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Background and purpose: Microleakage occurs in posterior composite restorations due to polymerization shrinkage. In recent years low shrinkage silorane-based composites have been introduced to reduce microleakage. The aim of this study was to evaluate the effect of three different restoration techniques on gingival microleakage of a silorane-based composite in class II restorations. Materials and methods: In this experimental study, class II cavities were prepared in mesial and distal surfaces in 40 sound human premolars. The gingival floor was located 1.0mm below the CEJ. Dimension of cavities were 3mm buccolingually and 1.5mm in axial depth of gingival floor. The specimens were randomly divided into 4 groups. Group1 (control) was restored incrementally with silorane based composite (Filtek P90). Group 2, 3 and 4 were restored using glass fiber, flowable composite and resin-modified glass ionomer (RMGI) liners, respectively. After finishing and polishing of the restorations and thermo-cycling, the specimens were immersed in 2% Basic Fuschin for one week. Microleakage was determined under a stereomicroscope (40X). Data was statistically analyzed by Kruskal-Wallis test (P<0.05). Results: The statistical analysis revealed no significant difference in microleakage among study groups (P=0.243). Conclusion: The sealing ability of glass fiber inserts, flowable composite and resin modified glass ionomer liners is not better than that of the silorane-based composite alone in gingival margins of Class II restorations.

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Background and purpose: Deep fissures of occlusal surface in recently erupted first permanent molars are prone to accumulation of bacterial plaque. Sealing these fissures by appropriate flowing materials, as pit and fissure sealants, is a conservative way to prevent caries. The purpose of this study was to compare retention of flowable composite resin by resin modified glass ionomer sealant in six months period.
Materials and methods: The occlusal surfaces of the first permanent mandibular molars of 50 children aged 6 to 12 attending pediatric department in dental school affiliated with Qazvin University of Medical Sciences were assessed via Williams probe, intra-oral mirror, and diagnodent. After confirming absence of caries, flowable composite resin were placed on the left first permanent mandibular molars, and resin modified glass ionomer (RMGI) were placed on the opposite side. After 6 months, 46 patients referred for follow up, in whom the retention of sealants was assessed using sharp explorer and intra-oral mirror, and caries were assessed via diagnodent. Data was analyzed in SPSS20 applying Chi- square test.
Results: The retention of flowable composite (91.3%) was significantly more than that of the resin modified glass ionomer (56.5%) (P<0.05). There were no cases with total loss of material in flowable composite. No caries were observed using the diagnodent.
Conclusion: The flowable composite resin could be used as a fissure sealant agent, due to its greater retention compared to resin modified glass ionomer.
 

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Background and purpose: Antibacterial properties of restorative materials are of great advantage as they control the progression of tooth decay. The use of self-adhesive composite materials has some benefits such as easier application and reduced treatment time. Because the antibacterial properties of restorative materials can play an important role in preventing secondary decay, especially in cervical restorations, this study was designed to evaluate the in vitro antibacterial activity of self-adhesive flowable composite against Streptococcus mutans.
Materials and methods: An in vitro study was performed using 9 discs for each composite and glass ionomer group. The discs were prepared in three groups: micro-hybrid flowable composite samples, self-adhesive flowable composite samples, and self-curing glass ionomer samples. Direct contact test was used to compare the antibacterial properties of the discs. Data collection was done by direct contact test and visual counting of grown bacterial colonies. Data were recorded in a checklist developed according to the objectives of the study and analyzed using One-way ANOVA and Independent T-test in SPSS V22.
Results: Findings showed that the antibacterial effect of glass ionomer was greater than that of flowable micro-hybrid composite and self-adhesive flowable composite. Also, a significant difference was observed between the antimicrobial activity of flowable microhybrid composite and self-adhesive flowable composite against Streptococcus mutans (P<0.05).
Conclusion: Glass ionomer and self-adhesive composite have a higher antibacterial effect against Streptococcus mutans, so they can be used as alternatives to treat tooth decay