Dentistry Zinc phosphate cement is
the classic
dental cement par excellence. It is commonly used for
luting permanent metal and
zirconium dioxide restorations and as a base for
dental restorations. Zinc phosphate cement is used for cementation of
inlays,
crowns,
bridges, and
orthodontic appliances and occasionally as a
temporary restoration. It is prepared by mixing
zinc oxide (ZnO) and
magnesium oxide (MgO) powders with a liquid consisting principally of
phosphoric acid, water, and
buffers. It is the standard cement to measure against. It has the longest track record of use in dentistry. In recent years, newer adhesive cements on a different chemical basis have been added (e.g.
glass ionomer cement), but they have not displaced the classic phosphate cement, which continues to hold its own in the dental market with its simple and safe processing and good price-performance ratio. Zinc phosphate cement has only a low flexural strength and it does not stick to the dentin (it is a cement and not an adhesive). Zinc phosphate cement has high compressive strength, low film thickness, minimal setting shrinkage and thermal expansion and is biocompatible. Compared to other luting materials such as glass ionomer cement or composites, zinc phosphate cement is less sensitive to moisture. The excess produced during the cementation of dental restorations can be easily removed. Zinc phosphate cement has a high adhesive capacity to the tooth, metal, or even zirconium oxide. Despite its strong acidity, zinc phosphate cement does not damage the pulp (or the tooth nerve) during the setting phase. It is therefore used as liner to protect the pulp under composite fillings. Well-known dental brands in Germany and the world for zinc phosphate cement are Harvard cement and Hoffmann's cement. Otto Hoffmann invented this cement in 1892 and had it patented. Until the beginning of the First World War, he had a worldwide monopoly position with his cement. ==References==