Glass Filler Research Articles

Effect of Carbon and Glass Fillers on Tensile and Impact Strength, Water Absorption, and Degradation Properties of Sisal/Polyester Composites

ABSTRACT The inferior mechanical and water absorption properties of natural fibers are massive challenges to utilizing them for industrial applications. The study aims to enhance tensile strength, impact strength, water absorption, and degradation of sisal/polyester composites using glass and carbon fillers. Four fillers proportions (2.5 wt.%, 5 wt.%, 7.5 wt.%, 10 wt.%) and two sisal fiber proportions (20 wt.% and 30 wt.%) were taken to fabricate the composites. Experimentations were performed according to the ASTM standards. The fillers improved tensile and impact strength, water absorption, and degradation of the composites. Carbon-filled composites displayed better results than the corresponding glass-filled composites. Carbon fillers showed a maximum increment of 24.2% in tensile and 78.5% in impact strength for the dry 20/80 composites, and 14.7% in tensile and 57.3% in impact strength for the dry 30/70 composites. Moreover, carbon fillers reduced water absorption by 55.4% for the 20/80 composites and by 53.6% for the 30/70 composites. The highest values of tensile and impact strengths were obtained for the 5 wt.% carbon-filled 30/70 composite; whereas, the lowest water absorption was for the 10 wt.% carbon-filled 20/80 composite. The lowest degradation of 2% in tensile and impact strengths was exhibited for the 7.5 wt.% carbon-filled 20/80 composites.

Influence of the nanostructural characteristics of inorganic fillers on the physical properties of resin cements.

Light-curing resin cements, each comprising one of five different inorganic fillers (non-porous and porous spherical SiO2 particles, irregularly shaped glass and ZrO2 particles, and porous ZrO2 spheres), monomers, and polymerization initiators were prepared to determine the effect of filler morphology on the adhesive strength of the resin cement. The strength of adhesion to a computer-aided design/computer-aided manufacturing (CAD/CAM) resin block was investigated mechanically by measuring the tensile bond strength, flexural strength, and elastic modulus. The resin cement containing sub-micron porous ZrO2 spheres had significantly higher tensile bond strength than the other resin cements. The resin cement containing the porous ZrO2 spheres had markedly lower flexural strength and elastic modulus values than the resin cements containing SiO2 and glass fillers.

A Review on Manufacturing Processes of Biocomposites Based on Poly(α-Esters) and Bioactive Glass Fillers for Bone Regeneration.

The incorporation of bioactive and biocompatible fillers improve the bone cell adhesion, proliferation and differentiation, thus facilitating new bone tissue formation upon implantation. During these last 20 years, those biocomposites have been explored for making complex geometry devices likes screws or 3D porous scaffolds for the repair of bone defects. This review provides an overview of the current development of manufacturing process with synthetic biodegradable poly(α-ester)s reinforced with bioactive fillers for bone tissue engineering applications. Firstly, the properties of poly(α-ester), bioactive fillers, as well as their composites will be defined. Then, the different works based on these biocomposites will be classified according to their manufacturing process. New processing techniques, particularly additive manufacturing processes, open up a new range of possibilities. These techniques have shown the possibility to customize bone implants for each patient and even create scaffolds with a complex structure similar to bone. At the end of this manuscript, a contextualization exercise will be performed to identify the main issues of process/resorbable biocomposites combination identified in the literature and especially for resorbable load-bearing applications.

Service properties of porous liquid glass concrete

The article presents studies’ results of cementless lightweight concretes based on porous granular aggregate. Lightweight concrete components are specially synthesized from mixtures containing liquid sodium glass and thermal energy waste with various fineness. Thermal hardening of a matrix based on liquid glass and technogenic fillers at a temperature of 350ºС provided heat-insulating concrete with 480 kg/m3density and compressive strength of 4.7 MPa. The aim of the work is to study operational stability of lightweight concrete from genetically related components. Durability of lightweight concrete was evaluated in terms of hydro physical properties, resistance to frost and salt aggression, and cyclic heating. Methods of physical and mechanical testing of concrete have been used in the work. X-ray phase analysis and electron microscopy were used to study materials’ composition and structure. The results of complex tests showed stability of the structure of liquid glass concrete based on porous aggregate to the impact of operational factors. The lightweight concretes developed are characterized by a softening coefficient of 0.81; they withstood 50 cycles of alternating freezing and thawing, 20 cycles of cyclic exposure at a temperature of 1050ºС and 20 thermal cycles at a temperature of 250ºС; staying in aggressive sulfate and chloride magnesium solutions.

Regulating the glass network structure of SiO2f/SiO2 composite joints by in-situ silica diffusion

To expand the application of SiO2f/SiO2 composites, joining is one indispensable process. However, it is hard to take care of the property of the composites and simultaneously form a robust joint. Here, a B2O3–ZnO glass filler with a loose network structure was designed to realize the self-joining of SiO2f/SiO2 composites. Results revealed that silica has a relatively rapid diffusion rate in B2O3–ZnO glass which is beneficial for the fast replacement of the glass network former. After brazing, silica diffused into the brazing seam, became a new network former and thus regulated the glass network structure. As a result, the maximum working temperature of the joint increased 200 °C compared with pristine B2O3–ZnO glass. The joints own 23.3 MPa shear strength at room temperature and remain 22.3 MPa at 600 °C. This work offers a way to achieve the joining of SiO2f/SiO2 composites and break through the original maximum working temperature of the glass filler.

Polycarbosilane-derived ceramic coatings with crack-free morphology for improving oxidation resistance of steel

• Polycarbosilane-derived coatings with crack-free morphology were fabricated. • Addition of glass filler has the ability to fill the cracks in the coatings. • Polycarbosilane-derived coatings significantly improve the oxidation resistance of steel. Polycarbosilane-derived (PCS-derived) coatings with crack-free morphology and superior oxidation resistance were prepared on the Q235 steels by a dip-coating method. The effects of glass filler content on the phase composition, surface morphology, interface and oxidation resistance of the coatings were investigated. The fabricated coatings mainly consist of crystalline phases of SiC and Al 2 O 3 . The content of Al 2 O 3 phase increases with the increase in glass filler content. Addition of glass filler has the ability to fill the cracks resulting from the shrinkage of polycarbosilane during pyrolysis, and crack-free coatings can be obtained. Moderate addition of glass filler in the PCS-derived coatings can significantly improve the oxidation resistance of Q235 steel.

GLASSY FUNCTIONAL FILLERS OF GLASS IONOMER CEMENTS IN THE SrO–Al2O3–P2O5–SiO2–F SYSTEM

Based on glass in the SrO–Al2O3–P2O5–SiO2–F system, functional glass fillers for glass ionomer cements containing up to 13 wt. % fluorine were obtained. The high level of radiopacity of the filling material is due to the presence of the absorbing component of the glass filler - oxide and strontium fluoride, which are introduced into the glass together. The use of fusible fluorine-containing raw materials makes it possible to reduce the glass transition temperatures, which opens up prospects for the industrial development of the developed compositions at melting temperatures below 1500 °C. The value of the refractive index of glasses with a high fluorine content nD ~ 1.50 is more in line with the refractive index of the polymer matrix of glass ionomer cement, which ensures high aesthetic characteristics of the filling material. Samples of transparent filling glass ionomer cement with high compressive strength > 100 MPa and hardening time of 5 min were obtained.

GLASS FILLERS BASED ON THE SrO–Al2O3–B2O3–SiO2 SYSTEM FOR DENTAL COMPOSITES

Dental composite ?lling materials based on glass in the SrO–Al2O3–B2O3–SiO2 system was obtained. The glass filler meets the modern level of requirements for filling materials, and is characterized by high chemical resistance to water, acids and alkalis (class I), high transparency (more than 80 %), consistency with the polymer matrix according to CTE while maintaining of an acceptable melting temperature and no tendency to crystallization. It is shown that the developed glass filler provides a high level of biomedical, operational and functional properties of a dental composite based on it and competitiveness with respect to popular foreign analogue materials.

Nature-inspired Material – A Step Ahead in Dental Materials

Glass-ionomer is first choice widely used biomaterial in caries disease. The evolution of dental material science includes insertion of new components into conventional material. A literature-based review outline of biomaterials for dental restorations development was presented in nature-inspired context. This article is a tribute to the entire research community, for all listed and unlisted, involved throughout the ages in the science of dental materials with the key inventions and milestones for humanity well-being on Earth. Results. Since the Neolithic, the human mind has been seeking for a matter to replace missing tooth tissue imitating/mimicking natural organ in appearance and function, what we call biomimetic/biomimicry approach. However, this restoring philosophy does not refer to the natural composition of hard tooth tissues. Possibly, there is another one concept of drawing inspiration from nature for the design of future dental materials. Nature-inspired synthesis goes beyond aesthetic/and anatomical similarities, and delves into the mechanistic, physico-chemical features or structure-phase of natural systems. In this context, pure glass-ionomer might be taken into consideration as a starting material. However, the search for synthetic nature-inspired mesomaterial with a structural-phase composition analogous to enamel/dentine/cementum, transforming into the original host hard tissues, should focus on elongated hydroxyapatite dipole control for creating and organizing into enamel prisms, and the interwoven alignment of perpendicular clusters/bunches in a picket-fence resembling three-dimensional order. The results of previous studies confirming the possibility of the formation of apatite-enamel-like tissue in glass-ionomer are promising. The concept of inclusion of calcium phosphate nanocrystals/substitution of glass filler seems to be forward-looking. The future role of polyelectrolyte organic matrix based on synthetic tooth polypeptides crosslinked with modified analogues of natural adhesives is still undiscovered.

Effect of Glass Filler Geometry on the Mechanical and Optical Properties of Highly Transparent Polymer Composite.

In this work, we studied the influence of the geometry and degree of filling of glass dispersed particles on the optical and mechanical properties of flexible high-transmission composites, based on thermoplastic polyurethane. Glass spheres, glass flake and milling glass fiber were used as fillers. Studies of mechanical properties have shown that the introduction of any filler leads to a decrease in tensile strength and an increase in the elastic modulus of the composite material, however, with the introduction of glass flakes and milling glass fiber, a significant increase in the yield strength of the material is observed. The optical properties of composites with glass spheres decrease exponentially with an increase in the volume fraction of the filler. With an increase in the concentration of glass flakes and milling glass fiber to 10 vol.%, a sharp decrease in transmission is observed. With a further increase in concentration, the orientation of the filler along the film occurs, due to which the transmission in the visible range increases to values close to those of a pure polymer.

Optimal Surface Pre-Reacted Glass Filler Ratio in a Dental Varnish Effective for Inhibition of Biofilm-Induced Root Dentin Demineralization.

A unique type of dental varnish (DV) containing surface pre-reacted glass (S-PRG) fillers of different concentrations was evaluated to determine the unpresented optimal ratio for inhibiting root dentin bio-demineralization. S-PRG DVs (10% to 40%)-10%-S, 20%-S, 30%-S, and 40%-S-were applied to bovine root dentin blocks and compared with controls-0%-f (no S-PRG) and 5%-NaF (5%-NaF). The Streptococcus mutans biofilm challenge was executed inside and outside an oral biofilm reactor for 7 days. The specimens were examined using a confocal laser scanning microscope and swept-source optical coherence tomography. Furthermore, they were observed using a scanning electron microscope and analyzed using energy-dispersive X-ray spectroscopy. The roughness (SzJIS) due to leaching of DV materials and demineralization depth were significantly less in the S-PRG groups than the control groups (p < 0.05). Complete or partially plugged dentinal tubules (DTs) were observed in 20%-S, 30%-S, and 40%-S, while wide-open DTs were observed more in controls. Cylindrical tags were present in groups containing more than 20% S-PRG. F, Na, Al, and Sr were detected in a higher percentile ratio in the 20%-S, 30%-S, and 40%-S groups compared to 0%-f and 10%-S. Nonetheless, it is suggested that incorporating 20% to 30% S-PRG fillers in DVs would be effective enough as an anti-demineralization coating, together with supplementing minerals; further evaluation is required to validate these findings.

Sustainable Basalt Fibers vs. Traditional Glass Fibers: Comparative Study on Thermal Properties and Flow Behavior of Polyamide 66-Based Composites

In this work, basalt fibers (BF) have been investigated as possible natural and sustainable replacements for the common synthetic mineral filler—glass fibers (GF)—used in polyamide 66 matrix (PA66). Composites have been prepared at two different fiber concentrations (15 and 25 wt.%, respectively) by melt blending. The developed systems have been mainly characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), capillary rheology, and scanning electron microscopy (SEM). The kinetic parameters to thermal degradation through the Coats–Redfern method allowed us to attest a negligible effect of fiber type on thermal stability of the developed systems. Composites incorporating 15 wt.% of fiber content possessed the highest activation energy (≥230 kJ/mol). The introduction of BF and GF in PA 66 polymer, regardless of content, always led to an increase in crystallization and melting temperatures, and to a similar reduction in crystallinity degree and glass transition temperature. The shear viscosity of the basic polymer increased by the addition of fillers, particularly at low shear rate, with a pronounced effect in the case of basal fibers. A slightly higher shear thinning behavior of BF/PA66 with respect to GF/PA66 composites was confirmed by fitting the flow curves through the power law model. Finally, a worsening in fiber dispersion, by increasing the content in the matrix, and a weak compatibility between the two phases constituting the materials were highlighted through SEM micrographs.

Are inert glasses really inert?

The aim of this study was to investigate the degradation of inert glass fillers which are commonly used in conventional resin-based composites to provide radiopacity, reduce the polymerization shrinkage and improve the mechanical properties. 75mg of five different glass powders (1µm) was immersed separately into 50mL of acetic acid (pH 4) and tris buffer (pH 7.4) for up to 4 weeks. At each time point the glass powder was filtered and dried for characterization using ATR-FTIR and XRD to assess the degradation behavior and crystallization. ICP-OES, ISE and pH measurements were performed on the supernatant solutions to monitor the pH and ion release. Although FTIR and XRD analysis showed no significant glass degradation or crystallization upon immersion, there was a substantial release of ions from the inert fillers, especially from BABFG and CDL. Barium release for these fillers were 270 and 165ppm respectively. G018-373 glass presented the lowest ion release followed by GM27884 and BABG. The ion release was more pronounced in acidic conditions compared to neutral conditions apart from the fluoride release. Inert glasses are not as inert as previously thought. This may result in leaching of ions, potentially causing toxicity, reduction in mechanical properties, increased wear and subsequent failure of the composite material. The ions released from the inert glass may interfere with other glass fillers such as bioactive glass fillers, inhibiting degradation of the bioactive glass, beneficial ion release from the bioactive glass, pH neutralization and apatite formation.

In Vitro Wear of Glass-Ionomer Containing Restorative Materials.

Advertisements of glass-ionomer-containing restorative materials recommend suitability as load-bearing permanent or semi-permanent restorations. Historically, unacceptably high wear rates limit clinical indications of glass-ionomer-containing restorations in this regard. To compare the in vitro wear of contemporary glass-ionomer-containing dental materials commercially advertised for use in permanent dentition as load-bearing restorations in a chewing simulator. Resin composite was tested as a control. A resin-modified glass ionomer (Ionolux, VOCO gmbH), a high viscosity glass-ionomer hybrid system (Equia Forte HT with Equia Coat, GC America), and a bioactive ionic resin with reactive glass filler (Activa Bioactive Restorative, Pulpdent) were evaluated. Filtek Supreme Ultra (3M ESPE) is a visible light-activated resin composite that served as a control. Standardized flat disk-shaped specimens (n=12/group) were submitted to 500,000 cycles with continuous thermal cycling against steatite antagonists. Volumetric wear was measured at 1000, 10,000, 200,000, and 500,000 cycles. There was a statistically significant difference in mean volumetric wear for Activa Bioactive Restorative (p=0.0081, 95% CI: 0.3973, 0.4982) and Equia Forte HT (p<0.001, 95% CI: 1.2495, 1.8493), but no statistically significant difference in mean volumetric wear for Ionolux (p=0.6653) compared to control. Activa Bioactive Restorative wore approximately 60% less than, and Equia Forte HT twice more than Filtek Supreme Ultra on average, respectively. Compared to a resin composite, contemporary glass-ionomer-containing restorative materials advertised for use as load-bearing restorations display measurably variable in vitro wear rates.

Evaluation of the effectiveness of bioactive glass fillers against Candida albicans adhesion to PMMA denture base materials: An in vitro study

BackgroundDentures with antimicrobial properties are desirable for preventing Candida albicans adhesion. This study was to assess the effectiveness of bioactive glass (BAG) on C. albicans adhesion, surface roughness, and hardness of denture base materials. MethodsHeat-polymerized (HP) and autopolymerized (AP) acrylic resins were used to fabricate 240 disk specimens (120/material, 60/C. albicans, 60/surface roughness and hardness). Specimens were divided into five groups (n = 10) based on the BAG concentration: 0.5, 1.5, 3, 5, and 7.5 wt% of the acrylic powder, with a control group comprised of unmodified specimens. Direct culture method was used to assess C. albicans adhesion. A profilometer and Vickers hardness test were used to measure surface roughness and hardness respectively. Analysis of variance (ANOVA) and post hoc Tukey’s test were used for data analysis (α = 0.05). ResultsBAG addition significantly decreased the C. albicans count when compared with the control group (P < 0.001) for both HP and AP. Regarding surface roughness, there was no change in the HP acrylic resins (P> 0.05), while the AP acrylic resins exhibited significantly higher surface roughness with BAG addition (P < 0.001). The hardness of the HP and AP acrylic resins were significantly higher with the addition of BAG (P < 0.001). ConclusionsThe addition of BAG to HP and AP acrylic resins effectively decreases C. albicans adhesion. The roughness of AP acrylic resins increases with the addition of BAG, while the hardness of both HP and AP acrylic resins increase with the addition of BAG.

Physicochemical structure features of refractory compositions with inorganic binders

The article presents the study results of new inorganic binders and the physicochemical processes of their formation. The main purpose of the created materials is to make molds and cores for foundry production. Creating environmentally-friendly binders with a set of functional properties for foundry production is relevant worldwide. Therefore, scientists from different countries are paying special attention to the study of silicate and phosphate binders. The study analyzes the kinetics of the orthophosphoric acid interaction with several inorganic materials – pulverent pyrophyllite, disthene-sillimanite, a by-product of electrocorundum production, and sodium chloride. The phase and chemical composition of all formed binders have been established. In aluminum-containing compositions, those are represented by aluminum orthophosphates in crystalline and amorphous forms. Sodium metaphosphate is formed in the composition with sodium chloride. Peculiarities of the structuring compositions physical process with liquid glass and granular quartz filler due to steam-microwave treatment are determined. It is shown that structuring occurs due to dehydration, which is completed within 4…12 min, which allows reducing the liquid glass content in the composition to 1.5% while ensuring a high level of strength. The properties of structured compositions with the developed binding components are researched, and it is shown that all of them are competitive. Recommendations for their possible application were created.

Numerical simulation of strain-softening behavior of glass-filled polymer composites: Comparison of two-dimensional and three-dimensional analyses using Arruda-Boyce and Three-Network viscoplastic models

Most polymers and stiff-filler reinforced polymer composites exhibit post-yield strain-softening characteristics under large deformation mechanical loading. Singh et al. [Polymer Composites, 40 (12), pp. 4726–4741, 2019] conducted compression tests on glass-filled epoxy composites, altering the shape and volume percent of the glass fillers, and observed a dominant strain-softening tendency immediately after the yield stress values. This study aims to capture the post-yield strain-softening characteristics of glass-filled epoxy composites reported by Singh et al. using finite element analysis (FEA). Arruda - Boyce (AB) and Three Network (TN) viscoplastic constitutive material models are used as matrix behavior to perform numerical simulations on two-dimensional and three-dimensional representative volume elements (RVEs), where spherical (circular in 2D) and milled/cylindrical (rectangular in 2D) fillers are randomly positioned and oriented inside. When the calibrated AB and TN models were used to simulate the stress-strain response of the pristine matrix, both models numerically converged and were in good agreement with the experimental results. However, when filler-reinforced polymer composites are considered, the simulations using the AB model become unstable and fail to converge soon after the yield stress (at small strain values) is reached. Whereas simulations using the TN model take a short period to converge to large strain values compared to the former model. The existence of an extra elastic-viscoplastic network in the TN model improves stability in the model's strain-softening zone, allowing for faster numerical convergence. Therefore, the TN model can be used to simulate the strain-softening behavior of both pristine and stiff-filler-reinforced polymer composites under large deformations. The true stress versus true strain data retrieved from the FEA of the two-dimensional and three-dimensional simulations using the TN model were compared with experimental data. When the TN constitutive model was used in three-dimensional simulations instead of the AB viscoplastic model, the elastic modulus, yield stress, and post-yield strain-softening characteristics of the spherical particle and milled fibre epoxy composites were shown to predict the experimental data rather well.

Antibacterial dental resin composites (DRCs) with synthesized bis-quaternary ammonium monomethacrylates as antibacterial agents

Three bi-quaternary ammonium methacrylates (biQAMA-12, biQAMA-14, and biQAMA-16) with different alkyl chain length were synthesized with the purpose of endowing dental resin composites (DRCs) with antibacterial activity without sacrificing physicochemical properties of DRCs. All of biQAMAs were confirmed by 1H-NMR spectra and incorporated into Bis-GMA/TEGDMA (60 wt/40 wt) resin matrix with a mass fraction of 5 wt% as antibacterial agent. The obtained resin matrixes were mixed with commercial silaned glass fillers at a mass ratio of 30 wt/70 wt to prepare antibacterial DRCs. The double bond conversion (DC), antibacterial activity against S. mutans., surface charge density, water contact angle, water sorption (WS) and solubility (SL), mechanical properties, and cytotoxicity of biQAMAs containing DRCs were investigated. The DRC without biQAMAs was used as control. The results showed that all biQAMAs containing DRCs had antibacterial rate higher than 90%, and DRC with biQAMA-12 had the highest antibacterial rate due to its highest surface charge density. Adding 5 wt% of biQAMAs would not bring out negative effect on physicochemical properties of DRCs, except for increasing WS, but the resultant WS still met the ISO requirement on WS of restorative materials. Both biQAMA-14 and biQAMA-16 containing DRCs showed higher cytotoxicity than control, thus biQAMA-12 was considered as the optimal antibacterial agent in this research.

Comparative Evaluation of Clinical Performance of Three Different Glass Hybrid Restorations in High Caries Risk Patients: A Randomized Control Trial

BACKGROUND: Finding a restorative material that can survive and be quite resistant in high caries risk patients is very challenging, that’s why three different glass hybrid restorations were tested for their clinical performance for one year in high caries risk patients. AIM: This study was conducted to evaluate the clinical performance of three glass hybrid restorations; nano-ionomer restoration (Ketac Nano), bioactive ionomer glass fillers (Activa bioactive), and alkasite restorative material (Cention N) in Class I cavity in high caries risk patients after 1 year according to the FDI criteria for the assessment of dental restorations. METHODS AND MATERIALS: Fifteen cooperative patients, males or females with high caries risk who were approving to participate in the trial of age range 18–50 years, were selected in the present study. Every patient should have three or more posterior teeth having occlusal pits and fissure carious lesions. Three Class I cavities were performed for every patient and restored randomly with Ketac Nano™, Activa Bioactive™, and Cention N™. All three restorations were applied, according to the manufacturers’ instructions. Restorations were evaluated at baseline (immediately), after 3 months, 6 months, and 1 year by two blinded assessors using FDI criteria for the assessment of dental restorations measuring functional properties. STATISTICAL ANALYSIS USED: Evaluation of functional properties was checked by Kruskal–Wallis non-parametric test statistics at 0.05 level. Collected data were analyzed for descriptive statistics both graphically and mathematically in terms of frequency, percent, median, interquartile range, and mean and standard deviations. Differences in evaluations between materials (M1, M2, and M3) were carried out by Chi-squared test at 0.05 level. However, differences between follow-up times (T0, T1, T2, and T3) were carried out by Friedman’s test for related samples for non-parametric data. Variations caused by the three materials and follow-up times in addition to interaction between them were assessed by repeated measures ANOVA for ranked data at significance levels of 0.05. Data analysis was carried out using computer software Statistical Package for the Social Sciences SPSS (IBM-SPSSver.23.0 for MacOS). RESULTS: Results of functional properties of the three restorative materials revealed that at baseline (T0) and 3 months (T1), all cases (100%) of the three materials were clinically successful, with no significant difference between them. However, after 6 months, 58 cases (97%) of M1, 56 cases (93%) of M2, and 54 cases (90%) of M3 were clinically successful, with non-significant difference between them. Moreover, after 12 months, 55 cases (91.6%) of M1, 56 cases (93%) of M2, and 53 cases (88%) of M3 were clinically successful, with non-significant difference between them. CONCLUSION: In the purpose of restoring posterior permanent teeth in high caries risk patients, all three restorative materials demonstrated acceptable clinical performance in Class I cavities with the same success rate.

Properties of Bis-GMA free bulk-filled resin composite based on high refractive index monomer Bis-EFMA

With the aim to prepare Bis-GMA-free bulk-filled dental resin composite (DRC), Bis-GMA-free resin matrix was prepared by mixing Bis-EFMA with TEGDMA at two mass ratios (Bis-EFMA/TEGDMA = 50 wt/50 wt and 60 wt/40 wt), and the bulk-filled resin composites were then obtained by mixing resin matrix with silanated glass fillers at a mass ratio of 30 wt/70 wt. Bis-GMA based resin composites were used as control. Refractive indexes of resin matrixes were measured. Besides the depth of cure mentioned in ISO standard, double bond conversion (DC) and bottom/top Vickers hardness (VHN) ratio of resin composites were investigated to evaluate the curing depth. Physicochemical properties, such as flexural properties, volumetric shrinkage (VS), shrinkage stress (SS), water sorption (WS) and solubility (SL), and cytotoxicity of resin composites were tested and statistically analyzed (ANOVA, Tukey's, p = 0.05). The results showed that Bis-EFMA/TEGDMA resin matrixes had higher refractive indexes than Bis-GMA/TEGDMA resin matrixes. Viscosities of Bis-EFMA based DRCs were higher than Bis-GMA based DRCs. Bis-EFMA-based (50/50) DRC had comparable depth of cure, DC, and VHN as Bis-GMA-based (50/50) DRC (p > 0.05). Though Bis-EFMA/TEGDMA (60/40) had the highest refractive index in all resin matrix, the corresponding DRCs had the lowest depth of cure, DC, and bottom/top VHN ratio in all groups (p < 0.05). Replacing Bis-GMA with Bis-EFMA had no negative effect on flexural properties, WS and SL of DRCs, and could reduce VS and SS of DRCs. Results of CCK8 assay showed that all of DRCs had the same cytotoxicity (p > 0.05), and the thickness of sample had no influence on the cytotoxicity (p > 0.05). All the results indicated that Bis-EFMA could be used to replace Bis-GMA to prepare bulk-filled dental resin composites. According to the results of depth of cure, DC, and bottom/top VHN ratio, 50 wt/50 wt was more appropriate than 60 wt/40 wt as the mass ratio of Bis-EFMA and TEGDMA in the resin matrix for bulk-filled dental resin composites.