Bulk-fill Composite Materials Research Articles

Translucency of bulk-fill composite materials: A systematic review.

To conduct a systematic review on the translucency of bulk-fill (BF) composite materials, evaluating the factors influencing it and its clinical implications. A systematic search was performed on four databases (Embase, Medline/PubMed, Scopus, and Web of Science) for articles published until October 2, 2023. Search terms were: "translucency," "translucency parameter," "contrast," "contrast ratio," "bulk," "bulk-fill," "bulk fill," "composite," "resin," "resin based," "resin-based," "restoration," and "dental." In vitro studies, written in English language, investigating BF resin-based composites translucency were included. The risk of bias was performed with the RoBDEMAT tool. Of 590 screened articles, 13 were included in this review. They investigated 11 high-viscosity BF and 5 low viscosity ones. The limited number of the identified studies and the heterogeneity of the extracted data did not allow to conduct a meta-analysis. BF materials exhibit variability in translucency due to variations in experimental designs and the heterogeneous composition. BFs may behave differently in masking the substrate or in blending capacity.

An evaluation of dental paste-like bulk-fill composite wear using intra-oral scanner.

This study evaluates the wear resistance of dental paste-like bulk-fill composites compared to conventional paste-like composite resins using an intraoral scanner and 3-D analyzing software. Six different dental composite materials, including five bulk-fill composites and one conventional composite, were tested alongside natural human enamel as a control group. A computer-controlled chewing simulator for wear testing. A one-way ANOVA test was used to identify any significant differences between the means of the tested dental composite materials α=0.05. The results showed variability among bulk-fill composites, with some demonstrating wear resistance similar to conventional composites (p<0.05). Human enamel displayed the lowest wear values, but some bulk-fill composites matched this resistance(p>0.05). Significant variability was observed among bulk-fill composites but the results were comparable to those of conventional composites. The enamel control group demonstrated the lowest wear values, with some bulk-fill composites showing similar wear resistance. This study provides valuable information about the wear resistance of contemporary bulk-fill composite materials, commonly used in current clinical practice, contributing to enhancing clinical procedures.

The effect of different curing distances on the microhardness of flowable bulk-fill composite materials

Background: The microhardness of a composite resin is a vital parameter that is used to determine its clinical behavior. Measuring the microhardness of a composite resin has been used as an indirect method to assess its degree of conversion and extent of polymerization. The purpose of this in vitro study was to evaluate the effect of three curing distances (0, 2, and 4 mm) on the microhardness of the top and bottom surfaces of three types of flowable bulk-fill composite resins (smart dentin replacement, Opus bulk fill flow, and Tetric N). Material and method: Sixty-three specimens from the three types of composite resins (n=21) were fabricated using Teflon mold with a 4mm depth and a 5 mm internal diameter and cured for 20 seconds. For each material, three subgroups were fabricated according to the position of the light curing tip from the top surface; at 0, 2, and 4 mm distances. Microhardness was measured using the Vickers test with a 50-g load for 15 seconds for the top and bottom surfaces of all the samples. Results: The microhardness values were decreased in the following order; 0mm &gt; 2mm &gt; 4mm curing tip distance, for both sides and Tetric N had the highest microhardness values. Significant differences in microhardness were recorded between the top and bottom surfaces for all the specimens (p&lt;0.05). Conclusion: Increasing the distances between the tip of the light cure and the surface of flowable bulk-fill resins can significantly decrease the microhardness of the bottom surfaces compared to the top surfaces.

Cuspal deflection of teeth restored with bulk fill flowable composite resins, with and without fiber-reinforcement and evaluated by Micro-computed Tomography

Polymerisation shrinkage of composite resins is a clinical challenge which has been well documented in the literature. Many studies investigating polymerisation shrinkage stress measure cuspal deflection, which is a manifestation of this stress. The introduction of flowable bulk-fill composite (BFRBC) materials has streamlined the restorative process, though the shrinkage and cuspal deflection from these BFRBCs has not been compared with regards to its use with polyethylene fibers (Ribbond fibers). The authors describe a method to measure the cuspal deflection of flowable BFRBCs placed in cavities of standardised dimensions at distinct steps of the restorative process, with and without fiber-reinforcement and using x-ray micro-computed tomography. Co-ordinate points are established on the buccal and lingual aspects of scanned specimens using the Volume Graphics VG Studio max 3.2.5 (Hiedelberg, Germany 2018) software. The system allows for these landmarks to be established across each scan (of the same tooth), ensuring standardization of each specimen. Further anatomical points are used to enable analysis. Comparison of angles generated across these points determines the extent of cuspal deflection.•A method of measuring the cuspal deflection of composite resins is proposed.•Experimental procedures are provided.•Data analysis methods are outlined.

Teeth Restored with Bulk-Fill Composites and Conventional Resin Composites; Investigation of Stress Distribution and Fracture Lifespan on Enamel, Dentin, and Restorative Materials via Three-Dimensional Finite Element Analysis.

the aim of this study was to examine the stress distribution of enamel, dentin, and restorative materials in sound first molar teeth with restored cavities with conventional resin composites and bulk-fill composites, as well as to determine their fracture lifetimes by using the three-dimensional finite element stress analysis method. an extracted sound number 26 tooth was scanned with a dental tomography device and recorded. Images were obtained as dicom files, and these files were transferred to the Mimics 12.00 program. In this program, different masks were created for each tooth tissue, and the density thresholds were adjusted manually to create a three-dimensional image of the tooth, and these were converted to a STL file. The obtained STL files were transferred to the Geomagic Design X program, and some necessary adjustments, such as smoothing, were made, and STP files were created. Cavity preparation and adhesive material layers were created by transferring STP files to the Solidworks program. Finally, a FE model was created in the ABAQUS program, and stress distributions were analyzed. when the bulk-fill composite and conventional resin composite materials were used in the restoration of the cavity, the structures that were exposed to the most stress as a result of occlusal forces on the tooth were enamel, dentin, restorative material, and adhesive material. When the bulk-fill composite material was used in restoration, while the restorative material had the longest fracture life as a result of stresses, the enamel tissue had the shortest fracture life. When the conventional resin composite material was used as the restorative material, it had the longest fracture life, followed by dentin and enamel. when the bulk-fill composite material was used instead of the conventional resin composite material in the cavity, the stress values on enamel, dentin, and adhesive material increased as a result of occlusal forces, while the amount of stress on the restorative material decreased. In the fracture analysis, when the bulk-fill composite material was used instead of the conventional resin composite material, a decrease in the number of cycles required for the fracture of enamel, dentin, and restorative materials was observed as a result of the forces generated in the oral cavity.

Effect of polymerization mode on shrinkage kinetics and degree of conversion of dual-curing bulk-fill resin composites

ObjectivesTo assess the behavior of dual-cure and conventional bulk-fill composite materials on real-time linear shrinkage, shrinkage stress, and degree of conversion.Materials and methodsTwo dual-cure bulk-fill materials (Cention, Ivoclar Vivadent (with ion-releasing properties) and Fill-Up!, Coltene) and two conventional bulk-fill composites (Tetric PowerFill, Ivoclar Vivadent; SDR flow + , Dentsply Sirona) were compared to conventional reference materials (Ceram.x Spectra ST (HV), Dentsply Sirona; X-flow; Dentsply Sirona). Light curing was performed for 20 s, or specimens were left to self-cure only. Linear shrinkage, shrinkage stress, and degree of conversion were measured in real time for 4 h (n = 8 per group), and kinetic parameters were determined for shrinkage stress and degree of conversion. Data were statistically analyzed by ANOVA followed by post hoc tests (α = 0.05). Pearson’s analysis was used for correlating linear shrinkage and shrinkage force.ResultsSignificantly higher linear shrinkage and shrinkage stress were found for the low-viscosity materials compared to the high-viscosity materials. No significant difference in degree of conversion was revealed between the polymerization modes of the dual-cure bulk-fill composite Fill-Up!, but the time to achieve maximum polymerization rate was significantly longer for the self-cure mode. Significant differences in degree of conversion were however found between the polymerization modes of the ion-releasing bulk-fill material Cention, which also exhibited the significantly slowest polymerization rate of all materials when chemically cured.ConclusionsWhile some of the parameters tested were found to be consistent across all materials studied, heterogeneity increased for others.Clinical relevanceWith the introduction of new classes of composite materials, predicting the effects of individual parameters on final clinically relevant properties becomes more difficult.

Colour Stability Of Bulk Fill Composites: A Systematic Review

Background: The introduction of Bulk-Fill (BF) composite materials, among other new preparations, was one of the most recent innovations in operative dentistry. All bulk composites' colour stability is a source of concern. There has been a lot of research on the effects of different drinking solutions on the colour consistency of conventional resin-based composites, but little has been written about the colour changes of BF composite resins, which have been developed for the placement of somewhat thicker layers.&#x0D; Aim: Thus, the objective of this systematic review was to assess the colour consistency of various bulk-filled composites.&#x0D; Methods and Materials: A massive exploration of preexisting literature was done in order to locate all relevant research that addressed the sustainability of colour of BF composites under the effect of various. According to PRISMA standards, the current systematic evaluation was carried out. A thorough search for non-controversial existing literature on the websites like PubMed portal, MEDLINE portal, and Scopus portal was done in December 2022. There were no comparable articles in Cochrane online library. To make sure that all pertinent studies were found, search keywords were applied. Furthermore, all appropriate scientific papers from Jan 2010 to December 2022 on the effect of various beverages, polishing techniques, storage media, and oral fluids, bleaching protocols on the colour longevity of bulk-filled composite samples were included.&#x0D; Results: 18 studies were evaluated in this systematic review. 9 studies focused on the effect of different drinks and beverages like tea, coffee, wine, and acidic beverages over the changes in the colour of bulk-filled composites. There were 4 studies that evaluated the impact of different polishing mechanisms. There were 2 researches that described the influence of different bleaching techniques over the change in colour of bulk-filled composites. One study discussed the effect of reinforcement of glass fibers and polythene fibers in bulk-filled composites, the presence of different dentin substitutes and water solubility and water sorption impact over the change in colour. The number of specimens evaluated ranged from n=20 to n=800 across all the included studies. There was the use of two to ten composite materials across all the included studies.&#x0D; Conclusion: When there was an analysis of the effect of different beverages and drinks over the changes in colour then there were mixed results. Some studies found that colour changes in bulk-filled composites are lesser than in customary composites. While some studies revealed that alteration in colour is greater in bulk-filled composites when compared to customary composites. Some studies found no significant difference in colour change in conventional composite and bulk-filled composite. The polishing operations can have a serious influence on the staining impedance of bulk-fill composite resins.

Clinical Evaluation of Class I Posterior Restorations Restored with Smart Dentin Replacement Flowable Bulk-fill Composite Material in Bulk-fill and Incremental Technique – One-year Randomized Clinical Trial

ABSTRACT Aim and Objective: The aim and objective of this in vivo study are to evaluate the clinical performance of smart dentin replacement (SDR) flowable bulk-fill composite in class I restorations with incremental technique and bulk-fill technique. Materials and Methods Fifty patients with at least two class 1 cavities in the age group of 18–40 years were recruited. In all cavities, Xeno Vplus self-etch adhesive was applied. In one of the cavities, SDR was placed in bulk increments up to 4 mm as needed to fill the cavity 2-mm short of the occlusal surface. The occlusal part was placed with SureFil nanohybrid composite, and the other cavity was placed by incremental technique. The restorations were evaluated using FDI criteria. Results: Data were subjected to statistical analysis and analyzed using Chi-square test. After 1 year, all restorations received clinically excellent and clinically good scorings for each criterion. Conclusion: There is no statistically significant difference between the bulk-fill technique and the incremental technique using SDR after 1-year follow-up. CLINICAL RELEVANCE TO INTERDISCIPLINARY DENTISTRY The smart dentin replacement bulk-fill resin composites demonstrated good clinical durability as equal as conventional composites. It provides an advantage of less clinical time for placement in deep posterior cavities.

Effect of light-curing distance on the degree of convergence of the top and bottom sides of flowable bulk-fill composite materials

Background: Flow able bulk-fill materials were introduced to be used in one thick increment of an internal base underneath a conventional layer. However, complete polymerization of the whole layer, particularly the bottom surface, is essential to achieve biocompatibility and the best mechanical properties. Objective: To evaluate the effect of three light-curing distances (0, 2, and 4mm)on the degree of convergence(DC) of the top and bottom surfaces for three flowable bulk-fill composite resins; Smart dentin replacement, Opus bulk fill flow, and Tetric N flow. Methods:45 disk-shaped specimens with an internal diameter of 5 mm and a depth of4mm cured for 20 seconds were fabricated from the three composite resins (n=15). For each material, three subgroups were fabricated according to the position of the light tip from the top surface; at 0, 2, and 4mm distances. DC for the top and bottom sides of all the specimens was calculated using FTIR spectroscopy. The statistical significance for the mean values of DC% among the different groups was calculated using a one-way analysis of variance (ANOVA) and the Tukey test with a significance level of 0.05.

Investigating the Cytotoxicity of Dual-Cure Bulk-Fill Resin Materials on L929 Cells

The aim of this in vitro study was to investigate cytotoxic effects of dual-cure bulk-fill resin materials polymerized with a third-generation LED light-curing unit (LCU) on L929 fibroblast cells in terms of morphology and viability. Three novel dual-cure, flowable bulk-fill materials (Fill-Up!™), a bioactive material (ACTIVA™ BioACTIVE-RESTORATIVE™), and a dual-cure bulk-fill composite material (HyperFIL® HAp) polymerized by LED LCU (VALO™ Cordless) were tested. Each material was placed in plastic rings (4 mm × 5 mm) in a single layer. Unpolymerized rings filled with each material were placed in direct contact with cells and then polymerized. After polymerization, the removed medium was readded to wells. In this study, four control groups were performed: the medium-free control group, medium control group, physical control group, and light applied control group. Three samples were prepared from each group. After 24 h, the morphology of cells was examined and a WST-1 test was performed. The percentage of cell viability (PCV) of each group was calculated. The experiment was repeated three times. Data were analyzed by a Kruskal–Wallis Test and a Mann–Whitney U test. p &lt; 0.05 was considered significant. The PCV of all groups were found to be significantly lower than the medium control group (p &lt; 0.05). The lowest PCV was obtained in HyperFIL® Hap, while highest was in the Fill-Up!™. In the morphology of cells related to the experimental groups, it was observed that the spindle structures of cells were disrupted due to cytotoxicity; cells became rounded and intercellular space increased. There were no significant differences between the control groups (p &gt; 0.05). All control groups showed acceptable PCV (&gt;70%) and cells were spindle-like, similar to the original fibroblast cells. It can be suggested that clinicians should pay attention when applying dual-cure bulk-fill materials in deep cavities, or they should use a liner material under these materials.

Investigation of the Effects of Adhesive Materials of Different Types and Thicknesses on Dental Tissue Stress via FEM Analysis.

The aim of this study was to investigate the types and thicknesses of adhesive materials used in restorative treatment in dentistry in class I occlusal and class II disto-occlusal cavities and to examine the effects of stress distribution on enamel, dentin, restoration material, and adhesive material using the finite element stress analysis method. A 3-dimensional geometry of the tooth was obtained by scanning the extracted 26 numbered upper molar tooth with dental tomography. The 3D geometry obtained by using the Geomagic Design X 2020.0 software was divided into surfaces, and necessary arrangements were made. With the Solidworks 2013 software, 2 different cavity modeling, class I occlusal and class II disto-occlusal, with a cavity angle of 95 degrees on the 3D model, as well as 10, 30, and 50 micrometers thick, four types of adhesive materials and the modeling of the bulk-fill composite material on it were made. With finite element stress analysis, the stress distribution was analyzed using the Abaqus software. The materials used in the study are included in the simulation as isotropic linear elastic. Periodontal ligament and jawbone were not included in the analysis. A total of 600 N pressure was applied on the models. In our study, it was observed that the amount of stress on the tooth structures changed when the thickness, elastic modulus, and Poisson ratios of the adhesive material were changed. In addition, when all models are examined, it is seen that when the thickness is increased, more stress is placed on the adhesive material compared to the restoration, while when 50-micrometer-thick adhesive material is used, more stress is placed on the restoration compared to the adhesive material.

The Effect of Different Light-curing Units and Tip Distances on the Polymerization Efficiency of Bulk-fill Materials.

In an average class II posterior preparation, the curing light tip is placed at a distance from the restoration surface that far exceeds the 1-mm manufacturer's recommendation. This distance can have potentially detrimental effects on the curing efficiency of the light-curing unit as well as the properties of the resin-based composite restoration, especially at the bottom of the cavity preparation. The purpose of this study was to evaluate the effects of various types of light-curing units (LCUs) and the different curing distances on the degree of conversion (DC) and the surface hardness of bulk-fill composite materials. A total of 390 specimens of three resin-based composites (RBCs) were fabricated. Two bulk-fill RBCs, including Filtek Bulk Fill Posterior (3M ESPE GmbH, Seefeld, Germany) and Tetric N-Ceram Bulk Fill (Ivoclar Vivadent AG, Schaan, Liechtenstein), as well as a Filtek Z350 XT nano-filled composite (3M ESPE GmbH, Seefeld, Germany), were utilized. In this study, the Vickers microhardness number (VMN) and the DC were evaluated at 2 and 4 mm thicknesses. Polymerization for 20 seconds was performed using two high-power light-curing units, namely the polywave Bluephase G2 light-emitting diode (LED) LCU (Ivoclar Vivadent AG, Schaan, Liechtenstein) and the monowave Elipar Deep Cure S LED LCU (3M Oral Care, St Paul, MN, USA) at 0, 2, and 4 mm distance between the curing tip and the RBC surface. The results were analyzed using the two-way analysis of variance method. Scheffe's post-hoc multiple comparison tests were used to determine significant differences between the materials, the LCU, and the tip distances. The highest DC (70.17) was shown by Filtek Bulk Fill Posterior at a distance of 0 mm, whereas the lowest DC (45.99) was measured for the conventional Filtek Z350 XT at a 4 mm distance. Moreover, higher VMNs were shown by Filtek Bulk Fill and Filtek Z350 composites at 0 mm distance than by the Tetric N-Ceram Bulk Fill composite material when cured with a Bluephase G2 LCU. For all materials, a significant decrease in the DC and mean VMN values was observed at a 4 mm distance in comparison with 0 and 2 mm distances. The DC and VMN values among the studied bulk fill materials were more significantly affected by the material composition and curing protocols. The increased distance from the light tip has a detrimental effect on the mechanical properties of composite resin materials. Significant differences were observed in the curing efficiency of the two LCUs investigated.

Influence of Practitioner-Related Placement Variables on the Compressive Properties of Bulk-Fill Composite Resins-An In Vitro Clinical Simulation Study.

Aims: To determine if restoration location and/or execution behavior force parameters have an influence on the mechanical properties of bulk-fill composite dental restorations. Methods: Pressure transducers were placed within each quadrant of dental mannequin jaws. Cylindrical molds were placed above the transducers and filled with two bulk-fill composite materials, Filtek and Tetric, by four experienced dentists. Each dentist prepared five specimens per quadrant and material. The total placement time, mean force, number of peak forces (above 25 N), and mean peak(s) force during placement were measured. Then, the stiffness and maximal compressive strength of the specimens were determined while loading the specimens up to failure using a universal loading machine. Results: Placement time was affected by jaw (p < 0.004) and side (p < 0.029), with the shortest time demonstrated for the left side of the mandible. Force exerted during restoration placement was not normally distributed without differences in location (jaw) or material. A higher application force was found on the right side (p < 0.01). The number of peak forces was affected by side (p < 0.03), with less peaks on the left side. No significant differences were found in compressive strength when correlated to restoration location, participant, or material (p = 0.431). The stiffness values of Filtek (3729 ± 228 N/mm) were found to be 15% higher than Tetric (3248 ± 227 N/mm) (p < 0.005). No correlations were found between the compressive strength or stiffness and the amount of force applied during placement. Conclusions: The individual restoration material placement parameters did influence practitioner performance; however, these differences did not affect the mechanical properties of the final restoration.

The Effect of Different Light Curing Units and Tip Distances on Translucency Parameters of Bulk fill Materials

ObjectivesTo evaluate the effect of light curing unit (LCU) types and distance from light curing unit tip on the translucency parameters (TP) of bulk fill composite materials. Materials and MethodsTwo bulk-fill resin composites and one nanohybrid composite were used in this study. The specimens were divided into groups based on the type of curing unit used, and further subdivided based on the distance of the curing source to the surface of the resin composite. Translucency was evaluated at 4 mm thickness (for the bulk-fill) and 2 mm thickness (for nanohybrid) after curing using two different light curing units at zero, 2 mm, and 4 mm distance. The results were analyzed using two-way ANOVA at the significance level of a p-value of < 0.05. ResultsAmong all the tested materials, Filtek Bulk Fill Posterior RBC showed the highest TP at 0 mm distance when cured with Blue phase G2 LED LCU and it was the least affected by the differences in distances. However, Filtek Z350 nanohybrid composite had no significant differences between the three distances when cured with Blue phase G2 LCU. ConclusionTranslucency values among the studied bulk-fill materials are affected by material composition, curing units and the distance of the tip of the light source to the restoration surface.

Effects of thickness and aging of bulk-fill composite resins on surface microhardness and fluorescence properties

Objective: Evaluation of various bulk-fill composite materials with respect to the microhardness values of the top and base surfaces upon variation in the composite thickness. The effect of aging and comparison of the fluorescence properties exhibited by the materials at different thicknesses will also be examined. Materials and Methods: For all samples, calculations were carried out using a family F probability, with a repeated family design including interactions within and among the factors, which resulted in 135 sample units, with 27 samples per experimental group. Z350, AURA, TETRIC, SDR, and FBF composites were employed with thicknesses of 2, 3, and 4 mm, initially being submitted to microhardness measurements (n=9). Aging was carried out using an aqueous ethanol solution. After aging the microhardness values of the samples were measured again, and a comparative analysis was performed for the fluorescence of all samples. Results: Aging, sample thickness, and the type of material were found to affect both the surface microhardness and the fluorescence values. In addition, the AURA and SDR bulk-fill composites were the least susceptible to differences in thickness in terms of the top and base surface microhardness values. Conclusions: Although the manufacturers of some bulk-fill composites recommend the use of material increments of 4 mm, the results of this study suggest that further research is required before clinical application.

Comparison of Surface Roughness of Different Bulk-Fill Composite Materials Using One-Step Polishing Systems (An In-Vitro Study)

Surface qualities for resin composite restorations are important factors for any successful restoration. Thus, finishing and polishing procedures are paramount to achieving acceptable aesthetics and guaranteeing the longevity of composite restorations. This in-vitro study aimed to evaluate the influence of a one-step polishing system on the surface roughness of three bulk-fill composite resin materials. This article provides a new view into the effects of finishing and polishing on bulk-fill composites, which has received very little research. Hence, this in-vitro study was conducted to extensively evaluate the impact one-step polishing technique has upon the three bulk-fill composite resin materials' surface roughness. A total of thirty discs were prepared from three commercial resin composite [Filtek One Bulk-Fill (3M), Tetric EvoCeram Bulk-Fill (Ivoclar Vivadent), and Ecosite Bulk-Fill(DMG)] using a stainless-steel flat washer. The composite material was condensed within a mold and cured with light Intensity 1000 mw/cm for 20 seconds. All specimens were divided into three groups (n = 10): (1) EvoCeram, (2) Ecosite group, and (3) Filtek group. A single operator polished all specimens. The top surface of each sample was finished with a fine-grit tungsten carbide bur (X-mas Tree with Safe End, NTI-Kahla GmbH, and Germany) for 30 seconds. Then all specimens were polished for 30 seconds by using the OneGloss one-step polishing system. A calibrated mechanical profilometer was used to measure the Ra for each material. The lowest roughness value (0.19) was observed for the composite resin Tetric EvoCeram (Ivoclar). One-way ANOVA and LSD test showed significant differences among and between all experimental groups. Therefore, Tetric EvoCeram had the only clinically acceptable Ra values.

Micro-computed tomography for assessing the internal and external voids of bulk-fill composite restorations: A technical report.

PurposeThis technical report aims to describe and detail the use of micro-computed tomography for a reliable evaluation of the bulk-fill composite/tooth interface.Materials and MethodsBulk-fill composite restorations in tooth cavities were scanned using micro-computed tomography to obtain qualitatively and quantitatively valuable information. Two-dimensional information was processed using specific algorithms, and ultimately a 3-dimensional (3D) specimen reconstruction was generated. The 3D rendering allowed the visualization of voids inside bulk-fill composite materials and provided quantitative measurements. The 3D analysis software VG Studio MAX was used to perform image analysis and assess gap formation within the tooth-restoration interface. In particular, to evaluate internal adaptation, the Defect Analysis add-on module of VG Studio Max was used.ResultsThe data, obtained with the processing software, highlighted the presence and the shape of gaps in different colours, representing the volume of porosity within a chromatic scale in which each colour quantitatively represents a well-defined volume.ConclusionMicro-computed tomography makes it possible to obtain several quantitative parameters, providing fundamental information on defect shape and complexity. However, this technique has the limit of not discriminating materials without radiopacity and with low or no filler content, such as dental adhesives, and hence, they are difficult to visualise through software reconstruction.

The effect of composite placement technique on the internal adaptation, gap formation and microshear bond strength.

This study aimed to compare the efficiency of placement technique on internal adaptation, gap formation and microshear bond strength (SBS) of bulk-fill composite resin materials. Standardized class V cavities were prepared for microcomputed tomography (mCT) test and divided into four groups (n=12) as follows: Group SDR: Smart Dentin Replacement system/bulk fill; Group SF2: Sonic-Fill system/bulk fill sonic-activated composite placement system; Group CHU: Herculite-XRV-Ultra composite resin inserted with Compothixo/sonic-vibrated composite resin placement system; Group HIT: Herculite-XRV-Ultra composite resin applied with incremental technique. Self-etch adhesive (Optibond-XTR) was used for bonding in all groups. After 10000 thermocycling, mCT scans were taken to reveal gap formation at the toothrestoration interface and universal testing machine was used to test microshear bond strength SBS values (n=10). ANOVA, post-hoc Bonferroni and Tukey HSD tests were used for evaluating the gap formation and SBS values p=0.05. SF2 and CHU showed the best adaptability compared with both SDR and HIT. The difference between groups SDR and HIT was statistically significant (p<0.05).SBS values were found to be the highest for SF2, and the lowest for HIT groups (p>0.05). Bulk-fill composite resins placed either with sonic-activated or sonic-vibrated instrument demonstrated better adaptability, less gap formation and higher bond strength than both the bulk-fill flowable composite and conventional incremental techniques.

Evaluation of the color stability and surface roughness of dual-cure, bulk-fill composites

Aim: In recent years, tooth-colored, dual-cure, bulk-fill composite resins, which have attracted attention for their ease of use, constitute one of the latest developments in pediatric dentistry applications. This study aimed to evaluate the color stability and surface roughness properties of three different dual-cure, bulk-fill materials and one light-cure, bulk-fill composite material used in pediatric dentistry.&#x0D; Methodology: In this study, three different dual-cure, bulk-fill composites (Fill-Up, HyperFIL, Cention-N) and one light-polymerized bulk-fill composite (Reveal HD) were used. A total of 70 samples were obtained for surface roughness testing. The surface roughness testing was performed with a Hysitron TI 950 Triboindenter device. A total of 105 samples were obtained for the evaluation of color stability. Cherry juice, iced tea, and distilled water were used as solutions. Initial and final color measurements were made using a spectrophotometer. The color differences between measurements were recorded according to the CIEDE 2000 system.&#x0D; Results: The least surface roughness among the composite groups was observed in the light polymerized Cention-N composite samples in the experimental group. In the Fill-Up and Cention-N composite groups in the experimental group, the surface roughness of the samples left to self-polymerization and the samples polymerized with light showed a statistically significant difference (p &lt; 0.05). Among the composite groups, the highest amount of coloring was observed in the Fill-Up composite samples, which were left to self-polymerization and kept in cherry juice in the experimental group. The least coloration among the composite groups was observed in the Cention-N composite samples polymerized with light and kept in distilled water.&#x0D; Conclusion: Based on this information, a decrease in surface roughness and an increase in color stability can be expected due to self-polymerization and the light polymerization of dual-cured, bulk-fill composites.&#x0D; &#x0D; How to cite this article: Şivgan Güner Z, Bolgül B, İnandı T. Evaluation of the color stability and surface roughness of dual-cure, bulk-fill composites. Int Dent Res 2021;11(Suppl.1):266-273. https://doi.org/10.5577/intdentres.2021.vol11.suppl.39&#x0D; &#x0D; Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Investigation of the effect of different application techniques on microhardness in bulk-fill composite resins

Aim: The aim of this study was to investigate the effect of different application techniques on microhardness in one universal resin material and three different bulk-fill composite resin materials.&#x0D; Materials and Methods: In this study, one universal composite resin (Universal Restorative 200 [U], 3M-ESPE, USA) and three different bulk-fill composite resins (Filtek-One Bulk-Fill Restorative [F]; 3M-ESPE, USA: Tetric Evo-Ceram Bulk-Fill [E]; and Ivoclar-Vivadent, Liechtenstein; Tetric N-Ceram Bulk-Fill [N], Ivoclar-Vivadent, Liechtenstein) materials were used. A total of 60 disk-shaped samples, including 20 samples from each bulk-fill composite resin group, were prepared. The polymerization of the bulk-fill composite resins in one group was completed using a 2 mm (40 sec) + 2 mm (40 sec) incremental technique, and in the other group, it was completed using a 4 mm bulk technique (40 sec). The U composite resin (control group) polymerization was completed using a 2 mm + 2 mm (40 sec) incremental technique (n = 10). The Vickers microhardness (VHN) values ​​of the samples were calculated. The data were analyzed with Kruskal–Wallis and Mann–Whitney U tests (p &lt; 0.05).&#x0D; Results: Higher VHN values ​​were found in the U composite resin compared to those in the bulk-fill composite resins (p &lt; 0.05). In the bulk technique, a lower VHN value ​​was observed in the N bulk-fill composite resin than in the control group (p &lt; 0.05), while there was no difference between the N and E composite resin groups (p &gt; 0.05). A lower N bulk-fill composite resin was observed in the groups in which the incremental technique was applied than in the control group (p &lt; 0.05). When the techniques applied to the bulk-fill composite resins were evaluated within themselves, higher VHN values ​​were observed in the E composite resin in the group in which the incremental technique was applied but not in the group in which the bulk was applied.&#x0D; Conclusion: It was observed that the content differences of composite resins were effective at different VHN values. The U composite resin (control) group showed higher VHN values than all the bulk-fill composite groups.&#x0D; &#x0D; How to cite this article: Fidan M, Gönder HY. Investigation of the effect of different application techniques on microhardness in bulk-fill composite resins. Int Dent Res 2021;11(Suppl.1):32-7. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.6&#x0D; &#x0D; Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.