Diphenyliodonium Hexafluorphosphate Research Articles

Effect of diphenyliodonium hexafluorphosphate in the yellowing and properties of experimental resin cements

Aim: The yellowing effect is undesirable and can occur in the dental restoration margins when light-cured resin cements containing camphorquinone as photoinitiator is used. This study aimed to evaluate the effect of diphenyliodonium hexafluorphosphate (DPI) in photoinitiator systems that contained different concentrations of camphorquinone (CQ) and dimethylamino ethyl benzoate (EDAB) on resin cements. Methods: A base (1:1) of bisphenol A diglycidyl methacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA) was obtained, and 60wt% of glass fillers was added. Eight formulations were obtained: RC1 (0.5mol% CQ / 1mol% EDAB), RC2 (0.5mol% CQ / 2mol% EDAB), RC3 (1mol% CQ / 1mol% EDAB), RC4 (1mol% CQ / 2mol% EDAB), and RC5 to RC8, which contained the same bases plus 0.5mol% DPI. Experimental resin cements were evaluated by the degree of conversion (DC), L*a*b* color analysis, water sorption (WS) and solubility (S), flexural strength, and Elastic Modulus. The data were analyzed by three-way ANOVA, Tukey’s and Mann-Whitney tests (α = 0.05). Results: The combination of DPI and 0.5mol% CQ increased DC in RC6 and L* in RC5 without increasing the WS and a* b* values. CQ at 1mol% showed higher values of b* and lower values of a*, except for RC3. Groups with 2mol% EDAB showed higher DC. Conclusion: The addition of DPI reduces CQ, generating a decreased yellowing effect, while maintaining adequate properties in the resin cements, especially with 2mol% EDAB.

Influence of an iodonium salt on the properties of dual-polymerizing self-adhesive resin cements

Statement of problemDual-polymerizing self-adhesive resin cements present mechanical properties that may adversely affect the clinical performance of luted fiber-reinforced posts. PurposeThe purpose of this in vitro study was to evaluate the properties of dual-polymerizing self-adhesive resin cements after the addition of an onium salt. Material and methodsThe experimental groups were set according to the molar concentration of diphenyliodonium hexafluorphosphate (DPIHFP) (0.5, 1, and 2 mol%). The resin cements were submitted to a push-out bond strength test and assessed for flexural strength (ISO 4049/2009), degree of conversion (Fourier-transformed infrared spectroscopy), depth of polymerization, swelling coefficient, and degradation in solvent. The data were statistically analyzed by ANOVA, Tukey test, Kruskal-Wallis test, Dunn multiple comparison, and paired Student t test (α=.05). ResultsAll the RelyX U100 groups with onium salt showed the highest degree of conversion after 24 hours and 7 days (P<.001). However, no statistical difference was found among the BisCem groups (P=.054). The addition of 0.5 mol% DPIHFP increased the push-out bond strength and microhardness of RelyX U100 and promoted less degradation after immersion in solvent. The BisCem control group did not present a statistical difference from the experimental groups in terms of bond strength; the control group and the 0.5 mol% group showed no degradation in solvent. For swelling coefficient and flexural strength, no difference was found between the BisCem groups (P=.067 and P=.173), and the RelyX U100 2 mol% group presented the lower value (P<.001 and P=.048). Depth of polymerization was not statistically different in the experimental groups for either resin cement (P=.999). ConclusionsThe addition of 0.5 mol% DPIHFP improved the physical properties of dual-polymerizing self-adhesive resin cements.

Effects of camphorquinone concentrations on resins containing diphenyliodonium hexafluorphosphate

Effects of camphorquinone concentrations on resins containing diphenyliodonium hexafluorphosphate

Comparison of the Physical and Mechanical Properties of Resin Matrix with Two Photoinitiator Systems in Dental Adhesives.

This study evaluated the physical and mechanical properties of resin matrices in dental adhesives with two photoinitiator systems. Resin matrix specimens were made with five different kinds of photoinitiators. Neat resin consisted of 60% 2,2-bis[4-2(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (Bis-GMA) and 40% hydroxyethyl methacrylate (HEMA) by weight, along with camphorquinone (CQ, 1 mol %) and additional components (1 mol % each) as follows: Group 1, 2-(dimethylamino)ethyl methacrylate (DMAEMA); Group 2, ethyl-4-(dimethylamino) benzoate (EDMAB); Group 3, diphenyliodonium hexafluorphosphate (DPIHFP); Group 4, DMAEMA+DPIHFP; Group 5, EDMAB+DPIHFP. The degree of conversion (DC), flexural strength, flexural modulus, microhardness, and ultimate tensile strength were tested. The contribution of each photoinitiator to the DC in a selected group was analyzed with contour plots. One-way ANOVA and Tukey tests (p < 0.05) were used for statistical analyses. The DC of Groups 2, 4, and 5 was similar. The flexural strength was similar in all groups, but flexural modulus was significantly different. Group 3 had the lowest values for all physical and mechanical properties. Among all methods, the microhardness test revealed the greatest degree of difference among the five specimens. CQ, EDMAB, and DPIHFP were the most effective photoinitiators and CQ was the most influential factor for the DC rate.

Effect of diphenyliodonium hexafluorphosphate on resin cements containing different concentrations of ethyl 4-(dimethylamino)benzoate and 2-(dimethylamino)ethyl methacrylate as co-initiators

ObjectiveThe present study evaluated the influence of diphenyliodonium hexafluorphosphate (DPI) combined with two different amines [ethyl 4-(dimethylamino)benzoate (EDAB) and 2-(dimethylamino)ethyl methacrylate (DMAEMA)] on the properties of model resin cements. MethodsA comonomer base containing a 1:1 mass ratio of 2.2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA) was obtained, after which 1mol% of camphorquinone and 0.1mol% of hydroxyl butyl toluene were added to the comonomer blend. Concentrations of co-initiators varied at 0, 0.5 or 1mol% for DPI and in 1 or 2mol% for amines (DMAEMA or EDAB). Silanated Ba-Al-Si glass (60wt%) was added as filler. The combination of each amine and DPI concentration resulted in 12 formulations, which had the following properties analyzed: degree of conversion (DC), water sorption (Wsp) and solubility (Wsl), flexural strength (FS) and flexural modulus (Ef). Data for DC, FS and Ef were analyzed by two-way ANOVA and Tukey's test (α=0.05) and Wsp and Wsl by Kruskal–Wallis and Dunn tests (α=0.05). ResultsEDAB promoted a higher DC than did DMAEMA; however, DPI increased DC for all materials with DMAEMA. The physical properties of resin formulations containing EDAB were significantly better than those of groups with DMAEMA; however, DPI had a positive influence on the chemical and physical properties of the model resin cement containing DMAEMA, especially with higher concentrations of amine. SignificanceEDAB proved to be more reactive than DMAEMA, being less influenced by DPI. Resins containing a 1:2 CQ/amine ratio had better properties than those with 1:1.

Influences of iodonium salts on the properties of a hybrid composite resin containing BisS-GMA and expanding monomer modified epoxy

In order to reduce shrinkage and improve the mechanical properties of dental composite resins, we designed a hybrid resin formulation containing a novel matrix resin, BisS-GMA [bisphenol-Sbis( 3-methacrylato-2-hydroxypropyl)ether], and epoxy modified by a spiro-orthocarbonate (SOC) expanding monomer. Then, we tested the effects of an iodonium salt, diphenyliodonium hexafluorphosphate (DPIHFP), on the properties of the hybrid resin with seven different concentrations. The hybrid resin was polymerized by a ternary photo-initiator system. The volumetric shrinkage (VS), degree of conversion (DC) and compressive strength (CS) were assessed using AcuVol™, FTIR and a universal testing machine, respectively. The VS, DC and CS were improved with increasing DPIHFP concentration, but a high concentration of DPIHFP had a negative influence on the mechanical properties of the hybrid resin and offered no added improvement in the VS and DC. The best performance of a composite resin containing BisS-GMA and SOC-modified epoxy was achieved with 2wt% DPIHFP. The results also indicated that the resin containing BisS-GMA was superior to that containing Bis-GMA in terms of VS, DC and CS.

Relative photon absorption determination and the influence of photoinitiator system and water content on C=C conversion, water sorption/solubility of experimental self-etch adhesives

The present study aimed to determine the influence of photoinitiator/co-initiator system and the water content on polymerization efficiency, water sorption and solubility of experimental self-etch adhesives; as well as to understand the relation between photoinitiators and the curing unit on the resultant properties. Experimental adhesive formulations were formulated by mixing bis-2-methacyloyloxy-ethyl phosphate (2MP, Sigma Aldrich, USA) and 2-hydroxyethylmethacrylate (HEMA, Esstech Inc., USA) in equal parts by weight. Four photoinitiators were used: camphorquinone (CQ), phenantrequinone (PQ), trimethylbenzoyl-diphenyl-phosphine oxide (TPO) and bisacyl-phosphine oxide (BAPO). The tertiary amine ethyl-4-dimethylaminobenzoate (EDMAB) and the salt diphenyliodonium hexafluorphosphate (DPI) were tested as co-initiators. The following groups were tested: CQ+EDMAB, CQ+EDMAB+DEPI, PQ, PQ+EDMAB, PQ+DPI, PQ+EDMAB+DPI, TPO TPO+DPI, BAPO and BAPO+DPI. Materials were tested both without and with the addition of 10wt% of deuterium water (D2O). Photoinitiator absorption and the light-curing emission spectra were determined with a spectrophotometer to calculate the relative photons absorption (RPabs). Degree of conversion was obtained with Fourier-transformed infrared spectroscopy (FTIR/ATR). Water sorption and solubility were determined after successive weighting procedures. Results were analyzed by two-way analysis of variance (ANOVA) followed by Tukey׳s post-hoc test (α=0.05). PQ exhibited the highest RPabs values (334.9), followed by CQ (52.8), BAPO (33.7) and TPO (8.4). TPO-based material presented the highest DC in the neat state. Considering the formulations with water addition, TPO- and BAPO-based materials presented the highest values, whereas CQ- and PQ-based ones produced conversion values below 4.6. TPO- and BAPO-based materials presented superior performance than CQ- and PQ-based ones for water sorption and solubility. It was possible to conclude that self-etch adhesives ability to polymerize was not only dependent on the relation between light and photoinitiators spectra, but also individual characteristics of free radicals development and that groups formulated with TPO and BAPO presented superior properties as those formulated with CQ and PQ.

Synthesis, characterization, and photocuring of siloxane-oxirane monomers

The aim of this study was to synthesize, characterize, and evaluate alternative monomers for use in dentistry. Three siloxane-oxirane low-shrinkage monomers were synthesized, and the products’ conversion was followed by Fourier transform-infrared spectroscopy. The products obtained were characterized by 1H and 13C NMR and evaluated for viscosity and a refractive index. The polymerization was evaluated by formulating two experimental photoinitiation systems, which varied for the presence of 1,2 ethanediol. A ternary system with camphorquinone (CQ), ethyl 4-dimethylaminobenzoate (EDAB), and diphenyliodonium hexafluorphosphate (DPI) was used as control. The degree of conversion was assessed by differential scanning calorimetry (DSC). The NMR confirmed the synthesis success with 75, 87, and 55% yields for the monomers synthesized. The viscosity and the refractive index of the monomers showed favorable rheological and physical behaviors for application in dentistry. Moreover, the presence of 1,2-ethanediol increased the degree of conversion of the siloxane-oxirane monomers. This study showed a simple and effective way to synthesize siloxane-oxirane monomers with a high potential for application in dental materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1728–1733

Mechanical properties of model composite resin containing nanosilver filler

Purpose: Previous studies have successfully added nanosilver particles in commercial restorative composites to inhibit the growth of Streptococcus mutans and Lactobacillus. The aim of the present study was to evaluate the flexural strength (FS), flexuralmodulus (E), Knoop hardness (KH) and changes in surface roughness (Ra) and gloss after simulated toothbrushing of model composites resins containing nanosilver filler. Methods and materials: A co-monomer blend of bis-GMA diluted in a 80:20 ratio with TEGDMA was used as model resin matrix. The photoinitiator system was composed by 1mol% of camphorquinone, 2mol% of ethyl-4-dimethylamino benzoate and 0.5mol% of diphenyliodonium hexafluorphosphate. Hydroxy butyl toluene (0.1mol%) was used as inhibitor. The composite resins were loaded according to the following groups: Control – 60wt% of silanated Ba-Al-Si glass fillers; G1 – 59.94wt% Ba-Al-Si glass fillers + 0.06wt% of nanosilver fillers; G2 – 59.875wt% Ba-Al-Si glass fillers + 0.125wt% nanosilver fillers; G3 – 59.75wt% Ba-Al-Si glass fillers + 0.25wt% nanosilver fillers; G4 – 59.5wt% Ba-Al-Si glass fillers + 0.5wt% nanosilver fillers; G5 – 59.0wt%Ba-Al-Si glass fillers + 1wt%nanosilver fillers; and G6 – 58.0wt% Ba-Al-Si glass fillers + 2wt% nanosilver fillers. The FS and E tests were performed in a universal testing machine with a crosshead speed of 0.5mm/min (n=10); KH was performed with a load of 25 gf during 15 s (n=8). Ra was measured with contact profilometer and the Gloss (n=8) with a glossmeter before and after simulated toothbrushing with toothpaste slurry, load of 150 g and frequency of 4Hzduring 2h. Thedata of E andKHwere submitted to one-wayANOVA; FS datawere compared by Kruskal–Wallis. The data of Ra and Gloss were analyzed by repeated-measure two-way ANOVA and t-test for paired specimens. Results: Significant differences were not found among the groups for FS (p=0.377), E (p=0.660) and KH (p=0.542). However, toothbrushing had a negative influence on the Ra and Gloss results of all tested groups (p<0.05). Conclusion: The incorporation of nanosilver fillers had no influence on the mechanical properties of the tested model composites.

Improved polymerization efficiency of methacrylate-based cements containing an iodonium salt

ObjectiveThis study evaluated the effect of adding diphenyliodonium hexafluorphosphate (DPI) as a third component of the free-radical photoinitiator system of model resin cements on their photopolymerization kinetics/stress and fundamental properties. MethodsA model resin cement containing a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane and triethyleneglycol dimethacrylate was obtained. Camphorquinone (1mol%) and 2-(dimethylamino)ethyl methacrylate (2mol%) were added to monomer blend. Six mixtures were obtained by incorporation of 0 (control), 0.25, 0.5, 1, 2, or 4mol% of DPI. The cements were loaded with a 60% mass fraction of silanated glass fillers. Polymerization kinetics (using Fourier-transform near-infrared spectroscopy), flexural strength and modulus, water uptake/solubility, and polymerization stress were assessed. Data were statistically analyzed using one-way ANOVA and Student–Newman–Keuls’ test (P≤0.05). ResultsIn the DPI-modified materials, the onset of autodeceleration occurred earlier and at higher conversion compared with the control cement. The addition of DPI also led to a more active early-stage polymerization. The flexural modulus was generally higher for DPI-containing materials. Water uptake and solubility were generally lower for materials with DPI fractions ≥0.5%. Significant increase of polymerization stress was observed only in the group with 1mol% of DPI compared with the control cement. SignificanceThe effect of DPI on the photopolymerization reactivity of the cement is concentration-dependent; the use of DPI could result in better polymerization efficiency of resin-based cements.

Sal de iodônio aumenta a resistência coesiva de uma resina adesiva experimental na presença de solvente

This study evaluated the effect of organic solvent concentration on the tensile strength for an experimental adhesive resin containing a ternary photoinitiator system. A monomer blend based on the Bis-GMA, TEGDMA and HEMA was used as a model dental adhesive resin. Two photoinitiation systems were used: a binary system camphorquinone (CQ) and ethyl 4-dimethylamine benzoate (EDAB)] and a ternary system CQ, EDAB and diphenyliodonium hexafluorphosphate (DPIHFP)]. Varied ethanol concentrations were added to the resins, viz. 0, 5, 10, 20, 30, 40 wt%. The ultimate tensile strength test was used to investigate the influence of the solvent amount on the resistance of resins. Furthermore, the use of iodonium salt in photoinitiation system increased the cohesive strength when compared with the binary system. Regardless of solvent concentration, the cohesive strength of polymers containing diphenyliodonium was higher than for the binary photoinitiator system.

Iodonium salt improves the dentin bonding performance in an experimental dental adhesive resin

The aim of this study was to evaluate the influence of an iodonium salt on the immediate and long-term microtensile bond strength to dentin of an experimental dental two-step, self-etching adhesive system. A model dental adhesive resin was formulated using bisphenol A glicidyl dimethacrylate (Bis-GMA), triethylene glicol dimethacrylate (TEGDMA), and hydroxyethyl methacrylate (HEMA), which was polymerized using four combinations of photo-initiators and coinitiators. A group using only camphorquinone (CQ), two binary systems (CQ and ethyl 4-dimethylamine benzoate (CQ+EDAB), CQ and diphenyliodonium hexafluorphosphate (CQ+DPIHFP)) and a ternary system (CQ+EDAB+DPIHFP) was investigated. Clearfil SE Bond (CSEB) was used as a commercial reference. Bond strength to bovine dentin was assessed through microtensile bond tests measured in MPa in a universal testing machine. The beam specimens were stored in distilled water at 37°C for 24h and 1 year. Two-way ANOVA and Student–Newman–Keuls' post-hoc tests were used to compare means of groups (α=5%) and failure modes classified under magnification. After 24h, the ternary system showed a bond strength similar to that of the binary system CQ+EDAB and the commercial material. After 1 year of storage, the μTBS values of the group CQ+EDAB+DPIHFP showed a bond strength significantly higher (p<0.05) than those of the CQ, CQ+DPIHFP, and CQ+EDAB groups and no difference from that of the CSEB group. The ternary photo-initiator system with iodonium salt maintained increased bond strength to dentin of model self-etching adhesive systems after 1 year of aging.

Onium salt reduces the inhibitory polymerization effect from an organic solvent in a model dental adhesive resin

This study evaluated the effect of organic solvent concentration on the polymerization kinetics for a model dental adhesive resin containing a ternary photoinitiator system. A monomer blend based on the bis-GMA, TEGDMA, and HEMA was used as a model dental adhesive resin, which was polymerized using a binary system [camphorquinone (CQ) and ethyl 4-dimethylamine benzoate (EDAB)] and a ternary system [CQ, EDAB, and diphenyliodonium hexafluorphosphate (DPIHFP)]. Additionally, these blends had 0, 10, 20, 30, and 40 wt % ethanol added. Real-time Fourier transform infrared spectroscopy was used to investigate the polymerization reaction over photoactivation time. Data were plotted, and Hill's three-parameter nonlinear regression was performed for curve fitting. The addition of a solvent to the monomer blends decreased the polymerization kinetics, directly affecting the rate of polymerization, delaying vitrification, and attenuating the Trommsdorf effect. The introduction of DPIHFP displayed a strong increase in reaction kinetics, reducing the solvent inhibition effect. After 10 s of photoactivation, the binary system obtained in 0, 10, 20, 30, and 40% of ethanol, a degree of conversion of 44.6, 26.3, 13.4, 1.15, and 0.0%, respectively, whereas when a ternary system was used, the values were 54.6, 40.5, 27.4, 14.5, and 3.4%. An improvement was observed in the polymerization kinetics of a model dental adhesive resin when using a ternary photoinitiation system, making the material less sensitive to the residual presence of a solvent before photoactivation.

Onium salt improves the polymerization kinetics in an experimental dental adhesive resin

The aim of this study was to evaluate the influence of an onium salt in the polymerization kinetics of a dental adhesive model resin. A monomer mixture, based on Bis-GMA, TEGDMA and HEMA, was used as a model dental adhesive resin, which was polymerized using camphorquinone (CQ) as a photo-initiator in addition to either binary or ternary photo-initiator systems. The binary systems were formulated with different concentrations of diphenyliodonium hexafluorphosphate or ethyl 4-dimethylaminobenzoate in relation to the monomer and 1mol% of CQ. The ternary system was a blend of 1mol% of CQ, 2mol% of ethyl 4-dimethylamino benzoate and 0.25, 0.5, 1, 2 or 4mol% of onium salt. Real time Fourier Transform infrared spectroscopy was used to investigate the polymerization reaction over the photo-activation time. When CQ was used as photo-initiator, a slow polymerization reaction was observed and a lower monomer conversion. The addition of a second component (onium salt or amine) increases the polymerization rate and conversion independent on the co-initiator concentration. Ternary photo-initiator system showed an improvement on the polymerization rate of the dental adhesive model resin leading to high conversion in short photo-activation time. Also, a mechanism for initiating polymerization using an amine or onium salt as a co-initiator component is proposed.