Clinical Studies

Toothbrush Types and Retention of Microorganisms: How to choose a Biologically sound toothbrush?

  • Richard T. Glass, DDS, PhD
     Pick up any dental professional or trade journal and at least 25-30% of (he advertisements bark the virtues of one toothbrush or another. (Figure 1) The sales-pitches talk about toothbrush head design and angles. bristle texture and rounding, even electric motors and bristles that change colors. Such is also true of secular magazines, presenting only a slightly different approach, often brandishing approvals by various professional organizations. Yet, what is the real function of the toothbrush? This hygienic device is intended to remove microorganism substrates and the microorganisms themselves without creating harm to the tissues, because the major dental diseases are infectious in nature. If this last statement is true, then it stands to reason that criteria for toothbrush selection should certainly take into consideration the function of the device. In order 10 provide data for making such decisions, a number of different tooth-brushes from a variety of manufacturers were exposed to a wide range of microorganisms. The question being asked with each study: "Does the toothbrush retain microorganisms and/or allow for the increase in number of microorgan-isms?"


      The initial study examined tooth-brushes from patients who were consid-ered healthy, patients who had dental or mucosal diseases, and toothbrushes which had never been used.1 The data demonstrated that substantial numbers of pathogenic and opportunistic microor-ganisms were found on toothbrushes used by healthy patients and those with dental disease. Alarmingly, this study also demonstrated that toothbrushes could be contaminated in the manufac-turing process and that the microorgan-isms could be retained for long periods. The study also alluded to the importance of where the toothbrushes were stored between use (e.g., the bathroom, desk drawers, purses.) Another study considered Beta-hemolytic Streptococci and Candida albicans infected toothbrushes (unpublished data). This study found that clear or transparent toothbrushes retained fewer Streptococci than colored or opaque toothbrushes. Toothbrush color and ornateness had no effect on C'andida retention. Further, it was demonstrated that if disinfection procedures were employed, even if the numbers of microorganisms could be lessened on the bristle surfaces, that the mid-bristles and bristle depths or anchoring points allowed for substantial retention of microorganisms. The study suggested the variables of moisture retention, light penetration, and bristle-bristle closeness influenced microorganism retention. A subsequent investigation consid-ered virus c9ntamination of tooth-bruslies.2 Herpes Simplex Virus, Type I was found to infect toothbrushes after a short exposure of the brush to the microorganism (10 minutes). Tooth-brushes that remained in moist environments retained microorganisms for a considerable period of time (nearly 1/2 of the virus was retained for seven days). This study demonstrated that simple rinsing arid tapping of the toothbrush reduced the number of virus and that toothbrushes that had fewer bristle-tufts retained fewer viruses. Vital staining of toothbrushes demonstrated retention of virus on synthetic bristle defects and sharp edges and in natural bristle central cores. A follow-up study was completed (unpublished data) on 100 synthetic 3, and 4 row toothbrushes, 100 synthetic 5 for toothbrushes and 100 natural toothbrushes (3,4, and 5 row). These toothbrushes were infected with either Candida, Herpes, or Bacteroides. Again, in all categories of microorganisms, the natural bristle toothbrushes and the 5 row synthetic bristle toothbrushes retained more microorganisms than the 3 and 4 row synthetic bristle toothbrushes. In this investigation, probably because the microbial media was more abundant on the bristle surfaces, Candida and Bacteroides actually increased in number and allowed for other microorganisms (probably airborne contaminants) to grow symbiotically.

     Recent studies have been performed on a wider variety of microorganisms. Staphylococcus aureus, Pseudomas aeuruginosa, Escherichia coli, Bacillis subtilis, Serratia marcenscens, Baker's yeast, Herpes Simplex Virus, Type I and Parainfluenza Virus, Type III were all found to adhere to toothbrush bristles and to the plastic of the toothbrush head and handle. There was a consistent retention of all microorganisms on Oral B, Reach, and Colgate toothbrushes, including virus, after a short exposure to microorganisms. On the most favorable toothbrushes (Oral B light or translucent toothbrushes), there was only a 10 ml reduction of bacteria and yeast after 24 hours of drying. Consistently with both virus strains, Oral B toothbrushes retained fewer viruses than either Reach or Colgate toothbrushes. Similarly, the darker toothbrushes and toothbrushes with opacities "sparkles" of Colgate and reach had much higher retention for virus as compared to the pastel, translucent, and clear toothbrushes of Oral B.


      Several conclusions can be drawn from the multiple studies that have been performed on toothbrushes. First, it is clear that all of the presently available toothbrushes have the ability to be infected by a wide range of microorganisms, including virus which produce recurrent vesicular lesions and the common cold. It is also clear that anaerobic microorganisms can infect toothbrushes and that under certain circumstances, bacteria and yeast can actually proliferate. Second, toothbrush bristles are contaminated, not just on the surfaces, but also in defects and pits on the bristles and throughout the entire length of the bristles, including the insertion points in the toothbrush head. Third, the number of bristles per tuft, the number of tufts per row, and the number of rows per head have a definite relationship to the ease of infection and the retention of microorganisms by toothbrushes. As a general finding, the fewer bristles per tuft, the fewer tufts per row, and the fewer rows per head have the best results. Fourth, light colored, translucent, or clear head toothbrushes have less retention of microorganisms. Toothbrush head opaqueness, including "sparkles," toothbrush head oratness, and toothbrush head and bristle porosity increase the retention of microorganisms. Finally, it is apparent that the present toothbrushes, which were basically designed about the time of signing of the Constitution of the United States, need to be re-evaluated. Clearly, the function of this hygienic device needs to be balanced with the ability to resist infection.


1. Two row clear or light colored translucent toothbrushes appear to be the most biologically sound.
2. Toothbrushes should be stored in the bedroom rather than the bathroom, which is the most contaminated room in the house. Research also suggests an increasing role for ultraviolet toothbrush sanitation devices in decreasing the number of microorganisms on tooth-brushes (the Pollenex Daily Dental Sanitizer).
3. Healthy individuals should change their toothbrushes every two weeks. Those who have severe oral or systemic diseases and those undergoing cancer chemotherapy, cardiac surgery, or organ transplantation should change toothbrushes more frequently.
4. Toothbrushes should be changed (a) at the beginning of an illness, (b) when the patient first [eels better and (c) when tile patient feels completely well. This sequence of toothbrush changes the ability of the toothbrush to act as a microorganism reservoir allowing for re-infection.
5. The image of the toothbrush needs to be changed from a "lifelong friend" or other interpersonal image to that of a hygienic device which must be changed at very regular and frequent intervals.


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