These oxides have an important role to play in optimizing properties of interest to ceramists, such as the softening point of the glass, or its thermal expansion, and its mechanical and chemical durability. All leucite reinforced dental porcelains contain appreciable amounts of sodium, lithium and calcium oxides that fine tune their properties to a desirable range, and control firing temperatures, thermal expansion and slump resistance. The question of how these network modifiers affect chemical solubility still remains. That success in itself argues against these situations. However, that is not the only evidence for the chemical durability of porcelain.
Acetic acid is usually easier to come by in large quantities than saliva is.
At the end of the test, the disks are washed and dried. We can examine some of the actual effects of chemical solubility, such as the amount of porcelain lost to dissolution, the attack depth that this represents, and the amount of 'fluxes' leached out of the porcelain and absorbed into the patient's body as a result of this dissolution. It is possible to calculate how much porcelain will dissolve in the oral environment at this lower temperature, using the Arrhenius method, a widely used analytical tool in chemical technology to relate rates of reactions at different temperatures. Arrhenius method calculations show that the amount of porcelain dissolved in the ISO test is equivalent to the amount of porcelain dissolved in the acid in two years 4,5 . Some reasonable assumptions made in this calculation were that excessive exposure to acidulated fluoride, or other acidic media did not occur.