A comparison between the effect of zirconia-coated FRC and glass fiber posts on the fracture resistance of endodontically treated teeth

  Background and Aims : The root fracture resistance of endodontically treated teeth depends on the types of posts. The aim of this study was to compare the effect of two types of bonded non-metallic posts with different elasticity modulus on the fracture resistance of endodontically treated teeth under compressive loads.   Materials and Methods: In this in vitro experimental study, 20 fresh extracted mandibular premolars were selected and sectioned adjacent to the CEJ and then were endodontically treated. The specimens were randomly divided into two groups (n=10). After post space preparations, the fiber RTD Light posts (R.T.D, France) and zirconia coated fiber posts (ICE light, Danville) were cemented into the root canals. Composite resin (Lumiglass R.T.D, France) cores were built up. Aluminium foil was used to mimic the PDL, and the specimens were embedded in acrylic resin and tested in a Universal Testing Machine. A compressive load was applied at a 90 degree angle until fracture at a crosshead speed of 1mm/min. Data were analyzed using one-way ANOVA and T test .   Results: The mean fracture resistance of R.T.D group was (1083.11 ± 156.74 (N)) and the mean of ICE light group was (865.18 ± 106.24 (N)). The highest mean fracture resistance was observed in RTD fiberglass and a statistically significant difference was observed between the two groups (P<0.001).   Conclusion: FRC posts with zirconia coating due to unfavorable fractures of the teeth should be used with caution, and thus, fiber posts are preferred

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