Background. Adhesive resin is increasingly used as a modeling liquid for composite. Based on previous studies, elution of some components from the composite mass negatively affects the oral tissues. Since few studies have focused on the effect of adhesive resin on composite mass, this study aimed to investigate the effect of dental adhesion factors as modeling liquid on the elution of substances from composite restorations. Materials and Methods. Sixty-four composite specimens (6 × 2 mm diameter × height) were prepared in four groups (n = 16) by using a Teflon ring. Composite mass was incrementally applied in four layers (0.5 mm). The control group contained no material between the layers, but other groups had one of the single bond, SE bond, and wetting resin adhesives between the layers. Specimens were immersed in distilled water and methanol. The amount of released triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), and camphorquinone (CQ) was monitored by gas chromatography after 24 hours and 7 days. Data were analyzed with SPSS software through Kruskal–Wallis and Mann–Whitney
U
tests (α = 0.05). Results. The highest rate of released TEGDMA comonomer was seen in the wetting resin group in the water medium. The highest rate of released UDMA monomer was seen in SE bond and wetting resin groups in the methanol medium after 24 hours. The highest amount of released CQ in the methanol medium was observed in the SE bond group after 7 days. Conclusion. Single bond adhesive can be used as modeling liquid since it has no significant effect on the elution of components from composite mass. Whereas, wetting resin and SE bond adhesives are not suitable to be used as modeling liquid due to the high amounts of released TEGDMA and UDMA.
Introduction: Hardness is one of the basic properties of dental materials, specially composite resins which is relevant to their polymerization. The aim of this study was to evaluate the effect of light curing distance and the color of clear Mylar strips on surface hardness of Silorane-based (SCR) and Methacrylate-based composite resins (MCR).Materials and methods: 40 samples of MCRs (Filtek Z250) and SCRs (Filtek P90) were prepared in size of 5 mm×2 mm (80 samples in total). The samples divided into 8 groups (10 samples in each one) based on the color of clear Mylar strips (white or blue) and distance from light curing source (0 mm or 2 mm). All the samples cured for 40 second and stored in incubator for 24 hours in 37°C temperature. Surface hardness test was done by Vickers test machine and the collected data were analyzed by one-way ANOVA and paired T-test by using SPSS software version 13 at significant level of 0.05.Results: MCRs cured with blue Mylar strips from 0 mm distance had the highest (114.5 kg/mm2) and SCRs cured with white Mylar strips from 2 mm distance had the lowest (42.2 kg/mm2) mean of surface hardness. Also, the results of comparison among SCRs and MCRs showed significant differences among all groups (all P values <0.01).Conclusion: The hardness decreased as the distance increased and the blue Mylar strips provided higher hardness than clear ones. Also, Filtek Z250 showed higher hardness compared to Filtek P90.
Introduction
The success of bonded restorations depends on effective bonding between restorative materials and tooth structure, and it prevents microleakage. New dentin bonding systems have been introduced which promotes this concept. The aim of this study was to compare the amount of microleakage between ‘single bond’ vs ‘Prompt L-Pop’ during different time periods.
Materials and methods
In this clinical trial study, 60 nonretentive class five cavities were prepared on buccal surfaces of human premolars which were scheduled to be removed for orthodontic purposes. The cavities were restored using two different bonding agents; fifth generation (Single Bond) and sixth generation (Prompt L-Pop) and then filled with resin composite (Filtek Z-250). The samples in both groups were extracted after placing the restoration in three periods of time: Immediately, 1 week and 6 months postplacement. Specimens were sealed with two layers of nail varnish except for 1 mm around restoration and immersed in a silver nitrate solution for 24 hours. The teeth were then sectioned longitudinally and the degree of microleakage was determined by stereomicroscope based on standard usual criteria.
Results
Single bond showed more leakage at dentin margin than enamel margin in all three extraction periods and differences were significant among three groups (p < 0.05). In samples which were restored with Prompt L-Pop only in groups of 6 months there were significant differences between enamel and dentin margins. At enamel margin there were no significant differences between microleakage of groups according to the passage of time (p > 0.05).
Conclusion
The results of this study using two different bonding systems, indicate that adhesion to enamel was more valuable than dentin and perhaps systems that include self-etching primers are less sensitive to remaining moisture on dentin and they are less affected during different time periods.
How to cite this article
Samimi P, Barekatain M, Alaei S. Comparison of Microleakage of Composite Restorations using Fifth and Sixth Generation Dentin Bonding Agent: An in vivo Study. J Contemp Dent Pract 2012;13(5):632-636.
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