Extrinsic stain removal with a sodium hexametaphosphate-containing dentifrice: comparisons to marketed controls

Repeated exposure to chlorhexidine and tea has long been recognized to promote extrinsic tooth stain. Previously, the merits of a modified, rapid clinical trial model using chlorhexidine and tea in combination with restricted brushing to accelerate staining have been established. A nine-week randomized and controlled, examiner blind, parallel group clinical trial was conducted to compare selected chemical and mechanical approaches for stain removal using this model. After prophylaxis, stain was induced during a 3-week pre-treatment period, and then the healthy adult volunteers were randomized to one of three treatment groups: an experimental whitening dentifrice containing a combination of sodium hexametaphosphate and soluble pyrophosphate; a marketed alumina-based high abrasive dentifrice; or a lower abrasive control dentifrice. At baseline, three and six weeks, dental stain was measured on the facial and lingual surfaces of the eight anterior teeth using the Lobene index. A total of 94 subjects completed the study. Both the chemical and abrasive dentifrices showed statistically significant reductions in stain area (p < 0.05) relative to the control after three weeks. After six weeks, adjusted mean stain area scores were 0.35, 0.41 and 0.49 for the sodium hexametaphosphate, alumina and regular dentifrice groups, respectively. While the alumina dentifrice showed only a directional benefit, the sodium hexametaphosphate differed statistically (p = 0.023) from the control. Subjects in both the chemical and abrasive dentifrice groups showed statistically significant reductions relative to baseline for Lobene composite stain, stain area and stain intensity (p < 0.05) at six weeks. There were no statistically significant differences in stain levels between the sodium hexametaphosphate and alumina dentifrice groups at any time. This study demonstrates that following six weeks of treatment, sodium hexametaphosphate-containing dentifrices are effective in removing extrinsic tooth stain, with performance at least comparable to that seen with more abrasive dentifrices.