Zinc phosphate
Names | |
---|---|
IUPAC name
Zinc phosphate
| |
Identifiers | |
3D model (
JSmol ) |
|
ChemSpider | |
ECHA InfoCard
|
100.029.040 |
PubChem CID
|
|
RTECS number
|
|
UNII | |
CompTox Dashboard (EPA)
|
|
| |
| |
Properties | |
H4O12P2Zn3 | |
Molar mass | 454.11 g·mol−1 |
Appearance | white solid |
Density | 3.998 g/cm3 |
Melting point | 900 °C (1,650 °F; 1,170 K) |
Boiling point | 158 °C (316 °F; 431 K) |
insoluble | |
−141.0·10−6
cm3/mol | |
Refractive index (nD)
|
1.595 |
Structure | |
monoclinic | |
Thermochemistry | |
Std enthalpy of (ΔfH⦵298)formation |
− 2891.2 ± 3.3 |
Hazards | |
NFPA 704 (fire diamond) | |
Flash point | Non-flammable |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
Zinc phosphate is an
Minerals
Natural forms of zinc phosphate include minerals
Use
Dentistry
Zinc phosphate cement is the classic
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
- .
- ISBN 978-3527306732.
- ^ Menke, Joseph T. "Zinc Phosphate Coatings on NonFerrous Substrates -- Part I". PFOnline. Retrieved 2006-08-07.
- ^ Raab D: Befestigung von Zirkonoxidkeramiken. DENTALZEIZUNG 2007: 6; 32-34. http://www.zwp-online.info/archiv/pub/pim/dz/2007/dz0607/dz607_032_034_hoffmann.pdf
- ^ Raab D: Befestigung von Vollkeramiken aus Zirkonoxid. ZAHNARZT WIRTSCHAFT PRAXIS 2007: 12; 98-101. http://www.zwp-online.info/archiv/pub/gim/zwp/2007/zwp1207/zwp1207_098_101_hoffmann.pdf
- ^ Raab D: Fixation of all ceramic restorations – the advantages of cementation. DENTAL INC 2008: March / April 50-53.
- ^ Raab D: Befestigung von Zirkonoxidkeramiken. ZAHN PRAX 2008: 11; 16-19.
- ^ Raab D: Fixation of full ceramic restorations – the advantages of cementation. 全瓷修复的粘接 — 水门汀的优势. DENTAL INC Chinese Edition 2008: Sonderdruck.
- ^ Raab D: Konventionelle Befestigung von Vollkeramikrestaurationen. ZAHN PRAX 2009: 12; 84-86.
External links