Conventional Flowable Composites Research Articles

Evaluation of Marginal Adaptation of a Self-Adhering Flowable Composite Resin Liner: A Scanning Electron Microscopic Study.

Background:“Self-adhering composite resins,” are claimed to eliminate the need for a separate acid etching and bonding agent application step, thus simplifying the direct restorative procedure, both regarding the technique sensitivity and the duration of treatment.Aim:The aim of this study is to evaluate the marginal adaptation of self-adhering flowable composite (Dyad flow) in comparison to the conventional flowable composite (Tetric N-flow) under scanning electron microscope (SEM).Settings and Design:This in vitro study was conducted on 44 extracted human maxillary premolars.Materials and Methods:Box-only Class II cavities on the distal surface were prepared with the dimensions of 4 mm buccolingual width, 2 mm mesiodistal depth, and gingival margin at the cementoenamel junction. They were divided into two groups of 22 teeth each and were restored accordingly: Group I – Gingival floor lined with Tetric N-Flow and were restored with Tetric N-Ceram; Group II – Gingival floor lined with Dyad flow and were restored with Herculite Precis. After thermal cycling, the sectioned tooth-restoration interfaces were evaluated for the marginal adaptation under SEM at ×200 magnification.Statistical Analysis Used:The resultant data were statistically analyzed by applying Chi-square test, using the SPSS (version 16.0) software.Results and Conclusion:There was no statistically significant difference between the study groups regarding the marginal adaptation. The marginal adaptation of the self-adhering flowable composite when used as a liner in Class II restorations was comparable to that of the conventional flowable composite.

Genotoxic potential of dental bulk-fill resin composites

ObjectiveTo investigate both genotoxicity and hardening of bulk-fill composite materials applied in 4-mm layer thickness and photo-activated for different exposure times. MethodsThree flowable bulk-fill materials and one conventional flowable composite were filled in molds (height: 4mm) and irradiated for 20 or 30s. The top (0mm) and bottom (4mm) specimen surface were mechanically scraped, and eluates (0.01g composite in 1.5ml RPMI 1640 cell culture media) prepared for each material, surface level and irradiation time. Genotoxicity was assessed in human leukocytes using both the alkaline comet assay and cytokinesis-blocked micronucleus assay, and Knoop hardness (KHN) was measured at the top and bottom specimen surface (n=8). ResultsAt both irradiation times, none of the bulk-fill composites significantly affected comet assay parameters used in primary DNA damage assessment or induced significant formation of any of the scored chromatin abnormalities (number of micronuclei, nuclear buds, nucleoplasmic bridges), whether eluates were obtained from the top or bottom surface. Furthermore, no decrease in KHN from the top to the bottom surface of the bulk-fill materials was observed. On the other hand, the conventional composite irradiated for 20s showed at 4-mm depth a significant increase in the percentage of DNA that migrated in the tail and a significant increase in the number of nuclear buds, as well as a significant decrease in KHN relative to the top surface. SignificanceBulk-fill resin composites, in contrast to conventional composite, applied in 4-mm thickness and photo-activated for at least 20s do not induce relevant genotoxic effects or mechanical instability.

Characteristics of low polymerization shrinkage flowable resin composites in newly-developed cavity base materials for bulk filling technique.

The purpose of this study was to evaluate polymerization shrinkage and other physical properties of newly-developed cavity base materials for bulk filling technique, with the brand name BULK BASE (BBS). Polymerization shrinkage was measured according to ISO/FDIS 17304. BBS showed the significantly lowest polymerization shrinkage and significantly higher depth of cure than conventional flowable resin composites (p<0.05). The Knoop hardness, flexural strength and elastic modulus of that were significantly lower than conventional flowable resin composites (p<0.05). BBS had the significantly greatest filler content (p<0.05). SEM images of the surface showed failure of fillers. The lowest polymerization shrinkage was due to the incorporation of a new type of low shrinkage monomer, which has urethane moieties. There were no clear correlations between inorganic filler contents and polymerization shrinkage, flexural strength and elastic modulus. In conclusion, the low polymerization shrinkage of BBS will be useful for cavity treatment in dental clinics.

Comparison of traditional and simplified methods for repairing CAD/CAM feldspathic ceramics.

PURPOSETo evaluate the adhesion to CAD/CAM feldspathic blocks by failure analysis and shear bond strength test (SBSt) of different restorative systems and different surface treatments, for purpose of moderate chipping repair.MATERIALS AND METHODSA self-adhering flowable composite (Vertise Flow, Kerr) containing bi-functional phosphate monomers and a conventional flowable resin composite (Premise Flow, Kerr) applied with and without adhesive system (Optibond Solo Plus, Kerr) were combined with three different surface treatments (Hydrofluoric Acid Etching, Sandblasting, combination of both) for repairing feldspathic ceramics. Two commercial systems for ceramic repairing were tested as controls (Porcelain Repair Kit, Ultradent, and CoJet System, 3M). SBSt was performed and failure mode was evaluated using a digital microscope. A One-Way ANOVA (Tukey test for post hoc) was applied to the SBSt data and the Fisher's Exact Test was applied to the failure analysis data.RESULTSThe use of resin systems containing bi-functional phosphate monomers combined with hydrofluoric acid etching of the ceramic surface gave the highest values in terms of bond strength and of more favorable failure modalities.CONCLUSIONThe simplified repairing method based on self-adhering flowable resin combined with the use of hydrofluoric acid etching showed high bond strength values and a favorable failure mode. Repairing of ceramic chipping with a self-adhering flowable resin associated with hydrofluoric acid etching showed high bond strength with a less time consuming and technique-sensitive procedure compared to standard procedure.

COMPARISON OF DEGREE OF CONVERSION AND MICROLEAKAGE IN BULKFILL FLOWABLE COMPOSITE AND CONVENTIONAL FLOWABLE COMPOSITE(AN IN VITRO STUDY)

INTRODUCTION: Composite restorative materials represent one of the many successes of modern biomaterials research, since they replace biological tissue in both appearance and function. Several aspects during selection of composite restorative materials should be considered, among which are the degree of conversion and microleakage. OBJECTIVES: The objective of this study is to compare the degree of conversion and microleakage in bulkfill flowable and conventional flowable composite. MATERIALS AND METHODS: Bulk-fill flowable composites (SDR, Dentsply), (Filtek Bulkfill flowable, 3M ESPE) and conventional flowable composite (X-Flow, Dentsply), (Filtekz350xt flowable, 3M ESPE) were tested. 28 cylindrical specimens were prepared from each material in Teflon mold. Degree of conversion (DC) was determined using Fourier transform infrared spectroscopy (FTIR) test. 44 non-carious molars were selected and Class V cavities were made and filled with composite in bulk increment then immersed in a basic fuschine dye. Samples were sectioned in the center of the restoration and observed with a 40x stereomicroscope; extent of dye penetration was measured. Statistical analysis of the results was performed using ANOVA and Post Hoc for DC, Kruskall-Wallis and Mann Whitney test for microleakage. RESULTS: A statistically significant difference was recorded for the degree of conversion test between the groups with p (<0.001). Microleakage test showed no statistically significant difference between the four groups at occlusal margins with p=0.563, nor at the cervical margins with p=0.243. CONCLUSIONS: Within the limitations of the current study, it was concluded that the bulkfill flowable composite (SDR) had better DC in comparison to the other three flowable composites used in the study. It was also concluded that it had the best marginal seal in both occlusal and cervical margin among all the groups.

Degree of Conversion and BisGMA, TEGDMA, UDMA Elution from Flowable Bulk Fill Composites.

The degree of conversion (DC) and the released bisphenol A diglycidyl ether dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) monomers of bulk-fill composites compared to that of conventional flowable ones were assessed using micro-Raman spectroscopy and high performance liquid chromatography (HPLC). Four millimeter-thick samples were prepared from SureFil SDR Flow (SDR), X-tra Base (XB), Filtek Bulk Fill (FBF) and two and four millimeter samples from Filtek Ultimate Flow (FUF). They were measured with micro-Raman spectroscopy to determine the DC% of the top and the bottom surfaces. The amount of released monomers in 75% ethanol extraction media was measured with HPLC. The differences between the top and bottom DC% were significant for each material. The mean DC values were in the following order for the bottom surfaces: SDR_4mm_20s > FUF_2mm_20s > XB_4mm_20s > FBF_4mm_20s > XB_4mm_10s > FBF_4mm_10s > FUF_4mm_20s. The highest rate in the amount of released BisGMA and TEGDMA was found from the 4 mm-thick conventional flowable FUF. Among bulk-fills, FBF showed a twenty times higher amount of eluted UDMA and twice more BisGMA; meanwhile, SDR released a significantly higher amount of TEGDMA. SDR bulk-fill showed significantly higher DC%; meanwhile XB, FBF did not reach the same level DC, as that of the 2 mm-thick conventional composite at the bottom surface. Conventional flowable composites showed a higher rate of monomer elution compared to the bulk-fills, except FBF, which showed a high amount of UDMA release.

Evaluation of Radiopacity of Bulk-fill Flowable Composites Using Digital Radiography.

New flowable composites that may be bulk-filled in layers up to 4 mm are indicated as a base beneath posterior composite restorations. Sufficient radiopacity is one of the several important requirements such materials should meet. The aim of this study was to evaluate the radiopacity of bulk-fill flowable composites and to provide a comparison with conventional flowable composites using digital imaging. Ten standard specimens (5 mm in diameter, 1 mm in thickness) were prepared from each of four different bulk-fill flowable composites and nine different conventional flowable composites. Radiographs of the specimens were taken together with 1-mm-thick tooth slices and an aluminum step wedge using a digital imaging system. For the radiographic exposures, a storage phosphor plate and a dental x-ray unit at 70 kVp and 8 mA were used. The object-to-focus distance was 30 cm, and the exposure time was 0.2 seconds. The gray values of the materials were measured using the histogram function of the software available with the system, and radiopacity was calculated as the equivalent thickness of aluminum. The data were analyzed statistically (p<0.05). All of the tested bulk-fill flowable composites showed significantly higher radiopacity values in comparison with those of enamel, dentin, and most of the conventional flowable composites (p<0.05). Venus Bulk Fill (Heraeus Kulzer) provided the highest radiopacity value, whereas Arabesk Flow (Voco) showed the lowest. The order of the radiopacity values for the bulk-fill flowable composites was as follows: Venus Bulk Fill (Heraeus Kulzer) ≥ X-tra Base (Voco) > SDR (Dentsply DeTrey) ≥ Filtek Bulk Fill (3M ESPE). To conclude, the bulk-fill flowable restorative materials, which were tested in this study using digital radiography, met the minimum standard of radiopacity specified by the International Standards Organization.

Evaluation of Er,Cr:YSGG Laser Effect on Microshear Bond Strength of a Self-Adhesive Flowable Composite in the Dentin of Permanent Molar: An In Vitro Study

Aim and Background. Recently, new restorative materials such as self-adhesive flowable composites, because of their simple use and no need to bonding and etching, are considered important, particularly in pediatric dentistry. The aim of this study is to evaluate the effect of Er,Cr:YSGG laser on microshear bond strength of self-adhesive flowable composite on permanent teeth dentin in vitro. Material and Methods. In this experimental study, 40 dentin sections were prepared from healthy third molars and divided into two groups according to their surface preparation by Er,Cr:YSGG laser or without laser, only with silicon carbide paper. In each group, two groups of 10 teeth were treated with self-adhesive flowable composite (Dyad) and conventional flowable composite (acid etch and bonding). Samples were stored in normal saline and after 48 hours their bond strength was measured. The failure mode of samples was observed on stereomicroscope. In order to analyse the results, the one way ANOVA and Tukey's test for multiple comparisons were used. Result. The maximum bond strength was related to conventional flowable composite with laser preparation group (24/21 Mpa). The lowest one was seen in Dyad composite without laser emitting (9/89 Mpa). The statistical difference between this two groups was significant (P value = 0/0038). The microshear bond strength differences between Dyad composite groups with laser preparation (mean = 16/427 ± 1/79) and without laser preparation (mean = 12/85 ± 1/90) were statistically significant too (P value = 0/01). Conclusion. Self-adhesive flowable composite has lower microshear bond strength than conventional flowable composite. Moreover, the laser irradiation as a surface treatment can improve this bond strength.

Comparative evaluation of shear bond strength and nanoleakage of conventional and self-adhering flowable composites to primary teeth dentin.

Background:The latest advancement in adhesive dentistry is the development of self adhering flowable composite resin which incorporates the self-etch adhesion technology to eliminate the steps of etching, rinsing, priming and bonding. Few studies have addressed resin bonding to primary teeth.Aim:The aim of this study was to compare the shear bond strength and nanoleakage of conventional and self adhering flowable composites to primary teeth dentin.Settings and Design:This study was conducted in the Department of Pedodontics and Preventive Dentistry, I.T.S Dental College, Hospital and Research Centre, Greater Noida; in association with the Department of Mechanical Engineering, I.T.S Engineering College, Greater Noida; and the Advanced Instrumentation Research Facility (AIRF), Jawaharlal Nehru University, New Delhi.Materials and Methods:Sixty of the ninety primary teeth were evaluated for shear bond strength and thirty for nanoleakage. The samples were divided into three groups; Group I – Dyad Flow (Kerr), Group II – Fusio Liquid Dentin (Pentron Clinical Technologies) and Group III – G-aenial Universal Flo (GC). Shear bond strength was determined using a universal testing machine. Nanoleakage pattern was observed under scanning electron microscope.Results:The shear bond strength of conventional flowable composite was significantly greater than self adhering flowable composite (p<0.05). Nanoleakage scores of both conventional and self adhering flowable composites were comparable.Conclusions:Self adhering flowable composites combine properties of composites and self etch adhesives, eliminating the need for separate bond application that simplifies direct restorative procedure. The evolution of self adhering materials could open new horizons for pediatric dentistry.

The effect of bulk-fill flowable composites on the fracture resistance and cuspal deflection of endodontically treated premolars

The aim of this study was to evaluate the effect of bulk-fill flowable composites on cuspal deflection and fracture resistance of endodontically treated teeth. Forty-two maxillary premolars were subjected to endodontic treatment followed by the preparation of mesioocclusodistal cavities. Teeth were divided into six groups according to restorative materials as follows: Group 1: Clearfil Majesty Flow and Clearfil Majesty Posterior; Group 2: Venus Bulk Fill and Clearfil Majesty Posterior; Group 3: Clearfil Majesty Posterior; Group 4: Vertise Flow and Clearfil Majesty Posterior; Group 5: SDR and Clearfil Majesty Posterior; and Group 6: x-tra base and Clearfil Majesty Posterior. A single-step self-etch adhesive (OptiBond All-in-One) was applied to all groups, except Group 4. The cavities were restored with a centripetal incremental insertion technique and flowable composites using a 2-mm-thick base material, except for Group 3. The distance between cusp tips was measured before and after the cavity preparations, after the restorations, and after thermal cyclus with a digital micrometer. After measuring, each tooth was subjected to compressive loading with a stainless steel ball (4 mm diameter) perpendicular to the occlusal surface with a crosshead speed of 1 mm/min, and mean loads necessary to fracture were recorded in Newtons. The data were statistically analyzed by Kruskal–Wallis test. No statistically significant differences were found between groups in fracture strength or cuspal deflections (p > 0.05). Bulk-fill flowable composite bases did not change the cuspal deflection or fracture resistance of endodontically treated teeth, compared with that of a conventional flowable base and conventional resin composite.

Evaluation of bond strength of splinting materials to the teeth using three adhesive systems-an in vitro study

Aim: To evaluate the bond strength of two splinting materials (orthodontic wire and ribbond) to the tooth structure using cyanoacrylate (CA) ester, self-adhering flowable composite (Vertise flow) and conventional flowable composite as adhesives. Materials and Methods: A total of 120 human central incisors free of any carious lesions were selected for the study. To obtain the specimens, 120 human central incisors were embedded in the blocks of rapid polymerizing self-cure acrylic resin with two teeth each. The specimens were divided into six groups with ten specimens each. Group I-Orthodontic wire bonded with CA, Group II-Orthodontic wire bonded with flowable composite Group III-Orthodontic wire bonded with Vertise flow, Group IV-Ribbond bonded with CA, Group V-Ribbond bonded with flowable composite and Group VI-Ribbond bonded with Vertise flow. The adhesive force in newtons to debond the splinting material was measured in tension using universal testing machine. The force at which the splint system failed was noted. The data obtained were statistically analyzed using one-way ANOVA and significant differences were subjected to Tukey's post-hoc test at a confidence interval of 0.05. Results: Bond strength with the orthodontic wire groups was significantly less compared with Ribbond groups p Conclusion: Orthodontic wire groups demonstrated significantly lower bond strength compared to ribbond groups. Among the adhesives CAs showed significantly lower bond strength compared to Vertise flow and conventional flowable composite.

Physico-mechanical characteristics of commercially available bulk-fill composites

ObjectivesBulk-fill composites have emerged, arguably, as a new “class” of resin-based composites, which are claimed to enable restoration in thick layers, up to 4mm. The objective of this work was to compare, under optimal curing conditions, the physico-mechanical properties of most currently available bulk-fill composites to those of two conventional composite materials chosen as references, one highly filled and one flowable “nano-hybrid” composite. MethodsTetric EvoCeram Bulk Fill (Ivoclar-Vivadent), Venus Bulk Fill (Heraeus-Kulzer), SDR (Dentsply), X-tra Fil (VOCO), X-tra Base (VOCO), Sonic Fill (Kerr), Filtek Bulk Fill (3M-Espe), Xenius (GC) were compared to the two reference materials. The materials were light-cured for 40s in a 2mm×2mm×25mm Teflon mould. Degree of conversion was measured by Raman spectroscopy, Elastic modulus and flexural strength were evaluated by three point bending, surface hardness using Vickers microindentation before and after 24h ethanol storage, and filler weight content by thermogravimetric analysis. The ratio of surface hardness before and after ethanol storage was considered as an evaluation of polymer softening. Data were analyzed by one-way ANOVA and post hoc Tukey's test (p=0.05). ResultsThe mechanical properties of the bulk-fill composites were mostly lower compared with the conventional high viscosity material, and, at best, comparable to the conventional flowable composite. Linear correlations of the mechanical properties investigated were poor with degree of conversion (0.09<R<0.41) and good with filler content (R>0.8). Softening in ethanol revealed differences in polymer network density between material types. ConclusionThe reduction of time and improvement of convenience associated with bulk-fill materials is a clear advantage of this particular material class. However, a compromise with mechanical properties compared with more conventional commercially-available nano-hybrid materials was demonstrated by the present work. SignificanceGiven the lower mechanical properties of most bulk-fill materials compared to a highly filled nano-hybrid composite, their use for restorations under high occlusal load is subject to caution. Further, the swelling behaviour of some of the bulk-fill materials may be a reason for concern, which highlights the critical requirement for a veneering material, not only to improve aesthetic quality of the translucent material, but to reduce the impact of degradation.

In vitro bonding effectiveness of new self-adhering flowable composite to calcium silicate-based material

The purpose of this study was to compare in vitro bonding effectiveness of Vertise Flow (VF), a new self-adhering flowable composite (FC), and Ultimate Flow (UF), a conventional FC, to BioAggregate (BA), and to investigate whether the use of self-etch or etch-andrinse adhesive improved the bond strength of VF to BA. Shear bond strengths of FC to BA were measured for this reason. Data were analyzed using Wilcoxon and Mann-Whitney U-tests (p=0.05). There were significant differences of bond strengths after 24- and 72-h (p<0.05, p<0.001). After 72-h, self-adhering FC may be used successfully with BA and no other adhesive, as an alternative to the combined use of conventional FC and self-etch adhesives. The use of etch-and-rinse adhesives with self-adhering FC may improve adhesion to BA.

Contraction stress, elastic modulus, and degree of conversion of three flowable composites

The aim of this study was to measure the contraction stress of three flowable resin composites and to correlate the stress with the elastic modulus and the degree of conversion. One low-shrinkage (Venus Diamond Flow) and two conventional (Tetric EvoFlow and X-Flow) flowable composites were polymerized for 40s with a light-emitting diode (LED) curing unit. Contraction force was continuously recorded for 300s using a stress-analyser, and stress values were calculated at 40s and at 300s. The maximum stress rate was also calculated for each specimen. The elastic modulus of each composite was assayed using a biaxial flexural test, and degree of conversion was analysed with Raman spectroscopy. X-Flow exhibited higher stress values than the other tested materials. Venus Diamond Flow showed the lowest stress values at 40s and at 300s, and the lowest maximum stress rate. Stress values were correlated with elastic modulus but not with degree of conversion, which was comparable among all tested materials.