Toothbrushes commonly harbor pathogenic oral bacteria, and most patients may lack awareness of proper toothbrush care, according to a study.

Researchers conducted an observational study of 30 adult participants who were randomly assigned to use new toothbrushes for periods of either 1 or 3 months under their usual hygiene conditions. Toothbrush heads were then collected and analyzed for bacterial contamination, including Streptococcus mutans, Staphylococcus aureus, and Enterobacteriaceae, measured in colony­forming units. The participants also completed a questionnaire regarding their toothbrush storage habits and knowledge of toothbrush hygiene and contamination.

All of the toothbrushes demonstrated contamination with the tested microorganisms. Compared with toothbrushes used for 1 month, those used for 3 months showed higher bacterial levels for Staphylococcus aureus and Enterobacteriaceae. Mean counts increased from about 4.5 ± 0.3 to 5.5 ± 0.4 log units for S aureus and from 4.4 ± 0.3 to 6.0 ± 0.4 for Enterobacteriaceae. In contrast, Streptococcus mutans levels were similar between the 1­ and 3­month groups, with mean values of approximately 4.2 ± 0.3 at 1 month and 4.7 ± 0.3 at 3 months.

Patient knowledge was limited. For instance, 93% of the participants reported no prior instruction on proper toothbrush storage or disinfection techniques, and 73% of them were unaware of the contamination risk. Nearly all of the patients rinsed their toothbrushes after use, but 97% of them didn’t use antiseptic solutions.

Storage and handling practices were associated with bacterial levels. Toothbrushes stored in the bathroom or with other toothbrushes as well as those handled with fingers to remove excess water showed higher levels of bacterial contamination. The use of a protective bristle cover was associated with lower levels of S aureus and Enterobacteriaceae.

Not all of the bacteria followed the same pattern. While S aureus and Enterobacteriaceae increased over time, S mutans levels didn’t differ meaningfully between 1­ and 3­month use, suggesting variation in persistence across bacterial species.

The study was limited by its small sample size and potential variability in patient hygiene practices and environments. As an observational analysis, the researchers were unable to establish causal relationships between behaviors and contamination.

Overall, the findings suggested that toothbrush contamination may be common and influenced by routine behaviors, while patient awareness remains low.

“[T]he poor knowledge of the participants about the degree of contamination of their toothbrushes is a challenge to overcome,” wrote lead study author A. A. L. Moura­Filho, of the Division of Endodontics in the Department of Restorative Dentistry at the State University of Campinas Piracicaba Dental School in Brazil, and colleagues,

The study authors reported no conflicts of interest.

Source: International Journal of Dental Hygiene