Charcoal Toothbrushes and Bacterial Contamination: a Clinical Trial.

Plain-language summary

This randomized controlled clinical trial aims to evaluate the antibacterial effectiveness of toothbrushes with charcoal-impregnated bristles compared to conventional toothbrushes without charcoal. The main objective is to assess and compare the microbial contamination on the toothbrushes after 21 days of use. Thirty-two healthy dental students from the Faculty of Dental Medicine of Rabat (16 males and 16 females, aged 18-24) were enrolled through convenience sampling. Participants were randomly assigned to two groups: Group A: Colgate Double Action Medium toothbrushes with charcoal-impregnated bristles. Group B: Colgate Double Action Medium toothbrushes without charcoal (control group). Participants brushed their teeth twice daily for two minutes using the rolling technique and a standardized fluoride toothpaste (1450 ppm). They were instructed not to use mouthwash or antiseptic toothpaste, to rinse brushes only with tap water (without touching the bristles), to store them vertically with bristles facing upward, and to keep them uncovered and at least one meter away from toilets. After 21 days, used toothbrushes were collected in sterile pouches and transferred to the microbiology laboratory. A quarter of the bristles from each brush head was aseptically cut, immersed in sterile saline solution, and vortexed to dislodge microorganisms. Aliquots of 200 µL were inoculated onto blood agar (Columbia agar base enriched with sterile blood). After incubation at 37°C for 48 hours, colony-forming units (CFU) were manually counted to estimate microbial contamination levels (CFU/mL). Clinical data (Silness and Löe plaque index, Löe and Silness gingival index, and DMF index) were collected at baseline. Statistical analysis was performed using Jamovi software. The comparison of CFU counts between groups aimed to determine whether charcoal impregnation reduces microbial contamination of toothbrush bristles. This study involves minimal risk and no investigational drug or device. Ethical approval was obtained from the Ethics Committee of the Faculty of Dental Medicine of Rabat.

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