DENTAL CEMENTS DR.LINDA MAHER

DENTAL CEMENTS Are hard, brittle materials formed by mixing powder and liquid together.

USES OF DENTAL CEMENTS: Have much variations of uses 1\PULPAL PROTECTION: When the dentin remaining over the pulp is too thin, dental cement is placed over it to provide protection to the pulp from 1\ bacterial invasion 2\ from chemicals contained in restorative materials. 3\also act as thermal insulators 4\mechanical support to withstand compressive strength

Cements used in pulp protection 1.CAVITY VARNISHES 2.LOW-STRENGTH BASE/LINER Calcium hydroxide cement 3.HIGH STRENGTH BASE/LINER GIC

. 2\LUTING CEMENT: viscous material placed between the tooth and the prosthetic restoration that sets and firmly attaches the prosthesis to the tooth They are 2 types: 1\Permanent cements 2\temporary cements

3\RESTORATIONS: 1\crown and bridge cementation 2\orthodontic prackits . Luting cements are used in 1\crown and bridge cementation 2\orthodontic prackits 3\RESTORATIONS: Cements are not frequently used as permanent restorations because(they have low strength- low wear resistant-high solubility) The exception is GIC Can be used as temporary filling material.

PROPERTIES OF DENTAL CEMENTS Strength Strength depends on the amount of powder in the mix.(the more the powder the better the strength) Resin cements are the strongest and zinc oxide eugenol is the weakest. Solubility Dissolves easily in oral fluids Esthetics Cements are available in a variety of shades

TYPES OF DENTAL CEMENTS 1\Zinc oxide eugenol cement 2\Zinc phosphate cement 3\Zinc Polycarboxlyate cement 4\Glass ionomer cement 5\Resin cement

Zinc oxide eugenol cement . Zinc oxide eugenol cement

COMPOSITIONS: Powder: zinc oxide Liquid: eugenol

PROPERTIES 1\Not very strong. More suitable as temporary cementation. 2\ can be irritant if directly contacted the pulp or oral mucosa 3\Sedative to the pulp because it has antibacterial effect 4\can not be used under composite or any resin material (because eugenol will interfere with the polymerization process of resin)

ADVANTAGES: DISADVANTAGES: Easy to use. Sedative to the pulp Low strength. High solubility. Can not be used under composite.

MANIPULATION Equal amounts of liquid and powder in a glass slab. Move liquid to the powder until desired consistency is achieved. Difficult to clean.

. Zinc phosphate cement

COMPOSITIONS: Powder: zinc oxide. Liquid: phosphoric acid and water.

PROPERTIES 1\Acidic PH=4.2 2\Irritates the pulp, so it is not recommended in teeth with vital pulp. 3\Adequate strength and rigidity.

ADVANTAGES: DISADVANTAGES: Low film thickness Not expensive Strong . ADVANTAGES: Low film thickness Not expensive Strong DISADVANTAGES: Initially Irritates the pulp. High solubility.

MANIPULATION A cooled glass slab is used( to increase the working time). Powder is added slowly to the liquid in small increments Each increment is mixed for 10-15 seconds. Proper consistency is achieved when the mix strings 1 inch above the slab. Difficult to clean.

Zinc polycarboxylate cement . Zinc polycarboxylate cement

COMPOSITIONS: Powder: zinc oxide Liquid: polyacrylic acid.

PROPERTIES 2\Working time can be increased by cooling the glass slab. 1\Viscosity is higher than most other cements 2\Working time can be increased by cooling the glass slab.

ADVNTAGES DISADVANTAGES: . ADVNTAGES 1\Good adhesion to the tooth structure (chemical and mechanical bond) 2\Nonirritating to the pulp. 3\Easy to use DISADVANTAGES: 1\High solubility. 2\Lower strength. 3\Short working time.

MANIPULATION Mix in a glass slab or non absorbent paper pad Mix for 30-60 seconds until the mix is creamy. Use immediately

. REZIN CEMENTS

. BASICALLY ARE modified composite resins with lower viscosity used as adhesive materials. IT CAN BE : 1\light cured 2\dual cured 3\self cured

. 1\Light cured Used for: non metallic restorations and thin porcelain veneers. 2\Dual cured(light activated and chemically activated) Used for: Porcelain or indirect inlays, onlays, crowns and bridges. 3\Self cured( chemically activated) Used for: metal crowns and bridges; porcelain inlays, onlays, crowns and bridges.

ADVANTAGES High strength Insoluble in water Esthetic Excellent adherence to tooth structure

DISADVANTAGES Requires additional steps. Difficult to remove excess cement after it sets.

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