Dental cements are materials of comparatively low strength, but they are used extensively in dentistry when strength is not a prime consideration.
Use of Dental Cements
The Dental cements are generally used as:
• An adhesive luting (cementing) agent for bonding fixed restorations such as crowns, bridges, inlays, and onlays.
• A temporary restoration, often for sedative reasons.
• A permanent restoration in non-stress- bearing areas.
• A pulp-capping material for exposed or nearly exposed pulps.
• A root canal sealer by itself or in conjunc-tion with gutta percha (an organic substance).
• An adhesive for bonding orthodontic brackets and bands.
COMMON VARIETIES OF DENTAL CEMENTS USED IN DENTAL OFFICES
The calcium hydroxide is one of the most biocompatible Dental cements used in the field of Dentistry. Because of this property of calcium hydroxide it is widely used as sedative lining in deeply carious teeth. However, its use is mainly limited to this, because of its poor strength properties.
Use as Cavity Liner and Base
Both aqueous (made with water) and non- aqueous (made with a liquid other than water) suspensions of calcium hydroxide have been shown to promote the creation of secondary dentin. Because of this benefit, calcium hydroxide became the most popular dental cements to be used as a one-step cavity liner and base.
However, its use as a base usually need a reinforcement by a layer of zinc phosphate or some other cement to provide adequate strength to base, because of its poor strength. In recent times, calcium hydroxide generally overlaid with a base of glass ionomer. Calcium hydroxide cements are available as premixed products or as two-component formulas.
In case of premixed calcium hydroxide dental cements, a small amount of material is placed directly into its place of application in the cavity of the tooth, covering the pulpal area and dentinal tubules. The material sets or harden by air- drying with an air syringe.
In case of two-component calcium hydroxide an equal amount of each component (base and catalyst) is mixed quickly (in about 30 seconds) on a small, polycoated mixing pad, with a small, ball-shaped, tipped instrument, using a circular motion. After the material is mixed, the operator applies it over the vital areas of the tooth. The material hardens on its own, with perhaps acceleration of the setting time by use of flow of air. Any excess material is removed with the help of an explorer or excavator.
Use as Endodontic Sealer or Temporary Endodontic Filling Material
Calcium hydroxide cement and zinc oxide eugenol dental cements are very widely used in endodontic (root canal) procedures as a permanent sealer with gutta percha. In addition, it is often used as a temporary bactericidal filling material.
Polycarboxylate dental cements (sometimes called carboxylate cements) were the first generation of permanent dental cements to show true adhesion to tooth structure. They are composed of zinc and magnesium oxides, polyacrylic acid, and copolymers. Most polycarboxylates have a thick, syrupy-like liquid that contains the polyacrylic acid and copolymers.
With excellent bond strengths to stainless steel, polycarboxylates are often used as a luting agent for cementing orthodontic bands. They can also be used as a liner or a base under amalgam or composite restorations.
Due to sensitive to moisture, these dental cements should not be allowed to sit unmixed on the pad but should be mixed immediately after measurement.
Zinc Phosphate Cement
Zinc Oxide Eugenol
Glass ionomer cement