Background and Aim: Because of polymerization shrinkage and high viscosity of posterior composites, there are some difficulties in using them in posterior restorations. Several methods have been represented to reduce the effect of shrinkage. The aim of this study was to investigate the effect of curing flowable composites under condensable ones in adaptation and microleakage reduction of posterior composite restorations.Materials and Methods: In this experimental in vitro study, forty class II MO cavities were prepared on extracted intact molar and premolar human teeth. Gingival margins were placed 1 mm apical to CEJ. The teeth were divided into two groups. In group 1, flowable composite (Filek Flow, 3M, ESPE, USA) with 0.5-1 mm thickness was applied and cured following application of bonding agent (Single Bond, 3M, ESPE, USA). The rest of the cavity was filled by condensable composite (p60, 3M, ESPE, USA). In group 2 the flowable composite was not cured, and the condensable composite was applied in two increments. After light curing of composites, all the specimens were thermocycled and then immersed in 0.3% basic fuschin. Specimens were sectioned and evaluated for degree of dye penetration under a stereomicroscope. Data were analyzed by Mann-Whitney test with p<0.05 as the level of significance.Results:. There was no significant difference between the two studied groups regarding microleakage. Conclusion: Based on the results of this study, neither cured nor uncured flowable composite under condensable composite can omit microleakage in posterior composite restorations.

Objectives: This study aimed to compare the shear bond strength (SBS) of self-adhesive and conventional flowable composites and resin-modified glass-ionomer cement (RMGIC) to primary dentin. Materials and Methods: In this in vitro, experimental study, the buccal surface of 48 primary canine and first molar teeth was longitudinally sectioned to expose dentin. The teeth were randomly divided into three groups (n=16) of 37. 5% phosphoric acid+ OptiBond+ Premise Flow composite (group 1), Vertise Flow composite (group 2) and RMGIC (group 3). A plastic cylindrical mold was placed on the exposed dentin and filled with restorative materials. The samples were then immersed in distilled water at 37° C for 24 hours, subjected to 1000 thermal cycles between 5-55° C and underwent SBS test. The mode of failure was determined under a stereomicroscope. Data were analyzed using one-way ANOVA and Tukey’ s test. Results: A significant difference was noted in SBS of the groups (P<0. 05). The SBS of conventional flowable composite was significantly higher that of RMGIC and self-adhesive flowable composite (P<0. 05). The difference in SBS of RMGIC and self-adhesive flowable composite was not significant (P>0. 05). Failure at the dentin-restoration interface (adhesive failure) had the highest frequency in groups 1 and 2. The frequency of adhesive failure was 100% in group 3. Conclusions: Within the limitations of this study, the conventional flowable composite yielded the highest SBS to primary dentin. Self-adhesive flowable composite and RMGIC showed the lowest SBS with no significant difference with each other.

Background and Objectives: In most instances, it is necessary to restore endodontically treated teeth by a simple method, with low cost in a short time. The purpose of this study was to evaluate the effect of flowable composite in fracture resistance of endodontically treated maxillary premolars restored with composite.Method and Materials: In this in vitro study, 48 sound human maxillary premolars, extracted for orthodontic reasons closed apex, were randomly divided into 3 groups of 16. In groups 2, 3 after preparation of the standard access cavity and endodontic treatment, the palatal cusp was reduced to 1.5 mm coronal to the CEJ, leaving the remaining buccal cusp 3mm in buccolingual thickness at the height of contour and similar thickness in CEJ. Samples were prepared as follows: intact (unprepared) teeth (Group 1), composite restoration. Without flowable composite (Group 2), composite restoration with 2 mm thickness of flowable composite (Group 3). After therrnocycling, each tooth was loaded in compression until fracture occured. Data were analyzed with one-way ANOVA and Tukey test. The pattern of fracture was analyzed by Chi- Square test.Results: The mean fracture resistance in groups 1-3 were 689.59±179, 632.86±119 and 583.92 ±186 (in N) respectively. The differences between groups were not statistically significant (p>0.05). The maximum number of favorable fractures occurred in group I. There were greater number of unfavorable fracture in groups 2 and 3.Conclusion: Composite restoration of endodontically treated maxillary premolars had satisfactory results. Flowable composite had no significant effect on fracture resistance of teeth and did not result in favorable fracture.

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.

Objectives: The durability of composite restorations is directly affected by the mechanical properties of the composite. The aim of this study was to evaluate the hardness and wear resistance of self-adhesive flowable composite (SAF) in comparison with conventional flowable composites. Materials and Methods: In this in vitro study, 50 composite specimens were prepared in brass molds with 10mm ×10mm ×2mm and divided into five groups (n=10). Specimens included three conventional flowable composites (Grandio flow, Filtek flow and Admira fusion flow), one self-adhering flowable composite (SAF, Vertise flow) and a microhybrid composite (filtek z250). After polishing, the micro-hardness of the specimens was measured in a Vickers hardness device, and the specimens were then subjected to 5000, 10000, 20000, 40000, 80000 and 120000 wear cycles in a wear tester. One-way ANOVA/Games-Howell, Kruskal Wallis, and Friedman tests were used for statistical analysis. The significance level was set at P<0. 05. Results: The surface micro-hardness of the SAF was significantly lower than that of the microhybrid composite (P=0. 01). There was no significant difference between the surface hardness of the different tested flowable composites (P>0. 05). Also, the wear resistance of the studied composites was not significantly different in various cycles (P>0. 05). Conclusion: Based on our results, SAF would not be an ideal substitute for conventional flowable composites in high-stress areas.

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.

Introduction: Due to high viscosity, adaptation of packable composite to cavity walls is doubtful. This study investigates the effect of flowable composite liner on the dentinal bond strength of packable composite after thermal and mechanical cycling and its comparison with hybrid composites.Materials & Methods: In this experimental study, Single Bond was applied on the dentinal surface of 30 third molars. The teeth were randomly divided into three groups: In group I, P60 with Filtek Flow, in Group II, composite P60 alone, and in Group III, composite Z100 were used. After thermocycling, each group was randomly divided into two sub-groups (control and experimental) and only experimental subgroups were tested under load cycling (50 Newton, 100000 load cycles). Microtensile bond strength of all samples was measured and the failure mode was examined with a stereomicroscope. The results were statistically analyzed by Kurskal Wallis, Mann Whitney and Fisher’s Exact test.Results: Before load cycling, the mean bond strength and standard deviation of group 1 was 25.49±2.35, group 2 was 35.63±3.57 and group 3 was 30.61±5.56 MPa, which was statistically significant (P<0.05). After load cycling, the mean bond strength and standard deviation of group 1 was 24.37±1.42, group 2 was 31.36±2.63 and group 3 was 26.87±9.16 MPa. The difference was not statistically significant. The difference between control and experimental groups was not statistically significant in any of the materials.Conclusion: Flowable composite liner was not effective on the bond strength of packable composite to dentin and it was the same as hybrid composite pre and post cycling.

Background and Aim: Novel dental materials including nanocomposites have been introduced in recent years. It is claimed that they have superior properties such as high esthetic, low wear, increased filler content resulting in better mechanical properties, and releasing ions i.e. fluoride and amorphous calcium phosphate that are important for enamel remineralization. Considering these features, if they have retention and microleakage rates comparable with conventional sealants, these materials can be appropriate alternatives to conventional resin sealants in future.The current study aimed at comparing. microleakage of a flowable nanocomposite, a flowable composite, and a conventional sealant in fissure sealant therapy of the permanent teeth.Materials and Methods: First of all, 42 extracted sound human maxillary first premolars were collected and were randomly divided into 3 equal groups. Then the teeth were embedded in self-cure acrylic resin. Occlusal fissures of the samples were cleaned using explorer, enameloplasty with 1/4 round diamond bur and water/air spray was done. The prepared surfaces were etched using 36% phosphoric acid gel for 15s, rinsed and dried. Bonding agent was placed in the pits and fissures, cured for 10s after thinning with air. In the first, second, and the third group conventional sealant, flowable composite, and flowable nanocomposite were placed, respectively; and light cured for 40s. The samples were thermocycled (1000 cycles between 5-55oC) and then immersed in 2% basic Fuchsine solution for 24hs. They were then cut bucculingually and microleakage evaluation was done using stereomicroscope. The obtained data was analyzed using Kruskal wallis tests.Results: There was no significant difference in microleakage rate of the study groups. (P>0.05).Conclusion: Considering the condition of the study, it can be concluded that flowable composite and flowable nanocomposite can be used as suitable alternatives to conventional sealants in fissure sealant therapy of the permanent teeth.