RESUMO
The Soladey™ toothbrush has a moisture-permeable titanium dioxide (TiO2) resin core in the replacement brush end of a handle activated by light conversion power cells. Purported to have an antibacterial effect and remove more plaque than an ordinary toothbrush, this study was undertaken to establish output measurements of the dry and wet TiO2 core of the toothbrush during typical illumination of the handle, then quantify lipid peroxidation in three distinct lipid-containing solutions, and bactericidal effects in a live bacterial suspension grown from suctioned oral secretions. METHODS: Within a range of illumination of the power cells in the handle, corresponding flow of electrons emitted from dry and wetted TiO2 cores was measured. The claim that an antibacterial effect can be attributed to generation of reactive oxygen-mediated lipid peroxidation of cell membranes was tested by exposing three lipid substrates to the light-activated ionic toothbrush tips for incremental periods of time. Products of lipid peroxidation were quantified using 3 commercially available assays, and bactericidal effects were assessed by scoring colony-forming units. RESULTS: Illumination of the handle generated quantifiable increases in electrons flowing from the wetted TiO2 core. Immersion of the TiO2 core end of illuminated toothbrush handles into lipid substrates showed linear effects of incremental exposure times on products of lipid peroxidation, but no evidence of a bactericidal effect occurring within 15 minutes. CONCLUSIONS: This validates capacity of the wetted current- activated TiO2 core to generate time-dependent lipid peroxides, particularly in the sonicated matrix containing disrupted cell membranes. Finding no time-dependent reduction in colony- forming units and less lipid peroxidation in a suspension of intact cells casts doubt that the ionic toothbrush has an immediate antibacterial effect while brushing teeth. If a toothbrush with a TiO2 core is self-disinfecting between uses, bactericidal effects requiring longer periods of exposure might still confer a hygienic advantage.