RESUMO
Aim: To investigate the effects of bleaching with 35% hydrogen peroxide on the structure of tooth enamel and the role of two remineralizing agents for their potential to remineralize any damaged regions of enamel. Materials and Methods: Freshly extracted 32 mature permanent central incisors were selected and sectioned at the level of the cemento?enamel junction. The teeth were divided into four groups consisting of eight teeth each: No bleaching (control) [Group 1], bleaching with 35% hydrogen peroxide [Group 2], bleaching with 35% hydrogen peroxide followed by application of casein phosphopeptide amorphous calcium phosphate fluoride paste [Group 3], and bleaching with 35% hydrogen peroxide followed by application of xylitol?coated calcium phosphate fluoride varnish [Group 4]. The enamel surfaces were analyzed under the scanning electron microscope and quantitative energy dispersive X?ray analysis. Results: Results were statistically analyzed by one?way analysis of variance and Tukey’s posthoc test. Group 2 revealed changes in enamel surface morphology and a statistically significant decrease in mineral content. Groups 3 and 4 showed statistically significant remineralization potential. Intergroup comparison showed that samples in Group 4 had a higher mineral content compared to Group 3. Conclusions: The application of the tested remineralizing agents following bleaching was effective in repairing the enamel surface morphology with higher efficacy for the fluoride varnish product. Since bleaching regimes with high concentrations of hydrogen peroxide adversely affect the enamel surface, these findings can translate to clinical practice to reduce the long?term damaging effects of tooth bleaching
RESUMO
Context: The study assesses the apical sealing ability of two obturating materials (resilon and gutta-percha) with their sealants by means of the dye penetration method using India ink. Aims: To compare the resistance to apical dye penetration between resilon (with Epiphany sealer; Epiphany®, Pentron clinical technologies, USA) and gutta-percha (with AH Plus sealer; Dentsply, Maillefer, Germany). It was hypothesized that there would be no difference between the two groups with regard to apical dye penetration. Settings and design: Hundred mandibular first premolars from individuals aged between 20 to 25 years were selected after their lengths were standardized. Materials and Methods: Instrumentation was performed with NiTi hand protaper files (Dentsply, Maillefer) using EDTA paste and copious irrigation with 2.5% sodium hypochlorite. Experimental group 1 consisted of roots that were treated with Epiphany primer and obturated with resilon (with Epiphany sealer). Experimental group 2 consisted of those obturated with gutta-percha using AH Plus sealer. The samples were immersed in blue India Ink and cleared using 5% nitric acid. Dye penetration was assessed under a stereomicroscope. Statistical analysis: Mann-Whitney U test. Results: Roots obturated with resilon core material and Epiphany sealer exhibited lesser mean apical dye penetration (1.281 mm; SD: 0.742) in comparison to those obturated with gutta-percha and AH plus sealer (2.154 mm; SD: 0.814). The difference was found to be highly significant (P<0.0025). Conclusion: Resilon (with Epiphany sealer) provided better radicular apical sealing in comparison to gutta percha (with AH Plus sealer).