[7][1] Rather, they contain a peroxyborate anion [(B(OH)2OO)2]2−, which consists of a cyclic −B−O−O−B−O−O− core with a pair of hydroxy groups bonded to each boron atom.

There is a CAS number for each of the three traditional "hydrates", the three "peroxyborate" versions of each (interpreted as a hydrogen peroxide adduct) and the poorly-defined "anhydrate" NaBO3, a total of seven.

[1] Sodium perborate hydrolyzes (i.e. breaks down in contact with water), producing hydrogen peroxide and borate:[3] The resulting hydroperoxide then enter in equilibrium with boric acid B(OH)3, hydrogen peroxide H2O2, the hydroperoxyl anion −OOH, and the tetrahydroxyborate anion [B(OH)4]−:[2] As the concentration of the solution increases, other peroxoborate species become significant.

At high borate concentrations, the sodium perborate with dimeric anion crystallizes out, due to its relatively low solubility.

[citation needed] Sodium perborate monohydrate is quickly hydrolyzed into hydrogen peroxide and borate on contact with water.

[3] A 1979 double-blind crossover study[14] suggests that hydrogen peroxide, which is released during the use of this product, may prevent or retard colonization and multiplication of anaerobic bacteria, such as those that inhabit oral wounds.

The compound is inserted in the root canal and left in place for an extended period of time to allow it to diffuse into the tooth and bleach stains from the inside out.

A 1979 double-blind crossover study[22] suggests that hydrogen peroxide, which is released during the use of this product, may prevent or retard colonization and multiplication of anaerobic bacteria, such as those that inhabit oral wounds.

[26] Between 2005 and 2010, Amosan was manufactured in Belgium and sold under the Oral-B brand, belonging to Procter & Gamble after its 2005 acquisition of Gillette.

In December 2010, its use was banned in the EU, as the product is based on borate, which the union considers "carcinogenic, mutagenic, or toxic for reproduction".

[15] Vintage Brands Limited began manufacturing and selling Amosan Oral Antiseptic Rinse in 2014 because many consumers were disappointed that it was no longer available.

[27] Product review pages on Amazon[28] and public comment forums elsewhere[29] indicate a high level of frustration with the discontinuation by users who could find no effective alternative treatment.