Hindawi Publishing Corporation International Journal of Dentistry Volume 2010, Article ID 651869, 7 pages doi:10.1155/2010/651869 Research Article Clinical Implications of Power Toothbrushing on Fluoride Delivery: Effects on Biofilm Plaque Metabolism and Physiology M. Aspiras, 1 P. Stoodley, 2 L. Nistico, 3 M. Longwell, 3 and M. de Jager 1 1 Clinical and Scientific Affairs, Philips Oral Healthcare, 35301 SE Center Street, Snoqualmie, WA 98065, USA 2 National Centre for Advanced Tribology at Southampton (nCATS), School of Engineering Sciences, University of Southampton, Highfield, Southampton, SO17 1BJ, Uk 3 Center for Genomic Sciences, Allegheny-Singer Research Institute, 11th Floor South Tower, 320 East North Avenue, Pittsburgh, PA 15212-4772, USA Correspondence should be addressed to M. Aspiras, marcelo.aspiras@philips.com Received 2 December 2009; Accepted 4 February 2010 Academic Editor: Alexandre R. Vieira Copyright © 2010 M. Aspiras et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Dental biofilms are implicated in the formation of caries and periodontal disease. A major constituent of the supragingival biofilm is Streptococcus mutans, which produces lactic acid from sucrose fermentation, enhancing enamel demineralization and eventual caries development. Caries prevention through F inhibits enamel demineralization and promotes remineralization. Fluoride also exerts effects on metabolic activities in the supragingival biofilm such as aerobic respiration, acid fermentation and dentrification. In experimental S. mutans biofilms, adding 1000 ppm F to an acidogenic biofilm resulting from 10% sucrose addition increased pH to pre-sucrose levels, suggesting inhibition of acid fermentation. F effects on metabolic activity and sucrose utilization in interproximal plaque biofilms were also recorded. Addition of 10% sucrose reduced pH from neutral to 4.2, but subsequent addition of 1000 ppm F increased pH by 1 unit, inhibiting acid fermentation. 10% Sucrose addition also stimulated denitrification, increasing production of nitrous oxide (N 2 O). Addition of 1000 ppm F suppressed denitrification, indicating an additional mechanism by which F exerts effects in the active interproximal biofilm. Finally, fluid dynamic activity by power tooth brushing enhanced F delivery and retention in an experimental S. mutans biofilm, suggesting a potential novel benefit for this intervention beyond mechanical plaque removal. 1. Introduction The accumulation of dental plaque biofilms plays an important role in the development of caries, gingivitis, and periodontitis. Bacteria in dental biofilms constitute a viable community of microorganisms with complex ecological relationships that influence the microenvironment in which they reside [1, 2]. As these bacteria proliferate, they utilize nutrients from their immediate environment. In the case of supragingival plaque bacteria, saliva or external dietary carbohydrates from ingested food are major nutritional sources, while for subgingival plaque bacteria, proteins from gingival crevicular fluid or tissue breakdown products are the main nutritional reservoirs [1]. The expanding biofilm forms an irregular heterogeneous sponge-like structure containing clusters of bacterial cells surrounded by channels through which liquids such as saliva, ingested fluids, or mouthwash can flow [3]. Streptococcus mutans, which produces lactic acid from the fermentation of sucrose and is instrumental in caries formation, is a major constituent of supragingival biofilms [4]. The cariogenic aspect of S. mutans biofilms is due in part to an increase in the dissolution rate of hydroxyapatite, a mineral which constitutes more than 95% of tooth enamel. As acidity increases such that the pH drops below 5, increased demineralization of the enamel surface in turn accelerates the development of cavities. In addition, cariogenic bacteria on the periphery of the cell clusters, many of which are aerobes and facultative anaerobes, actively consume dissolved oxygen, resulting in oxygen deprived niches that favor proliferation of anaerobic pathogens [5]. The progressive development of the biofilm ecosystem in terms of these aerobic or anaerobic niches is