Optical Tooth Whitening from a Toothpaste Containing Clay and Charcoal

Objectives:
To measure the optical tooth whitening effects of silica-based fluoride toothpastes containing blue and green covarine or blue covarine and compared to a control toothpaste.
Methods:
The study was a double-blind and 4 product cross-over design. Following ethical review and informed consent, male and female subjects in good general health aged 18-55, with two natural, upper central incisors (UCI) without visible damage, gum recession, restorations or extrinsic/intrinsic stain were enrolled.

The test toothpastes were a silica-based fluoride toothpaste containing blue and green covarine plus clay and charcoal (Test1), and two prototype silica-based fluoride toothpaste formulations containing blue covarine (Test2 and Test3). The control was a silica-based fluoride toothpaste containing no optical actives, clay or charcoal.

Subjects brushed with 1.5g of a randomly allocated toothpaste (90s), followed by water rinsing. Digital images of the UCIs were taken before and after brushing using a digital imaging system.

Tooth whiteness parameter (WIO) was determined from the images. The outcome variable per subject was the average of the UCI values. Within group differences were assessed for statistical significance by paired t-test analysis. ANCOVA was performed for between group comparisons. Product and visit as fixed effects, product*visit as interaction effect, subject as random effect and baseline as covariate. Data analysis was performed with SAS V9.4 (SAS Institute Inc., USA); the statistical significance level was p<0.05.
Results: At study completion 61 subjects were available for analysis and there were no reported adverse events. Results shown in Table.






Conclusions:
All toothpastes significantly increased tooth whiteness. The increase in tooth whiteness was significantly greater for the silica-based fluoride toothpaste containing blue/green covarine plus clay/charcoal and both prototype formulations than the control toothpaste.