Effect of newer antioxidants on the bond strength of composite on bleached enamel.

AIM: The study aims to evaluate the effect of the application of two antioxidants on the bond strength of composite resin to bleached enamel. MATERIALS AND METHODS: Eighty enamel surfaces were obtained from forty human extracted premolars. Specimens were randomly divided into four groups (n = 20). Group 1: No bleaching (control); Group 2a: Bleaching with 15% carbamide peroxide gel; Group 2b: Bleaching, followed by application of 10% sodium ascorbate gel; Group 2c: Bleaching, followed by application of 5% proanthocyanidin agent. Surfaces were etched followed by application of total etch bonding system, and composite resin cylinders were bonded. Specimens were tested for shear bond strength. STATISTICAL ANALYSIS USED: One-way analysis of variance was used for multiple group comparison and post hoc Tukey's test for individual group-wise comparison. RESULTS: Significantly higher shear bond strength values were observed in Group 2c and 2b as compared with Group 1 and 2a (P < 0.05). Among the antioxidants, Group 2c showed significantly higher shear bond strength values than Group 2b (P < 0.05). CONCLUSION: It can be concluded that the use of antioxidant before bonding procedures on bleached enamel completely neutralizes the deleterious effects of bleaching and increases the bond strength significantly.

Comparative evaluation of microleakage of conventional and modifications of glass ionomer cement in primary teeth: An in vitro study.

AIMS: The aim of the present study was to evaluate the microleakage among conventional, resin modified glass ionomer cements (GIC), and compomer cements in primary teeth. MATERIALS AND METHODS: Forty-five over retained non carious primary molars beyond exfoliation time were collected and randomly divided into three groups (n = 15). Group A: GC Fuji II; Group B: Vitremer; Group C: Compoglass F. A standard Class V cavity was prepared on the buccal surface of each tooth with no mechanical retention and restored accordingly. Then all the samples were subjected to thermocycling for 250 cycles at different temperatures and covered with nail varnish. Later, samples were immersed in 0.5% methylene blue dye for 24 h. Teeth were sectioned buccolingually through the center of the restoration and studied under a stereomicroscope for dye penetration. Data obtained were analyzed using Kruskal-Wallis ANOVA and Mann-Whitney U-test. RESULTS: Samples restored with vitremer showed comparatively higher microleakage than the samples in other groups. However, overall there were no significant difference between the microleakage scores of the samples in all three groups (P > 0.05). CONCLUSION: It can be concluded that none of the three GICs was free from microleakage. Hence, further research is required to compare microleakage of the newer material.