'Fluxes' and chemical solubility in dental porcelains.
Materials such as sodium, potassium, magnesium, and calcium oxides are routinely added to glasses commonly called "fluxes." These materials act as modifiers that disrupt the network arrangement of atoms in glasses and are used to optimize their fusion, expansion, or chemical properties. Dental porcelains are made of glasses and ceramic components such as leucite. The international standards ISO 6872 and ISO 9693 mandate a chemical solubility test, in which a solubility limit (< 100 g/cm2 for the test) is set for dental porcelains. Dental porcelains that have passed this test are very stable in the oral environment and lose very small amounts of porcelain to dissolution by saliva. The oxides that leach from these porcelains are relatively benign, and are usually absorbed through the average diet in much larger quantities. In addition to these factors, the long and successful clinical history of restorations made out of dental porcelains is a strong argument for their safety and efficacy, when used in accordance to indications and recommended techniques.