Powered brushing and fluoride in a streptococcus mutans typodont biofilm

Stoodley, P., Nistico, L., Longwell, M., Gieseke, A., Debeer, D., Aspiras, M. and DeJager, M. (2009) Powered brushing and fluoride in a streptococcus mutans typodont biofilm. International Association for Dental Research (IADR) General Meeting, Miami, USA. 31 Mar - 03 Apr 2009.

Abstract

Objectives: to develop a typodont biofilm model to measure the effect of powered brushing on biofilm removal and the delivery of fluoride into biofilm remaining in accessible areas in an anatomically relevant geometry.

Methods: streptococcus mutans biofilms were grown on sections of a typodont (A-PZ Frasaco) for three or six days. The typodont sections contained either incisors and cuspids or premolars and molars. The biofilm was observed on various surfaces before and after brushing facial surfaces for 10 seconds with a powered toothbrush (Philips Sonicare FlexCare), according to manufacturer instructions. A pH microelectrode was used to measure profiles in the biofilm. To measure profiles of free fluoride ion in the biofilm we constructed a fluoride microelectrode. The electrode was calibrated and profiles measured in an agar gel.

Results: biofilm grew on the hard plastic tooth and soft gum materials of the typodont on all surfaces. The pH microelectrode showed that acid was produced in the presence of sucrose due to acid respiration. The pH dropped from approximately 7 to as low as 5.5. After hand brushing the typodont was reexamined. The facial surfaces were almost devoid of biofilm, however, there was still biofilm remaining in the interproximal spaces and molar occlusal surfaces. The fluoride microelectrode had a tip diameter of 5 µm and had a measurement range from approximately 1 to 1000 ppm F-, in a log-linear relationship.

Conclusion: the typodont model is a good system for quantifying biofilm removal and measuring remaining biofilm in “hard to reach locations” in an anatomically relevant model. Microelectrodes can be used to measure local activity and zones of acid production. The fluoride microelectrode has potential for measuring the local delivery of fluoride to biofilm on various typodont surfaces

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Contributors

Author: P. Stoodley

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