Dental Materials Quiz

Study Notes

Used for indirect pulp capping, when a cavity preparation leaves little dentin covering the pulp
Used for direct pulp capping when a micro pulp exposure is suspected
Supplied in paste-paste system
One paste contains calcium hydroxide in distilled water
Second paste contains salicylate (weak acid similar to eugenol), titanium oxide
Paste 1 contains calcium hydroxide, zinc oxide, zinc stearate and ethyl toluene sulphonamide
Paste 2 contains glycol salicylate, titanium dioxide, calcium sulfate, and calcium tungstate

Applied to surface of new metallic restorations to reduce galvanic action
Composed of natural gum (copal, rosin or synthetic resin) and organic solvent (acetone, chloroform or ether)
Varnish protects underlying tooth structure by acting as a film after solvents evaporate
Two applications are required

Materials designed to be used as dental restorations, to restore tooth structure loss
Thin residual layer of dentin puts the pulp at risk for thermal shock when tooth is exposed to hot/cold food
Thermal injury to the pulp may occur due to heat from filling material liberated during setting, or a base that sets by an exothermic reaction

Phosphoric acid in silicate materials and acrylic monomers present in some resin-based restorative materials can act as a barrier
The cements themselves can contain irritants
Cements are designed to create an adhesive bond at the tooth/restoration interface, to eliminate or reduce leakage at the margins

Insulating cement helps prevent galvanic shock but is not an ideal electrical insulator
Varnish consisting of less polar resins (polysterene) can be used to provide electrical barrier

The setting reaction of Zinc Phosphate Cement is: Zinc Oxide + Phosphoric Acid → Zinc Phosphate + Heat
The setting reaction of Silicophosphate Cement is: Silica + Phosphoric Acid → Silicophosphate + Heat
Copper Cement contains copper and inhibits bacterial growth

Zinc Oxide Eugenol has obtundent properties, useful for sedative and temporary fillings
Zinc Oxide Eugenol has bactericidal properties
Zinc Oxide Eugenol is not suitable for luting, due to the presence of free eugenol - causes discoloration and softening of composite surfaces
Ortho-ethoxybenzoic Acid (EBA) Cements are stronger and less soluble than Zinc Oxide Eugenol
Calcium Hydroxide Cements are commonly used as liners and bases, and have biocompatible properties

Polycarboxylate Cements provide minimal irritation to the pulp
Glass Ionomer/ Polyalkenoate Cement has a pH of 1.7, bonds chemically with stainless steel

Used as sedative and temporary fillings, due to its obtundent property
Can withstand amalgam condensation forces
Setting Reaction for Zinc Oxide Eugenol is: H2O + Zinc Oxide + Eugenol → Zinc Eugenolate
Unreinforced ZOE used when strength and solubility are not critical; for temporary restorations; has compressive strength of 20 MPa
Reinforced ZOE used for temporary and intermediate bases; contains additives like alumina, rosin and polymethyl methacrylate resin; compressive strength of 40 MPa
ZOE is not suitable for luting due to free eugenol being replaced by water, which causes hydrolysis of zinc eugenolate and disintegration of cement structure.