Effect of the sonicare flexcare power toothbrush on fluoride delivery through streptococcus mutans biofilms

Caries are caused by dental plaque biofilms that create acids when they metabolize dietary sugars such as sucrose. Fluoride can prevent caries by (1) enhancing remineralization of tooth enamel, (2) reducing enamel solubility in acidic conditions, and (3) inhibiting or modifying biofilm metabolism and reducing acidification. The efficacy of fluoride is not systemic but topical. Therefore, more effective delivery of fluoride to stagnation sites, such as the interproximal regions of posterior teeth, may contribute to the reduction of caries in these regions. Power brushing generates turbulence and currents in the fluid (ie, toothpaste-saliva mixture), and it is expected to increase the delivery of fluoride and other solutes into otherwise stagnant areas. To test this hypothesis, we used a 2-chamber method in which we measured the rate at which fluoride passed from one chamber into the other through a biofilm-colonized cellulose ester membrane under 3 conditions: no brushing, rotary power brushing (Oral-B Triumph Professional Care 9000), and sonic brushing (Sonicare FlexCare). For comparative purposes, we used the mass transfer coefficient (K) of fluoride, which is a measure of how quickly fluoride is delivered through the biofilm-colonized membrane. Power brushing significantly increased the delivery rate of fluoride through the biofilm compared with no brushing (P <.001). Rotary brushing increased the mass transfer coefficient of fluoride through the biofilm-colonized membrane by 79% (P = .002), whereas sonic brushing generated the greatest increase of 129% (P <.001). Sonic brushing generated a fluoride mass transfer coefficient that was 29% greater than that of rotary brushing (P <.05). This in vitro study supports an earlier clinical study that reported sonic brushing generated the greatest concentration of fluoride in interproximal plaque, followed by rotary brushing and manual brushing.