Background and Aim: Microleakage is a drawback of composite restorations and it is more noticeable in dentinal walls. Despite advances in dentin bonding agents, no adhesive can completely eliminate microleakage and provide a hermetic seal. This study aimed to compare microleakage of three resin bonding agents namely a universal adhesive, two-step self-etch system and two-step total-etch system. Materials and Methods: This in vitro, experimental study was conducted on 68 human molars. Class V cavities were prepared in the buccal or lingual surfaces of the teeth with occlusal margins in the enamel and gingival margins in dentin. The teeth were then randomly divided into four groups of 17. Group A: Adper Single Bond 2, group B: Clearfil SE Bond, group C: Scotchbond Universal adhesive (self-etch) and group D: Scotchbond Universal adhesive (total-etch). The teeth were then restored using different bonding agents and a microhybrid composite resin. The specimens were then subjected to 1000 thermal cycles between 5-55°C. The entire restoration surface except for 1mm around the margins was coated with nail varnish. The teeth were immersed in 2% methylene blue for 24 hours and sectioned longitudinally in a buccolingual direction and observed under a stereomicroscope to determine microleakage. Microleakage in use of the three bonding agents was compared using the Kruskal Wallis test (P<0.05). Results: Based on the Kruskal Wallis test, no significant difference was noted in enamel and dentin margins among different adhesives but the enamel margin showed less microleakage than the dentin margin. Conclusion: Different adhesive systems tested in this study showed similar microleakage at the enamel and dentinal margins.

Despite the increasing demand for fiber-reinforced composite (FRC) posts, their bonding to root canals is still subject to debate. Endodontic sealers may affect the bond strength between fiber posts and root canal dentin. Aim: To compare the effects of different sealers on fiber post bond strength. Methods: Sixty teeth were divided into 4 groups according to obturation method: GI, gutta-percha without any sealers; GII, gutta-percha and AH26 resin-based sealer; GIII, RealSeal point and RealSeal resin-based sealer, GIV, Guttaflow. Fiber posts were cemented into root canals. Specimens were sectioned, and the bond strength was measured in the middle area. The failure mode was evaluated. Data were analyzed by one-way ANOVA and post hoc test. Results: The highest bond strength was observed in the control group (2.95±1.12), and the least was in the Guttaflow group (1.15±0.78). There was a significant difference between bond strengths of the control and Guttaflow groups and between AH26 and Guttaflow groups (p<0.05). The failure mode was mainly adhesive between dentin and resin cement in all groups. Conclusions: Sealers may have a negative effect on the bond strength of fiber posts to root canal dentin.

Background and Aim: Debonding is the most commonly encountered failure in teeth restored with fiber posts that mainly occurs at the weakest interface (dentin-cement interface). Thus, reinforcement of this interface is mandatory. The aim of this study was to evaluate the effect of different root dentin surface treatments after post space preparation on bond strength of fiber posts cemented with a self-adhesive resin cement. Materials and Methods: Forty extracted sound single-rooted teeth underwent root canal therapy. After post space preparation, the teeth were assigned to four group of 10 teeth according to the type of dentin surface treatment: Group 1: 2% chlorhexidine rinse, group 2: 37% phosphoric acid etching and then irrigating with saline, group 3: rinse with xylene and then irrigation with saline, group 4: rinse with saline (control group). Then, fiber posts were cemented with Total cem cement and the teeth were sectioned horizontally. Specimens were observed under a stereomicroscope at X10 magnification and failure modes of each group were determined. Results were analyzed by one-way ANOVA. Results: There was no significant difference between the mean bond strength of the four groups (P=0.174). The highest mean bond strength value was found in phosphoric acid group (8.18±3.19 MPa) and the lowest belonged to the control group (6.21±1.81 MPa). Conclusion: Our results showed that dentin surface treatment with phosphoric acid before cementation of fiber posts with a self-adhesive cement improves the bond strength.