The chemical stain removal properties of 'whitening' toothpaste products: studies in vitro

Background A considerable number of toothpastes are available as tooth whit ening products. Most appear to contain ingredients that might remove extrin sic stains rather than change natural tooth colour. Extrinsic stain removal could be achieved by physical or chemical means. Aim The purpose of this study was to measure the chemical stain removal pro perties of a range of whitening toothpaste products and experimental formul ations using a standardised method in vitro. Materials and method 5 separate studies were conducted involving a total of 39 agents of which 28 were whitening products, 7 were experimental formula tions, 2 were oxidising mouthrinses used as positive controls, 1 was a popu lar fluoride toothpaste product as a benchmark control, and 1 was water as the negative control. The formulations and controls varied in each study. T he stain model was saliva/chlorhexidine/tea stain developed on optically cl ear acrylic to an optical density of at least 2.0. Groups of stained specim ens were exposed to standard slurries or solutions of each test agent for 1 minute periods up to 5 minutes. Optical density readings were taken at eac h 1 minute time point. Analyses were based on per cent stain remaining afte r 5 minutes and time to 75% stain remaining. Results 3 toothpaste products achieved 100% stain removal by 5 minutes; 2 o f these in 3 out of4 studies in which they were used. 4 experimental formul ations also achieved 100% stain removal. In general agents with high total stain removal also had short times to 75% stain remaining. The majority of agents tested had low total chemical stain removal and prolonged times to 7 5% stain remaining. A few agents were little different from water and sever al similar in effect to the conventional fluoride toothpaste. This method i n vitro tests agents under the best case scenario conditions for chemical s tain removal. Conclusion Only a small number of the whitening toothpaste products have go od chemical stain removal potential; the majority are unlikely to achieve t heir claimed benefits through chemical stain removal. There is clearly a ne ed for further data on the actual effects of such products using both metho ds in vitro and particularly in vivo or in situ.