Amalgam (dentistry) and the American Society of Dental Surgeons (ASDS), the only US dental association at the time, forced all of its members to sign a pledge to abstain from using the mercury fillings. This was the beginning of what is known as the first dental amalgam war. The dispute ended in 1856 with the disbanding of the old association. The American Dental Association (ADA) was founded in its place in 1859, which has since then strongly defended dental amalgam from allegations of being too risky from the health standpoint. Amalgam has been used for many years for restorations, commonly known as
Real element formula_1, Every involution is strongly real. Furthermore, every element that is the product of two involutions is strongly real. Conversely, every strongly real element is the product of two involutions. If and formula_1 is real in formula_2 and formula_30 is odd, then formula_1 is strongly real in formula_2. The extended centralizer of an element formula_1 of a group formula_2 is defined as making the extended centralizer of an element formula_1 equal to the normalizer of the set The extended centralizer of an element of a group formula_2 is always a subgroup of formula_2. For involutions or non-real elements, centralizer and