Aim: The aim of this study was to evaluate and compare the effect of 10% sodium ascorbate and propolis solution on the microtensile bond strength (MTBS) and resin tag penetration depth of composite after using 35% carbamide peroxide bleaching agent. Materials and Method: Sixty extracted human premolars were divided into five groups with 12 samples in each. Group I samples did not receive bleaching treatment and served as control. Group II samples were bonded with composite 2 weeks later, while those in Group III were bonded immediately after bleaching. The samples in Group IV and Group V were treated with antioxidants 10% SA and propolis solution at the rate of 1ml/min for 10 min, respectively, before composite bonding. The samples were then sectioned mesiodistally into two halves. One half was subjected to MTBS testing using a Universal Testing Machine. The other half was decalcified, sectioned, stained, and viewed under an optical light microscope to assess the resin tag penetration. The results obtained were statistically analyzed using a one-way analysis of variance followed by Post hoc test. Results: Group III showed significantly lower MTBS and resin tag penetration depth of composite compared to all other groups. Group V (propolis group) showed statistical significance with all groups except Group IV (SA group). Conclusion: Treatment with antioxidant propolis solution immediately following the bleaching will help to reverse the compromised bond strength which is comparable with sodium ascorbate.

Aims: To evaluate the effectiveness of grape seed extract (GSE) as a gutta-percha disinfectant and to compare the efficacy with 5% sodium hypochlorite, 2.5% sodium hypochlorite, and 2% chlorhexidine against Bacillus subtilis.Materials and methods: Minimum inhibitory concentration and minimum bactericidal concentration of GSE were calculated by serial dilution and well-diffusion method. Five hundred gutta-percha cones of ISO size 25 were divided into 10 equal groups (n = 50). The 10 groups of gutta-percha cones were inoculated with cultured Bacillus species and incubated for 72 hours for allowing bacterial growth. Each group was then treated with the test solutions for 1 and 5 minutes. The treated groups of gutta-percha cones were then incubated in brain heart infusion agar allowing for bacterial growth, which were later analyzed by the turbidity of the medium. The results were statistically analyzed.Results: Gutta-percha cones when treated with 2% chlorhexidine gluconate for 1 and 5 minutes showed the most inhibiting activity against B. subtilis. Grape seed extract was found to have limited activity against B. subtilis in both 1-and 5-minute interval. Both concentrations of NaOCl, 2.5 and 5%, showed reduced activity against B. subtilis. Conclusion:Grape seed extract though has antibacterial activity, when used as gutta-percha disinfectant, was found to be less effective than chlorhexidine gluconate against B. subtilis.Clinical significance: Different methods of gutta-percha cone disinfection have been advocated and GSE for gutta-percha cone disinfection was attempted owing to its herbal antibacterial nature.