Surface roughness and surface microhardness of bulk-fill and conventional resin composites after erosive-abrasive cycles: A laboratory study.

The aim of this study was to assess the microhardness and surface roughness of bulk-fill resin composites treated with and without the application of an oxygen-inhibited layer (OIL) and a polishing system. This in vitro experimental study consisted of 72 resin composite blocks divided into three groups: Tetric N-Ceram Bulk Fill, Opus Bulk Fill APS, and Filtek Bulk Fill. Each resin composite group was further divided into two subgroups: with and without OIL control. Subsequently, surface roughness and microhardness were measured before and after polishing. A t-test was used to compare independent and related measures. For the intergroup comparison of variation before and after polishing, the Kruskal–Wallis test with Bonferroni post hoc was used considering a significance level of p < 0.05. When comparing surface roughness, significant differences were observed between Opus Bulk Fill resin composite with and without OIL control (p = 0.003) before polishing. The same occurred when comparing Tetric N-Ceram resin composite with and without OIL control (p = 0.039) after polishing. In addition, the surface roughness of Filtek Bulk Fill, Opus Bulk Fill, and Tetric N-Ceram Bulk Fill resin composites, with and without OIL control, decreased significantly after polishing (p < 0.001), while surface microhardness significantly increased (p < 0.05), with the exception of Opus Bulk Fill resin with OIL control (p = 0.413). In conclusion, OIL control and polishing significantly improved the surface roughness and surface microhardness of Filtek Bulk Fill and Tetric N-Ceram Bulk Fill resin composites. However, in the case of Opus Bulk Fill resin composite, only its surface roughness was significantly improved.

To compare shrinkage stress, cuspal strain and fracture load of weakened premolars restored with different conventional and bulk-fill composite resins and restorative techniques. Fifty premolars received a 4.0 x 3.5mm mesio-occlusal-distal (MOD) class II preparation. The lingual and buccal cups were internally weakened. Specimens were restored according to the following 5 groups: Filtek Z350 XT/10 increments; Filtek Z350 XT/8 increments (both 3M Oral Care); Filtek Bulk Fill Flowable Restorative + Filtek Z350 XT (both 3M Oral Care); SDR + Spectra Basic (Dentsply Sirona); and Tetric N-Ceram Bulk Fill (Ivoclar Vivadent). Cuspal strains were measured using strain gauges (n = 10). After restoration, specimens were submitted to thermal/mechanical cycles and fractured. Post-gel shrinkage of the composites was determined. Additionally, residual shrinkage strains and stresses were analyzed using three-dimensional finite element analysis (3D-FEA). The data were statistically analyzed using one-way ANOVA and Tukey's HSD (α = 0.05). One-way ANOVA revealed statistically significant differences among composite resins (p < 0.001) for the post-gel shrinkage. Filtek Z350 XT had the highest post-gel shrinkage and no difference was found between Spectra Basic and Tetric N-Ceram Bulk Fill (p = 0.110). The Filtek Z350 XT/10 increments, Filtek Z350 XT/8 increments and Filtek Bulk Fill Flowable Restorative/Filtek Z350 XT had statistically significantly higher cuspal deformation values when compared to the SDR/Spectra Basic and Tetric N-Ceram Bulk Fill techniques. 3D-FEA confirmed higher stress levels in the incrementally filled conventional restorations. Fracture loads were not statistically significantly different. The bulk-fill restoration techniques resulted in less cuspal strain and stress than the incremental technique with conventional composite resin. Fracture resistance was not affected by the restorative techniques.

Aim: This study aimed to assess the effects of a hydroelectrolytic beverage on the surface roughness and microhardness of different bulk fill resin composites. Methods: Sixty resin composite samples were prepared and divided into three groups: FiltekTM Z350 (C), FiltekTM One Bulk Fill (BF-F), and Opus Bulk Fill APS (BF-O). These were further subdivided to analyze two beverage groups: GatoradeTM Lemon (GL) and distilled water (control). Surface roughness (Ra), surface microhardness (KHN), and scanning electron microscopy (SEM) results were evaluated (n=10). The data were subjected to two-way ANOVA (for roughness) or three-way ANOVA (for microhardness), followed by Tukey’s post hoc test (α=0.05). Results: The C group exhibited higher microhardness than the BF-F and BF-O groups, regardless of the solution used. A reduction in microhardness was observed in all groups when comparing initial and final time points. SEM images revealed variations in the size, amount, and arrangement of particles among the different resin composites. Conclusion: The study concluded that the microhardness of different bulk fill resin composites decreases when exposed to either the hydroelectrolytic beverage or distilled water. However, the type of immersion liquid did not influence the surface roughness of the evaluated composite resins.

Objectives: The aim of this study was to evaluate the effect of food-simulating liquids (FSLs) and thermal aging on the surface roughness and color stability of bulk-fill and conventional composites. Materials and Methods: A total of 320 disc-shaped samples were prepared, with 40 samples from each of 4 different bulk-fill composites (Filtek Bulk Fill, X-tra fil, Beautifil Bulk Restorative, and Estelite Bulk Fill Flow), and 4 conventional nano-filled composite resins (Filtek Z550, CeramX SphereTEC one, Admira, and Kalore). The prepared samples were randomly divided into subgroups for exposure to FSLs (ethanol, heptane, citric acid) and thermal cycling (TC) (n=10 per subgroup) for 28 days. Initial profilometric surface roughness measurements (Ra0) of all samples and AFM and SEM analyses of selected samples were followed by exposure to FSLs and TC. After completion of aging protocols, measurements and analyses were repeated to obtain the Ra1 (post-treatment surface roughness), and change in surface roughness (∆Ra1-0) was then calculated. Subsequently, initial color measurement of the samples was conducted using a spectrophotometer, followed by immersion of the samples in a coffee solution for 24 hours. Color measurements were repeated, and color change (∆E) was calculated. Two-way repeated measures ANOVA was used to compare Ra0 and Ra1 values and one-way ANOVA for comparing ∆Ra and ∆E values. Tukey and post hoc tests were employed for pairwise comparisons. The significance level was set at α=.05. Results: While the surface roughness of bulk-fill composites was affected by the protocols applied (p&amp;lt;0.05), conventional composites generally remained unaffected. Bulk-fill composites exhibited greater ΔRa and ∆E values. The highest ∆Ra and ∆E values were observed in the Beautifil Bulk Restorative group, with the greatest discoloration seen after immersion in citric acid. Conclusions: Thermal cycling and immersion in FSLs affect surface roughness and color stability of composite resins depending on the content and structure of the composites.

Acidic conditions can cause hydrolysis and accelerate degradation of resin composites (RCs). Since there are limited and controversial data on the effect of acids on bulk-fill RCs, this study assessed the surface roughness (SR) and flexural strength (FS) of these RCs under simulated carious and erosion conditions. Bars of Filtek Bulk Fill (FBF, 3M/ESPE), X-tra fil (XTF, Voco), Tetric N-Ceram Bulk Fill (TBF, Ivoclar/Vivadent), and Aura Bulk Fill (ABF, SDI) and a conventional RC [Filtek Z350XT (FZ, 3M/ESPE)] were allocated (n=15) to undergo caries or erosion conditions. The control group was kept in artificial saliva (AS). The bars were evaluated for SR change (final-baseline) and for three-point FS. Data were analyzed using ANOVA and Tukey's test. At the baseline (p <0.001), the SR of RCs ranked as follows: (TBF = XTF) < FBF (none differed from FZ) < ABF. The interplay between RCs and conditions affected SR change (p = 0.025). While after storage in AS, there was no difference among RCs, following carious and erosive conditions, ABF showed higher SR change. For FS (p <0.001), XTF > (FBF = FZ) > (TBF = FZ) > ABF, with no difference among control, carious and erosive conditions (p = 0.148). Depending on the restorative bulk-fill RCs, carious and erosive conditions roughen the surface but do not affect the FS of these materials.

Aim: This study aimed to evaluate the effect of polymerization with either a monowave (MW) or a polywave (PW) light-curing unit (LCU) on the degree of conversion (DC) and marginal adaptation following thermomechanical aging of an ormocer bulk-fill resin composite (RC) (Admira fusion X-tra Bulk Fill – AB), a methacrylate-based bulk-fill RC (Tetric N-Ceram Bulk Fill – TB) and a conventional RC (Tetric N-Ceram – TC). Methods: DC was assessed in five samples of each RC using Fourier transform infrared spectroscopy. For determination of marginal adaptation, standard preparations were made in 60 bovine incisors, divided into three groups, according to the RC. The bulk-fill RC was inserted in a single increment of 4 mm. In contrast, the conventional RC was inserted in three increments. Marginal gap was evaluated after thermomechanical aging. Data were analyzed using a two-way analysis of variance (ANOVA) and Tukey’s tests for multiple comparisons (α = 0.05). Results: The two-way ANOVA showed a significant effect (p<.05) of the RC factor but not of the LCU factor. The Tukey test showed that TB had the significantly lowest DC followed by TC, and with AB having the significantly highest DC. For the marginal adaptation, a significant effect was found for the LCU factor and the for the interaction RC × LCU (p<.05). Groups light-cured with PW showed significantly wider marginal gaps than MW. TC presented wider marginal gaps (17.36 µm) when cured with PW than when cured with MW (13.05 µm). The two bulk-fill RC resulted in similar marginal gap formation to each other. Conclusion: The ormocer-based bulk-fill RC showed a higher DC than the methacrylate-based bulk-fill RC but similar marginal adaptation. The LCU, MW or PW, had no significant influence on the DC, and no relevance on the marginal adaptation.

Aim The aim was to compare the effect of 10 and 20% carbamide peroxide (CP) on microhardness (MHN) and surface roughness of two commercially available bulk fill composites (X-tra fill Bulk Fill and Tetric EvoCeram Bulk Fill). Materials and methods A total of 50 specimens with both type composites were prepared using brass molds of inner diameter 10 mm and a height of 4 mm. Each type of composite was further divided into three groups, control group stored in artificial saliva for 14 days, other groups bleached with 10 and 20% CP respectively, for 14 days. Microhardness of the composite resin was tested with a Vickers hardness tester, whereas surface roughness was tested with profilometer. Results All the analysis was performed using Statistical Package for the Social Sciences version 18. The value of p &lt; 0.05 was considered statistically significant. Both 10 and 20% CP significantly reduced MHN of experimental composite resins. However, the mean surface roughness was significantly higher in X-tra fill Bulk Fill than Tetric EvoCeram Bulk Fill at 20% CP concentration. The mean MHN of Tetric EvoCeram was reduced when compared with X-tra fill at 20% CP. Conclusion There was a significant reduction in the MHN of restorative materials observed after exposure to CP under a clinically simulated bleaching regimen. However, increase in surface roughness was seen only at 20% CP. Clinical significance The physical properties, such as MHN and surface roughness have a crucial effect on the longevity of restorations and, moreover, on the esthetic demands of patients, but they may be compromised by bleaching treatments. The aim of this research paper was to assess the reaction of home bleaching agents on the physical properties of two Bulk Fill composite resin restorative materials. How to cite this article Francis G, Pradeep K, Ginjupalli K, Saraswathi V. Effects of Bleaching Agents on the Microhardness and Surface Roughness of Bulk Fill Composites. World J Dent 2017;8(3):196-201.

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.

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.

To evaluate surface roughness, hardness, and morphology changes of various bulk-fill resin composites eroded by different food-simulating liquids and beverages. One hundred and thirteen specimens were fabricated in polytetrafluoroethylene cylindrical mold (10 mm in diameter and 4 mm in thickness). Before immersion, baseline data of roughness, Vicker's microhardness were recorded and surface characteristics were examined using scanning electron microscopy (SEM). Each product of specimens (SDR, Dentsply; SonicFill, Kerr; Tetric N-Ceram Bulk Fill, Ivoclar Vivadent AG; and Filtek Bulk Fill, 3M ESPE) were divided into 5 groups for spicy and sour soup, spicy soup (Tom Yum), pineapple juice, passionfruit juice, and deionized water (served as a control). Specimens were then alternately immersed in storage agents for 5 seconds and artificial saliva for 5 seconds over 10 cycles. Specimens were stored in artificial saliva for 22 hours. This process was repeated for 28 days. After immersion, surface hardness and roughness of specimens were evaluated at 7, 14, 21, and 28 days and data were analyzed by two-way repeated ANOVA and Tukey's HSD (α = 0.05). Surface morphology of specimens was also examined on day 28. The SDR group had the most statistically significant decrement in hardness (25.65±1.74 kg/mm2 in mean difference) and increment in roughness (0.26±0.10 μm in mean difference; P < .05). Passionfruit juice caused the most surface changes in bulk-fill resin composites. SEM photomicrographs showed surface changes of all resin composites in varying degrees. Acidic food-simulating liquids and beverages significantly increased the surface roughness and decreased surface microhardness of bulk-fill resin composites after evaluation at the end of the 28-day immersion period. For restoration of the affected teeth in patients who consume acidic food and beverages, roughness and erosion of resin composites should be considered. All of bulk-fill resin-based composites except SDR may be suitable for restorations in these patients.

The purpose of this study was to determine the influence of finishing and polishing methods on surface properties of bulk-fill resin composites through surface roughness (Ra) and surface free energy (SFE) measurements, and scanning electron microscopy (SEM) observations. Three bulk-fill resin composites, Tetric EvoCeram Bulk Fill (TB), Filtek Bulk Fill (FB), and Filtek Bulk Fill Flowable Restorative (FF), and two conventional resin composites, Clearfil AP-X (AP) and Estelite ∑ Quick (EQ) were used. Seventy cured specimens of each resin composite were prepared and divided into seven groups of 10 specimens. Ra, SFE measurements, and SEM observations were conducted after finishing and polishing procedures. Three groups of specimens were finished with a fine grit diamond bur (FDB), and three with a tungsten carbide bur (CBB). After finishing, one group from each type of finishing was polished with aluminum oxide flexible disks (SSD) and one group from each type of finishing was polished with diamond particles embedded in a silicone point (CMP). A baseline group of samples that were neither finished nor polished after removing the translucent strips from the surface was examined. Although the baseline group showed significantly lower Ra values than the other groups, most resin composites showed lower Ra values with CBB+SSD than with the other finishing and polishing groups. Among the tested resin composites, EQ showed significantly lower Ra values than the other resin composites, regardless of the finishing and polishing methods. On the other hand, AP showed significantly higher Ra values than the other resin composites in all finishing and polishing groups, apart from FB with FDB. For the finished specimens, most resin composites showed higher SFE values with CBB than with FDB. For the polished specimens, all the tested resin composites with CMP showed lower γS values than those with SSD, regardless of the finishing method. The baseline groups of TB and FB showed significantly lower SFE values than the other finished and polished groups. In the SEM observations, all the examined resin composites showed rougher surfaces after finishing with FDB than with CBB. However, when comparing the different polishing methods (CMP and SSD), surface smoothness appeared to be material dependent.

Introduction In order to simplify the technique, reduce the time required for direct adhesive restorations, bulk-fill resin composites have been developed be applied in bulk placement up to 4 mm increments. Objective Evaluating the color change (ΔE) and the microtensile bond strength (μTBS) of bulk fill resin composites (BFRC) to dentin after the immersion in regular beverages and the application of bleaching systems. Method Forty-five human molar teeth were randomly distributed in three groups according to the filling material (n=15): Filtek Bulk Fill, Tetric N Ceram Bulk Fill and Filtek Z100. The restored teeth were immersed in coffee, wine and distilled water (n=5) for 72 hours. The color parameters were measured using a spectrophotometer, having as basis the CIE L*a*b*, before and after tooth staining and application of bleaching processes. Subsequently, the teeth were sectioned to obtain the specimens for the microtensile testing. The ΔE values were analyzed applying the Kruskal-Wallis and the Wilcoxon tests, and the μTBS values were analyzed applying the ANOVA and the Bonferroni tests (p&lt;0.05). Result There were no significant differences in the ∆E values when comparing the BFRCs to the conventional resin composite (CRC) in most of the experimental groups. The ∆E values did not present significant differences before and after the application of bleaching processes for all the tested resin composites. The BFRCs presented higher μTBS values than the CRC after exposure to distilled water, wine and bleaching agent. Conclusion The studied BFRCs presented similar color stability to the CRC. The BFRCs presented higher bond strength to the dentin than the CTC in most of the evaluated conditions. The bleaching agent was not effective in whitening the stained restored teeth.

Statement of the Problem: One of the problems with light-cured composite resins is the limitation and inadequate depth of curing and polymerization, resulting in low surface microhardness and restoration failure.Purpose: The present study aimed to compare the surface microhardness of two different bulk-fill composite resins and one conventional composite resin using the Vickers microhardness test.Materials and Method: In the present in vitro study, 108 samples from two different bulk-fill composite resins (Tetric N Ceram and Xtrafil) and one conventional composite resin (Filtek Z250)were prepared in metallic molds (2×4×10 mm) (n=36 for each composite resin). Six samples from each composite resin (n=6) underwent a hardness measurement test atspecific depths (0.1, 1, 2, 3, 4 and 5mm). The samples were then stored at 37ºC for 24 hours, followed by a microhardness test at the depths mentioned above.Results: In all the composite resin samples, microhardness decreased with an increase in depth. The highest microhardness was recorded in Filtek Z250, followed by Xtrafil,with no significant difference. The lowest microhardness was recorded in Tetric N Ceram bulk-fill. Both bulk-fill composite resins at all the depths exhibited depth-to-surfacestandard microhardness (>80%).Conclusion: According to the results, both evaluated bulk-fill composite resins exhibited favorable surface microhardness up to a depth of 5 mm.

The application of modeling resin could affect the surface quality and color of resin composites. To evaluate the effects of modeling resin on the microhardness, roughness, and color of composite restorations, with and without thermocycling. Sixty disc-shaped specimens for each resin composite were prepared in three groups: Group 1: A resin composite disc was cured against a polyester matrix and finished/polished; Group 2: A composite instrument was wetted with Bisco Modeling Resin (Bisco, Schaumburg, IL, USA) to smooth the composite surface, which was cured against a polyester matrix and finished/polished; Group 3: A composite instrument was wetted with modeling resin to smooth the composite surface, which was cured against a polyester matrix. Microhardness, roughness, and color were measured 24 hours after curing and after 10,000 thermocycles. Modeling resin significantly influenced the microhardness of GrandioSO (Voco, Cuxhaven, Germany) and Gradia Direct Posterior (GC America, Alsip, IL, USA), and the surface roughness of GrandioSO, Filtek Silorane (3M ESPE, St Paul, MN, USA), and Aelite All Purpose Body (Bisco) (p < 0.05). The microhardness of the Group 1 resin composites was affected by thermocycling (p < 0.05); however, thermocycling had no significant effect on surface roughness (p > 0.05). Tested composites showed clinically perceptible color changes after thermocycling. In Group 1, Filtek Ultimate (3M ESPE) showed the lowest color change (p < 0.05), and in Group 2, Filtek Silorane showed the highest significant color changes (p < 0.05). Modeling resin did not affect the microhardness, surface roughness, and color of Aelite LS Posterior (Bisco), Filtek Ultimate (3M ESPE), and Clearfil Majesty Esthetic (Kuraray Medical Inc, Tokyo, Japan) specimens. Also, thermocycling process only affected microhardness of tested resin composites. The effect of modeling resin on surface microhardness, roughness, and color stability of composite materials depends on the type of resin composite. In clinical practice, the adverse effects of modeling resin might be alleviated by a proper finishing and polishing procedure.

Objective: The aim of this in vitro study was to evaluate surface roughness and microhardness of two bulkfill resin composites after wet and dry finishing. Materials and methods: Two Types of resin composite materials SonicFill (Sonic-activated bulk-fill Nanohybrid resin composite) and X-tra fil (Bulk-fill micro- hybrid light-cured posterior resin composite) were used. Thirty samples were fabricated of each resin composite using a metal mold measuring (6mm x 4mm). Composites were applied to molds and placed between two transparent Mylar strips and pressed flat with a microscopic glass slide. A glass slab was placed on top of the upper Mylar strip and a constant pressure was applied. The samples were cured according to manufacturers' instructions. The samples were divided into three groups (n=10). Group A: No finishing (control group), Group B: wet finishing under water coolant, and group C dry finishing. Surface roughness was evaluated using a stereomicroscope and microhardness was measured by Vicker's hardness tester. Data were analyzed using one-way ANOVA (P<0.05).Results: X-tra fil showed a statistically significant higher surface roughness mean values than Sonicfill in group A (control group) and group C (dry finishing) at p value ≤ 0.015 and ≤ 0.001* respectively, while with the wet technique there was no statistically significant difference in the surface roughness mean values between X-tra fil and Sonicfill at p value> 0.05. The control group showed the lowest microhardness mean values in both materials. Dry finishing showed the highest microhardness mean values among the groups (P<0.05). Conclusion: Dry finishing and polishing increased the surface roughness and microhardness of X-tra fil (microhybrid) and (nanohybrid sonic activated) Sonicfill resin composites.