Laboratory assessment of tooth whitening by sodium bicarbonate dentifrices

The increasing emphasis on dental aesthetics has made tooth whitening an im portant function of a dentifrice. This laboratory study investigated the wh itening effect of toothbrushing with sodium bicarbonate-based dentifrices c ompared with standard dentifrices that do not contain sodium bicarbonate. S ix dentifrices and a distilled water control were tested for their ability to whiten teeth with intrinsic stain. The dentifrices contained different a brasive systems: (1) 45% NaHCO3; (2) 65% NaHCO3 (Arm and Hammer Dental Care (R)); (3) 94% NaHCO3; (4) 94% NaHCO3 + 1.5% H2O2; (5) silica (Crest(R) Regu lar Toothpaste); and (6) dicalcium phosphate (Colgate(R) Regular Toothpaste ). After a thorough rubber cup cleaning with a pumice slurry, the intrinsic color of the test teeth with a Vita(R) shade of A3 or darker was measured with a spectrophotometer using the standard L*a*b* color scale. Measurement s were taken on a total of 12 teeth per test dentifrice before treatment, a nd after 30, 60, 90 and 120 minutes of mechanical toothbrushing. No changes in L* (lightness/brightness) or a* (red-green hue) occurred, but significa nt differences in b* (yellow-blue hue) were observed over time. Compared to baseline tooth color, all four sodium bicarbonate-based dentifrices were s ignificantly effective in removing the yellow intrinsic tooth stain, while the water control, silica dentifrice, and dicalcium phosphate dentifrice de monstrated no significant change. Between-group comparisons showed that the four dentifrices containing sodium bicarbonate were significantly more eff ective than the water and dicalcium phosphate dentifrice groups. The commer cial dentifrice containing 65% sodium bicarbonate was also more effective t han the commercial silica dentifrice. Although continued toothbrushing from 30 to 120 minutes resulted in additional stain removal, most of the tooth whitening by the sodium bicarbonate-based dentifrices occurred in the first 30 minutes of brushing. In the studies conducted, dentifrices containing h igh concentrations of sodium bicarbonate were more effective at removing in trinsic tooth stain than dentifrices that do not contain sodium bicarbonate .