Clinical Oral Investigations

, Volume 22, Issue 3, pp 1123–1129 | Cite as

Fluoride in saliva and dental biofilm after 1500 and 5000 ppm fluoride exposure

  • Line Staun Larsen
  • Vibeke Baelum
  • Livia Maria Andaló Tenuta
  • Alan Richards
  • Bente Nyvad
Original Article



The aim of this randomized, double-blind, crossover study was to measure fluoride in saliva and 7-day-old biofilm fluid and biofilm solids after rinsing three times per day for 3 weeks with 0, 1500, or 5000 ppm fluoride (NaF).

Materials and methods

Following the 3-week wash-in/wash-out period, including 1 week of biofilm accumulation, saliva and biofilm samples were collected from 12 participants immediately before (background fluoride), and 10, 30, and 60 min after a single rinse. Biofilm samples were separated into fluid and solids, and samples were analyzed using a fluoride electrode (microanalysis).


The background fluoride concentration was statistically significantly higher in the 5000 compared to the 1500 ppm F rinse group in all three compartments (22.3 and 8.1 μM in saliva, 126.8 and 58.5 μM in biofilm fluid, and 10,940 and 4837 μmol/kg in biofilm solids). The 1-h fluoride accumulation for the 5000 ppm F rinse was higher than for the 1500 ppm F rinse in all three compartments, although not statistically significant for saliva and biofilm solids.


Regular exposure to 5000 ppm fluoride elevates background fluoride concentrations in saliva, biofilm fluid, and biofilm solids compared to 1500 ppm fluoride. Increasing the fluoride concentration almost 3.5 times (from 1500 to 5000 ppm) only elevates the background fluoride concentrations in saliva, biofilm fluid, and biofilm solids twofold.

Clinical relevance

Even though fluoride toothpaste may be diluted by saliva, the results of the present study indicate that use of 5000 ppm fluoride toothpaste might lead to improved caries control.


Fluorides Biofilm fluid Biofilm solids Saliva Dental plaque Dental caries 



This study was funded by the private funds “Tandlægeforeningen (FORSKU),” “Familien Hede Nielsens Fond,” and “Fonden til fremme af Odontologisk Videnskab af 2001.” The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study was approved by the Central Denmark Region Committees on Health Research Ethics (case no. 1-10-72-165-14).

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  1. 1.Section of Dental Pathology, Operative Dentistry and Endodontics, Department of Dentistry and Oral Health, HEALTHAarhus UniversityAarhus CDenmark
  2. 2.Section of Oral Epidemiology and Dental Public Health, Department of Dentistry and Oral Health, HEALTHAarhus UniversityAarhus CDenmark
  3. 3.Department of Physiological Sciences, Piracicaba Dental SchoolUNICAMPPiracicabaBrazil

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