Dental stain prevention by abrasive toothpastes : A new in vitro test and its correlation with clinical observations

A new in vitro test based on the removal of a model film from polished hydroxyapatite discs has been developed to predict more precisely the stain prevention properties of toothpastes in vivo. It is argued that dental stain prevention, as opposed to removal, is the predominant function provided by abrasive pastes suitable for unrestricted home use. It is necessary, therefore, to focus on abrasive systems capable of efficient removal of the relatively soft and invisible up-to-24-hour-old salivary pellicle formed between brushings, rather than on hamer visible mature stain. A cleaning model of this film has therefore been developed. The abrasive effect on the model film of a typical silica xerogel has been examined, and the data compared with clinical observation of stain build-up. A good correlation was apparent. Stain prevention increased dramatically from zero to 4% w/w silica, after which higher levels had little or no beneficial effect, despite a continuing increase in potential dentine damage.