Ethoxylated Bisphenol A Dimethacrylate Research Articles

Monomer Elution of Additive and Subtractive Manufactured Resins for Permanent Restorations.

Purpose: To evaluate the elution of residual monomers from resins used in additive and subtractive manufactured permanent restorations over a period of one month, using highperformance liquid chromatography (HPLC). Materials and Methods: Two additive manufacturing permanent crown resins (Crowntec, CT and VarseoSmile Crown Plus, VS) and a subtractive manufacturing resin nanoceramic (Cerasmart, CS) were used to fabricate 30 disc-shaped samples (10 × 2 mm) (n=10). The elution of bisphenol A ethoxylate dimethacrylate (BisEMA), urethane dimethacrylate (UDMA), and triethylene glycol dimethacrylate (TEGDMA) monomers was measured with HPLC at 1 day and 30 days after immersion. One-way analysis of variance (ANOVA) and post-hoc Tukey tests were used to evaluate differences in eluted monomer concentrations. Paired-sample t tests were used to test the differences in monomer concentration between storage times. Results: CS released BisEMA and UDMA residual monomers, while VS and CT released BisEMA and TEGDMA residual monomers. The residual monomer elution from CT was consistently lower than that from VS for both BisEMA (p <0.001) and TEGDMA (p <0.001). CS showed a decreasing release pattern in BisEMA (p =0.002) and UDMA (p <0.001) residuel monomers, whereas VS and CT showed an increasing release pattern in BisEMA (p <0.001) and TEGDMA (p <0.001) residuel monomers. Conclusions: The additive manufactured composite resins released higher amounts of residual monomers than the subtractive manufactured resin nanoceramic. Although the amounts of residual monomers released in the additive manufactured composite resins increased over time in contrast to subtractive manufactured resin nanoceramic, these values were below cytotoxic levels.

A thermostable ionic liquid-methacrylate-based polymer electrolyte for energy storage application

In recent years, gel polymer electrolytes (GPEs) incorporating ionic liquids (ILs) have been explored extensively for lithium-ion batteries due to their favourable thermal stability and high ionic conductivity. Gel polymer electrolytes can also improve the safety of lithium-ion batteries by eliminating the flammable organic solvents which are often used in traditional electrolyte systems. Herein, we report an efficient synthesis of a thermostable ionic liquid-methacrylate-based polymer gel electrolyte via a photo-initiated phase separation (PIPS) process in an inert environment. Anionic liquid phase of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI), coupled with a low molecular weight polyethylene glycol dimethyl ether (PEGDME), was combined with a solid phase of bisphenol A ethoxylate dimethacrylate (BEMA) at varying solid to liquid ratios to produce a thermally stable gel electrolyte. The highest ionic conductivity of 1.9 × 10−3 S cm−1 (at 30 °C) was achieved for the electrolyte with a solid-to-liquid ratio of 1:3 by weight. The Lithium metal cells utilizing these electrolytes and LiFePO4 as cathode active material exhibited the initial discharge capacity of 144 mAh g−1 with capacity retention of 85 % over 100 cycles in ambient temperature. The thermal stability of the cells was significantly improved upon increasing the EMIMTFSI content. This study illustrates the potential application of the IL-methacrylate gel polymer electrolyte system in enhancing the safety of Li-ion batteries through careful tuning of the composition. Their versatile properties also make them suitable for quasi-solid-state batteries with high energy density and safety.

Release Kinetics of Monomers from Dental Composites Containing Fluoride-Doped Calcium Phosphates.

This study analyse the type of release kinetic of specific monomers from dental resin composites containing various fluoride-doped calcium phosphates. The release behavior of urethane dimethacrylate (UDMA), ethoxylated bisphenol-A dimethacrylate (bis-EMA) and 1.6-hexanediol ethoxylate diacrylate (HEDA) was evaluated over a period of 35 days. Two tailored calcium phosphates doped with different concentrations of fluoride salts (VS10% and VS20%) were prepared and incorporated in the dimethacrylate matrix at various concentrations to generate a range of experimental composites. The release kinetics were characterized using mathematical models such as zero-order, first-order, Peppas and Higuchi models. The results showed that the first-order model best described the release kinetics. UDMA and HEDA exhibited significant differences in release compared to bis-EMA from day 1, while no significant differences were observed between UDMA and HEDA, except on day 35, when UDMA exhibited a higher release rate than HEDA. When comparing the release of each monomer, VS20-R20% had the highest total release percentage, with 3.10 ± 0.25%, whereas the composite VS10-R5% showed the lowest release percentage, with a total of 1.66 ± 0.08%. The release kinetics were influenced by the composition of the resin composites and the presence of calcium fluoride and sodium fluoride in the calcium phosphate played a role in the maximum amounts of monomer released. In conclusion, the release of monomers from the tested resin composites followed a first-order kinetic behaviour, with an initial rapid release that decreased over time. The composition of the resin monomers and the presence of fluoride salts influenced the release kinetics. The VS10-R5% and VS10-R10% resin composites exhibited the lowest total monomer release, suggesting its potential favourable composition with reduced monomer elution. These findings contribute to understanding the release behavior of dental resin composites and provide insights for the development of resin-based bioactive dental materials.

Effect of airborne particle abrasion treatment of two types of 3D-printing resin materials for permanent restoration materials on flexural strength.

This study aimed to assess the effects of airborne-particle abrasion (APA) on the flexural strength of two types of 3D-printing resins for permanent restoration. Two types of 3D printing resins (urethane dimethacrylate oligomer; UDMA, ethoxylated bisphenol-A dimethacrylate; BEMA) constituting different components were printed. The specimen surfaces were subjected to APA using 50 and 110µm alumina particles under different pressures. The three-point flexural strength was measured for each surface treatment group, and a Weibull analysis was performed. Surface characteristics were analyzed via surface roughness measurements and scanning electron microscopy. Dynamic mechanical analysis and nano-indentation measurements were limited to the control group. The three-point flexural strength according to the surface treatment was significantly lower in the UDMA group for large particle sizes and at high pressures; the BEMA group demonstrated low flexural strength for large particle sizes regardless of the pressure. After thermocycling, the flexural strengths of UDMA and BEMA significantly decreased in the group subjected to surface treatment. The Weibull modulus and characteristic strength of UDMA were higher than those of BEMA under different APA and thermocycling conditions. As the abrasion pressure and particle size increased, a porous surface formed, and the surface roughness increased. Compared with BEMA, UDMA featured a lower strain, greater strain recovery, and a negligible increase in modulus according to strain. Thus, surface roughness increased with the sandblasting particle size and pressure of the 3D-printing resin. Hence, a suitable surface treatment method to improve adhesion can be determined by considering physical property changes.

Effect of monomer composition and filler fraction on surface microhardness and depth of cure of experimental resin composites.

This study evaluated microhardness profiles and calculated depths of cure at 80% of the surface microhardness of experimental dental resin composites having different base monomer compositions and different filler fractions. Composites were prepared using four different base monomers (bisphenol A-glycidyl methacrylate [Bis-GMA], urethane dimethacrylate [UDMA], ethoxylated bisphenol-A dimethacrylate [Bis-EMA], and Fit-852) with triethylene glycol dimethacrylate (TEGDMA) used as a co-monomer at three filler:resin matrix weight percent fractions (50:50, 60:40, and 70:30). Uncured material was placed in 3D printed molds and light cured for 40 s from the top surface only. Knoop microhardness was measured at the top of the specimen, and at every 0.5mm up to 4mm in depth. Microhardness at the surface increased in all experimental composites as the filler fraction increased. When comparing base monomers, microhardness was the highest in UDMA-based composites, while Bis-GMA-based composites showed the lowest values. When comparing depth of cure as a function of base monomer type, both Bis-GMA and Bis-EMA showed significantly lower values than UDMA or Fit-852. Composites having 50wt% filler showed a significantly higher depth of cure than those with 60 and 70wt% filler. Base monomer and filler fraction significantly influence microhardness and depth of cure in these experimental composites.

Novel rechargeable nano-calcium phosphate and nano-calcium fluoride resin cements

ObjectiveIn most clinical circumstances, secondary caries at the margin of fixed dental restorations leads to restoration failure and replacement. Accordingly, the objectives of this study were to: (1) develop a novel rechargeable nano-calcium phosphate (NACP) and nano-calcium fluoride (nCaF2) resin-based cement; and (2) investigate their mechanical properties and calcium (Ca), phosphate (P), and fluoride (F) ion release, recharge, and re-release for the first time. MethodsThe cement matrix consisted of pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol-A-dimethacrylate (EBPADMA) was denoted PEHB. Four cements were fabricated: (1) PEHB+0%NACP+0%nCaF2 (experimental control); (2) PEHB+25%NACP+0%nCaF2, (3) PEHB+0%NACP+25%nCaF2; (4) PEHB+12.5%NACP+12.5% nCaF2. RelyX luting cement was used as a commercial control. Mechanical properties and long-term Ca, P, and F ion release, recharge, and re-release were evaluated. ResultsAdding 25% NACP, 25% nCaF2 and adding both 12.5% NACP and 12.5% nCaF2 to the cement matrix presented a significantly higher shear bond strength, flexural strength compared to the commercial control (p < 0.05) with a comparable outcome with no significant different (p > 0.05) compared to experimental control. The film thickness results of all cement groups met the ISO requirement (<50 µm). The resin cement group with both 12.5% NACP and 12.5% nCaF2 successfully released Ca, P, and F ions at 3.1 ± 0.01, 1.1 ± 0.05, and 0.51±0.01 mmol/L respectively. Moreover, it showed the ability to re-release Ca, P, and F ions at 0.62±0.01, 0.12±0.01, and 0.42±0.01 mmol/L respectively. ConclusionsThe resin cement group with both 12.5% NACP and 12.5% nCaF2 demonstrated the advantages of both types of bio-interactive fillers as it could release a higher level of ions than the resin cement with 25%nCAF2 and exhibited a better rechargeability compared to the resin cement with 25%NACP. Clinical significanceThe ability of this novel resin-based cement to release, recharge, and re-release Ca, P, and F ions could be one of the keys to lengthening the survivability of fixed dental restorations. These features could help to reduce the onset of secondary caries by enhancing the remineralization and preventing the demineralization of tooth structures.

Effects of two silane surface modifications with different functional groups on the thermal conductivity and mechanical properties of UV-cured composites with high ceramic filler loading

With rapid technological advancements, efficient thermal management is becoming increasingly important to sustain the stable operation of electronic devices. In this study, aluminum nitride (AlN) fillers with various acrylate monomers were subjected to two types of silane surface treatments to prepare composites with a high loading of AlN filler (65 wt%). The acrylates—isobornyl acrylate (IBOA), 1,4-butanediol diacrylate (BDDA), and trimethylolpropane triacrylate (TMPTA)—were mixed with bisphenol A ethoxylate dimethacrylate (Bis-EMA) as an oligomer, and phenylbis (2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) as a photo-initiator in different proportions to obtain resin matrices. Pristine AlN and AlN functionalized with APTES and MPS were used as fillers. The effect of the acrylate functional group in silanes on the thermal and mechanical properties of the acrylate resin was explored. The thermal conductivities of the IBOA/AlN/APTES and IBOA/AlN/TMPTA composites with a high loading of the filler functionalized with APTES and MPS were 1.34 and 1.57 W/(m∙K), respectively, 4.15 and 5.28 times higher than that of the composite with neat resin. The enhanced filler–matrix compatibility increased the tensile strength of the composites. The findings highlighted that silane functionalization of AlN can enhance the thermal conductivity and mechanical properties of the composite.

Novel rechargeable nanostructured calcium phosphate crown cement with long-term ion release and antibacterial activity to suppress saliva microcosm biofilms

ObjectiveResin cements with remineralizing and antibacterial properties are favorable for inhibition of caries. The objectives of this study were: (1) to investigate the capability of the novel dimethylaminohexadecyl-methacrylate (DMAHDM) and nano-sized amorphous calcium phosphate (NACP) containing cement to reduce saliva microcosm biofilm, and (2) to investigate the long-term ion release, recharge, and re-release of DMAHDM-NACP cement. MethodsPyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol-A-dimethacrylate (EBPADMA) were used to make PEHB monomer. Five cements were fabricated: (1) PEHB+0%NACP+0%DMAHDM (experimental control); (2) PEHB+25%NACP+0%DMAHDM, (3) PEHB+25%NACP+0%DMAHDM; (4) PEHB+25%NACP+3%DMAHDM; (5) PEHB+25%NACP+5%DMAHDM. RelyX luting cement was used as commercial control. Colony-forming units (CFU), lactic acid production, metabolic activities, and minimum inhibitory concentration (MIC) were performed. Long-term Calcium (Ca) and phosphate (P) ion release, recharge, and re-release were assessed. ResultsCompared to experimental and commercial controls, the NACP-DMAHDM cement significantly reduced CFU biofilm by 2–3 orders of magnitude, metabolic activities from 0.24±0.06 A540/cm2 to 0.03±0.01 A540/cm2, and lactic acid production from 27.7 ± 2.5 mmol/L to 5.4 ± 2.1 mmol/L (n = 6) (p<0.05). The DMAHDM showed an MIC value of 0.03 mg/L. However, when the DMAHDM was combined with PMGDM monomer, the MIC was greater than DMAHDM alone. The ion concentrations for the experimental groups significantly increased over time (1–84 days), indicating continuous ion release (n = 3) (p<0.05). Increasing the DMAHDM mass fraction from 0% to 5% and 3% to 5% significantly enhanced ion recharge and re-release at the third cycle (p<0.05). ConclusionsIncorporating DMAHDM and NACP into resin-based crown cement provides strong antibacterial action against saliva microcosm biofilm and presents a high level of Ca and P ion recharge abilities, exhibiting long-term Ca and P ion release and remineralization potential. Clinical SignificanceResin based cement containing NACP and DMAHDM were developed with remineralizing and potent antibacterial effects. This cement formulation showed ion release and remineralization potential and are promising formulations to inhibit the incidence of recurrent caries and could promote remineralization and be sustainable for the long term.

3D Printing of Noncytotoxic High-Resolution Microchannels in Bisphenol-A Ethoxylate Dimethacrylate Tissue-Mimicking Materials.

The ability to create cell-laden fluidic models that mimic the geometries and physical properties of vascularized tissue would be extremely beneficial to the study of disease etiologies and future therapies, including in the case of cancer where there is increasing interest in studying alterations to the microvasculature. Engineered systems can present significant advantages over animal studies, alleviating challenges associated with variable complexity and control. Three-dimensional (3D)-printable tissue-mimicking hydrogels can offer an alternative, where control of the biophysical properties of the materials can be achieved. Hydrogel-based systems that can recreate complex 3D structures and channels with diameters <500 μm are challenging to produce. We present a noncytotoxic photo-responsive hydrogel that supports 3D printing of complex 3D structures with microchannels down to 150 μm in diameter. Fine tuning of the 3D-printing process has allowed the production of complex structures, where for demonstration purposes we present a helical channel with diameters between 250 and 370 μm around a central channel of 150 μm in diameter in materials with mechanical and acoustic properties that closely replicate those of tissue. The ability to control and accurately reproduce the complex features of the microvasculature has value across a wide range of biomedical applications, especially when the materials involved accurately mimic the physical properties of tissue. An approach that is additionally cell compatible provides a unique setup that can be exploited to study aspects of biomedical research with an unprecedented level of accuracy.

Photopolymer formulation towards large scale additive manufacturing of autoclave capable tooling

Large-scale polymeric additive manufacturing (AM) is emerging as a method for producing prototype tooling in the aerospace industry. However, material options for oven/autoclave-capable tooling are currently limited to costly thermoplastics such as polyetherimide (PEI) and polyphenylene sulfide (PPS). Photopolymers can be formulated for oven/autoclave use and have advantages over thermoplastics such as ambient processing and rapid curing under low-energy ultraviolet light emitting diode (UV LED) lamps. This study presents initial photopolymer formulation work towards large-scale AM with bisphenol A ethoxylate dimethacrylate (Bis-EMA), a vinyl ester suitable for moderate autoclave/oven-curing temperatures (100–135 °C, 212–275°F). Bis-EMA photopolymers were prepared and cured in 3 mm thick specimens by UV irradiation to simulate large-scale AM conditions. Bis-EMA was also blended with pentaerythritol triacrylate (PETIA) to determine the influence of a high-functionality acrylate on cure response and material properties. For the same UV dose, an increase in PETIA content up to 50 wt% increased the Vickers Hardness Number (VHN) on the irradiated surface from 22.6 to 25.0. It also improved the ratio of top to bottom surface hardness from 65% to 91%, indicating possible improvement in through-thickness cure response. The addition of PETIA decreased the tensile modulus from 2.8 GPa to 2.1–2.3 GPa, and PETIA content above 20 wt% reduced the glass transition temperature (T g ) below the Bis-EMA control. A blend of 80 wt% Bis-EMA with 20 wt% PETIA yielded an optimal balance of improved through-thickness hardness over the Bis-EMA control while retaining thermal stability. To investigate suitability for oven/autoclave-capable tooling, this 80:20 photopolymer blend was reinforced with fiberglass and used to produce UV cured demonstration tooling via a pseudo-additive process. The tools were subjected to five oven cure molding cycles, and laser scanning showed an average deviation < 0.05 mm, indicating negligible degradation in the tool geometry. The hardness values of the tool stock material did not change significantly with thermal cycling, and the T g increased from 154 °C to 172 °C. This study is the first report of Bis-EMA/PETIA blends towards use in photopolymers for large-scale AM. The data confirm that Bis-EMA photopolymer formulations can achieve adequate through-thickness cure at the layer thicknesses typical of large-scale AM. An 80:20 Bis-EMA/PETIA blend was thermally stable within the low volume thermal cycles expected of a 3D printed prototype tool.

Novel rechargeable calcium fluoride dental nanocomposites

ObjectivesComposite restorations with calcium fluoride nanoparticles (nCaF2) can remineralize tooth structure through F and Ca ion release. However, the persistence of ion release is limited. The objectives for this study were to achieve long-term remineralization by developing a rechargeable nCaF2 nanocomposite and investigating the F and Ca recharge and re-release capabilities. MethodsThree nCaF2 nanocomposites were formulated: (1) BT-nCaF2:Bisphenol A glycidyl dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA); (2) PE-nCaF2:Pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA); (3) BTM-nCaF2:BisGMA, TEGDMA, and Bis[2-(methacryloyloxy)ethyl] phosphate (Bis-MEP). All formulations contained 15% nCaF2 and 55% glass particles. Initial flexural strength and elastic modulus, F and Ca ion release, recharge and re-release were tested and compared to three commercial fluoride-containing materials. ResultsBT and BTM nCaF2 composites were 3–4 times stronger and had elastic modulus 2 times that of resin-modified glass ionomer controls. PE-nCaF2 had comparable strength to RMGIs. All nCaF2 composites had significant F and Ca ion release and ion rechargeability. In F and Ca recharging cycles, PE-nCaF2 had the highest ion recharging capability among nCaF2 groups, followed by BT-nCaF2 and BTM-nCaF2 (p < 0.05). For all recharge cycles, ion release maintained similar levels, demonstrating long-term ion release was possible. Furthermore, after the final recharge cycle, nCaF2 nanocomposites provided continuous ion release for 42 days without further recharge. SignificanceNovel nCaF2 rechargeable nanocomposites exhibited significant F and Ca ion release over multiple recharge cycles, demonstrating continuous long-term ion release. These nanocomposites are promising restorations with lasting remineralization potential.

Influence of Alumina Nanoparticles on the Mechanical Properties of a Bioresin Composite

A significant part of the research and production activities is represented in the field of bioengineering by the biomaterials used in hard tissue restorations. They are of great interest in dental science, intending to improve technological aspects, monitoring their biological responses to the living organisms, but also to redesign economic aspects, beginning with the choice of raw materials. In the present work, light-curing composite biomaterials were made from a composite polymer matrix consisting of specific concentrations of bisphenol A-glycidyl methacrylate base monomer (Bis-GMA), a mixture of two co-monomers, triethylene glycol dimethacrylate and ethoxylated bisphenol A-dimethacrylate (TEGDMA/BisEMA), and two alumina nanopowder concentrations (5 wt.% and 10 wt.%). These materials were mechanically tested for flexural strength and compressive strength. The structural analysis of these materials consisted of SEM microscopy and EDX elementary mapping. In order to extract 3D projections of sample surfaces, but also to produce indicative values of their roughness, the SEM micrographs were processed with open-source software. In order to observe a clear evolution of the mentioned properties, the composite biomaterials were compared with materials formed only with the Bis-GMA/TEGDMA/BisEMA composite, and with a commercial composite resin, Filtek™ Supreme Ultra Universal Restorative, also. The findings showed an increase in the mechanical properties of the materials manufactured concerning the concentration of nanoparticles of aluminum. EDX analyzes confirmed the good homogeneity of nanoparticles in the polymer matrix. Mechanical properties of the manufactured nanocomposite biomaterials were reported 28.8 % higher than the control biomaterial. The comparison results with the commercial resin composite are encouraging.

Novel calcium phosphate ion-rechargeable and antibacterial adhesive to inhibit dental caries.

This study aimed to develop an antibacterial and calcium (Ca) and phosphate (P) rechargeable adhesive and investigate the effects of dimethylaminododecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) on dentin bonding, biofilm response, and repeated Ca and P ion recharge and re-release capability for the first time. Pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol A dimethacrylate (EBPADMA), 2-hydroxyethyl methacrylate (HEMA), and bisphenol A glycidyl dimethacrylate (BisGMA) formed the adhesive (PEHB). Three groups were tested: (1) Scotchbond (SBMP, 3M) control, (2) PEHB + 30% NACP, and (3) PEHB + 30% NACP + 5% DMAHDM. Specimens were tested for dentin shear bond strength, and Ca and P ion release, recharge, and re-release. Biofilm lactic acid production and colony-forming units (CFU) on resins were analyzed. The four groups had similar dentin shear bond strengths (p > 0.1). Adhesive with DMAHDM showed significant decrease in metabolic activity, lactic acid production, and biofilm CFU (p < 0.05). The adhesives containing NACP released high levels of Ca and P ions initially and after being recharged. This study developed the first Ca and P ion-rechargeable and antibacterial adhesive, achieving strong antibacterial activity and Ca and P ion recharge and re-release for long-term remineralization. Considering the restoration-tooth bonded interface being the weak link and recurrent caries at the margins being the primary reason for restoration failures, this novel calcium phosphate-rechargeable and antibacterial adhesive is promising for a wide range of tooth-restoration applications to inhibit caries.

Core-shell structured SiO2@ZrO2@SiO2 filler for radiopacity and ultra-low shrinkage dental composite resins

To overcome the interfacial problem between X-ray radiopaque ZrO2 fillers and polymer resin in dental composites, monodispersed SiO2@ZrO2@SiO2 (SZS) microspheres with narrow size distribution were prepared by a controlled sol-gel method. In the presence of SiO2 coating layer over SiO2@ZrO2 (SZ) microspheres, they were easily silanized same as SiO2 microspheres. Ethoxylated bisphenol A dimethacrylate (EBPADMA) with a higher molecular weight and a lower viscosity was used as base resin monomer mixed with a low amount of diluent triethylene glycol dimethacrylate (TEGDMA). Additionally, the addition of a small amount of pore agent acetone dicarboxylic acid (ADCA) produced some voids, thereby effectively reducing the polymerization shrinkage of the resin. The prepared dental composites combining 52 wt% monodispersed silica microsphere, 20 wt% SZS microspheres, exhibited significantly enhanced capacity in radiopacity (higher than tooth enamel) and very low shrinkage (<0.1%). It also has better mechanical properties than resin composites filled with SiO2 microspheres, and its strength can meet practical applications. The properties of the radiopaque dental composite were to be further tuned by varying the amount of SZS microspheres contents, and the radiopaque resin has an advantage over the commercial one in that it is clinically nondestructive.

An Evaluation of the Properties of Urethane Dimethacrylate-Based Dental Resins.

Most of the dental materials available on the market are still based on traditional monomers such as bisphenol A-glycidyl methacrylate (Bis-GMA), urethane dimethacrylate (UDMA), triethyleneglycol dimethacrylate (TEGDMA), and ethoxylated bisphenol-A dimethacrylate (Bis-EMA). The interactions that arise in the monomer mixture and the characteristics of the resulting polymer network are the most important factors, which define the final properties of dental materials. The use of three different monomers in proper proportions may create a strong polymer matrix. In this paper, fourteen resin materials, based on urethane dimethacrylate with different co-monomers such as Bis-GMA or Bis-EMA, were evaluated. TEGDMA was used as the diluting monomer. The flexural strength (FS), diametral tensile strength (DTS), and hardness (HV) were determined. The impacts of material composition on the water absorption and dissolution were evaluated as well. The highest FS was 89.5 MPa, while the lowest was 69.7 MPa. The median DTS for the tested materials was found to range from 20 to 30 MPa. The hardness of the tested materials ranged from 14 to 16 HV. UDMA/TEGDMA matrices were characterized by the highest adsorption values. The overall results indicated that changes in the materials’ properties are not strictly proportional to the material’s compositional changes. The matrices showed good properties when the composite contained an equal mixture of Bis-GMA/Bis-EMA and UDMA or the content of the UDMA monomer was higher.

UV-curable TiO2-polyacrylate composites for a dental implant simulation platform

This study develops a dental implant surgery composite material that allows learners to experience the drilling forces necessary to perform drilling into alveolar bone. Organic-inorganic TiO2-acrylate hybrid reactive precursors were first prepared in hydroethylacrylate (HEA) solvent using glycidylmethacrylate cordination-binding sol-gel polymerization of titanium tetrachloride in a simple one-pot hydrolysis process. HEA, used in place of alcohol, served as both of a solvent and a reactive monomer in later photopolymerization. The use of HEA eliminates the need to remove the diluent solvent. An average TiO2 nanoparticle size of about 20−30 nm was measured using dynamic light scattering equipment. The obtained TiO2-acrylate hybrid reactive precursors were mixed with bisphenol-A ethoxylate dimethacrylate and photoinitiators to prepare TiO2-polyacrylate composite films after ultraviolet-light illumination. Experimental results demonstrate that the contact angle of the composite films decreased with increasing TiO2-acrylate hybrid precursor content, whereas the glass transition temperature and hardness of the composite films increased. By varying TiO2- polyacrylate hybrid composition, a alveolar bone model was fabricated. The forces (> 7 N) necessary to drill cortical and cancellous bone were measured.

Novel Crown Cement Containing Antibacterial Monomer and Calcium Phosphate Nanoparticles.

Oral biofilm accumulation at the tooth–restoration interface often leads to recurrent dental caries and restoration failure. The objectives of this study were to: (1) develop a novel bioactive crown cement containing dimethylaminohexadecyl methacrylate (DMAHDM) and nano-sized amorphous calcium phosphate (NACP), and (2) investigate the mechanical properties, anti-biofilm activity, and calcium (Ca2+) and phosphate (PO43−) ion release of the crown cement for the first time. The cement matrix consisted of pyromellitic glycerol dimethacrylate and ethoxylated bisphenol-A dimethacrylate monomers and was denoted PEHB resin matrix. The following cements were tested: (1) RelyX luting cement (commercial control); (2) 55% PEHB + 45% glass fillers (experimental control); (3) 55% PEHB + 20% glass + 25% NACP + 0% DMAHDM; (4) 52% PEHB + 20% glass + 25% NACP + 3% DMAHDM; (5) 51% PEHB + 20% glass + 25% NACP + 4% DMAHDM; (6) 50% PEHB + 20% glass + 25% NACP + 5% DMAHDM. Mechanical properties and ion release were measured. Streptococcus mutans (S. mutans) biofilms were grown on cements, and colony-forming units (CFUs) and other biofilm properties were measured. The novel bioactive cement demonstrated strong antibacterial properties and high levels of Ca2+ and PO43− ion release to remineralize tooth lesions. Adding NACP and DMAHDM into the cement did not adversely affect the mechanical properties and dentin bonding strength. In conclusion, the novel NACP + DMAHDM crown cement has excellent potential for restoration cementation to inhibit caries by suppressing oral biofilm growth and increasing remineralization via Ca2+ and PO43− ions. The NACP + DMAHDM composition may have wide applicability to other biomaterials to promote hard-tissue formation and combat bacterial infection.

Influence of ionic interactions on lithium diffusion properties in ionic liquid-based gel polymer electrolytes

In this study, we characterize a ternary gel polymer electrolyte (GPE) composed of bisphenol A ethoxylate dimethacrylate (BEMA) and N-propyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr13TFSI) ionic liquid and we particularly study the influence of salt content and polymer network composition. The effect of salt concentration in liquid solutions (1-x)Pyr13TFSI-xLiTFSI (molar ratio R = x/(1-x)) is finely characterized by Arrhenius measurements, PFG-NMR and Raman spectroscopy. They highlight ions interactions evolution with the salt content. For lower salt concentrations, ions pairs with bidentate coordinations [Li(TFSI)2]- are preferentially formed. A salt content rise leads to the formation of ionic aggregates where several Li+ are bound by TFSI− to form [Liz(TFSI)y](z-y) large clusters. These ionic arrangements changes modify the mean charge of the complexes involving Li. It leads to better cycling performances with higher salt concentration contrary to the ionic conductivity evolution. When the binary solution is added to the GPE, a dual transport mechanism, by diffusion in the liquid phase and hops assisted by segmental motion, is confirmed. The Li transference number is improved with success by enhancing this segmental motion with the addition of a linear polymer (poly(ethylene glycol) methyl ether methacrylate, me-PEGMA). Cycling with 70% of theoretical capacity and improved high current ability is achievable at 25 °C with a dual me-PEGMA/BEMA polymer network.

Novel rechargeable nano-CaF2 orthodontic cement with high levels of long-term fluoride release

ObjectivesFluoride-containing orthodontic cements are used to combat white spot lesions (WSLs) in enamel. However, the fluoride (F) ion releases from these cements are relatively low and short-term. The objectives of this study were to develop a novel rechargeable orthodontic cement with nanoparticles of calcium fluoride (nCaF2) to provide long-term and high levels of F release, and to investigate F recharge and physical and cytotoxic properties. MethodsThe nCaF2 with a mean particle size of 58 nm were synthesized using a spray-drying method. Pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol A dimethacrylate (EBPADMA), 2-hydroxyethyl methacrylate (HEMA) and bisphenol A glycidyl dimethacrylate (BisGMA) were used to prepare the cements (denoted PE and PEHB resins). A resin-modified glass ionomer (RMGI) served as control. Enamel shear bond strength (SBS), cytotoxicity, and F ion recharge and re-release were evaluated. ResultsnCaF2 cements had good SBS and excellent biocompatibility that were comparable to RMGI (p > 0.1). After a recharge for 1 min, the F re-release from PEHB + 30%nCaF2 cement was 80% higher than RMGI (p < 0.05). Increasing nCaF2 content from 20% to 30% greatly increased the F ion re-release (p < 0.05). The F ion re-release of nCaF2 cements did not decrease with increasing the number of recharge and re-release cycles (p > 0.1). ConclusionsA novel F ion-rechargeable orthodontic cement containing nCaF2 was developed with clinically acceptable enamel SBS, good biocompatibility, and sustained F ion recharge and re-release that were 1.8 folds that of a commercial RMGI. Clinical SignificanceNovel rechargeable nCaF2 orthodontic cement is promising to provide the needed long-term and high levels of F ion releases to inhibit WSLs in orthodontics.

Mechanical properties, accuracy, and cytotoxicity of UV-polymerized 3D printing resins composed of Bis-EMA, UDMA, and TEGDMA

Statement of problemThree-dimensional printing has the potential for clinical applications, and additive manufacturing materials for dental use merit further investigation. PurposeThe purpose of this in vitro study was to evaluate the properties of materials formulated with ethoxylated bisphenol A-dimethacrylate (Bis-EMA), urethane dimethacrylate (UDMA), and triethylene glycol dimethacrylate (TEGDMA) as 3D printing resins for ultraviolet digital light processing (UV-DLP) 3D printers and to characterize the mechanical and biological properties and accuracy of the printed objects. Material and methodsTen different light-polymerized resins were formulated using Bis-EMA, UDMA, and TEGDMA. Their viscosities were measured, and only 7 resins with viscosities lower than 1500 centipoise (cP) were selected for 3D printing and further material characterization. The light-polymerized resins were printed into representative shapes using a custom-made 3D printer equipped with a 405-nm UV-DLP projector as the light source. The printed specimens were subjected to biologic, mechanical, and accuracy tests, and the data were submitted to 1-way ANOVA and Tukey post hoc comparisons (α=.05). ResultsPhotopolymerizable resins made of Bis-EMA, UDMA, and TEGDMA were successfully formulated for 3D printing to fabricate objects of various shapes and sizes. TEGDMA served as the diluent to reduce the viscosity and increase the degree of conversion, while UDMA and Bis-EMA provided strength as demonstrated by the mechanical testing. All the printed objects passed cytotoxicity testing. The flexural strengths of the printed specimens ranged between 60 MPa and 90 MPa; flexural modulus ranged between 1.7 GPa and 2.1 GPa; and surface hardness ranged between 14.5 HV and 24.6 HV. These represent similar mechanical properties to those of currently used clinical resin materials. In the accuracy test, the resin mixture composed of 80% Bis-EMA, 10% UDMA, and 10% TEGDMA had the highest accuracy, with a 0.051-mm deviation from the original design. ConclusionsBis-EMA, UDMA, and TEGDMA are good candidates for the formulation of 3D printing resins for dental use. The printed objects demonstrated favorable biological and mechanical properties. Further, the accuracy of the printed specimens showed potential for clinical application.