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What Is Dental Cement?
Dental cement is used to connect a fixed prosthesis, such as a crown or bridge, to the underlying tooth structure. It can also be used as a pulp-protecting agent, cavity-lining material or temporary filling. Most dental cements come as a powder which is mixed with water to form a viscous liquid. Modern cements, such as glass ionomer cement, also come in capsule form which is mixed in a special machine. Dental cements can be classified as either permanent or temporary. Permanent cement is used to permanently attach a prosthesis. Temporary dental cement is used between appointments mainly for evaluation purposes.
Zinc oxide eugenol (ZOE) cement
Zinc oxide eugenol cement (ZOE) is an oil-based cement used primarily as a temporary dental cement. ZOE has an anti-inflammatory effect on the pulp and is especially useful for cementation on prepared teeth with exposed dentinal tubules.
Composition
Zinc oxide eugenol cement comes in two forms, either a powder (zinc oxide) and liquid (eugenol, olive oil, zinc acetate), or as a two-paste system with a similar formulation to the powder and liquid.
Indications
- Temporary cementation of crowns and bridges
- Cavity base and lining material
- Provisional restoration of teeth
Advantages
- Soothes pulp
- Good sealing ability
- Neutral PH
- Least technique sensitive dental cement
Disadvantages
- Brittle (weakest cement)
- Eugenol inhibits polymerisation of resin so should be avoided if final restoration is resin-based
- Most soluble cement in mouth fluids
- Low strength
Zinc phosphate cement
Zinc phosphate cement has the longest history of all the dental cements and still the preferred choice for many dentists. The cement does not have a chemical bond to the underlying tooth structure so is used mainly as a luting agent for many types of indirect restorations.
Composition
Zinc phosphate comes as a powder (zinc oxide), which acts as the base, and a liquid (aqueous solution of phosphoric acid). The two are mixed by hand to form the cement. This is normally done on a chilled glass slab due to the mixture’s exothermic reaction which gives off a lot of heat.
Indications- Cementation of crowns, bridges, inlays and onlays
- Temporary restorations
- Cavity liner
Advantages
- Long clinical history
- Low cost
- Excess material is easily removed
- Low film thickness
- High compressive strength
Disadvantages
- High acidity can cause pulpal irritation
- Exothermic (technique sensitive)
- Weak aesthetics
- Soluble in mouth fluids
- No chemical adhesion