RESUMO
Statement of Problem: A strong bond of fiber post to resin core, as well as to dentin would critically ensure the durability of restorations in endodontically treated teeth
Purpose: The purpose of this study was to evaluate the effect of etch-and-rinse dentin bonding systems on the bond strength between resin core and fiber post after application of 24% hydrogen peroxide
Materials and Method: Twenty-four fiber posts [RTD; St. Egèven, France] were treated with 24% hydrogen peroxide for 10 minutes. They were randomly divided into 4 groups [n=6] based on the bonding agent used: Group P: Prime and Bond, Group O: One Step, Group S: Single Bond and Group E: Excite. Each group was prepared according to the manufacturer's instructions. For all posts, a flowable composite core [?liteFlo, Bisco, USA] were built-up over the bonded area. Each specimen was sectioned to produce 2 sticks, 1mm in thickness and underwent microtensile bond strength [µTBS]. Data were analyzed using one-way ANOVA at the 0.05 level. The fractured surfaces of all sticks were evaluated by stereomicroscope [× 20]. SEM assessment of two sticks from each group was performed to evaluate the surface morphology
Results: The means and SDs of micro TBS were: Group P: 10.95 +/- 1.74; Group S: 10.25 +/- 2.39; Group E: 9.52 +/- 2.07; and Group O: 9.12 +/- 1.34. There was no statistic means and SDs ally significant difference in bond strength means between the groups used [p> 0.05]
Conclusion: The results of this study indicated the bonding agents used had no significant influence on the bond strength of fiber post to composite core
RESUMO
There is a principle rule about marginal seal in durability and clinical success of restorative treatments. Polymerization shrinkage and microleakage are critical limitations of dental composites. The aim of this study was to evaluate the effect of two different curing units on microleakage of class V composite restorations in different conditions. In this in vitro study, class V cavities were prepared on the buccal surfaces of 80 extracted premolar teeth. Conventional halogen curing unit [optilux 501] and high intensity light-emitting-diodes [LEDmetron] were used to polymerize resin composite [Z100] from two distance 2 and 8 mm. Four groups after 24 hours and the other four groups were restored for 3 months in water at 37 degree C, immersed in dye solution and then teeth were sectioned longitudinally and evaluated for dye penetration. Data were statistically analyzed using Kruskal-Wallis and Mann-Withney tests to compare the different groups. Using Kruskal Wallis test, no significant difference in microleakage was demonstrated between the different light cure units in the 8 groups. Mann-Whitney test at the dentin side showed that, QTH could significantly reduce the microleakage compared to LED [p=0.007]. Increase in distance and storage time did not influence the microleakage. At 2 mm distance, the difference between LED and QTH was significant [p=0.038], but no significant difference was seen at 8 mm distance. Increased distance for LED and QTH did not cause any microleakage. According to the results of this study, it can be concluded that the use of turbo light guide in LED would decreases the output of the light. Therefore, QTH system is recommended to be used in shallow cavities