In Vitro Microleakage of Class V Composite Restorations in Use of Three Adhesive Systems

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

Effect of Intracanal Dentin Conditioning with Xylene, Phosphoric Acid and Chlorhexidine on Bond Strength to Glass Fiber Post with Self-Adhesive Cement

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

Enamel thickness after preparation of tooth for porcelain laminate.

In this investigation the thickness of enamel in the gingival, middle, and incisal thirds of the labial surface of the anterior teeth were measured regarding preparation of the teeth for porcelain laminate veneers.Part one, 20 extracted intact human maxillary central and lateral incisors ten of each were selected. The teeth were imbedded in autopolimerize acrylic resin. Cross section was preformed through the midline of the incisal, middle and cervical one-third of the labial surface of the teeth. The samples were observed under reflected stereomicroscope and the thickness of enamel was recorded. Part II, the effect of different types of preparation on dentin exposure was evaluated. Thirty maxillary central incisor teeth were randomly divided into two groups: A: Knife-edge preparation. B: Chamfer preparation. All samples were embedded in autopolimerize acrylic resin using a silicon mold. The samples were cut through the midline of the teeth. The surface of the samples were polished and enamel and dentin were observed under the stereomicroscope.Data were analyzed by ANOVA-one way test. The results of this study showed that the least enamel thickness in the central incisor was 345 and in lateral incisor is 235 μ this thickness is related to the one-third labial cervical area. Maximum thickness in maxillary central and lateral incisors in the one-third labial incisal surface was 1260 μ and 1220μ, respectively. In the second part of the study, the tendency of dentinal exposure was shown with the chamfer preparation, but no dentinal exposure was found in the knife-edge preparation. The differences between groups were significant (