Tooth and Composite Discoloration After Photodynamic Therapy with Different Photosensitizers and Cleansers Under Accelerated Aging Conditions

<b>Introduction:</b> This study aimed to evaluate tooth and composite discoloration after photodynamic therapy using different concentrations of photosensitizers, combined with various cleaning agents (water, 2.5% sodium hypochlorite and 17% EDTA), immediately and after accelerated aging. <b>Methods:</b> In this <i>in vitro</i> study, 104 bovine maxillary central incisors were selected. Enamel-dentin discs (7×7×2 mm) were prepared from the middle of the crown and subjected to an artificial demineralization and remineralization cycle for 14 days. The samples were divided into 13 groups: Photodynamic therapy using methylene blue or toluidine blue at two concentrations of 50 µg/ml and 100 µg/ml, each with three detergents (water, 2.5% sodium hypochlorite, or 17% EDTA), and a control group: disinfection with chlorhexidine 2%. The surface of the dentin was bonded, and the composite resin was applied. All specimens underwent 100 hours of xenon lamp exposure. Tooth and composite colors were measured at baseline, after photodynamic therapy, and after accelerated aging. Statistical analysis was performed using one-way ANOVA and Tukey's HSD. <b>Results:</b> Color change caused by methylene blue (50 µg/ml) and rinsing with EDTA or sodium hypochlorite was below the perceptibility threshold (ΔE<3.3). According to the Tukey HSD test, no significant difference was observed between this group and the control group (<i>P</i>>0.05). All groups demonstrated clinically perceptible composite discoloration. <b>Conclusion:</b> Tooth discoloration after photodynamic therapy with 50 µg/ml methylene blue and rinsing with EDTA or sodium hypochlorite is not visually detectable. Photodynamic therapy with 100 µg/ml methylene blue or toluidine blue leads to the discoloration of composite restorations.