Biofilm Plaque and Hydrodynamic Effects on Mass Transfer, Fluoride Delivery and Caries

ABSTRACTBackground.The biofilm concept of dental plaque now is widely accepted in the dental clinic, particularly with respect to its importance to oral hygiene. A number of reviews have focused on the microbial ecology of biofilm with regard to oral health; however, there has been less focus on how the interaction of biofilms and hydrodynamics with mass transfer (the movement of molecules and particulates) and physiological processes may relate to caries.Types of Studies Reviewed.The authors reviewed reports in the microbiology and dental literature addressing microbiological, engineering and clinical aspects of biofilms with respect to mass transport and microbial physiology, with an emphasis on fluoride ions (F−).Conclusions and Practical Implications.These data illustrate how dental plaque biofilms may affect the delivery of cariogenic agents, such as sucrose, or anticariogenic agents, such as F−, into and out of the biofilm, with subsequent consequences for the development of physio-chemical microenvironments at the tooth surface. Increasing the flow rate in an overlying fluid (such as saliva or mouthrinse) increases transport from the fluid into and through biofilms. Increasing the delivery of anticariogenic agents such as F− into the plaque biofilm, by generating strong fluid flows, may be a useful strategy for enhancing the anticaries effects of F− in areas of the mouth where complete biofilm removal is not possible with routine daily cleaning techniques.