RESUMO
AIM: This was to evaluate the influence of root canal filling pastes on microshear bond strength (µSBS) of an adhesive system to primary dentine. METHODS: Human (32) primary molars were randomly assigned into four experimental groups (n = 8): zinc oxide eugenol paste (ZOE); iodoform paste (Guedes-Pinto paste); calcium hydroxide paste thickened with zinc oxide; and no filling paste (control). Flat dentine surfaces were covered with a 1 mm-thick layer of the pastes for 15 min at 37 °C. The pastes were mechanically removed from dentine surfaces, followed by rinsing and drying. After adhesive application (Adper Single Bond 2, 3M ESPE), starch tubes were placed over pre-treated dentine and filled with composite resin (Z250, 3M ESPE). The µSBS test was performed after 24 h of water storage at 37 °C. The failure mode was evaluated using a stereomicroscope. The µSBS values (MPa) were analysed with one-way ANOVA and Tukey post-hoc tests (α = 0.05). RESULTS: The lowest µSBS values were achieved when ZOE was used. No difference was found among other filling pastes compared with control group. All specimens showed adhesive/mixed failures. CONCLUSIONS: Zinc oxide eugenol paste negatively influenced the bond strength of adhesive systems to primary dentine. Iodoform-based Guedes-Pinto paste and calcium hydroxide paste thickened with zinc oxide did not influence the microshear bond strength values.
Assuntos
Colagem Dentária , Dentina , Materiais Restauradores do Canal Radicular , Dente Decíduo , Cimento de Óxido de Zinco e Eugenol , Dentina/efeitos dos fármacos , Humanos , Hidrocarbonetos Iodados , Técnicas In Vitro , Teste de Materiais , Dente Molar , Pulpectomia , Obturação do Canal Radicular , Resistência ao Cisalhamento , Cimento de Óxido de Zinco e Eugenol/farmacologiaRESUMO
AIM: To evaluate the in vitro toxicity of irrigating solutions and pharmacological associations used in the pulpectomy of primary teeth. METHODOLOGY: The cell viability (MTT), lipid peroxidation (TBARS), alkaline comet assay and GEMO tests were performed to evaluate the cytotoxicity and genotoxicity of solutions: sodium hypochlorite (1% and 2.5%), 2% chlorhexidine, 6% citric acid and 17% EDTA, which were tested, individually and in association, exposing human peripheral blood mononuclear cells (MTT, TBARS and alkaline comet assay), at 24 and 72 h, and dsDNA (GEMO). After performing the Kolmogorov-Smirnov test, data were analysed by anova followed by Dunnett's post hoc test, and Kruskal-Wallis followed by Dunn post hoc test. A significance level was established at P < 0.05. RESULTS: All irrigating solutions and pharmacological associations reduced cell viability at 24 h (P < 0.05). These reductions were maintained after 72 h, except for EDTA and associations of sodium hypochlorite (1% and 2.5%) with EDTA and of chlorhexidine with EDTA. Lipid peroxidation at 24 h was caused by EDTA and by 2.5% sodium hypochlorite with EDTA; it was also caused at 72 h by sodium hypochlorite (1% and 2.5%) and the three associations with citric acid (P < 0.05). All groups caused DNA damage when assessed by the alkaline comet assay, at 24 h and 72 h (P < 0.05). In the GEMO assay, all groups caused dsDNA damage (P < 0.05), except for chlorhexidine with EDTA. CONCLUSION: All groups showed some level of toxicity. Amongst the main solutions, chlorhexidine presented less cytotoxic potential. EDTA was the least cytotoxic of the auxiliary irrigant solutions, and the association of these two solutions showed the lowest toxicity potential amongst all groups.
Assuntos
DNA/efeitos dos fármacos , Leucócitos Mononucleares/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Pulpectomia/efeitos adversos , Dano ao DNA , Leucócitos Mononucleares/metabolismo , Irrigantes do Canal Radicular , Dente Decíduo , Testes de ToxicidadeRESUMO
AIM: To evaluate the cytotoxicity, oxidative stress and genotoxicity in vitro of four iodoform pastes and three calcium hydroxide pastes. METHODOLOGY: Peripheral blood mononuclear cells (PBMCs) and pure calf thymus DNA (dsDNA) were exposed to extracts of the pastes. Cytotoxicity was assessed with the MTT assay. Generation of reactive oxygen species (ROS) was evaluated using a DCFH-DA assay, and lipid peroxidation was evaluated using a TBARS assay. Genotoxicity was evaluated using the alkaline comet assay and Genomodifier capacity assay (GEMO). All tests were performed after 24 h and 72 h of cell exposure, except GEMO. After performing the Kolmogorov-Smirnov test, data were analysed by Kruskal-Wallis and Dunn's post-tests, and anova with Dunnett's post-test, with a significance level established at P < 0.05. RESULTS: The MTT assay revealed that chlorhexidine, Maxitrol and neomycin sulphate + bacitracin pastes decreased cell viability after 24 h (P < 0.05). No group was associated with a significant decreased cell viability or lipid peroxidation after 72 h. Calcium hydroxide pastes increased the cell viability levels at both experimental times (P < 0.05). Lipid peroxidation was observed with the exposure of cells to calcium hydroxide pastes after 24 h (P < 0.05). Exposure to chlorhexidine, Guedes-Pinto and calcium hydroxide pastes resulted in a significant increase in ROS after 24 h (P < 0.05), whereas iodoform pastes and Calen thickened with zinc oxide significantly increased the ROS after 72 h (P < 0.05). The comet assay revealed that exposure of the PBMCs to iodoform pastes did not damage DNA at either period of time (P > 0.05). However, chlorhexidine paste caused DNA damage in dsDNA (P < 0.05). Calcium hydroxide pastes caused DNA damage in both tests (P < 0.05). CONCLUSION: The pastes varied in their ability to induce cytotoxicity, genotoxicity and oxidative stress. In general, Guedes-Pinto, Maxitrol and neomycin sulphate + bacitracin pastes exhibited better biocompatibility in vitro.