Assessment of Impact of Various Root Canal Irrigants on the Adherence of the Gelatinase-producing and the Gelatinase-deficient E. faecalis Strains to Dentin.

AIM: Present study was planned to assess the impact of various root canal irrigants on the adhesion of different Enterococcus faecalis (E. faecalis) strains to the dentinal surface. MATERIALS AND METHODS: A total of 80 freshly extracted first and second molars were used in the present study. Preparation of dentin discs was done followed by a random division into four study groups and one control group. Four study groups included; 2.5 % sodium hypochlorite (NaOCl), 2 % chlorhexidine (CHX), 2.5 % NaOCl + saline + 2 percent CHX and 2.5 % NaOCl + 17 % ethylene diamine tetra-acetate (EDTA) + 2.5 % NaOCl group respectively. In the control group (E), sterilized dentin discs were incubated with sterile TSB solution. Division of all the groups into two subgroups were done depending upon the type of strain of E. faecalis used. Incubation of all the specimens was done followed by assessment with XTT assay and measurement of Optical density (OD). All the results were compiled and analyzed by Statistical Package for the Social Sciences (SPSS) software. RESULTS: Among the groups containing gelatinase producing strains; maximum score was exhibited by 2.5 percent sodium hypochlorite solution followed by 2.5 % NaOCl + 17 % Ethylene Diamine tetra-acetate (EDTA) + 2.5 % NaOCl group (group D). On comparing the OD values among various study groups incubated with Gelatinase producing strain, significant results were obtained. Gelatinase-producing E. faecalis showed a significantly higher amount of adherence to dentin, in comparison to the gelatinase-deficient E. faecalis strains. CONCLUSION: Lesser quantity of bacteria is recovered from specimens in whom CHX was added to the irrigation protocol. CLINICAL SIGNIFICANCE: Production of gelatinase by E. faecalis might lead to an increase in adhesiveness of E. faecalis to the dentin.

Impact of Different Antioxidants on the Bond Strength of Resinbased Composite on Bleached Enamel-An In Vitro Study.

AIM: The aim of this in vitro investigation was to assess the impact of various anti-oxidants namely 5% proanthocyanidin, 10% sodium ascorbate, 10% alpha tocopherol, and 10% green tea on the bond strength of resin-based composite on bleached enamel. MATERIALS AND METHODS: One hundred twenty human maxillary central incisors which were freshly extracted for periodontal reasons, having intact labial surface were us ed in this study. Specimens were randomly divided into six groups (n = 20). Group A: negative control-no bleaching treatment, group B-positive control -bleaching, group C-bleaching + 5% proanthocyanidins, group D-bleaching +10% green tea, group E - bleaching +10% alpha -tocopherol, group F-bleaching + 10% sodium ascorbate. Surfaces were etched followed by application of total-etch bonding system, and composite resin cylinders were bonded. Specimens were tested for shear bond strength using the universal testing machine. STATISTICAL ANALYSIS USED: The data obtained were subjected to ANOVA and post hoc Tukey's test for statistical analysis. RESULTS: After using bleaching agents and antioxidants for the different groups, Group A has the highest bond strength and group B has the lowest bond strength. Amongst the antioxidants group D showed significantly higher bond strength as compared group C, group E, and group F. CLINICAL SIGNIFICANCE: Use of antioxidants instantly following the bleaching procedure and before resin bonding reverses the compromised bond strength of composite resin on bleached enamel without sitting tight for a time of one day to one month. CONCLUSION: Bleaching of enamel reduced the shear bond strength. All the antioxidants used in this study increased the bond strength of bleached enamel. Among the antioxidant groups, green tea extract showed significantly higher bond strength compared to proanthocyanidin, tocopherol, and sodium ascorbate.