In vitro evaluation of adhesion/proliferation of human gingival fibroblasts on demineralized root surfaces by toluidine blue O in antimicrobial photodynamic therapy.

BACKGROUND: Antimicrobial photodynamic therapy (aPDT) in Dentistry has important effects as bacterial destruction in areas with periodontal disease. Some dyes applied in aPDT could present low pH and, consequently, result in tooth demineralization. This study evaluated demineralization produced by aPDT with toluidine blue O (TBO) at low pH and analyzed adhesion/proliferation of human gingival fibroblasts (HGF). METHODS: In the 1st phase, bovine enamel and root dentin fragments received 2 treatments: PDT4 group (TBO-100 µg/ml-pH 4-60s) plus laser (660 nm, 45 J/cm(2), 1.08 J, 30 mW, 30 s, spot 0.024 cm(2), 1.25 W/cm(2), sweeping, non-contact) and CA group (citric acid plus tetracycline-pH 1-180 s). Surface hardness loss and tooth wear were statistically analyzed (Student's t test, ANOVA/Tukey, p<0.05). In the 2nd phase, human dentin fragments were divided in C (control group-scaling and root planing), PDT4 and CA. HGF (10(4), 5th passage) were cultured on these fragments for 24, 48 and 72 h and counted in scanning electron microscopy photographs. Number of HGF was analyzed using repeated-measures ANOVA and Tukey (p<0.05). RESULTS: Percentage of surface hardness loss was similar in dentin for PDT4 (71.5%) and CA (76.1%) (p>0.05) and higher in enamel for CA (68.0%) compared to PDT4 (34.1%) (p<0.05). In respect to wear, no difference was found between PDT4 (dentin: 12.58 µm, enamel: 12.19 µm respectively) and CA (dentin: 11.74 µm and enamel: 11.03 µm) (p>0.05). Number of HGF was higher after 72 h in CA group (2.66, p<0.05) compared to PDT4 (2.2) and C (1.33). CONCLUSION: PDT4 is not as aggressive as CA for enamel. However, dentin demineralized promoted by PDT4 does not stimulate HGF adhesion and proliferation as CA.

The effect of mouthwashes containing biguanides on the progression of erosion in dentin.

BACKGROUND: Dental erosion is caused by frequent exposure to acids without the involvement of microorganism. This study analyzed the effect of biguanides (polyhexamethylene biguanide - PHMB and chlorhexidine - CHX) on dentin erosion due to their possible influence on the enzymatic degradation of the demineralized organic matrix. METHOD: Sixty bovine dentin specimens were prepared. On both sides of their surface, nail varnish was applied to maintain the reference surfaces for the determination of dentin loss. Samples were cyclically de- and remineralized for 6 days. Demineralization was performed with a 0.87 M citric acid solution (6×5 min daily). Thereafter, samples were treated with distilled water (negative control), 0.12% CHX (positive control), 0.07% PHMB, Sanifill Perio Premium™ (0.07% PHMB plus 0.05% NaF), or F solution (0.05% NaF) for 1 min and then subjected to enzymatic challenge for 10 min using a bacterial collagenase (Clostridium hystoliticum, 100 µg/ml). Dentin loss was assessed using profilometry (µm) daily. Data were analyzed using 2-way repeated measures-ANOVA and Bonferroni's test (p < 0.05). RESULTS: Dentin loss progressed significantly for all groups during the 6 days. After the 3rd day, Sanifill Premium™, CHX, and PHMB significantly reduced dentin erosion compared to control. On the 6th day, the lowest mean (±SD) dentin loss was observed for Sanifill Perio Premium™ (94.4 ± 3.9 µm). PHMB and CHX led to intermediate dentin loss (129.9 ± 41.2 and 135.3 ± 33.5 µm, respectively) that was significantly lower than those found for negative control (168.2 ± 6.2 µm). F (157.4 ± 6.1 µm) did not significantly differ from negative control. CONCLUSIONS: Sanifill Perio Premium™ mouthwash has a good potential to reduce dentin loss, which might be associated with the presence of PHMB.