RESUMO
OBJECTIVE: This study aimed to evaluate the esthetic efficacy, cytotoxicity, and kinetics of decomposition of hydrogen peroxide (H2O2) present in a commercial bleaching gel with 35% H2O2 (BG35%) chemically activated with manganese oxide (MnO2). METHODS AND MATERIALS: After incorporating 2 mg/mL, 6 mg/mL, and 10 mg/mL of MnO2 into BG35%, the stability of pH and temperature of the products were analyzed. To assess the esthetic efficacy (ΔE and ΔWI), the BG35%s with MnO2 were applied for 45 minutes on enamel/dentin discs (DiE/D). BG35% or no treatment were used as positive (PC) and negative (NC) controls, respectively. To analyze the cell viability (CV) and oxidative stress (OXS), the same bleaching protocols were performed on DiE/D adapted to artificial pulp chambers. The extracts (culture medium + gel components that diffused through the discs) were applied to pulp cells and submitted to H2O2 quantification. BG35% with MnO2 that showed the best results was evaluated relative to kinetic decomposition of H2O2, with consequent generation of free radicals (FR) and hydroxyl radicals (OHâ¢). The data were submitted to the one-way analysis of variance complemented by Tukey post-test (α=0.05). Data on kinetics of H2O2 decomposition were submitted to the Student's-t test (α=0.05). RESULTS: All the BG35%s with MnO2 showed stability of pH and temperature, and the gel with 10 mg/mL of this activator had an esthetic efficacy 31% higher than that of the PC (p<0.05). Reduction in OXS and trans-amelodentinal diffusion of H2O2 occurred when all the BG35%s with MnO2 were used. The addition of 6 and 10 mg/mL of MnO2 to BG35% increased the CV in comparison with PC, confirmed by the cell morphology analysis. An increase in FR and OH⢠formation was observed when 10 mg/mL of MnO2 was added to BG35%. CONCLUSION: Catalysis of BG35% with MnO2 minimized the trans-amelodentinal diffusion of H2O2 and toxicity of the product to pulp cells. BG35% containing 10 mg/mL of MnO2 potentiated the decomposition of H2O2, enhancing the generation of FR and OHâ¢, as well as the efficacy of the in-office tooth therapy.
Assuntos
Clareadores Dentários , Clareamento Dental , Estética Dentária , Humanos , Peróxido de Hidrogênio/química , Compostos de Manganês , Óxidos , Clareamento Dental/métodosRESUMO
OBJECTIVES: This paper aims to assess the whitening effectiveness and toxicity of tooth-bleaching protocols applied to enamel/dentin disks simulating mandibular incisors (ICs) and premolars (PMs). MATERIALS AND METHODS: A 10% hydrogen peroxide (H2O2) gel was applied for 3 × 15, 1 × 15, or 1 × 5 min to enamel/dentin disks simulating mandibular ICs and PMs, and the trans-enamel and trans-dentinal diffusion products were applied to human dental pulp cells (1 h). Professional therapy (35% H2O2-3 × 15 min) was used as positive control, and non-bleached samples were used as negative control. Cell viability and morphology, oxidative stress generation, and odontoblastic marker expression were assessed. The H2O2 diffusion and enamel color change (ΔE) were also analyzed. RESULTS: The 10% H2O2 gel induced significant cell viability reduction only when applied 3 × 15 min, with the intensity of oxidative stress and down-regulation of odontoblastic markers being higher in the IC group. The other experimental bleaching protocols caused slight alterations regarding the cell parameters evaluated, with intensity being related to enamel/dentin thickness. These effects were also correlated with higher H2O2 diffusion in the IC group. ΔE values similar as positive control were found for the 10% 3 × 15 and 1 × 15 protocols on IC group, after 4 and 6 sessions. CONCLUSION: Application of a 10% H2O2 bleaching gel for 15 or 45 min to thin dental substrate significantly minimizes cell toxicity in comparison with highly concentrated gels associated with similar esthetic outcomes by increasing the number of bleaching sessions. CLINICAL RELEVANCE: Bleaching gels with 10% H2O2 applied in small teeth for short periods may be an interesting alternative to obtain whitening effectiveness without causing toxicity to pulp cells, which may be able to reduce the tooth hypersensitivity claimed by patients.
Assuntos
Esmalte Dentário/efeitos dos fármacos , Estética Dentária , Peróxido de Hidrogênio/farmacologia , Peróxido de Hidrogênio/toxicidade , Clareadores Dentários/farmacologia , Clareadores Dentários/toxicidade , Clareamento Dental/métodos , Fosfatase Alcalina/análise , Biomarcadores/análise , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Polpa Dentária/citologia , Géis , Humanos , Técnicas In Vitro , Odontoblastos/efeitos dos fármacos , Estresse Oxidativo , Fatores de TempoRESUMO
The aim of this study was to evaluate the potential of dehydroleucodine (DhL), a new drug isolated from a medicinal herb used in Argentina, for activation of bovine oocyte. Several DhL concentrations and exposure times after ionomycin (Io) treatment were tested. The optimal DhL treatment, found for parthenogenetic development, was employed to produce bovine embryos by intracytoplasmic sperm injection (ICSI) and somatic cell nuclear transfer (SCNT). The best parthenogenic embryo developments were observed with 5 µM Io for 4 min followed by 5 µM DhL concentration and after 3-h exposure time (52.3% cleavage; 17.4% morulae; 7.3% blastocyst; n = 109). This treatment generated no significant differences with standard Io plus 6-dimethylaminopurine (DMAP) treatment in preimplantation embryo development. In our conditions, the embryo development reached after ICSI and SCNT assisted by the DhL treatment did not differ in terms of cleavage and blastocyst development from activation with standard Io plus DMAP treatment (p > 0.05). In conclusion, DhL utilization to activate oocytes and induce development of parthenogenotes, ICSI-embryos or SCNT-embryos is reported here for first time.