Flowable Bulk-fill Composites Research Articles

Kinetic of Light Transmission during Setting and Aging of Modern Flowable Bulk-Fill Composites

Kinetic of Light Transmission during Setting and Aging of Modern Flowable Bulk-Fill Composites

Correlation between Dental Composite Filler Percentage and Strength, Modulus, Shrinkage Stress, Translucency, Depth of Cure and Radiopacity.

Filler content in dental composites is credited for affecting its physical and mechanical properties. This study evaluated the correlation between the filler percentage and strength, modulus, shrinkage stress, depth of cure, translucency and radiopacity of commercially available high- and low-viscosity dental composites. Filler weight percentage (wt%) was determined through the burned ash technique (800 °C for 15 min). Three-point bend flexural strength and modulus were measured according to ISO 4049 with 2 mm × 2 mm × 25 mm bars. Shrinkage stress was evaluated using a universal testing machine in which composite was polymerized through two transparent acrylic rods 2 mm apart. Shrinkage was measured from the maximum force following 500 s. The translucency parameter (TP) was measured as the difference in color (ΔE00) of 1 mm thick specimens against white and black tiles. The depth of cure was measured according to ISO 4049 in a cylindrical metal mold (4 mm diameter) with a 10 s cure. Radiopacity was measured by taking a digital X-ray (70 kVp for 0.32 s at 400 mm distance) of 1 mm thick specimens and comparing the radiopacity to an aluminum step wedge using image analysis software. The correlation between the filler wt% and properties was measured by Pearson's correlation coefficient using SPSS. There was a positive linear correlation between the filler wt% and modulus (r = 0.78, p < 0.01), flexural strength (r = 0.46, p < 0.01) and radiopacity (r = 0.36, p < 0.01) and negative correlation with translucency (r = -0.29, p < 0.01). Filler wt% best predicts the modulus and strength and, to a lesser extent, the radiopacity and translucency. All but two of the high- and low-viscosity composites from the same manufacturer had statistically equivalent strengths as each other; however, the high-viscosity materials almost always had a statistically higher modulus. For two of the flowable composites measured from the same manufacturer (3M and Dentsply), there was a lower shrinkage stress in the bulk-fill version of the material but not for the other two manufacturers (Ivoclar and Tokuyama). All flowable bulk-fill composites achieved a deeper depth of cure than the flowable composite from the same manufacturer other than Omnichroma Flow Bulk.

Comparative evaluations of shear bond strength of mineral trioxide aggregate, Biodentine, and calcium-enriched mixture to bulk-fill flowable composite using three different adhesive systems: An in vitro study

Objective: The objective of the study was to assess the shear bond strength of bulk-fill flowable composite resin smart dentin replacement plus when bonded to mineral trioxide aggregate (MTA)-angelus, biodentine, and calcium-enriched mixture (CEM) at two different aging periods (15 min and 72 h) using three distinct adhesive systems. In addition, the study identified the specific modes of failure (adhesive, cohesive, or mixed) using a stereomicroscope and scanning electron microscope. Materials and Methods: One hundred and twenty-six cylindrical acrylic blocks used in the study were sorted into three groups based on the bioactive substance used to fill the 3-mm diameter and 3-mm high hole in the center of each block. The groups were MTA, Biodentine, and CEM. The specimens were then divided into subgroups based on the aging interval (15 min and 72 h) of the bioactive material and the adhesive system used (two-step total-etch, two-step self-etch [SE], and one-step SE) while bonding to the restorative bulk-fill flowable composite. The shear bond strength values were measured with a universal testing machine, and the data were analyzed using two-way and one-way analysis of variance, followed by a post hoc test. The specimens were assessed under stereomicroscope and scanning electron microscope to characterize the mode of bond failure (cohesive, adhesive, or mixed). Results: The study showed that the type of adhesive system and the time of bonding affected the shear bond strength of bulk-fill composite to the pulp capping agents (P &lt; 0.05). For MTA, the highest bond strength was observed with two-step SE group at 15 min (18.16 ± 2.97 MPa) (P &lt; 0.05). CEM exhibited the highest bond strength with two-step SE group at 72 h intervals (8.77 ± 1.76) (P &lt; 0.05). The highest bond strength for biodentine group was observed with total-etch group (8.54 ± 1.35 Mpa) and two-step SE (8.19 ± 1.94 Mpa) bonded at 72 h interval (P &lt; 0.05). The majority of the samples in the MTA group (29/42) and CEM group (20/42) showed a cohesive fracture, whereas Biodentine group (22/42) had an adhesive fracture in most of its samples. Conclusion: MTA demonstrated the highest bond strength with two-step SE group at 15 min, and CEM exhibited the highest bond strength with two-step SE groups at 72 h interval. For biodentine group, the type of adhesive used did not impact the bond strength values.

Evaluation of surface microhardness and gingival marginal adaptation of three different bulk-fill flowable resin composites: A comparative study.

To evaluate surface microhardness and gingival marginal adaptation of three different bulk-fill flowable resin composites (FB-RBCs) in Class V cavities with enamel or dentin margins before and after thermocycling (TMC). Three available FB-RBCs were used; Palfique Bulk Flow (PaBF) (Tokuyama Dental), SDR Flow+ Bulk Fill Flowable (Dentsply Sirona), and I-Flow Bulk Fill (I-Dental). Thirty discs were prepared from each type of FB-RBCs. The discs were subjected to Vickers microhardness tester machine. Class V cavities were prepared on 180 molars. Gingival margins of half the specimens were prepared above CEJ and the other half below CEJ. Cavities were restored with FB-RBCs for gingival marginal adaptation test. Two-way ANOVA was used in microhardness, while three-way ANOVA was used for marginal adaptation. The used materials showed statistically significant differences in microhardness and marginal adaptation. Regarding microhardness, PaBF showed the highest value before TMC and SDR was the highest after TMC. Regarding marginal adaptation, SDR revealed the best marginal adaptation than PaBF and I-flow, either subjected to TMC or not. The longevity of cervical restorations depend on both the location of the cavity margin and the material used. The microfractures in resin composite surface due to low surface microhardness as well as marginal gaps seen in laboratory studies could be considered as an indicative parameter for clinical problem associated with marginal differences.

The Effect of Gravity on Marginal Integrity of Different Flowable Bulk-Fill Resin Composites.

Background and Objectives: The aim of this quantitative research was to investigate the effect of gravitational forces on the marginal integrity of different bulk-fill composites by micro-CT imaging. Materials and Methods: Fifty caries-free human third molars extracted for prophylactic purposes were used in this study. Each tooth was prepared with two proximal box cavities, with dimensions of 3 mm × 3 mm × 5 mm. Five distinct groups, each comprising 20 cavities, thus totaling 100 cavities for this study: (1, Group CON): Clearfil Majesty Flow + Clearfil Majesty Esthetic (as the control); (2, Group FBR): Filtek Bulk-fill Flowable Restorative + Clearfil Majesty Esthetic; (3, Group XTB): Voco Extrabase + Clearfil Majesty Esthetic; (4, Group SDR): SDR + Clearfil Majesty Esthetic; and (5, Group SNC): Sonicfill. When restoring the mesial cavities, the occlusal surfaces of the teeth in the mold were positioned upwards, counteracting the force of gravity. In contrast, for the restoration of the distal cavities, the occlusal surfaces were aligned downwards, to be parallel with the gravitational pull. After restorative procedures, each tooth was treated with 5000 thermal cycles. A solution of ammoniacal silver nitrate (AgNO3) was employed as a tracing agent. The micro-CT scans were conducted and the total volume of silver nitrate and the total volume of restorations within the relevant region of interest were calculated in "mm3" with software. Two-way ANOVA and Tukey tests were performed at a significance level of p = 0.05 with Graphpad Prism v 8.2.1 software. Results: Both gravity effect and interaction showed no statistical differences (p > 0.05). Statistically significant differences were observed in the restorative materials (p < 0.05). Conclusions: Gravitational forces do not emerge as a major factor affecting the marginal integrity of flowable bulk-fill composites in class II restorations. The chemical composition of the composites plays a more crucial role, with the XTB composite showing higher microleakage ratios compared to the others.

Profiling Elastoplastic and Chemical Parameters to Assess Polymerization Quality in Flowable Bulk-Fill Composites.

In the chronology of polymer-based composite materials, flowable bulk-fill composites represent the most recent development. They enable a significant reduction in treatment time by being applied in larger increments of 4 to 5 mm. The aim of the investigation was to assess the polymerization quality and mechanical performance of a new formulation that has just entered the market and was still in experimental formulation at the time of the investigation, and to compare these results in the context of clinically established materials of the same category. Adequate curing in increments of up to 4 mm could be confirmed both by profiling the elastoplastic material behavior of large increments in 100 µm steps and by real-time assessment of the degree of conversion and the associated polymerization kinetic. A slightly lower amount of filler in the experimental material was associated with slightly lower hardness and elastic modulus parameters, but the creep was similar and the elastic and total indentation work was higher. The kinetic parameters were assigned to the specific characteristics of each tested material. The mechanical macroscopic strength, evaluated in a three-point bending test and supplemented by a reliability analysis, met or exceeded the standards and values measured in clinically established materials, which for all materials is related to the higher flexibility of the beams during testing, while the modulus of elasticity was low. The low elastic modulus of all flowable bulk-fill materials must be taken into account when deciding the clinical indication of this material category.

Alterations in Surface Gloss and Hardness of Direct Dental Resin Composites and Indirect CAD/CAM Composite Block after Single Application of Bifluorid 10 Varnish: An In Vitro Study

The surface characteristics of the restorative material are essential to its longevity. Since resin composites are polymeric-based materials, they could be degraded when exposed to oral conditions and chemical treatment. Certain chemical solutions, such as fluoride varnish, have the potential to deteriorate the resin composite’s surface properties such as gloss and hardness. The current study aimed to assess and compare the surface gloss and hardness of different types of dental resin composites (nanohybrid, ormocer, bulk-fill flowable direct composites, and indirect CAD/CAM resin composite blocks (BreCAM.HIPC)) after a single application of Bifluorid 10 varnish. A total of 80 disc-shaped resin composite specimens were evenly distributed in four groups of 20 specimens. These were divided into two equal subgroups of specimens with topical fluoride (TF) application (n = 10) and without TF application (n = 10). The specimens were examined for surface gloss and hardness. Independent sample t-test was used to investigate statistically the effect of TF on the gloss as well as the hardness of each material. One-way ANOVA and post hoc tests were used to assess the difference in gloss and hardness among the materials without and with TF application. The significance level was adjusted to p ≤ 0.05. The results of gloss showed that the TF application led to a significant reduction in gloss values of all tested composites. The gloss among the various materials was significantly different. The TF had no significant effect on the hardness of nanohybrid, bulk-fill flowable, and BreCAM.HIPC composites (p = 0.8, 0.6, and 0.3, respectively). On the other hand, the hardness of ormocer was significantly reduced after TF application. Comparing the different resin composite materials, the hardness significantly differed. This study concluded that surface gloss and hardness seem to be impacted by the type and composition of the resin composites and vary depending on fluoride application.

Thermal Sensing of Photo-Activated Dental Resin Composites Using Infrared Thermography.

The goal of this study was to compare the pulp temperature increase during light curing of different composite thicknesses in deep class I cavities using two thermal sensing tools. Round occlusal class I cavities with a remaining dentin thickness (RDT) of 1 mm from the cavity floor were performed on 15 extracted sound molars. Samples were divided into three groups (n = 5). In group A, cavities were restored using the Filtek Z350 XT conventional composite through the incremental filling technique, whereas group B cavities were restored using the Filtek Bulk-Fill flowable composite through the bulk-fill technique. Specimens of the Filtek Bulk-Fill flowable composite using the incremental filling technique were used to restore cavities in group C. An infrared thermal camera (IRT; Flir, Wilsonville, OR, USA) and K-type thermocouple (Perfect Prime TC0520, New York, NY, USA) were used to measure the heat generated during composite photo-polymerization. There were no significant differences within the same group using either the thermocouple or IRT (p > 0.05). One-way ANOVA showed no significant differences between groups A and C (p > 0.05), whereas group B was significantly different from groups A and C with each sensing tool (p < 0.05). IRT and thermocouple heat readings were comparable. Based on the current findings, the bulk-fill technique resulted in the lowest heat generation among the groups. Therefore, increasing the light-curing time and the number of composite increments was directly correlated with increases in intra-pulpal temperature.

An Analysis of Water Sorption of Some Composites Used in Dentistry

This study aimed to investigate the water sorption levels of 3 different condensable bulk fill composites, two flowable bulk fill composites, two microhybrid composites, one nanofilled composite, and one nanohybrid composite material polymerized with the same beam device on the 14th and 30th days.We evaluated nine different composite materials. The materials were prepared as cylindrical blocks (n=7) with a diameter of 7 mm and a thickness of 2 mm and polymerized. Each sample was kept in distilled water for specified times and measured by the ISO 4049 method.We used The Kruskal-Wallis test to compare more than two independent groups where numerical variables had no normal distribution. The Dwass-Steel-Critchlow-Fligner test evaluated differences between the groups if the non-parametric tests were applied. We used The Wilcoxon test to compare the numerical variables without normal distribution (water sorption values in the 14th and 30th-day measurements for each cement material).For water sorption, there was no statistically significant difference between the water sorption values of the resin composite materials on the 14th and 30th days. No statistically significant difference was found in comparing water sorption values between the 14th and 30th measurements for each resin composite material. There is a need for more extended studies by keeping the conditions constant for the evaluated composites and for bulk fill composites to be evaluated with 4mm samples.

Comparative evaluation of genotoxicity and cytotoxicity of flowable, bulk-fill flowable, and nanohybrid composites in human gingival cells using cytome assay: An in vivo study.

Biocompatibility is one of the major prerequisites for safe clinical application of materials. Resin composites release their components into oral environment following restoration which cause adverse reactions. To evaluate and compare the genotoxicity and cytotoxicity of flowable, bulk-fill flowable, and nanohybrid composites with glass ionomer cement in human gingival cells using epithelial-based cytome assay. Sixty healthy patients with noncarious cervical lesions were selected and randomly assigned to four groups (n = 15): Group A, glass ionomer cement; Group B, flowable composite; Group C, bulk-fill flowable composite; and Group D, nanohybrid composite. Class V restorations were done in each group with the respective restorative materials. Samples of epithelial cells were collected from gingiva before (control) (T1) and after 10 and 30 days (T2 and T3) postrestoration and examined for the presence of micronuclei and other nuclear anomalies. The results were subjected to statistical analysis using Friedman's test and Kruskal-Wallis test. The highest level of cytotoxicity was noted at T2 time point with a significant decline at T3 time point. Least cytotoxic damage was exhibited by Group A followed by Group D. Highest cytotoxic effect was shown by Group B followed by Group C. There was no significant level of genotoxicity induced by any of the materials tested at different time points. There is significant cytotoxicity induced by the tested composite materials which had no long-term effects and no genotoxicity was induced by any of the restorative materials tested.

Fracture Load of Molars Restored with Bulk-fill, Flowable Bulk-fill, and Conventional Resin Composite After Simulated Chewing.

This study aimed to compare the fracture toughness of molars with wide mesio-occlusal-distal (MOD) cavities restored with regular and flowable bulk-fill resin composite and a conventional resin composite after 250,000 mechanical cycles of chewing simulation. Thirty-two extracted mandibular third molars were selected and class II MOD cavities involving 2/3 of the intercuspal width and 4 mm depth were prepared. Teeth were divided into four groups based on resin composite type and insertion technique (n=8): (1) CT, unprepared teeth (control); (2) CV, conventional resin composite (Tetric N-Ceram, Ivoclar Vivadent) with incremental technique; (3) R-BF, regular bulk-fill resin composite (Tetric N-Ceram Bulk Fill, Ivoclar Vivadent) with a single increment; and (4) F-BF, flowable bulk-fill resin composite (Tetric N-Flow Bulk Fill, Ivoclar Vivadent) with a single increment, except for a 1-mm-thick layer at the occlusal surface, restored with conventional resin composite (Tetric N-Ceram). All specimens were evaluated to detect the presence and propagation of enamel cracks using a LED transilluminator before and after 250,000 mechanical cycles (SD Mechatronic GmbH). After a chewing simulation, they were subjected to a compressive force in a universal testing machine (DL-2000, EMIC) until fracture. The maximum fracture load of the specimens was measured (N) and the fracture patterns were classified based on the fracture site (above or below the cementoenamel junction [CEJ]). Data were statistically analyzed with one-way ANOVA. All specimens survived after 250,000 mechanical cycles, and no statistically significant differences among groups were observed regarding the fracture toughness (p<0.05). The fracture analysis demonstrated that failures below the CEJ were more common in CV (75%), while CT, R-BF, and F-BF showed this type of failure in 38%, 63%, and 63% of the specimens, respectively. The results of the crack analysis showed that the occurrence of new cracks and crack propagation was also higher in CV (33.3%), followed by R-BF, F-BF, and CT (14%, 14%, and 11% of the specimens, respectively). Teeth restored with regular and flowable bulk-fill composites showed similar fracture toughness after the chewing simulation compared to those restored with the conventional resin composite and unprepared teeth. Furthermore, teeth restored with both regular and flowable bulk-fill composites showed a lower incidence of enamel cracks and fractures below the CEJ compared to those restored with the conventional resin composite.

The Repair of Resin-Modified Glass Ionomers with Bulk-Fill Flowable and Packable Composites using the Eight-Generation and Universal Dentin Bonding Agents

Background: To investigate shear bond strength regarding the repair of resin-modified glass ionomers (RMGIs) with bulk-fill flowable and packable composites using eighth-generation and universal dentin bonding agents. Materials and Methods: One-hundred-fifty specimens were prepared using polymethylmethacrylate-resin injected into preformed cylinders. Inverted recessed holes with convergent walls 4 mm deep and 4 mm wide were created using Operative Friction Grip 330L and inverted diamond burs. These holes were used as reservoirs for RMGI II LC. The resulting RMGI specimens were roughened with medium coarse diamond burs and placed in distilled water for 24 hours at 37o C to remove debris. RMGI surfaces were etched with 37% phosphoric acid for 20 seconds, rinsed with copious water, and air-dried without desiccation. Each RMGI specimen was placed in an Ultradent bonding clamp in preparation for adding the tested material. Specimens were divided into 6 groups: (1) Bulk-fill flowable composite (BFF) no adhesive (control), (2) Packable composite (PC) no adhesive (control), (3) BFF + iBond, (4) BFF + Futurabond-DC, (5) PC + iBond, and (6) PC + Futurabond-DC. Shear bond Strength was determined using an Ultra Tester Machine. Results: The SBS among and between groups were statistically assessed with repeated measures multivariate analysis of variance (MANOVA). The Tukey honestly significant difference test with an alpha level of 0.05 was used for post-hoc testing. Repeated measures MANOVA indicated that there were important differences between groups (Wilk’s lambda, P &lt; 0.0001), with BFF + Futurabond-DC resulting in the highest SBS. Conclusion: The study indicates that BFF combined with eighth-generation dentin bonding adhesive is a reliable method for the repair of RMGIs.

Effect of deep margin elevation on fracture resistance of premolars restored with ceramic onlay: In vitro comparative study.

This in vitro comparative study aimed to compare the influence of two levels of deep margin elevation (2 and 3 mm) with either bulk-fill flowable composite or short fiber-reinforced flowable composite on the fracture resistance of maxillary first premolars restored with ceramic onlays. Fifty sound-extracted maxillary first premolar teeth were selected to prepare mesio-occluso-distal cavities with standardized dimensions. The cervical margins were extended 2 mm below the cemento-enamel junction on both mesial and distal sides. These teeth were randomly divided into five groups: Group I: no box elevation (control group). Group II: 2 mm marginal elevation with bulk-fill flowable composite. Group III: 2 mm marginal elevation with short fiber-reinforced flowable composite. Group IV: 3 mm marginal elevation with bulk-fill flowable composite. Group V: 3 mm marginal elevation with short fiber-reinforced flowable composite. After cementation, all teeth were subjected to a fracture resistance test using the universal testing machine, and the mode of failure was analyzed using a digital microscope at 20x magnification. The result showed a non-significant difference in the fracture resistance between 2 and 3 mm marginal elevation (p>0.05) with respect to each restorative material used for deep margin elevation. However, the fracture resistance of teeth elevated with short fiber-reinforced flowable composite was significantly higher than those elevated with bulk-fill flowable composite at both levels 2 and 3 mm, p=0.041 and 0.038 respectively. The fracture resistance of premolars restored with a ceramic onlay was not influenced by the levels of deep margin elevation (2 or 3 mm). However, marginal elevation with short fiber-reinforced flowable composites provided higher fracture resistance than those elevated with bulk-fill flowable composites, and those without marginal elevation. Key words:Fracture Resistance, Short fiber reinforced flowable composite, Bulk-fill flowable composite, Ceramic onlay, Cervical margin elevation.

Effect of dentin roughening and type of composite material on the restoration of non-carious cervical lesions: an in vivo study with 18 months of follow-up.

The purpose of this study was to evaluate the impact of dentin roughening and the type of composite resin used (either bulk-fill flowable or nanohybrid) on the restoration of non-carious cervical lesions (NCCLs) with an 18-month follow-up period. This prospective split-mouth study included 36 patients, each with a minimum of 4 NCCLs. For each patient, 4 types of restorations were performed: unroughened dentin with nanohybrid composite, unroughened dentin with bulk-fill flowable composite, roughened dentin with nanohybrid composite, and roughened dentin with bulk-fill flowable composite. A universal bonding agent (Tetric N Bond Universal) was applied in self-etch mode for all groups. The restorations were subsequently evaluated at 6, 12, and 18 months in accordance with the criteria set by the FDI World Dental Federation. Inferential statistics were computed using the Friedman test, with the level of statistical significance established at 0.05. The 4 groups exhibited no significant differences in relation to fracture and retention, marginal staining, marginal adaptation, postoperative hypersensitivity, or the recurrence of caries at any follow-up point. Within the limitations of the present study, over an 18-month follow-up period, no significant difference was present in the clinical performance of bulk-fill flowable and nanohybrid composite restorations of non-carious cervical lesions. This held true regardless of whether dentin roughening was performed.

Comparative evaluation of fracture resistance of endodontically treated teeth restored with and without horizontal posts, using packable and bulkfill flowable composite: An in vitro study

Comparative evaluation of fracture resistance of endodontically treated teeth restored with and without horizontal posts, using packable and bulkfill flowable composite: An in vitro study

The versatility of flowable composites. Part 2: clinical uses

Flowable composite (FC) is a type of tooth-coloured restorative material with a lower viscosity compared to other types of resin composites. FC is considered as a versatile dental material, with a wide range of application. FCs have progressively gained importance in clinical dentistry. The increase in consumer demand has resulted in a gradual upsurge of dental professionals relying on composites in injectable form. Scientific and technological improvements in their properties and handling characteristics have not only seen FCs grow in popularity, but resulted in the development of different generations and types of dental FCs suitable for use in all cavity types, lining, core build-ups, and most recently, bulk-fill flowable composites. CPD/Clinical Relevance: To provide clinicians with an overview of the indications and clinical applications of the conventional FCs.

Depth of Cure, Hardness, Roughness and Filler Dimension of Bulk-Fill Flowable, Conventional Flowable and High-Strength Universal Injectable Composites: An In Vitro Study.

(1) Objective: To evaluate and compare the depth of cure (DOC) of two bulk-fill flowable composites (Filtek Bulk Fill Flowable Restorative and Tetric EvoFlow Bulk Fill), two conventional flowable composites (Filtek Supreme XTE Flowable Restorative and G-ænial Flo X) and one high-strength universal injectable composite (G-ænial Universal Injectable). (2) Methods: specimens were placed in a stainless-steel mold with an orifice of 4 mm in diameter and 10 mm in depth and light-cured for 20 s using a light emitting diode (LED) light-curing unit (LCU) with an irradiance of 1000 mW/cm2; depth of cure was assessed using the ISO 4049 scrape technique, and the absolute length of the specimen of cured composite was measured in millimeters with a digital caliper. The same procedure was repeated with 14 samples for each material under investigation, for a total number of 70 test bodies. Material roughness and hardness results were also investigated using, respectively, a 3D laser confocal microscope (LEXT OLS 4100; Olympus) at ×5 magnification and a Vickers diamond indenter (Vickers microhardness tester, Shimadzu®, Kyoto, Japan) under 10-N load and a 30 s dwell time. SEM images at 3000 and 9000 magnification were collected in order to study the materials’ filler content. Statistical analysis were performed by a commercial statistical software package (SPSS) and data were analyzed using multiple comparison Dunnett’s test. (3) Results: The average DOC of both bulk-fill composites was more than 4 mm, as a range of 3.91 and 4.53 mm with an average value of 4.24 and 4.12 mm, while that of the conventional flowable composites was much lower, as a range of 2.47 and 2.90 mm with an average value of 2.58 and 2.84 mm; DOC of the high-strength injectable composite was greater than the one of traditional composites, but not to the level of bulk-fill materials, as a range of 2.82 and 3.01 mm with an average value of 3.02 mm. Statistical analysis revealed significant differences (p-values < 0.05) in the depth of cure between bulk fill flowable composites and other composites, while there was no difference (p-values > 0.05) between the materials of the same type. (4) Conclusions: Bulk-fill flowable composites showed significantly higher depth of cure values than both traditional flowable composites and high-strength injectable composites.

Flowable fiber-reinforced versus flowable bulk-fill resin composites: Degree of conversion and microtensile bond strength to dentin in high C-factor cavities.

To compare flowable fiber-reinforced and flowable bulk-fill resin composites regarding their degree of conversion (DC) and microtensile bond strength (μTBS) to dentin in high C-factor class I cavities. One flowable fiber-reinforced (EverX Flow, GC) and two flowable bulk-fill composites (SDR, Dentsply, and Tetric N-flow Bulk fill, Ivoclar Vivadent) were tested. Regarding DC, 10 cylindrical-shaped specimens were prepared from each material (N= 30), measured using Fourier-Transform Infrared Spectroscopy (FTIR). Regarding , class I cavities (4.5× 4.5× 3) were prepared on flat dentin surfaces of 30 molars, divided into three equal groups, restored with the three restorative materials, thermocycled, sectioned to create 1 mm × 1 mm cross-sectional beams, then tested using a universal testing machine. Failure mode was assessed using a stereomicroscope. Two-way ANOVA and Tukey's HSD post-hoc tests were used in DC, while One-way ANOVA was used for . The used materials showed statistically significant differences in DC with the fiber-reinforced composite having the highest value. No statistically significant differences were found between the materials regarding their . Flowable fiber-reinforced composite provided the most DC performance compared to the flowable bulk-fill composites. The three used restorative materials provided comparable bonding ability to dentin in high C-factor cavities. Flowable fiber-reinforced resin composite is preferred as a dentin-replacement material in high-stress bearing areas. However, both flowable fiber-reinforced and bulk-fill resin composites are equally effective in bonding to dentin in high C-factor cavities.

Evaluation of the mechanical behavior of bulk-fill and conventional flowable resin composites using dynamic micro-indentation.

The purpose of this research was to investigate the mechanical behavior of commercially available bulk-fill and conventional flowable resin composites using the dynamic micro-indentation method. The effect of inorganic filler content on mechanical properties was also assessed. Weight percentages of the inorganic filler in the resin composite were measured using the ashing technique. The results showed that dynamic hardness and elastic modulus tended to increase with inorganic filler content. Furthermore, the differences in mechanical properties between top and bottom surfaces were less pronounced in bulk-fill flowable resin composites compared with conventional flowable resin composites. In conclusion, the mechanical properties of bulk-fill flowable resin composites are affected by filler content. Moreover, bulk-fill flowable resin composites have a higher polymerization depth than conventional flowable resin composites when sample thickness is 4 mm.

Comparative Evaluation of Marginal Microleakage Between Bulk-Fill, Preheated Bulk-Fill, and Bulk-Fill Flowable Composite Resins Above and Below Cemento-Enamel Junction Using Micro-Computed Tomography: An In Vitro Study

Objective: The aim of this study was to compare the marginal microleakage between bulk-fill, preheated bulk-fill, and bulk-fill flowable composite resins above and below cemento-enamel junction (CEJ) using micro-computed tomography. Methods: Sixty freshly extracted premolar teeth were prepared with a slot shaped cavities of a total of 120 Class II: 3 mm (bucco-lingual), 2 mm (mesio-distal) with mesial gingival margin located 1 mm coronal to CEJ, and distal gingival margin located 1 mm apical to the CEJ. The samples were randomly divided into two main groups according to the restorative material (Tetric EvoCeram and 3M Filtek), and each group was further sub-divided into three subgroups according to the consistency (bulk fill, preheated bulk fill, and bulk fill flowable). The specimens were thermocycled (500 cycles, 5–55 °C, 30 seconds dwell time) and immersed in a 50% ammonical silver nitrate for 24 hours. Microleakage was evaluated using micro-CT. Data analyzed via three-way ANOVA and random forest model (a machine learning algorithm). Results: There was no statistically significant three-way interaction between type of composite, location of gingival margin related to CEJ, and filling technique (P = 0.103). However, the random forest model (a machine learning algorithm) showed type of composite is the most influential factor. Conclusion: Within the limitations of this study, considering the importance of the type of composite, the teeth restored with preheated bulk fill composite showed decrease in microleakage in comparison with bulk fill flowable composite.