Glycerol Dimethacrylate Research Articles

The application of synthetic wollastonite in digital light processing 3D printing

In this study, 3D printable organic-inorganic resins were developed using glycerol dimethacrylate, which can be synthesised from glycerol obtained as a by-product of the biodiesel production process, and wollastonite synthesised from reagent-grade materials, the by-product of the aluminium fluoride manufacturing process, silica gel waste or natural rock. The developed recyclable waste-based material was proven to be compatible with the widely available desktop DLP 3D PICO2 39 printer. It allowed straightforward additive manufacturing of true 3D structures with sub-millimetre spatial definition using standard printing parameters. This opens the way for the production of inorganic objects from reusable industrial waste.

A dual-functional α-diketone-based disulfide monomer for visible LED photopolymerization: Mitigating volumetric shrinkage and triggering polymerization

A α-diketone-based disulfide monomer (OHS), which serves the function of both volumetric shrinkage decreases and photopolymerization initiation under the irradiation of 405 light-emitting diode (LED) was designed and synthesized. The photochemical and photoinitiating performances were study by ultraviolet–visible spectrophotometer, electron spin resonance spin trapping (ESR-ST) experiments and real-time infrared spectrometer (FTIR). Despite OHS exhibits weak absorption at approximately 405 nm, OHS can effectively produce aromatic sulfur radicals to induce photopolymerization of itself and the bisphenol A glycerolate dimethacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) photopolymerizable system under 405 nm LED exposure. With increasing OHS addition, the final double bond conversion and maximum polymerization rate of the Bis-GMA/TEGDMA system improved, reaching up to 86.0% and 2.33% s-1, respectively. Importantly, OHS significantly reduces the volumetric shrinkage ratio of the Bis-GMA/TEGDMA photopolymerizable system, with the volumetric shrinkage ratio (5.01%) of the system containing 5% OHS declining by almost 50% compared to that (8.51%) of the control system without OHS. This reduction is attributed to reversible characteristic of the disulphide bonds and intermolecular hydrogen bondings. Furthermore, OHS has little influence on the gelation ratio, thermostability, and frictional resistance of the cured film.

Photopolymerization initiated by p-diethylene glycol monomethyl ether cinnamyl formamide-based disulfide under 455 nm LED with minimized volume shrinkage

This study introduces a novel p-diethylene glycol monomethyl ether cinnamyl formamide-based disulfide monomer, N,N′-(disulfanediylbis(2,1-phenylene)) bis(4-(4-(2-(2-methoxyethoxy)ethoxy) phenyl)-2-oxobut-3-enamide) (Mp-BSCF), designed to reduce the volume shrinkage of photosensitive resins and initiate monomer polymerization under 455 nm LED light irradiation. The photochemical properties and photoinitiation efficiency of Mp-BSCF are systematically investigated using UV–vis absorption spectroscopy, electron paramagnetic resonance (EPR) and real-time infrared spectroscopy. Although its weak absorption around 455 nm, Mp-BSCF can generate arylthiyl radicals under 455 nm LED irradiation, and then effectively initiate the polymerization of triethylene glycol dimethacrylate (TEGDMA)/A glycerolate dimethacrylate (Bis-GMA) system. Increasing Mp-BSCF addition enhances the final double bond conversion and maximum polymerization rate of the TEGDMA/Bis-GMA system, reaching up to 82.0 % and 2.02 % s−1, respectively. Notably, Mp-BSCF significantly reduces the volume shrinkage of the photopolymerization system, with the addition of 10 % Mp-BSCF resulting in a 50 % reduction compared to the control system. This reduction is attributed to the dynamic reversible nature of the SS bond “breaking-recovery” and the intermolecular hydrogen bond interaction. Additionally, Mp-BSCF improves the thermal stability, friction resistance, and hardness of the TEGDMA/Bis-GMA photopolymerization system.

Ion release mechanisms in composites containing CaP particles and hydrophilic monomers

ObjectiveTo investigate the effect of hydrophilic/permeable polymer matrices on water sorption/solubility (WS/SL), Ca2+ release, mechanical properties and hydrolytic degradation of composites containing dicalcium phosphate dihydrate (DCPD) particles. MethodsSix composites were tested, all with 10 vol% of glass particles and either 30 vol% or 40 vol% DCPD. Composites containing 1BisGMA:1TEGDMA in mols (at both inorganic levels) were considered controls. Four materials were formulated where 0.25 or 0.5 of the BisGMA/TEGDMA was replaced by pyromellitic dianhydride glycerol dimethacrylate (PMGDM)/ polyethylene glycol dimethacrylate (PEGDMA). Composites were tested for degree of conversion (FTIR spectroscopy), WS/SL (ISO 4049) and Ca2+ release (inductively coupled plasma optical emission spectroscopy). Fracture toughness (FT) and biaxial flexural strength/modulus (BFS/FM) were determined after 24 h and 60 days in water. The contributions of diffusional and relaxational mechanisms to Ca2+ release kinetics were analyzed using the semi-empirical Salim-Peppas model. Data were analysed by ANOVA/Tukey test (alpha: 0.05). ResultsWS/SL was higher for composites containing PMGDM/PEGDMA compared to the controls (p < 0.001). Only at 40% DCPD the 0.5 PMGDM/PEGDMA composite showed statistically higher Ca2+ release than the control. Relaxation diffusion was the main release mechanism. Initial FT was not negatively affected by matrix composition. BFS (both DCPD fractions) and FM (30% DCPD) were lower for composites with hydrophilic/permeable networks (p < 0.01). After 60 days in water, composites with PMGDM/PEGDMA presented significant reductions in FT, while all composites had reductions in BFS/FM. SignificanceIncreasing matrix hydrophilicity/permeability significantly increased Ca2+ release only at a high DCPD fraction.

Glycerol Acrylate-Based Photopolymers with Antimicrobial and Shape-Memory Properties.

In this paper, for the first time, photopolymers were synthesized from glycerol acrylates with different numbers of functional groups, 2-hydroxy-3-phenoxypropyl acrylate, glycerol dimethacrylate or glycerol trimethacrylate, without and with the addition of vanillin styrene. The photocuring kinetics were monitored by real-time photorheometry. The mechanical, rheological, thermal, antimicrobial and shape-memory properties of the photopolymers were investigated. All polymers synthesized demonstrated antibacterial activity against Escherichia coli and Staphylococcus aureus, as well as antifungal activity against Aspergillus flavus and Aspergillus niger. 2-Hydroxy-3-phenoxypropyl acrylate-based polymers showed thermoresponsive shape-memory behavior. They were able to maintain their temporary shape below the glass transition temperature and return to their permanent shape above the glass transition temperature. Synthesized photopolymers have potential to be used as sustainable polymers in a wide range of applications such as biomedicine, photonics, electronics, robotics, etc.

Validation of a human saliva model for the determination of leachable monomers and other chemicals from dental materials

This study aimed to prove the validity of a mixture of chemicals, including salts, small organic molecules, mucin, and α-amylase, as saliva surrogate (“artificial saliva”) for assessing leakage of methacrylate monomers and other constituents from dental materials. To achieve this, we developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of 2-hydroxyethyl methacrylate (HEMA), triethylene glycol dimethacrylate (TEGDMA), diurethane dimethacrylate (UDMA), bisphenol A glycerolate dimethacrylate (BisGMA), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), bisphenol A (BPA), and five homologues of ethoxylated bisphenol A dimethacrylate (BisEMA EO2–6) in unstimulated and artificial saliva, and compared their concentrations in the two saliva media following either spiking with a mixture of the compounds or incubation of test specimens of printed biomaterials. Test specimens were immersed in unstimulated/artificial saliva, incubated at 37 °C for 24 h, and saliva aliquots were extracted with methanol and subsequently analyzed by LC-MS/MS. The method was validated with regard to matrix effects, linearity, selectivity, lower limits of quantification (LLOQ), precision, bias and combined measurement uncertainty (u′). The performance characteristics of the method were comparable for unstimulated and artificial saliva samples. The combined u’ for individual chemicals at a concentration of 10 × LLOQ were within the range of 5.3–14 % for unstimulated saliva and 6.9–16 % for artificial saliva, except for the BisEMA homologues. Combined u’ for the latter were 27–74 % in unstimulated saliva, and 27–79 % in artificial saliva. There was no detectable release of BPA from the test specimens, and the TPO concentrations were mainly below the LLOQ. TEGDMA and UDMA were detected in the highest quantities, and at comparable concentrations in the unstimulated and artificial saliva. For all BisEMA homologues, the release was higher in unstimulated saliva than in artificial saliva. The study showed that the artificial saliva model can be a suitable replacement for native saliva, but might underestimate leakage of more lipophilic methacrylates.

Chemical Modification of Dental Dimethacrylate Copolymer with Tetramethylxylylene Diisocyanate-Based Quaternary Ammonium Urethane-Dimethacrylates-Physicochemical, Mechanical, and Antibacterial Properties.

In this study, two novel quaternary ammonium urethane-dimethacrylates (QAUDMAs) were designed for potential use as comonomers in antibacterial dental composite restorative materials. QAUDMAs were synthesized via the reaction of 1,3-bis(1-isocyanato-1-methylethyl)benzene with 2-(methacryloyloxy)ethyl-2-decylhydroxyethylmethylammonium bromide (QA10+TMXDI) and 2-(methacryloyloxy)ethyl-2-dodecylhydroxyethylmethylammonium bromide (QA12+TMXDI). Their compositions with common dental dimethacrylates comprising QAUDMA 20 wt.%, urethane-dimethacrylate monomer (UDMA) 20 wt.%, bisphenol A glycerolate dimethacrylate (Bis-GMA) 40 wt.%, and triethylene glycol dimethacrylate (TEGDMA) 20 wt.%, were photocured. The achieved copolymers were characterized for their physicochemical and mechanical properties, including their degree of conversion (DC), glass transition temperature (Tg), polymerization shrinkage (S), water contact angle (WCA), flexural modulus (E), flexural strength (FS), hardness (HB), water sorption (WS), and water leachability (WL). The antibacterial activity of the copolymers was characterized by the minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) against Staphylococcus aureus and Escherichia coli. The achieved results were compared to the properties of a typical dental copolymer comprising UDMA 40 wt.%, Bis-GMA 40 wt.%, and TEGDMA 20 wt.%. The introduction of QAUDMAs did not deteriorate physicochemical and mechanical properties. The WS and WL increased; however, they were still satisfactory. The copolymer comprising QA10+TMXDI showed a higher antibacterial effect than that comprising QA12+TMXDI and that of the reference copolymer.

Monomer release, cell adhesion, and cell viability of indirect restorative materials manufactured with additive, subtractive, and conventional methods.

The aim of this study was to measure residual monomer, cell adhesion, and cell viability of 3-dimensional printable permanent resin (PR), hybrid ceramic block (HCB), and indirect composite (IC) produced with additive, subtractive, and conventional techniques. Five 8 × 8 × 2 mm3 samples of each material were prepared for each experiment. In a 24-h period, monomer release was analyzed with high-performance liquid chromatography, and cell viability and adhesion were evaluated with the water-soluble tetrazolium salt test. Data were analyzed with IBM SPSS Statistics 26.0 statistical software, and results were regarded as significant at α = 0.05. Monomer release (triethylene glycol dimethacrylate, urethane dimethacrylate, and Bisphenol A glycerolate dimethacrylate) was significantly higher in the IC group. Mean cell viability was significantly lower in the HCB group than in the IC group. All monomers in the tested materials were released at rates that were below clinical significance. Cell adhesion rates in the groups were similar. Cytotoxic response was classified as minor in the HCB and PR groups and non-cytotoxic in the IC group.

Dual-Cure Adhesives Using a Newly Synthesized Itaconic Acid-Based Epoxy Acrylate Oligomer.

Herein, a novel biomass-derived itaconic acid (IA)-based epoxy acrylate oligomer (EAO) is synthesized by means of the esterification reaction of the epoxy group of bisphenol A diglycidyl ether (BADGE) with the carboxylic group of IA. The detailed chemical structure of the as-prepared bisphenol A diglycidyl ether diitaconate (BI) is characterized via the KOH value, FT-IR spectrum, and 1H-NMR spectrum. Further, a dual-cure adhesive system is formulated using BADGE, acrylic acid, and trimethylolpropane triacrylate with various BI contents, and the adhesive performance is investigated by measuring the thermal stability, adhesive properties, pencil hardness, and surface energy properties. Thus, the dual-cure adhesive with a BI content of 0.3 mol is shown to provide excellent thermal stability, along with an adhesive strength of 10.7 MPa, a pencil hardness of 2H, and a similar surface energy to that of a typical polycarbonate film. In addition, the properties of the BI-based dual-cure adhesive are compared with those of the dual-cure adhesives based on bisphenol A glycerolate diacrylate or bisphenol A glycerolate dimethacrylate.

A resin adhesive with balanced antibacterial and mineralization properties for improved dental restoration

ObjectiveAiming to develop an adhesive formulation that achieves a harmonious equilibrium between antibacterial efficacy and mineralization potential, 2-methacryloyloxy ethyl phosphorylcholine (MPC), N,N-dodecylvinylimidazole (DCV), and Sr-doped hydroxyapatite (Sr/HAp) nanorods were incorporated as functional constituents into the adhesive matrix, employing carefully optimized proportions. MethodsThe adhesive formulation comprised a blend of bisphenol A glycerolate dimethacrylate (Bis-GMA), 2-hydroxyethyl methacrylate (HEMA), and 1,6-hexanediol dimethacrylate (HDDMA) monomers. The effects of MPC and DCV additions, ranging from 1% to 4% (wt%), on various aspects such as adhesive curing kinetics, bonding strength, water contact angle, mechanical properties, and antibacterial activities against Streptococcus mutans (S. mutans) and Human Saliva Bacterial Flora (HSBF), was investigated both individually and in combination. Following the determination of the optimized MPC/DCV ratio, the effect of Sr/HAp on the mineralization potential of the adhesives was evaluated by soaking the samples in 1.5 times simulated body fluid (SBF) at 37 °C for 3 days followed by examination using scanning electron microscopy (SEM). Additionally, biocompatibility assay was conducted using L929 fibroblasts. ResultsThe introduction of MPC and DCV did not interfere the CC conversion degree of the resin blends in all the preparations. Notably, the incorporation of 3 wt% MPC demonstrated a significantly enhancement in the hydrophilicity of the adhesive, resulting in reduced bacterial adsorption. The addition of 3 wt% DCV exhibited potent antibacterial properties against attached bacteria. Furthermore, the introduction of 8 wt% Sr/HAp displayed a positive effect on mineral deposition on the adhesive surface. Importantly, all adhesive formulations demonstrated negligible cytotoxicity. Although a decrease in bonding strength was observed upon the introduction of MPC/DCV, the supplementation of Sr/HAp exhibited a reinforcing effect, effectively compensating for the decline. This beneficial outcome can be attributed to a substantial improvement in the flexural strength/modulus of the composite adhesive. SignificanceThe adhesive, simultaneously having ability in inhibiting bacteria adsorption, killing bacteria and promoted mineralization, holds great potential in achieving strong bonding strength for dental restoration applications to minimize repair failure.

Novel mechanically strong and antibacterial dimethacrylate copolymers based on quaternary ammonium urethane-dimethacrylate analogues.

This study assumed that the quaternary ammonium urethane-dimethacrylate derivative (QAUDMA-m, where m was 8, 10, 12, 14, 16, 18, and corresponded to the number of carbon atoms in the N-alkyl substituent) can be used to achieve copolymers with high mechanical performance and antibacterial activity. Photocured copolymers of bisphenol A glycerolate dimethacrylate (Bis-GMA) 40wt%, QAUDMA-m 40wt%, and triethylene glycol dimethacrylate (TEGDMA) 20wt% (BG:QAm:TEG) were characterized by the degree of conversion (DC), flexural strength (FS), flexural modulus (E), hardness (HB), and antibacterial properties (the number of bacteria colonies adhered to copolymer surfaces and inhibition zone diameter (IZD)) against Staphylococcus aureus and Escherichia coli. Reference copolymers of Bis-GMA, urethane-dimethacrylate monomer (UDMA), and TEGDMA (BG:TEG and BG:UD:TEG) were also characterized. The DC of BG:QAm:TEGs ranged from 0.59 to 0.68, HB from 83.84 to 153.91MPa, FS from 50.81 to 74.47MPa, and E from 1986.74 to 3716.68MPa. The number of S. aureus and E. coli bacteria adhered to BG:QAm:TEG surfaces was from 0 (no bacteria observed) to 6.47 and 4.99log(CFU/mL), respectively. IZD was from 10 and 5mm (no inhibition zone) to 23 and 21mm, respectively. Three copolymers: BG:QA8:TEG, BG:QA10:TEG, and BG:QA12:TEG had similar or better mechanical properties than the reference copolymers, but unlike them, they showed high antibacterial activity against both bacteria strains. The obtained copolymers can offer a good, mechanically efficient, bioactive alternative to BG:TEG and BG:UD:TEG copolymers. The use of such materials can help to make progress in dental health care.

Simulation study of shape memory polymer networks formed by free radical polymerization

Chemically crosslinked thermoset shape memory polymers (TSMPs) can combine the strength required for load-carrying structures and devices with stimuli-responsive properties that can allow them to perform crack-closing or other multifunctional properties. In particular, UV-curable shape memory polymers can be used for 3D printing, and to enhance the design process, a molecular dynamics (MD) modeling framework was developed to study them. The MD simulations were used to calculate thermophysical, mechanical, and shape memory properties for glycerolate dimethacrylate after UV-curing to form a polymer network. Semiquantitative agreement between simulation and experiment was achieved for the different properties compared. By examining various conditions for network formation, a range of distinct cross-linking topologies were generated and their effects on properties were evaluated. In particular, it was found that the percentage of monomers with the maximum number of possible links with other monomers had a greater correlation with recovery stress than the number of monomers reacted overall. A new topological fingerprint, the average minimum pathway between monomers, was proposed and found to have the strongest correlation with recovery stress than all properties examined.

Cytotoxicity and Microbiological Properties of Copolymers Comprising Quaternary Ammonium Urethane-Dimethacrylates with Bisphenol A Glycerolate Dimethacrylate and Triethylene Glycol Dimethacrylate.

Using dental composite restorative materials with a copolymeric matrix chemically modified towards bioactive properties can help fight secondary caries. In this study, copolymers of 40 wt.% bisphenol A glycerolate dimethacrylate, 40 wt.% quaternary ammonium urethane-dimethacrylates (QAUDMA-m, where m represents 8, 10, 12, 14, 16 and 18 carbon atoms in the N-alkyl substituent), and 20 wt.% triethylene glycol dimethacrylate (BG:QAm:TEGs) were tested for (i) cytotoxicity on the L929 mouse fibroblast cell line; (ii) fungal adhesion, fungal growth inhibition zone, and fungicidal activity against C. albicans; and (iii) bactericidal activity against S. aureus and E. coli. BG:QAm:TEGs had no cytotoxic effects on L929 mouse fibroblasts because the reduction of cell viability was less than 30% compared to the control. BG:QAm:TEGs also showed antifungal activity. The number of fungal colonies on their surfaces depended on the water contact angle (WCA). The higher the WCA, the greater the scale of fungal adhesion. The fungal growth inhibition zone depended on the concentration of QA groups (xQA). The lower the xQA, the lower the inhibition zone. In addition, 25 mg/mL BG:QAm:TEGs suspensions in culture media showed fungicidal and bactericidal effects. In conclusion, BG:QAm:TEGs can be recognized as antimicrobial biomaterials with negligible biological patient risk.

Fabric phase sorptive extraction of monomers released from dental resins in alcoholic beverages prior to their HPLC-UV determination

Fabric Phase Sorptive Extraction (FPSE) combined with High Pressure Liquid Chromatography coupled to UV (HPLC-UV) was applied for the simultaneous determination of organic monomers bisphenol-A (BPA), bisphenol A glycerolate dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), and urethane dimethacrylate (UDMA)]that can be released from dental resins [in alcoholic beverages. The FPSE procedure was optimized with regards to the critical parameters that affect the performance of the method: a) FPSE membrane type and size, b) sample loading volume c) elution solvent, d) volume of elution solvent, e) stirring rate during extraction and elution, f) extraction time, and g) desorption/elution time. The developed FPSE-HPLC-UV method was subsequently validated in terms of linearity, trueness, precision and selectivity, showing satisfactory results. The limits of detection (LOD) and limits of quantification (LOQ) were equal to 0.06 ng/μL and 0.2 ng/μL, respectively. Relative recoveries ranged between 92.0% and 99.2% in white wine samples, and between 85.4% and 95.0% in vodka samples for within-day assay (n = 5). For between-day assay (n = 3 × 4), recoveries ranged between 92.0% and 101.8% in white wine samples, and between 88.4% and 95.2% in vodka samples. The method was successfully implemented in the investigation of monomers released from alcoholic beverages incubated with dental resins for a period of 24 h and 7 days.

Physicochemical Properties of Novel Copolymers of Quaternary Ammonium UDMA Analogues, Bis-GMA, and TEGDMA.

This study aimed to elucidate the physicochemical properties of copolymers comprising 40 wt.% bisphenol A glycerolate dimethacrylate (Bis-GMA), 40 wt.% quaternary ammonium urethane-dimethacrylate analogues (QAUDMA-m, where m corresponds to the number of carbon atoms in the N-alkyl substituent), and 20 wt.% triethylene glycol dimethacrylate (TEGDMA) copolymers (BG:QAm:TEGs). The BG:QAm:TEG liquid monomer compositions and reference compositions (40 wt.% Bis-GMA, 40 wt.% urethane-dimethacrylate (UDMA), 20 wt.% TEGDMA (BG:UD:TEG) and 60 wt.% Bis-GMA, 40 wt.% TEGDMA (BG:TEG)) were characterized in terms of their refractive index (RI) and monomer glass transition temperature (Tgm) and then photocured. The resulting copolymers were characterized in terms of the polymer glass transition temperature (Tgp), experimental polymerization shrinkage (Se), water contact angle (WCA), water sorption (WS), and water solubility (SL). The prepared BG:QAm:TEG liquid monomer compositions had RI in the range 1.4997-1.5129, and Tgm in the range -52.22 to -42.12 °C. The BG:QAm:TEG copolymers had Tgp ranging from 42.21 to 50.81 °C, Se ranging from 5.08 to 6.40%, WCA ranging from 81.41 to 99.53°, WS ranging from 25.94 to 68.27 µg/mm3, and SL ranging from 5.15 to 5.58 µg/mm3. Almost all of the developed BG:QAm:TEGs fulfilled the requirements for dental materials (except BG:QA8:TEG and BG:QA10:TEG, whose WS values exceeded the 40 µg/mm3 limit).

Antimicrobial dual‐cured photopolymers of vanillin alcohol diglycidyl ether and glycerol dimethacrylate

AbstractConsidering the current efforts for to develop new antimicrobial polymers from renewable resources suitable for application in environmentally friendly light‐based technologies, novel dual‐cured photopolymers of vanillin alcohol diglycidyl ether and glycerol dimethacrylate are developed. The kinetics of the sequential and simultaneous dual‐curing processes, combining free radical and cationic photopolymerizations, is investigated by real‐time photorheometry. Comparison of dual‐curing systems with different ratios of biobased epoxy and acrylate monomers revealed that the increase in the acrylate content increases the photocuring rate and improves the mechanical performance (Young's modulus increases from 76.64 to 190.71 MPa) and thermal stability (the 10% weight loss increases from 227 to 274°C) of the polymers, while the increase in the vanillin epoxy content results in better antimicrobial activity. Developed photopolymers create unfavorable conditions for the growth of microorganisms and reduce their population by up to 0% in 24 h. The excellent antibacterial and antifungal activity of new photopolymers allows them to be considered as biobased alternatives to petroleum‐based antimicrobial coatings, films, or optical 3D printed objects.

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.

Design of a polymerizable dithioaniline derivative with double functions of reducing volume shrinkage and initiating polymerization for LED photopolymerization

This work reports a photopolymerizable dithioaniline derivative (OMABS), having the double functions of reducing volume shrinkage and initiating polymerization under light emitting diode (LED) irradiation. Its photochemistry and photoinitiation properties were investigated by UV–vis absorption spectroscopy, electron paramagnetic resonance spectroscopy (EPR), real-time infrared spectroscopy (RTIR) and confocal micro-Raman spectroscopy. OMABS shows a weak absorption around 385 nm and 405 nm, but can generate arylthiyl radicals to effectively initiate the polymerization of bisphenol A glycerolate dimethacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) system and itself under 385 and 405 nm LED irradiation, and the double bond conversion reaches up to 83.2 %. Significantly, OMABS can obviously reduce the volume shrinkage of Bis-GMA/TEGDMA system, and the volume shrinkage (4.89 %) of Bis-GMA/TEGDMA with OMABS system declines by almost half compared with that (8.10 %) without OMABS system due to the existence of dynamic reversible SS bond and intermolecular hydrogen bonding interaction. Moreover, OMABS has little influence on the gel yield, thermal stability and frictional resistance of the Bis-GMA/TEGDMA system.

Characterization of the Mechanical Properties, Water Sorption, and Solubility of Antibacterial Copolymers of Quaternary Ammonium Urethane-Dimethacrylates and Triethylene Glycol Dimethacrylate

The use of dental composites based on dimethacrylates that have quaternary ammonium groups is a promising solution in the field of antibacterial restorative materials. This study aimed to investigate the mechanical properties and behaviors in aqueous environments of a series of six copolymers (QA:TEG) comprising 60 wt.% quaternary ammonium urethane-dimethacrylate (QAUDMA) and 40 wt.% triethylene glycol dimethacrylate (TEGDMA); these copolymers are analogous to a common dental copolymer (BG:TEG), which comprises 60 wt.% bisphenol A glycerolate dimethacrylate (Bis-GMA) and 40 wt.% TEGDMA. Hardness (HB), flexural strength (FS), flexural modulus (E), water sorption (WS), and water solubility (SL) were assessed for this purpose. The pilot study of these copolymers showed that they have high antibacterial activity and good physicochemical properties. This paper revealed that QA:TEGs cannot replace BG:TEG due to their insufficient mechanical properties and poor behavior in water. However, the results can help to explain how QAUDMA-based materials work, and how their composition should be manipulated to produce the best performance. It was found that the longer the N-alkyl chain, the lower the HB, WS, and SL. The FS and E increased with the lengthening of the N-alkyl chain from eight to ten carbon atoms. Its further extension, to eighteen carbon atoms, caused a decrease in those parameters.

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.