This in vitro study evaluated the biocompatibility and abrasivity of whitening and conventional toothpastes. Samples of conventional (non-whitening)-Edel White Infant (EWI)-and whitening toothpastes-Edel White Whitening (EWW), Edel White CAREFORTE (EWC), Colgate Total 12 Ò Professional (C), and Oral-B Whitening (OB)were dissolved in culture medium (0.2 g sample weight per mL). Human gingival fibroblasts (hGF) were placed in contact with different dilutions of culture media that had been previously exposed to these toothpastes. Cytotoxicity was then assessed using the methyl tetrazolium test (MTT) and the cell survival rate was determined. Genotoxicity was assessed by the micronucleus test (MNT) and the number of micronuclei was determined before and after exposure to the toothpaste solutions. The enamel surface roughness was evaluated in specimens of bovine teeth (n = 10 per group) before and after 10,000 brushing cycles, using the investigated toothpastes. The results were statistically analyzed using the Mann-Whitney U test and two-way ANOVA (p < 0.05). According to the MTT assay, EWW and OB presented significant cytotoxicity (p < 0.01), but no genotoxic (MNT) effects (p > 0.05). C toothpaste was statistically significantly abrasive to the enamel surface (p < 0.01). The findings of this study may be helpful for individualized selection of commercial toothpastes, as some whitening toothpastes present significant cytotoxicity and conventional toothpaste cause significant surface changes.
This study aimed to perform an in vitro evaluation of the effect of photosensitizers used in photodynamic therapy (PDT) on tooth color change when used in combination with conventional endodontic treatment. Forty extracted human mandibular premolars were accessed and underwent root canal therapy and PDT. Photosensitizers were used in accordance with the experimental groups: MB (n=10) - PDT with Methylene Blue at 0.01%; TB (n=10) - PDT with Toluidine Blue at 0.01%; MG (n=10) - PDT with Malachite Green at 0.01%, at the concentration of 0.1mg/mL; and PC (n=10) - positive control, PDT with Endo-PTC cream stained with Methylene Blue at 25%. The samples were irradiated with 660-nm diode laser by means of a 330-μm-diameter optical fiber cable at a power density of 40mW for 120s. After light curing, the photosensitizers were removed from the specimens with 10mL sodium hypochlorite at 1%. A reflectance spectrometer was used for evaluation of color prior to and 60days after the experimental procedure based on the CIE L*a*b* system. According to ANOVA test, there were statistically significant differences between the experimental groups (p=0.003). Tukey's test showed a significant difference between PC and TB (p=0.008), as well as between MG and TB (p=0.009). However, there was no statistically significant difference between PC, MG (p=0.957) and MB (p=0.103). It was concluded that the use of PDT as an adjuvant to root canal therapy, using different photosensitizers, led to color change in tooth structure.
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