Fluoride and trimetaphosphate association as a novel approach for remineralization and antiproteolytic activity in dentin tissue.

OBJECTIVE: The study evaluated the effect of solutions containing fluoride (F) and/or sodium trimetaphosphate (TMP) and F/TMP on the inhibition of MMP-2 and MMP-9, and on dentin remineralization in vitro. DESIGN: Bovine root dentin blocks were prepared, and caries-like lesions were induced in two thirds of the surface. Blocks were then randomly divided into 13 groups/solutions (n = 10): Placebo; 0.3 %, 1 % and 3 % NaOH-hydrolyzed TMP; 0.3 %, 1 % and 3 % TMP; 250, 500 and 1100 ppm F; 250 ppm F + 0.3 % TMP; 500 ppm F + 1 % TMP and 1100 ppm F + 3 % TMP. One third of each specimen was treated with the respective solutions in pH-cycling. The mineral concentration (gHAp × cm-3 × µm) was determined by computed X-ray microtomography, and data submitted to ANOVA and Student-Newman-Keuls' test (p < 0.05). The ability of the solutions to inhibit MMP-2 and MMP-9 activity was assessed by zymography. RESULTS: F/TMP association led to less mineral loss in the deeper region of the lesion and reduced the depth of lesions when compared to its counterpart without TMP (p < 0.001). 3 % TMP (hydrolyzed or not), 500 ppm F and 1100 ppm F completely inhibited MMP-2 activity, while for MMP-9 such effects were only achieved by treatment with 1100 ppm F + 3 % TMP. CONCLUSION: Treatment with 1100 ppm F + 3 % TMP fully inhibits the gelatinolytic activity of MMPs-2 and - 9 and shows greater remineralizing capacity in artificial caries lesions in dentin. However, hydrolyzing TMP does not improve its anti-proteolytic activity and its remineralizing capacity.

Evaluation of bleaching efficacy, microhardness, and trans-amelodentinal diffusion of a novel bleaching agent for an in-office technique containing hexametaphosphate and fluoride.

OBJECTIVE: This study evaluated in vitro the effects of calcium gluconate (CaGlu), sodium fluoride (NaF), sodium hexametaphosphate (HMP), and NaF/TMP added to a 35% hydrogen peroxide (H2O2) bleaching gel on the color change, enamel hardness, and trans-amelodentinal diffusion. MATERIALS AND METHODS: Enamel discs/bovine dentin (n = 150) were divided according to the bleaching gel: 35% H2O2 (H2O2); 35% H2O2 + 0.1% NaF (H2O2/NaF); 35% H2O2 + 1% HMP (H2O2/HMP); 35% H2O2 + 0.1% NaF + 1% HMP (H2O2/NaF/HMP), and 35% H2O2 + 2% CaGlu (H2O2/Caglu). The bleaching gels were applied three times (40 min/session) at 7-day intervals between each application. Then, color alteration (ΔE), whitening index (ΔWID), percentage of surface hardness loss (% SH), cross-sectional hardness (ΔKHN), and trans-amelodentinal diffusion were determined. Data were submitted for analysis of variance (ANOVA), followed by the Student-Newman-Keuls test (p < 0.05). RESULTS: All bleaching gels showed significant color changes after treatment (p < 0.001). ΔE and ΔWID were similar among the evaluated gels. Mineral loss (% SH and ΔKHN) and trans-amelodentinal diffusion of hydrogen peroxide were lower for H2O2/NaF/HMP; the H2O2/CaGlu group presented the highest values about the other groups (p < 0.001). CONCLUSION: It is possible to conclude that the addition of NaF/HMP to the in-office bleaching agent did not interfere with the bleaching efficacy and reduced enamel demineralization and H2O2 diffusion. CLINICAL SIGNIFICANCE: The association of NaF/HMP to the bleaching gel can be used as a novel approach for minimizing the adverse effects of H2O2 by-products and with similar clinical efficacy.