SureFil SDR Flow Research Articles

Influence of Modulated Photo-Activation on Shrinkage Stress and Degree of Conversion of Bulk-Fill Composites.

This study aimed to evaluate the polymerization properties of bulk-fill materials (low and high-viscosity) by using high-intensity continuous light and intermittent photo-activation in terms of polymerization shrinkage stress and degree of conversion (DC). The following Bulk-fill and Conventional nanofilled resin composites were evaluated: Filtek Z350XT Flow (3M/ESPE), SureFil SDR Flow (Dentsply), Filtek Bulk Fill Flow (3M/ESPE), Filtek Z350XT (3M/ESPE) and Filtek Bulk Fill Posterior (3M/ESPE). A LED device (DB 685, Dabi Atlante) was used for both protocols: continuous uniform and intermittent photo-activation (light-on and light-off cycles) with identical radiant exposure (14 J/cm2). The polymerization shrinkage stress (n=6) was evaluated by inserting a single increment of 12 mm3 between two stainless steel plates (6×2 mm) adapted to a Universal Testing Machine (UTM), at different times. Measurements were recorded after photo-activation. The degree of conversion was evaluated by Fourier transformed infrared spectroscope (FTIR) with an attenuated total reflectance (ATR) accessory (n=5). Data were analyzed by three-way ANOVA and Tukey's HSD (α=0.05) tests. Bulk Fill Posterior presented higher shrinkage stress values when photo-activated with the intermittent technique (p<0.05). The intermittent photo-activation increased the degree of conversion for the low-viscosity bulk-fills (p<0.05). Therefore, the use of modulated photo-activation (intermittent) must be indicated with caution since its use can influence the shrinkage stress and degree of conversion of composites, which varies according to the resin formulations.

EVALUATION OF GINGIVAL MICROLEAKAGE IN CLASS II COMPOSITE RESTORATIONS: AN IN VITRO STUDY

Introduction: Evaluation of microleakage is important for assessing the success of new restorative materials and methods. The aim of this study was to assess the microleakage of class II restorations with different flowable composites as liners and two different polymerization techniques classic and soft start. Materials and Methods: 40 extracted human premolars teeth with class II cavity preparation medial and distal (80 cavities) were divided into four groups: 1.Vertise Flow (VF)+micro hybrid composite Herculite 2.Surefil SDR Flow (SDRF)+micro-hybrid composite Herculite 3.Tetric Flow (TF)+micro-hybrid composite Herculite 4.control group micro-hybrid composite Herculite. Mesial cavities are polymerized with classic and distal cavity with soft start technique of polymerization. After that, the samples were immersed in 0.5% AgNO3 solution and sectioned into the mesiodistal direction. Using a stereomicroscope (Nikon - Japan), with a magnification of 40x, the gingival microleakage of cavities was examined. Data were analyzed using Fisher's and Student's tests. Results: After using the classical polymerization technique, all three used flowable composites VF+Herculite, SDRF+Herculite, TF+Herculite showed less gingival microleakage than the control group. This difference was statistically significant. After the application of the soft-start technique of polymerization, VF+Herculite and SDRF+Hercules showed a statistically significant reduction in gingival microleakage, while TF+Herculite showed a comparable result with control group, without a statistically significant difference. There was no statistically significant difference between classical and soft start polymerization techniques. Conclusion: Flowable composites in this study have reduced gingival microleakage and can be used as liners in the restoration of II class cavities.

In situ measurement of dental resin-based composite volumetric shrinkage and temperature effects using in-fibre bragg grating methods

ObjectivesResin-based composites (RBCs) are commonly used in dental restorations. It is known that RBCs undergo volumetric shrinkage during photo-polymerization leading to a detrimental increased stress state at the RBC-tooth interface and potentially early restoration failure. The objectives of this in vitro study were: (1) to ascertain whether shrinkage strain could be measured using in-fibre Bragg grating (FBG) technology, without confounding effects of temperature; and (2) to ascertain whether FBGs can detect alteration in shrinkage strain with introduction of a surface condition change at the RBC-cavity analog interface. MethodsAluminum cavity analogs with simulated cavity dimensions 3.5 mm height x 2 mm width x 8 mm length and 2 mm wall thickness were secured in a 3D printed experimental jig. Two FBGs were used in the RBC space, one that was covered with a polyimide tube and that measured only temperature, and another that was affected by both mechanical strain and temperature. Experiments to determine if the two FBG system could be used to compensate for thermal artefacts were contrived to verify that a tube-covered and bare FBG measure the same temperature effect (n = 5). In situ photo-polymerization experiments, which consisted of using controlled amounts of SureFil SDR Flow + RBC, were performed to study RBC shrinkage behavior. As-machined (n = 10) and micro-etched (n = 11) cavity analogs were used. Significant differences in FBG measurements, which could indicate the ability of FBGs to detect alterations in strain across surface preparations, were determined using one tail t-tests at 95% confidence. Finally, additional temperature experiments were conducted 5 h after initial light exposure using the same light irradiation regiment to investigate temperature effects within a cured RBC system (n = 3). ResultsFor temperature measurement, the tubing-covered and bare FBGs measured temperature changes with time-lag of 3.7 ± 1.4 s (tubing-covered FBG relative to bare). For measurements in cured RBC, the bare FBG and tubing-covered FBG measured different strains, with the bare FBG measuring larger apparent strains because this FBG is affected by thermal volumetric expansion of the RBC and a temperature increase of the FBG itself. The tubing covered FBG, that is isolated from volumetric expansion effects, measured relatively less. The interpretation of these results is that thermally-compensated strain measures (in-situ) could require simultaneous use of two FBGs (one strain isolated). In situ measurements of the photo-polymerization procedure for as-machined analogs at two time-points, 500 and 1000 s, were determined to be −485.43 ± 131.06 μstrain and −524.96 ± 134.78 μstrain, respectively. For air-abraded surfaces measures were significantly lower at (p < 0.001) −211.36 ± 12.38 μstrain and −228.07 ± 49.08 μstrain, respectively. ConclusionsTo measure shrinkage strain and compensate for associated thermal effects from photo-polymerization, systems employing two FBGs, one of them isolated from thermal volumetric expansion, may be required. The presented approach proved capable of detecting significant alteration in strain across two surface preparations.

Flexural Properties and Elastic Modulus of Different Esthetic Restorative Materials: Evaluation after Exposure to Acidic Drink.

Background Acidic beverages, such as soft drinks, can produce erosion of resin composites. The purpose of the present study was to investigate mechanical properties of different esthetic restorative materials after exposure to acidic drink. Methods Nine different composites were tested: nanofilled (Filtek Supreme XTE, 3M ESPE), microfilled hybrid (G-ænial, GC Corporation), nanohybrid Ormocer (Admira Fusion, Voco), microfilled (Gradia Direct, GC Corporation), microfilled hybrid (Essentia, GC Corporation), nanoceramic (Ceram.X Universal, Dentsply De Trey), supranano spherical hybrid (Estelite Asteria, Tokuyama Dental Corporation), flowable microfilled hybrid (Gradia Direct Flo, GC Corporation), and bulk fill flowable (SureFil SDR flow, Dentsply De Trey). Thirty specimens of each esthetic restorative material were divided into 3 subgroups (n=10): specimens of subgroup 1 were used as control, specimens of subgroup 2 were immersed in 50 ml of Coca Cola for 1 week, and specimens of subgroup 3 were immersed in 50 ml of Coca Cola for 1 month. Flexural strength and elastic modulus were measured for each material with an Instron Universal Testing Machine. Data were submitted to statistical analysis. Results After distilled water immersion, nanofilled composite showed the highest value of both flexural strength and elastic modulus, but its flexural values decreased after acidic drink immersion. No significant differences were reported between distilled water and acidic drink immersion for all other materials tested both for flexural and for elastic modulus values. Conclusions Even if nanofilled composite showed highest results, acidic drink immersion significantly reduced flexural values.

Sealing Capacity of Bulk-fill Resin in Endodontically Treated Teeth

The objective of the study is to evaluate the cervicalapical sealing of bulk-fill flow resins associated with a universal adhesive system, in endodontically treated teeth, considering two methods of evaluation. The samples used in the bacterial leakage analysis were autoclaved, filled inside a laminar flow chamber, and divided into four experimental groups (n = 8) according to the restorative material: Filtek Bulk-fill flow; Surefil SDR flow; TetricEvoflow and the positive control. The samples were inoculated with the Enterococcus faecalis (E. faecalis), every 7 days and the microleakage was evaluated on a daily basis for 60 days. Microleakage tested with dye (n = 5) was considered in 2-time intervals of evaluation (24 hours and 72 hours), and the results were obtained in scores from 0-5. Data were submitted to the statistical tests, at a level of significance of 0.05. About 12.5% of the FBF specimens showed bacterial microleakage as from the thirteenth day, and SDR, from the 20th day. TEF presented the highest percentage of microleakage at 40 days, concluding the 60 days with 37.5% of viable specimens. The Log-rank test revealed that the survival curve of TEF was statistically significant in comparison with those of the other groups. In the test with dye TEF and SDR presented the highest and lowest rate of microleakage, respectively, with statistically significant differences in the time interval of 72h. The resins FBF, SDR, and TEF were incapable of promoting the hermetic sealing of fillings in the root canal system. No bulk-fill flux studied was able to completely eliminate microleakage, despite the best performance with respect to the microleakage time presented by Filtek Bulk fill, followed by Surefil SDR flow.

The biocompatibility of resin composite materials on different stem cells.

Objectives: Composite resins should undergo attentive tests to specify their biocompatibility before they have contact with the teeth, regardless of physico-mechanical properties. Hence, this study has been carried out to assess the knowledge of potential cellular responses and biological effects of composite resins on three different cells after two different exposure times. Methods: The composites Surefil SDR flow, Dentsply Caulk/ABD (SS), X-tra base flowable, Voco Cuxhaven Germany (XB), Venus Bulk Flow, Voco Cuxhaven Germany (VB), Filtek Bulk Flow, 3 M/ESPE-USA (FB), Tetric-Evo bulk flow, Ivoclar Vivadent, Schaan, Liechtenstein (TE) were immersed into molds (Height: 4 mm, Width: 6 mm) and polymerized according to manufacturer's instructions. Human gingival fibroblasts (HGFs), cortical neuron cells (CNCs) and dental pulp stem cells (DPSCs) were inoculated into 24-well plates, separately. Then, the insert membranes with a 3 µm pore width compatible for plates were inserted and dental composite samples were added. The experimental procedures were performed after 24 h and 72 h. The cell viability of the cells was obtained from an MTT assay. Total antioxidant (TAS) and oxidant (TOS) status were examined by using real assay diagnostic kits. The dynamic process of apoptosis analysed by using annexin V-FITC staining with flow cytometry. Human beta defensins were assessed by RT-PCR. Lastly, supernatants were analysed for production of IL6, IL8 and IL10 cytokines. Results: According to analysis of variance, there were significant differences between three cells. There was an increase in the cytotoxicity values in some groups after 72 h. A 24 h and 72 h experiment revealed that VB was the strongest cytotoxic agent, followed sequentially by XB and FB. Exposure of cells to the composites of SS, XB, VB, FB and TE for 24 h reduced the cell number approximately by 6, 24, 35.6, 28.6 and 1%. A 72 h reduced the cell number for 25.3, 31.6, 40.6, 50.3 and 8%, respectively, by SS, XB, VB, FB and TE. Conclusions: It can be concluded that from all these data, if the three cell cultures are compared, cortical neuron cells were more sensitive to the resin composites.

Physical and photoelastic properties of bulk-fill and conventional composites.

PurposeThis study evaluated the influence of thickness increment on degree of conversion (DC), Knoop microhardness (KHN), and polymerization-shrinkage stress (PSS) by photoelasticity of three dental composites.MethodsFor DC and KHN, 45 samples were prepared and divided into nine groups (n=5), according to composite (microhybrid [Filtek Z250 - Z250], bulk-fill flowable [SureFil SDR Flow - SDR], and nanohybrid composite [N’Durance - NDU]) and increment thickness (1, 1.5, and 3 mm). PSS was measured by photoelastic analysis. Composites were placed into a photo-elastic model cavity and light-cured. DC and KHN data were subjected to two-way ANOVA and Bonferroni post hoc test. PSS results were qualitatively evaluated through Kruskal–Wallis test.ResultsSDR showed the highest DC values. At top and bottom surfaces, the highest KHN was obtained by Z250. Z250 showed higher PSS than SDR in 1.5 mm increments. NDU showed higher PSS than SDR in 3 mm increments.ConclusionThe bulk-fill composite demonstrated better DC and similar KHN and PSS in deeper layers compared to conventional composites. Bulk-fill composites may perform as well as conventional nanohybrid and microhybrid composites.

Surface Roughness and Hardness of Dental Resin-Composites Intended for Bulk-fill Placement

Objective: To evaluate the surface roughness and hardness of high and low consistency bulk-fill resin-composites and to compare them with other conventional resin-composites.Materials and Methods: The study was divided into five groups according to type of resin-composite as follows: group I: Low consistency bulk-fill SureFil SDR Flow (SF), group II: Low consistency bulk-fill Venus Bulk Fill (VB), group III: High viscosity bulk-fill Tetric EvoCeram, group IV: Conventional Beautifil Flow Plus F03 (BF) and group V: Conventional GrandioSo (GS). A total of 10 disc-shaped specimens (15 mm diameter × 2 mm thickness) were prepared from each material for both surface roughness and hardness testing. Specimens were stored in distilled water for 24 hours before testing. For the determination of surface roughness values, Surface Profile Gage (Positector, SPG, Deflesko Corporation, New York, USA) was used. Hardness testing was carried out using Digital Microhardness Tester (Zwick/Roell, IDENTEC, ZHVµ-S, West Midlands, England). Data were analyzed using a One-way ANOVA and Bonferroni post-hoc test. P < 0.05 was considered statistically significant. Results: Considering different filler loading, monomer system and consistency of the material, the hardness values ranged between 49.8 and 97.3 (VHN) and the surface roughness ranged between 5.6 and 17.1 (µm). One way ANOVA revealed a significant differences between the studied materials for surface roughness (P = 0.000) and microhardness (P = 0.000). Bonferroni post-hoc test revealed significant differences between surface roughness results of all studied resin-composites (p < 0.05). There was also significant differences between hardness values of all investigated resin-composites (P = 0.000) except between SF and VB (P = 0.701). Significantly greater hardness and surface roughness were recorded for materials with higher filler loading than those with lower filler loading.Conclusions: Within the range of studied resin-composites, the values of surface roughness and hardness were principally dependent on the extent of filler loading, the type of resin system and the material consistency.

Cytotoxic and biological effects of bulk fill composites on rat cortical neuron cells

The aim of this study was to investigate potential cellular responses and biological effects of new generation dental composites on cortical neuron cells in two different exposure times. The study group included five different bulk-fill flow able composites; Surefil SDR Flow, X-tra Base Flow, Venus Bulk Flow, Filtek Bulk Flow and Tetric-Evo Flow. They were filled in Teflon molds (Height: 4 mm, Width: 6 mm) and irradiated for 20 s. Cortical neuron cells were inoculated into 24-well plates. After 80% of the wells were coated, the 3 µm membrane was inserted and dental filling materials were added. The experiment was continued for 24 and 72 h. Cell viability measured by MTT assay test, total antioxidant and total oxidant status were examined using real assay diagnostic kits. The patterns of cell death (apoptosis) were analyzed using annexin V-FITC staining with flow cytometry. Β-defensins were quantitatively assessed by RT-PCR. IL-6, IL-8 and IL-10 cytokines were measured from the supernatants. All composites significantly affected analyses parameters during the exposure durations. Our data provide evidence that all dental materials tested are cytotoxic in acute phase and these effects are induced cellular death after different exposure periods. Significant cytotoxicity was detected in TE, XB, SS, FBF and VBF groups at 24 and 72 h, respectively.

Influence of Polishing System on the Surface Roughness of Flowable and Regular-Viscosity Bulk Fill Composites.

This study evaluated the influence of polishing protocols on the surface roughness of flowable and regular bulk fill composites. Five bulk fill composites were tested: SureFil SDR Flow (SDR), Tetric EvoFlow Bulk fill (TEF), Filtek Bulk Fill Flowable (FIF), Tetric EvoCeram Bulk Fill (TEC), and Filtek Bulk Fill Posterior (FIP). Two polishing protocols were tested: Sof-Lex and Astropol. Astropol created a smoother surface for FIP (P < .05); however, the polishing protocol did not influence surface roughness on TEC (P > .05). SDR, TEF, and FIF exhibited rougher surfaces when polished. Sof-Lex created rougher surfaces for bulk fill composites. It was concluded that surface roughness was related to material composition rather than the polishing system.

Effect of Sonic Resin Composite Delivery on Void Formation Assessed by Micro-computed Tomography.

The aim of this study was to quantify the internal void volume formation in commercially available, resin composites inserted using conventional or sonic insertion methods, and analyzed using three-dimensional (3D) micro-computed tomography (μCT). Four resin composites were evaluated: one conventional (Herculite, Ultra, Kerr Corporation, Orange, CA, USA), one flowable bulk fill (SureFil SDR Flow, Dentsply International, York, PA, USA), and two packable bulk fill (SonicFill, Kerr Corporation, and Tetric EvoCeram Bulk Fill, Ivoclar Vivadent Inc, Schaan, Liechtenstein). Eight groups were evaluated according to each resin composite type and insertion method (conventional or sonic; n=5). Forty ABS 3D-printed cylindrical molds, 5.0 mm in diameter and 4.0 mm in depth, were fabricated. For the conventional resin composite, the mold was filled incrementally (two layers), while for bulk-fill resin composites, insertion was performed in a single increment. The sonic insertion method was performed using a specific handpiece (SonicFill Handpiece, Kerr Corporation). Resin composites were light cured using a multipeak light-emitting diode light-curing unit (VALO, Ultradent Products Inc, South Jordan, UT, USA) in its regular mode. Samples were evaluated by μCT, and data were imported into software (Amira, version 5.5.2, VSG, Burlington, MA, USA) for 3D reconstruction, from which the percentage of void volume was calculated. Data were analyzed using two-way analysis of variance and Tukey post hoc test at a preset alpha of 0.05. The conventional insertion method resulted in reduced porosity, compared with sonic insertion, for SureFil SDR Flow and Tetric EvoCeram bulk fill. The sonic insertion method did not demonstrate any influence on void formation for Herculite Ultra or SonicFill. Results suggest that the sonic insertion method might increase void formation during resin composite delivery, depending on restorative material brand.

Evaluation of polymerization shrinkage of dental composites by microcomputed tomography

Objective: The aim of this study was to evaluate the polymerization shrinkage of different commercially available dental composites with micro-computed tomography (μ-CT). Method: The study group included eight different flowable composites; Surefil SDR Flow (SDR), Charisma Flow (CHF), Clearfil Majesty Flow (CMF), Vertise Flow (VF), Grandio Flow (GF), Filtek Supreme Ultimate Flow (3MEFU), Filtek Bulk Flow (3MBF), X-Tra Base Flow (XTB). Composite materials were placed in standard cylindrical teflon molds and these were scanned for 1 h using μ-CT Skyscan 1172. Polymerization was not observed during scanning since the internal chamber of the equipment was completely dark. When the scanning was complete, materials were polymerized with LED light as per producer recommendations and rescanned with Skyscan 1172 using the same parameters. After the scanning process was over, test materials were analyzed using μ-CT-CTAn software programme. Results: Data were analyzed using Kruskal Wallis, Mann Whitney U and Wilcoxon test at a significance level of α=0.05. Polymerization shrinkage ranged between 1.44% (CMF) and 2.73% (CHF). Bulk-fill and Self-adhesive composites were significantly lower (p<0.05) than those of the others. Conclusion: All tested materials were able to achieve acceptable shrinkage at 2-4 mm depth. The higher shrinkage of hybrid composites over that of other groups may indicate a potential for higher interfacial stresses. However, the bulk fill composite showed low shrinkage that may prove less damaging to the interface.

Effect of composite type and placement technique on cuspal strain.

To compare the cuspal strain in Class II restorations made with bulk-fill and conventional composite resins. Fifty extracted maxillary premolars were mounted into phenolic rings and divided into five groups (n=10). Specimens received standardized MOD preparations. A two-step self-etch adhesive was applied and the preparations were restored using a custom matrix as follows: Filtek Supreme Ultra in eight 2-mm increments (FSUI); Filtek Supreme Ultra in bulk (FSUB); SonicFill in bulk (SF); SureFil SDR flow in bulk, covered with a 2-mm occlusal layer of Filtek Supreme Ultra (SDR/FSU); Tetric EvoCeram Bulk Fill in bulk (TEBF). Strain gages bonded to the buccal and lingual cusps recorded cuspal strain during restorations. End strain values were determined and data were subjected to Kruskal-Wallis testing, followed by one-way ANOVA and Tukey´s post hoc test. Combined strain values and standard deviations (in µɛ) were: FSUI: 723±102.8, FSUB: 929.2±571.9, SF: 519.1±80.2, SDR-FSU: 497.4±67.6 and TEBF: 604.5±127.1. A significant difference was found between group FSUI and groups SF, SDR-FSU, and TEBF. Group FSUB showed significantly higher mean strain and greater standard deviation than all other groups due to cuspal fractures, and was thus excluded from the statistical analysis. The tested bulk-fill composite resins exerted less strain onto tooth structure than the incrementally placed conventional composite resin, although the magnitude of generated strain was product-dependent. Bulk-filling with conventional composite resins is contraindicated. Bulk-fill composite resins exerted less strain onto adjacent tooth structure than a traditional composite, even when that composite is was placed incrementally. Bulk-filling with traditional composite resins is unpredictable and contraindicated.

Shear bond strength of different surface treatments in bulk fill, microhybrid, and nanoparticle repair resins.

ObjectivesThe purpose of this study was to evaluate the influence of surface treatment and different types of composite resin on the microshear bond strength of repairs.Materials and methodsSeventy-two specimens (n=72) were prepared using a nanoparticle resin and stored in artificial saliva at 37 ± 1°C for 24 h. After this period, the specimens (n=24) were restored with microhybrid resin P60 (3M ESPE), nanoparticle resin Filtek Z350 (3M ESPE), and Bulk Fill Surefil SDR Flow (Dentsply) composite resins. Previously, the surfaces of the samples were treated, forming the following subgroups (n=12): (A) conditioned with 37% phosphoric acid for 30 s, and (B) abrasioned with a diamond tip for 3 s and conditioned with 37% phosphoric acid. In all groups, before insertion of the composite resin, the adhesive system Adper Single Bond 2 was actively applied and photopolymerized for 20 s.ResultsThe microshear test was executed to assess bond strength. Kruskal–Wallis (p<0.05) and Mann–Whitney statistical tests showed significant statistical difference considering that the bulk-fill resin turned out to have a lower bond strength than the conventional nanoparticle and microhybrid composites. With regard to the technique, the roughening with diamond bur followed by the application of phosphoric acid exhibited values higher than the exclusive use of acid.ConclusionThe microshear bond strength of the composite resin repairs varies in accordance with the type of composite resin utilized, and roughening the surface increased the bond strength of these materials.

Comparative Evaluation of the Depth of Cure and Degree of Conversion of Two Bulk Fill Flowable Composites.

Since the development of resin based composites, several improvements have been made to improve their physical and chemical properties. In an attempt to fasten and simplify the restoration process, a new class of resin based composite materials, called the bulk fill resin based composites have been introduced, which has been claimed to achieve a depth of cure of 4 mm without affecting the properties of the material. To comparatively evaluate the depth of cure of two different bulk fill flowable composite resins by ISO 4049 method and to evaluate the degree of conversion of the same composite resins with Fourier Transform Infrared (FTIR) spectroscopy method. Composite resin specimens (n=10) per group were prepared with bulk fill flowable composites, Surefil SDR flow (Dentsply Caulk, Milford, DE, USA) designated as Group A and Filtek bulk fill (3M ESPE, St.Paul, MN, USA) designated as Group B. Depth of cure was determined according to "ISO 4049; Depth of Cure" method, and FTIR spectroscopy method was used to estimate the degree of conversion of both the bulk fill flowable composites. The degree of conversion of monomer to polymer was estimated individually in coronal half (Group A1 and B1) and pulpal half (Group A2 and Group B2) by dividing each specimens into two halves. The data were analysed using Student's unpaired t-test at 5% level of significance. The mean depth of cure of Group A was 3.89 mm (±0.103) and for Group B was 3.54 mm (±0.129). The degree of conversion percentage for Group A1=78.51 (±47.8), Group A2= 31.9 (±22.4), Group B1=39.8 (±5.2), Group B2=37.4 (±6.4). Statistical analysis revealed significant difference in the depth of cure between the two bulk fill flowable composites with Group A higher than Group B. The degree of conversion of the coronal half of Group A1 was significantly higher when compared to Group B1. Surefil SDR bulk fill resin has better depth of cure and degree of conversion compared to Filtek bulk fill composites.

Microcomputed Tomography Evaluation of Volumetric Shrinkage of Bulk-Fill Composites in Class II Cavities.

This study aimed to quantify polymerization shrinkage of one conventional and three bulk-fill composites, under bonded and unbonded conditions, in Class II preparations using 3D microcomputed tomography (μCT) and report its location. Preparations (2.5 mm occlusal depth × 4 mm wide × 4 mm mesial box and 1 mm beyond the CEJ distal box depth) were made in 48 human extracted molars (n = 6). Four composites were tested, one regular (Vitalescence/VIT) and three bulk-fill: SureFil SDR Flow (SDR), Tetric EvoCeram Bulk Fill (TET), and Filtek flowable Bulk Fill (FIL). Teeth were divided into four groups according to restorative material used and subdivided into two subgroups, according to the presence of an adhesive system (XP Bond) application (bonded [-B]) or its absence (unbonded [-U]). Each tooth was scanned three times: (1) after cavity preparation, (2) before and (3) after composite light-curing. Acquired μCT images were imported into 2D and 3D software for analysis. Significantly different volumetric shrinkage between bonded and unbonded conditions was observed only for TET group (p<0.05), unbonded presenting significantly higher volumetric shrinkage. Among the bonded groups, TET-B presented significantly lower shrinkage than both SDR-B and FIL-B but not significantly different from VIT-B. Generally, shrinkage occurred at occlusal and distal surfaces. When applied to bonded Class II cavities, TET exhibited significantly lower volumetric shrinkage compared to the other bulk-fill composites. However, it also exhibited the highest difference of volumetric shrinkage values between unbonded and bonded cavities. Volumetric polymerization shrinkage occurred with all composites tested, regardless of material type (conventional or bulk-fill) or presence or absence of bonding. However, volumetric shrinkage has been reduced or at least maintained when bulk-fill composites were used compared to a conventional composite resin, which makes them a potential time saving alternative for clinicians. (J Esthet Restor Dent 29:118-127, 2017).

Influence of the Compliance and Layering Method on the Wall Deflection of Simulated Cavities in Bulk-fill Composite Restoration.

The aim of this study was to investigate the effects of the layering method and compliance on the wall deflection of simulated cavities in bulk-fill and conventional composite restorations and to examine the relationships between the wall deflection and the polymerization shrinkage, flexural modulus, and polymerization shrinkage stress of composites. Six light-cured composites were used in this study. Two of these were conventional methacrylate-based composites (Filtek Z250 and Filtek Z350 XT Flowable [Z350F]), whereas four were bulk-fill composites (SonicFill, Tetric N-Ceram Bulk-Fill, SureFil SDR Flow [SDR], and Filtek Bulk-Fill). One hundred eighty aluminum molds simulating a mesio-occluso-distal cavity (6 W×8 L×4 D mm) were prepared and classified into three groups with mold wall thicknesses of 1, 2, and 3 mm. Each group was further subdivided according to the composite layering method (bulk or incremental layering). Linear variable differential transformer probes were used to measure the mold wall deflection of each composite (n=5) over a period of 2000 seconds (33.3 minutes). The polymerization shrinkage, flexural modulus, and polymerization shrinkage stress of the six composites were also measured. All groups with bulk filling exhibited significantly higher deflection compared with groups with incremental layering. The deflection decreased as mold wall thickness increased. The highest and lowest polymerization shrinkage stresses were recorded for Z350F (5.07 MPa) and SDR (1.70 MPa), respectively. The correlation between polymerization shrinkage and the mold wall deflection decreased with increasing wall thickness. On the other hand, the correlation between flexural modulus and the mold wall deflection increased with increasing wall thickness. For all groups, wall deflection correlated strongly with polymerization shrinkage stress.

Evaluation of marginal leakage of bulk fill flowable composite resin filling with different curing time using micro-computed tomography technology

Purpose: To evaluate marginal leakage of bulk fill flowable composite resin filling with different curing time by using microcomputed tomography technology. Materials and Methods: 30 previously extracted human molars were randomly divided into 6 groups based upon restorative system and different curing time. Class II cavities (vertical slot cavities) were prepared. An individual metallic matrix was used to build up the proximal wall. The SonicFill or SureFil SDR flow was inserted into the preparation by using 1 bulk increment, followed by light polymerization for different curing times. The different exposure times were 20, 40, and 60 seconds. All specimens were submitted to 5,000 thermal cycles for artificial aging. Micro-CT scanning was performed by using SkyScan 1272. One evaluator assessed microleakage of silver nitrated solution at the resin-dentin interface. The 3D image of each leakage around the restoration was reconstructed with CT-Analyser V.1.14.4. The leakage was analyzed with the Mann-Whitney test. Results: Significant differences were observed between the light curing times, but no significant differences were found between the bulk fill composite resins. Increasing in the photoactivation time resulted in greater microleakage in all the experimental groups. Those subjected to 60 seconds of light curing showed higher microleakage means than those exposed for 20 seconds and 40 seconds. Conclusion: Increasing the photoactivation time is factor that may increase marginal microlekage of the bulk fill composite resins. Further, micro-CT can nondestructively detect leakage around the resin composite restoration in three dimensions.

Transmission of violet and blue light through conventional (layered) and bulk cured resin-based composites

ObjectivesThis study measured the transmission of light in the ‘violet’ (350≤λ≤425nm) and ‘blue’ (425<λ≤550nm) spectral ranges from a polywave® LED curing light through different thicknesses of four commercial, resin-based composites (RBCs). Material and methodsSamples of conventional layered RBCs (Tetric EvoCeram A2, Filtek Supreme Ultra A2B), and bulk-curing resins (Tetric EvoCeram Bulk Fill IVA, and SureFil SDR Flow U) were prepared. Three samples of each RBC were made at thicknesses of 0.1, 0.7, 1, 2, and 4-mm. The uncured RBC specimens were affixed at the entrance aperture of a 6-inch integrating sphere and light-cured once for 20s using a polywave® LED curing light (Bluephase G2) on its high power setting. The spectral radiant power transmitted through each RBC in the ‘violet' and ‘blue' regions was measured using a fiberoptic spectrometer. ResultsAs RBC thickness increased, an exponential attenuation of transmitted light was measured (R2>0.98). Attenuation was greater for the ‘violet’ than for the ‘blue’ spectral regions. At the light tip, the violet light component represented 15.4% of the light output. After passing through 4-mm of RBC, the violet light represented only between 1.2–3.1% of the transmitted light depending on the RBC. Depending on RBC, approximately 100mW from the Bluephase G2 was transmitted through 0.1-mm of RBC in the ‘violet’ range, falling at most to 11mW after passing through 2-mm of RBC, and to only 2mW at 4-mm depth. ConclusionsIncreasing RBC thickness results in an exponential decrease in light transmission. This attenuation is RBC-dependent with shorter wavelengths (violet) attenuated to a greater extent than longer wavelengths (blue). Clinical relevanceDespite the increased translucency of bulk curing RBCs, spectral radiant power shorter than 425nm from a curing light is unlikely to be effective at a depth of 4-mm or more.

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.