High-viscosity Bulk-fill Composites Research Articles

Marginal Adaptation of In Vitro Class II Restorations Made Out of Bulk or Conventional Composite Using Single- or Multi-Layered Techniques.

Objective: Testing the influence of various restorative materials (conventional or bulkfill composites) and filling techniques (single- or multi-layered techniques) on the in vitro marginal adaptation of large class II direct composites with supra and sub-gingival margins subjected to thermomechanical loading (TML). Methods: A total of 40 prepared teeth were attributed randomly to five experimental groups. In Group 1, restorations were made of multi-layered high-viscosity conventional composite (Tetric EvoCeram); in Groups 2 and 3, restorations were made of a high viscosity bulkfill composite (Tetric EvoCeram Bulk Fill) applied in one (Group 2) or three layers (Group 3); in Groups 4 and 5, restorations were made of a flowable bulkfill composite (SDR flow) applied in one (Group 4) or two layers (Group 5), covered with a layer of high-viscosity conventional composite (Ceram-X Universal). A single adhesive (OptiBond FL) was used in all groups. All specimens were submitted to a staged TML comprising three phases (2 × 500,000 and 1,000,000 cycles) at 50 N with 3350 thermal cycles (5 to 55 °C) every 500,000 cycles. The tooth-restoration interfaces on proximal surfaces were evaluated quantitatively by scanning electron microscopy, before and after each TML phase, hence at three timepoints (T0, T1, T2 and T3). The following segments were considered for evaluation: proximal, vertical enamel margins (assessed individually on both restoration sides), cervical enamel (restoration side above CEJ) and cervical dentin margin (restoration side below the CEJ). Results: TML induced a significant reduction in continuous adaptation at both enamel and dentin margins in all groups, with percentages of continuous margins ranging from 75.2 to 91.8% at T0, and decreasing to values ranging from 21.3 to 73.9% at T3. Both composite systems and layering protocols had a significant influence on marginal adaptation of the restorations, with statistical associations depending on the restoration group and the timepoint considered. Defective margins in enamel were all of a cohesive nature with micro-fractures, while in dentin, interfacial gaps were the main defect observed. Conclusions/Clinical significance: The present results highlighted significant degradation of marginal adaption after long-term in vitro fatigue test using materials even with high-viscosity conventional resin composites, applied with a proper layering approach in medium-large sub-gingival cavities. While no significant differences were observed at the dentin cervical margins, there was a tendency for better adaptation at the enamel margin when using a higher modulus material with a multi-layered technique.

Effect of Fast High-Irradiance Photo-Polymerization of Resin Composites on the Dentin Bond Strength.

This study investigated the influence of conventional (10 s at 1160 mW/cm2) and fast high-irradiance (3 s at 2850 mW/cm2) light curing on the micro-tensile bond strength (μTBS) of bulk-fill resin composites bonded to human dentin. Sixty-four extracted human molars were ground to dentin and randomly assigned into eight groups (n = 8 per group). After application of a three-step adhesive system (Optibond FL), four different bulk-fill composites (two sculptable and two flowable composites) were placed. Of these, one sculptable (Tetric PowerFill) and one flowable (Tetric PowerFlow) composite were specifically developed for fast high-irradiance light curing. Each composite was polymerized with the conventional or the fast high-irradiance light-curing protocol. The specimens were cut into dentin-composite sticks, μTBS was determined and failure modes were analyzed. Statistical analysis was performed using t-test for independent observations and one-way ANOVA. A statistical difference between the curing protocols was only found for Tetric PowerFlow, where the conventional protocol (23.8 ± 4.2 MPa) led to significantly higher values than the fast high-irradiance light-curing protocol (18.7 ± 3.7 MPa). All other composite materials showed statistically similar values for both polymerization protocols. In conclusion, the use of fast high-irradiation light curing has no negative influence on the μTBS of the investigated high-viscosity bulk-fill composites. However, it may reduce the dentin bond strength of flowable bulk-fill composite.

Do high-viscosity bulk-fill composites polymerize sufficiently at deep layers?

Do high-viscosity bulk-fill composites polymerize sufficiently at deep layers?

Low- and high-viscosity bulk-fill resin composites: a comparison of microhardness, microtensile bond strength, and fracture strength in restored molars.

The aim of this study was to compare low- and high-viscosity bulk-fill composites for Knoop microhardness (KHN), microtensile bond strength (MTBS) to dentin in occlusal cavities, and fracture strength (FS) in molars with mesialocclusal- distal restoration. Disk-shaped samples with different thicknesses (2 or 4 mm) of low-viscosity (SDR Flow, Dentsply) and high-viscosity bulk-fill composites (Filtek BulkFill, 3M ESPE; and Tetric-N Ceram Bulk Fill, Ivoclar Vivadent) were prepared for top and bottom KHN analysis (n=10). MTBS to dentin and fracture pattern was evaluated in human molars with occlusal cavities restored with (n=10): conventional nanocomposite (Z350XT, 3M ESPE), low-viscosity (Filtek Bulk-fill Flow, 3M ESPE) or high-viscosity bulk-fill composites (Filtek BulkFill). The FS and fracture pattern of human molar with mesial-occlusal-distal restorations submitted or not to thermomechanical cycling were investigated (n=10) using: intact tooth (control), and restoration based on conventional microhybrid composite (Z250, 3M ESPE), low-viscosity (SDR Flow) or high-viscosity bulk-fill composites (Filtek BulkFill). The data were submitted to split-plot ANOVA (KHN), one-way ANOVA (MTBS), two-way ANOVA (FS) followed by Tukey's test (α=0.05). For KHN, there was no significant difference for the resin composites between the top and bottom. For MTBS, no significant differences among the materials were detected; however, the low-viscosity composite presented lower frequency of adhesive failures. For FS, there was no significant difference between composites and intact tooth regardless of thermomechanical cycling. Low- and high-viscosity bulk-fill composites have comparable microhardness and microtensile bond strength when used in occlusal restorations. Likewise, the bulk-fill composites present similar fracture strength in molars with mesio-occlusal-distal restorations.

Evaluation of the Polymerization Properties of Bulk-Fill Composite Resins

Introduction: The aim was to evaluate the polymerization properties of bulk-fill composite resins in terms of the degree of conversion (%DC), Vickers hardness (HV). SonicFill (SF, Kerr, CA, USA), Tetric Evo Ceram Bulk-Fill (TECBF, Ivoclar Vivadent Schaan, Lichtenstein), and X-trafil (XTF, Voco GmbH, Cuxhaven, Germany) were investigated. Methods: The samples prepared from composites (n = 10) were polymerized via three different curing modes (standard mode: 20 s, high-power mode: 12 s, extra power mode: 6 s) using a polywave LED. %DC was determined by FTIR-ATR-spectroscopy. HV was measured at the top and bottom of the specimens. Data were analyzed by two way ANOVA, and Bonferroni’s post-hoc respectively (α=0.05). Results: Except TECBF (%41.10 ± 3.1) in three different curing modes, all materials showed no significant inferior %DC. In all curing modes, the highest hardness ratio was found in XTF (0.84 ± 0.03 GPa), and the lowest hardness ratio was found in the TECBF (0.78 ± 0.02GPa). In the cases where the extra power mode of the Valo Led was applied, the lowest degree of conversion and hardness were also measured. Conclusion: It has been observed that the examined properties of some tested materials change with the curing time and power of the light and however, the results are dependent on the material.Extra power mode of the Valo Led negatively affected high viscosity bulk-fill composites in terms of their polymerization properties

Physical-Mechanical Properties of Bulk Fill Composites Submitted to Biodegradation by Streptococcus mutans.

The aim of this study was to evaluate the Streptococcus mutans biofilm influence on the roughness (Ra), gloss (GU), surface hardness (KHN) and flexural strength (FS) of high viscosity bulk fill composites. Filtek Bulk Fill (FBF), Tetric N Ceram Bulk Fill (TNC), X-tra fil Bulk Fill (XF) and Filtek Z350 (FZ) were used. Ten discs of each composite were prepared for Ra, KHN and GU and 20 bars for the FS. After 24 h, specimens were polished and initial analyzes performed. Samples were sterilized and subjected to biodegradation for 7 days and final analyzes performed. Representative samples of each group were evaluated in Scanning Electron Microscope. Data were submitted to ANOVA two factors and Tukey test. XF presented the highest values (p<0.05) of Ra before and after biodegradation (0.1251; 0.3100), and FZ (0.1443) the lowest after biodegradation (p<0.05). The highest GU values (p<0.05) were observed for FZ (71.7; 62) and FBF (69.0; 64.6), and the lowest (p<0.05) for TNC (61.4; 53.3) and XF (58.5; 53.5), both before and after biodegradation. For KHN the highest values were obtained by XF (151.7; 106), and the (p< 0.05) lowest values for TNC (62.2; 51.8), both before and after biodegradation. The highest values (p<0.05) of FS were observed for FZ (127.6) and the lowest (p<0.05) for TNC (86.9); after biodegradation, XF (117.7) presented the highest (p<0.05) values compared to TNC and FZ." In conclusion, biodegradation increased Ra and decreased GU and KHN for all. Concerning FS, degradation provided a significant decreased value only for FZ.

Effect of layer thickness on the elution of monomers from two high viscosity bulk-fill composites: A high-performance liquid chromatography analysis.

Aim:The aim is to evaluate the effect of different layer thickness on the amount of elution of monomers from two high viscosity bulk-fill composites after 24 h and 1 month storage in ethanol using high-performance liquid chromatography (HPLC) analysis.Materials and Methods:Forty-eight samples prepared from two high viscosity bulk-fill composite resins; Tetric EvoCeram Bulk Fill and x-tra fil were divided into three groups (n = 8) based on their layer thickness, i.e., Group 1 (2 mm), Group 2 (4 mm), and Group 3 (6 mm) and were then subdivided based on their storage period. The analysis of the eluates was performed using HPLC unit. Statistical analysis was performed using One-way ANOVA, independent sample t-test, and paired “t” test at a significance level of 0.05 (P < 0.05).Results:Increase in layer thickness resulted in increased amount of bisphenol A-glycidyl methacrylate (Bis-GMA) and urethane dimethacrylate (UDMA) elution for both composites, i.e., Group 3 > Group 2 > Group 1 and there was statistically significant difference among all the groups. Tetric EvoCeram Bulk Fill showed a statistically significant increase in amount of Bis-GMA and UDMA elution for all groups compared to x-tra fil. Furthermore, increase in storage period resulted in statistically significant increase in amount of Bis-GMA and UDMA elution for both composites, i.e., Group 1B > Group 1A, Group 2B > Group 2A, and Group 3B > Group 3A. The mean value of UDMA elution was higher when compared to that of Bis-GMA elution for both composites and there was statistically significant difference for all groups.Conclusion:Within the limitations of this in vitro study, it was concluded that increase in layer thickness resulted in increased amount of Bis-GMA and UDMA elution for both Tetric EvoCeram Bulk Fill and x-tra fil.

Fracture Resistance and Marginal Adaptation of Capped and Uncapped Bulk-fill Resin-based Materials.

This study tested the fracture resistance of capped and uncapped bulk-fill composite restorations and compared them to a conventional composite. Also, the effect of different radiant exposure was investigated. Flowable and high-viscosity bulk-fill composites (SureFil SDR, Filtek Bulk-Fill Posterior, and Tetric N-Ceram Bulk-Fill) and a nanohybrid resin composite (Filtek Z350 XT) were used. Standardized class II cavities were prepared on extracted premolars, and different restoration protocols were used. In protocol 1 (control), restoration was applied using a layering technique; in protocol 2, restoration was applied in bulk with a capping layer; in protocol 3, restoration was applied in bulk without a capping layer; and in protocol 4, restoration was applied in bulk without a capping layer, and the light curing time was extended. After thermocycling, the restorations were examined for marginal gaps and then subjected to the fracture resistance test using a universal testing machine. Statistical analysis was carried out using two-way analysis of variance (ANOVA) followed by one-way ANOVA at a significance level of α = 0.05. A statistically significant difference in the fracture resistance of the tested materials and protocols was detected. Filtek Bulk-Fill Posterior achieved the highest fracture resistance values regardless of the protocol used, and its results were comparable to those of Filtek Z350. SDR and Tetric N-Ceram Bulk-Fill achieved their highest strengths when a capping layer was added. Tetric N-Ceram Bulk-Fill showed improvement in fracture resistance with extended light curing, while SDR and Tetric N-Ceram Bulk-Fill achieved similar results with the addition of a capping layer. The uncapped bulk-fill group showed more gap-free margins than the capped group. The new high-viscosity bulk-fill composite restorations seem to have adequate fracture resistance. However, the results are material dependent, and some materials perform better with a capping layer and extended light curing.

How do the optical properties of the bulk fill posterior composites change after 2 years of simulated toothbrushing?

The objective of this study was to evaluate the alteration of the optical properties of bulk Fill resin-based composites after 2 years of simulated toothbrushing. Three high-viscosity bulk fill resin composites and one conventional sculptable resin composite (control) were analyzed. Five specimens of each resin composite were prepared, and roughness, color, translucency and gloss were evaluated initially and after one and two years of simulated toothbrushing. The specimens were submitted to electric simulated toothbrushing (14600 strokes/100g) using a commercially available toothbrush with soft fibers and toothpaste slurry in a proportion of 1:2 by weight. The brushing scheme was of 40 cycles per day (2 cycles per second / 280 cycles in a week). The optical properties and the roughness data were analyzed by a multifactor analysis of variance (MANOVA) and a Tukey post hoc test. The baseline and final values of Ra and Sa were submitted to linear regression analyses, all of which were performed at a significance level of p=0.05. Gloss and roughness presented statistical differences between the resin-time interactions in all composite resins. The gloss (72.5%) and roughness (89.4%) worsened significantly after brushing, but the authors didn’t find statistically significant differences when evaluating translucency and color. Based in the results, it could be concluded that the simulated brushing degraded the brightness and roughness of the used high-viscosity bulk fill composites.

The shear bond strength of repaired high-viscosity bulk-fill resin composites with different adhesive systems and resin composite types

This study compared the effect of different adhesive systems and composite resins on the shear bond strength (SBS) of repaired high-viscosity bulk-fill composites(Tetric EvoCeram Bulk Fill) and investigated failure modes. One hundred twenty cylindrical bulk-fill composite blocks (diameter 5 mm) were fabricated and thermocycled for 5000 cycles (5–55 °C). Specimens were roughened by diamond bur and divided into 8 groups (n = 15). Bulk-fill blocks were repaired with the same material or nanohybrid composite resin(Tetric EvoCeram Nanohybrid) (diameter 3 mm) using different adhesive systems:Tetric N-Bond Universal (TSE);37% phosphoric acid etching + Tetric N-Bond Universal (TER); Clearfil SE Bond (CSE); 37% phosphoric acid etching + AdperTMSingle Bond 2(SB). After repair procedures, all specimens were thermocycled again. The shear bond strengths were measured for all specimens using a universal test machine (crosshead speed of 1 mm/min). Cohesive strengths of bulk-fill composites were measured and described as control group. Debonded surfaces were observed with a stereomicroscope under 10x magnification to determine mode of failure. The SBS data of all groups was statistically analyzed by two-way ANOVA and Bonferroni correction test (p < 0.05). The specimens repaired with bulk-fill composites showed significantly higher SBS values (25.86 ± 5.74, 27.05 ± 4.93, 24.49 ± 6.95MPa) than those with nanohybrid composites (20.41 ± 3.70, 22.08 ± 6.37, 18.74 ± 6.40 MPa) for TER,CSE,SB, respectively (p < 0.05). There were no significant differences in SBS according to the type of adhesive systems for both repair materials (p > 0.05). The predominant mode of failure was a mixed type in the restorative material except for the ones repaired with nanohybrid composites using AdperTMSingle Bond 2. High-viscosity bulk-fill composites could be successfully repaired with the same materials. SBS of repaired bulk-fill composites reached cohesive strength for all tested groups.

Bonding Interaction and Shrinkage Stress of Low-viscosity Bulk Fill Resin Composites With High-viscosity Bulk Fill or Conventional Resin Composites

To analyze the shrinkage stress, bonding interaction, and failure modes between different low-viscosity bulk fill resin composites and conventional resin composites produced by the same manufacturer or a high-viscosity bulk fill resin composite used to restore the occlusal layer in posterior teeth. Three low-viscosity bulk fill resin composites were associated with the conventional resin composites made by the same manufacturers or with a high-viscosity bulk fill resin composite, resulting in six groups (n=10). The bonding interaction between resin composites was tested by assessing the microshear bond strength (μSBS). The samples were thermocycled and were tested with 1-mm/min crosshead speed, and the failure mode was evaluated. The post-gel shrinkage (Shr) of all the resin composites was measured using a strain gauge (n=10). The modulus of elasticity (E) and the hardness (KHN) were measured using the Knoop hardness test. Two-dimensional finite element models were created for analyzing the stress caused by shrinkage and contact loading. The μSBS, Shr, E, and KHN data were analyzed using the Student t-test and one-way analysis of variance. The failure mode data were subjected to chi-square analysis (α=0.05). The stress distribution was analyzed qualitatively. No significant difference was verified for μSBS between low-viscosity bulk fill resin composites and conventional or high-viscosity bulk fill composites in terms of restoring the occlusal layer (p=0.349). Cohesive failure of the low-viscosity bulk fill resin composites was the most frequent failure mode. The Shr, E, and KHN varied between low-viscosity and high-viscosity resin composites. The use of high-viscosity bulk fill resin composites on the occlusal layer reduced the stress at the enamel interface on the occlusal surface. The use of high-viscosity bulk fill resin composites as an occlusal layer for low-viscosity bulk fill resin composites to restore the posterior teeth can be a viable alternative, as it shows a similar bonding interaction to conventional resin composites as well as lower shrinkage stress at the enamel margin.

Repair bond strength of bulk fill composites after different adhesion protocols.

BackgroundRepairs in composite resin restorations are common procedures in clinical practice. Many surface treatment options have been proposed to improve the adhesion between the old and new composite. The objective of this study was to evaluate the microtensile bond strength of repairs performed on aged bulk fill and conventional composites after different adhesion protocols.Material and MethodsFirst, 84 specimens (8x8x4 mm3) of a microhybrid composite and a high-viscosity bulk fill composite were prepared and aged. Afterward, they received a mechanical surface treatment by means of abrasion with a diamond bur, followed by division into six groups according to the adhesion protocol employed: PSA - etching with 35% phosphoric acid + silane + etch-and-rinse adhesive; SA - silane + etch-and-rinse adhesive; PA - etching with 35% phosphoric acid + etch-and-rinse adhesive; A - etch-and-rinse adhesive; PU - 35% phosphoric acid + universal adhesive; and U - universal adhesive. The repairs were performed with a microhybrid composite. Repaired resin blocks were cut into sticks (8x1x1 mm3) and submitted to a microtensile test. Fractured specimens were evaluated to determine the failure pattern (adhesive or cohesive). Data were analyzed by two-way ANOVA.ResultsNo statistically significant differences were found in bond strength values among different adhesion protocols and composite types.ConclusionsThe repair bond strength of a bulk fill composite was similar to that found in a conventional composite, with no distinction among adhesion protocols. Key words:Dental restoration repair, composite resins, adhesiveness.

Internal and marginal adaptation of high-viscosity bulk-fill composites in class II cavities placed with different adhesive strategies.

The aim of this study was toevaluate internal and marginal adaptation of high-viscosity bulk-fill composites to enamel and dentin with a self-etch (SE) and an etch-and-rinse adhesive (ER) without and with artificial aging. 128 MOD cavities in extracted human molars were prepared, randomly assigned to 8 groups (n = 16), bonded with either OptiBond FL (OFL, ER) or Xeno V+ (X, SE), and restored in 4mm horizontal bulk layers with SonicFill (SF), Tetric EvoCeram Bulk fill (TEC), and x-tra fil (XF). Incremental layering technique with Premise (P) served as control. Half of the specimens each (n = 8) were subjected either to water storage (1day, 37°C) or prolonged storage (180days) and thereafter thermocycling. Replicas were analyzed for marginal gap formation. After sectioning, interfacial adhesive defects were assessed. Results were statistical analyzed. (1) Internal adaptation: Except for TEC/OFL at enamel without artificial aging, no significant differences between bulk-fill composites and the control were observed. All groups at dentin with OFL showed less internal adhesive defects than that with X (p < 0.05). (2) Marginal adaptation: Nosignificant differences were observed between bulk-fill composites and controlexcept for P after artificial aging (p > 0.05). All other composites, regardless of artificial aging, formed significantly more marginal gaps at enamel with X compared to with OFL (p ≤ 0.05). Simplified restorations with high-viscosity bulk-fill composite showed comparable internal and marginal adaptation to incrementally placed fillings. A superiority of the 3-step ER approach was seen compared to the 1-step SE adhesive irrespective of the bulk-fill composite used.

Comparative Evaluation of Depth of Cure of Three High Viscosity Bulk Fill Composites versus Conventional Composite: An In Vitro Study

Comparative Evaluation of Depth of Cure of Three High Viscosity Bulk Fill Composites versus Conventional Composite: An In Vitro Study

Fracture resistance of posterior teeth restored with high-viscosity bulk-fill resin composites in comparison to the incremental placement technique.

Aim:Comparative evaluation of the fracture resistance of maxillary premolar teeth restored with two high-viscosity bulk-fill composites and incrementally placed composite.Materials and Methods:Seventy-five freshly extracted maxillary premolar teeth were selected. Fifteen specimens served as positive control (Group 1). Mesio-occluso-distal cavity preparation was prepared on the rest of the specimens. These specimens were further divided into four groups: unrestored teeth (Group 2), teeth restored with incrementally placed nanocomposite (Group 3), teeth restored with high-viscosity bulk-fill giomer (Group 4), and teeth restored with high-viscosity bulk-fill nanocomposite (Group 5). The specimens were then subjected to compressive axial load using Instron universal testing machine. Data were analyzed using data were analyzed using Statistical package for social sciences software (SPSS v 20.0, IBM Corp.).Results:The positive control group exhibited highest fracture resistance (1104.70 ± 122.2 N). There was no statistically significant difference seen in between the incrementally placed nanocomposite and high-viscosity nanocomposite (P > 0.05). The fracture resistance values displayed by the high-viscosity bulk-fill giomer were found to be statistically lower than the other two groups.Conclusion:High-viscosity bulk-fill nanocomposite may substitute incrementally placed nanocomposite with respect to fracture resistance.