RESUMO
OBJECTIVES: The final irrigation solution should have the capability of a chelation agent to remove the smear layer. The purpose of this study was to determine the effect of EDTA, novel silver citrate, and chitosan nanoparticles as a final irrigation solution on the mechanical properties of root canal dentine, namely the flexural strength and elastic modulus. METHODS: Thirty-two intact, single, and straight roots, with no caries, no cracks, and no restoration of premolars, were assigned into four groups of 8 teeth each. Group 1: irrigated with EDTA; Group 2: irrigated with novel silver citrate; Group 3: irrigated with chitosan nanoparticles; Group 4: irrigated with saline as control. Using a Universal Testing Machine, each sample was tested for flexural strength and elastic modulus with a three-point bend test. The data were analysed using one-way ANOVA and followed by the Tukey's test with a significance level of 95%. RESULTS: Chitosan nanoparticles generated the highest flexural strength and elastic modulus of root canal dentine (212.03 +- 1.64 and 16.40 +- 1.05, respectively) than EDTA (127.10 +- 0.90 and 7.37 +- 0.94) and novel silver citrate (177.87 +- 2.03, and 12.27 +- 1.01) (p<0.05). However, chitosan nanoparticles have similar flexural strength and elastic modulus of root canal dentine when compared to saline (213.76 +- 1.48, 17.02 +- 1.14, respectively) (p>0.05). CONCLUSION: Among final irrigations used, chitosan nanoparticles produced the highest flexural strength and elastic modulus of root canal dentine compared to EDTA and novel silver citrate.
RESUMO
BACKGROUND: Recently patients need faster treatments, and delaying restoration is not possible following bleaching treatment. The purpose of this study was to determine the effect of antioxidants, namely 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea and 10% Aloe vera extract on the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide. MATERIAL AND METHODS: Seventy premolars were randomly assigned into 7 groups of 10 each. Group 1: bleaching treatment and no antioxidants application. Group 2: composite was built-up immediately after bleaching. Group 3: bleached specimens received composite build-up delayed by 2 weeks. Group 4, 5, 6 and 7: bleached specimens received an application of 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea, and 10% Aloe vera before composite build-up. Specimens were immersed in artificial saliva, stored in an incubator 37°C (24 hours), thermocycling, and tested using a universal testing machine. Data were analyzed by one-way ANOVA and Tukey's test with 95% level of significance. RESULTS: Bleaching caused significantly reduced shear bond strength (p<0.05), and application of 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea and 10% Aloe vera produced significantly greater shear bond strength compared to bleached group (P <0.05). However, no significant differences occurred between antioxidant groups (P >0.05). CONCLUSIONS: Application of antioxidants increased the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide. 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea and 10% Aloe vera extracts produced the same effect on the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide. Key words:Antioxidants, shear bond strength, composite resin, extra-coronal bleaching.
