In vitro evaluation of the microbial contamination on new toothbrushes: a preliminary study
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Published on: November 21, 2025
Cássio do Nascimento1, Thayla Tessa Scarabel, Paola Kirsten Miani
1Department of Dental Materials and Prosthodontics, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Monte Alegre, Ribeirão Preto-SP, Brazil.
Objective:
The presence and survival of microorganisms on toothbrush bristles might play a role on the etiology of oral infections. The aim of this in vitro study was to evaluate the presence of bacterial contamination on new toothbrushes before oral contact.
Materials And Methods:
Forty toothbrushes from five different manufacturers were used in this experimental study. Each manufacturer was divided according to conventional local of obtaining: industry, drugstore, market, and perfumery. The toothbrush heads were completely immersed into tubes containing 5.0 mL of sterile peptonated water (dilution 1:10). A group of eight tubes containing the sterile solution was used as control. After 21 days of anaerobic incubation, occurrence of contamination was visually evaluated and confirmed by light microscopy.
Results:
Bacterial growth in the medium, indicative of bristles contamination, was found in a total of 19 out of 40 samples (47.5%) evaluated: 6 out of 14 samples (42.85%) from industry group, 4 out of 8 samples (50.0%) from drugstore, 5 out of 10 samples (50.0%) from market, and 4 out of 8 samples (50.0%) from perfumery. Only the toothbrushes with bristles coated with chlorhexidine did not show contamination. The Gram-negative sporulating bacilli were the most prevalent form recovered.
Conclusions:
Except for chlorhexidine group, bacterial growth was observed in all groups evaluated irrespective local of obtaining.
