MCQ

1. Permanent cement which is mixed on a glass slab

A. Bonding Agents

B. Glass Ionomer

C. Zinc Oxide Eugenol

D. Zinc Phosphate

Answer: D

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To control the setting of zinc phosphate, it should always be mixed on a cool, dry glass slab, and the whole surface area of the slab should be used during the mix to minimise heat production. .