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This study sought to evaluate the physical and antimicrobial properties of a thermopolymerizable acrylic resin (PMMA) modified with metallic methacrylate monomers -zirconia (ZM), tin (TM), and di-n-butyl (DNTMB) methacrylates. Color stability was evaluated before and after immersion of samples in a staining solution by a digital spectrophotometer. The mechanical brushing test was evaluated by the roughness test. The flexural strength test used a mechanical testing machine. Human keratinocytes were used to assess cell viability and the biofilm formation assay was carried out for 5 days, in a microcosms model after one year of specimen storage. For statistical analysis, the method chosen was based on adherence to the normal distribution model and equality of variances (p < 0.05). The addition of DNTMB to PMMA promoted great antimicrobial action, acceptable cytocompatibility, without hampering the physical-mechanical properties of the commercial material. Therefore, the modified PMMA proved to be a promisor alternative to conventional resins. This study sought to evaluate the physical and antimicrobial properties of a thermopolymerizable acrylic resin (PMMA) modified with metallic methacrylate monomers -zirconia (ZM), tin (TM), and di-n-butyldimethacrylate-tin (DNTMB) methacrylates. Color stability was evaluated before and after immersion of samples in a staining solution using a digital spectrophotometer. The mechanical brushing test was evaluated by the roughness test. The flexural strength test used a mechanical testing machine. Human keratinocytes were used to assess cell viability and the biofilm formation assay was carried out for 5 days in a microcosm model after one year of specimen storage. For statistical analysis, the method chosen was based on adherence to the normal distribution model and equality of variances (p < 0.05). The addition of DNTMB to PMMA promoted great antimicrobial action, acceptable cytocompatibility, without hampering the physical-mechanical properties of the commercial material. Therefore, the modified PMMA proved to be a promising alternative to conventional denture base resins for dental use. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the mechanical and physical properties of experimental HEMA-containing and HEMA-free resin adhesives. Materials and Methods: Experimental HEMA-free adhesives containing alternative dimethacrylates (bis-EMA 10 [B10], bis-EMA 30 [B30], PEG 400 [P400], PEG 1000 [P1000], PEG 400 UDMA [UP400]) were formulated and compared with a HEMA-containing adhesive (control). The adhesives were characterized by rheological analysis, polymerization kinetics (PK), water sorption (WS), and solubility (SL) tests. Flexural strength (FS) and flexural modulus (E) tests were performed under dry or wet conditions (distilled water or 70% ethanol solution). One-way and two-way ANOVA as well as Tukey's test were used to evaluate differences between groups (p < 0.05). Results: The control group showed the lowest viscosity and was the only one with a degree of conversion lower than 50%. The control and the P1000 adhesive showed the statistically significantly highest WS (p < 0.05). The control and the UP400 adhesive showed the highest FS and E, and the dry-stored specimens showed more improved mechanical strength than did the wet-stored specimens (p < 0.05). Conclusion: The physicomechanical properties of some of the HEMA-free adhesives were substantially improved when compared with those of the control, indicating that they could be potential monomers for the development of HEMA-free adhesive systems. [ABSTRACT FROM AUTHOR]

Objective. The aim of the present study was to characterize a novel resin-based monoblock endodontic obturation system consisting of a polymeric cone and a resin-based endodontic sealer. Methods. The preliminary tests performed for the experimental cone were as follows: cohesive strength, dimensional stability, standardization of the diameter and taper, calcium ion release, and radiopacity, for the characterization of the experimental sealer, film thickness and flow tests were performed. Tests were performed according to the American National Standards Institute/American Dental Association (ANSI/ADA) Standards Nos. 57 and 78. The experimental cone was compared to gutta-percha, whereas the experimental sealer was compared to AH Plus. Data were analyzed by Student's t-test (α = 0.05). Results. The experimental cone had superior values for cohesive strength and dimensional stability compared to gutta-percha. Regarding calcium ion release, the experimental system continued to release calcium ions after 30 days. Film thickness was similar for both endodontic sealers; conversely, the experimental resin-based sealer achieved higher values for flow compared to AH Plus. Conclusion. The experimental resin-based monoblock obturation system fully met the requirements of the ANSI/ADA Standard No. 78 and the ANSI/ADA Standard No. 57, except for radiopacity. Considering this, further studies are still needed to evaluate other radiopacifiers and the effect of their incorporation on the physicochemical properties of this novel resin-based monoblock endodontic obturation system. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the solubility and the fluoride release of different materials used for orthodontic band cementation in different solutions and at different times.Materials and Methods: Three materials were selected: Ultra Band-Lok (UBL); RelyX (RLX) and Ketac-Cem (KTC). Sixteen standard samples from each material were prepared, according to the manufacturers' instructions. The samples were stored in two different solutions (n = 8): 0.9% saline solution (pH 7.0) and 0.1 mol/l lactic acid (pH 4.0). The storage solutions were changed after 24 h and after 7, 15 and 30 days. The fluoride release was determined with an ion-specific electrode (Analion). For the solubility evaluation, the formula Wsl = (m1-m2)/V was used to determine the loss of mass. Data were submitted for statistical analysis using the non-parametric Kruskal-Wallis test.Results: With respect to the solubility, immersion in lactic acid increased the solubility when compared with saline solution (P < 0.01). In both the solutions, there were differences among materials (P < 0.01) with the following rankings: UBL < RLX < KTC for lactic acid and UBL < RLX < KTC for saline solution. The ranking of fluoride release was UBL < KTC < RLX. In the two tested solutions, RLX exhibited the highest fluoride release (P < 0.01), whereas KTC showed more fluoride release than that of UBL (P < 0.05). Fluoride release decreased over time and the storage solution influenced the fluoride-releasing capacity of some materials.Conclusions: It was found that fluoride release was influenced by storage solution, materials and immersion time. Materials and storage solution were the significant factors for solubility. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of different water concentrations in the solvents of self-etching primers on microtensile bond strength (μTBS) of an experimental adhesive system. Materials and Methods: Five experimental self-etching primers with 0, 5, 10, 20 and 40 (wt%) water as solvent were formulated. An experimental adhesive resin (AD-50) was also synthesized to create one experimental self-etching adhesive system. Clearfil SE Bond (CSEB) was used as the commercial reference. Sixty bovine incisors were randomly separated into 6 groups. Buccal enamel was removed to expose the superficial coronal dentin; this surface was polished wet to create a standardized smear layer. After rinsing, water was removed, leaving the surface visibly dried. The dentin surfaces were etched with primer and air dried, adhesive resin was applied and photoactivated, then the composite resin restoration was placed. After storage for 24 h, the specimens were sectioned with a cooled diamond saw at low speed. Microtensile bond strength was measured and data were analyzed with one-way ANOVA/Tukey's test (α = 0.05). Results: ANOVA showed that primer composition was a significant factor for bond strength. There was no significant difference in bond strengths between the primers with a water concentration of 40% (53.9 ± 12.7 MPa), 20% (51.1 ± 11.5 MPa, and 10% (47.5 ± 11.4 MPa), and CSEB (50.7 ± 9.8 MPa). The groups with 5% (38.6 ± 12.9 MPa) and 0% (31.5 ± 7.5 MPa) water presented similar bond strengths amongst themselves but were statistically significantly lower than that of the other groups. Conclusion: The water concentration in the primer solvent exercises a significant influence on the bond strength of this experimental self-etching adhesive system. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the pulp response to direct capping with self-etching adhesive systems using sodium hypochlorite as a hemostatic agent. Method and Materials: Twenty-six human third molars scheduled for extraction were selected from undergraduate students of dentistry. Class I cavities with pulp exposures were performed. To control bleeding, 2.5% sodium hypochlorite was used for 20 seconds, followed by washing with saline solution. The pulp exposures were capped with calcium hydroxide (n = 10) or adhesive system (n = 16). All cavities were restored with adhesive system and composite resin. Half of the samples of each capping material were extracted after 30 days and the remaining after 90 days. The samples were prepared for histological analysis (hematoxylin-eosin) and bacterial detection (Brown & Hopps) and evaluated according to standard ranking. Data were submitted to statistical analysis (Mann-Whitney test). Results: There was a significant difference (P < .05) only in relation to dentin barrier formation. Pulps dressed with calcium hydroxide showed dentin barrier formation in all specimens, obliterating the exposure site. No inflammatory response was associated with material. In the experimental group, after 30 days, there was an attempt for healing with reparative dentin deposition, presenting a mild to moderate inflammatory infiltrate. Similar findings were found after 90 days, decreasing the inflammatory response. Bacteria were not detected in any specimen evaluated. Sodium hypochlorite was effective for hemostatic control. Conclusion: Calcium hydroxide produced better biological performance than the self-etching adhesive, and sodium hypochlorite did not interfere with the pulp repair. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the clinical performance of two polyacid-modified resin composites (Dyract AP and F2000) in posterior teeth after 1 year of clinical service. Materials and Methods: Seventy-two Class I restorations were performed in 33 patients (average age 25 years) by one operator. Eighty-two per cent of the restorations were located in molars. Before the proceedings, patients were informed about the aim of the study and they gave written consent to participate. At least one restoration of each material was placed in each individual. The materials were applied according manufacturer's instructions. Following finishing and polishing, one examiner performed the clinical baseline examination using the adapted USPHS system. To be included in the clinical trial, a restoration had to be rated "Alpha". After one year, 25 patients were recalled and 56 restorations were evaluated using the adapted USPHS system. Results: All restorations were classified as clinically satisfactory (Alpha or Bravo). However, there was a decrease in restoration quality compared to baseline. Statistical analysis (X² and Fisher's exact test) demonstrated differences only in relation to superficial roughness, with exhibiting F2000 more surface roughness than Dyract AP (p < 0.01). Conclusion: Based on the methodology employed, all restorations were satisfactory after one year and the two materials performed similarly, except for the surface roughness criteria. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the effect of blood contamination and decontamination procedures performed at different stages of bonding, on the microtensile bond strength (µTBS) of an etch-and-rinse adhesive to dentin. Materials and Methods: Standardized cylindrical cavities were prepared in bovine incisors and were randomly divided into five groups, each one was treated using these experimental conditions - Control: etching-rinsing/bonding without blood contamination; Group 1: etching-rising/blood contamination/decontamination/bonding; Group 2: etching-rising/bonding/blood contamination/decontamination; Group 3: etching-rising/bonding/blood contamination/decontamination/etching-rising/bonding; and Group 4: etching-rising/blood contamination/decontamination/etching-rising/bonding. Specimens were prepared for µTBS and were evaluated both immediately and after 6 months of storage in distilled water. Results: Blood contamination significantly reduced the µTBS (P < 0.001). Groups 2 and 3 showed the lowest µTBS values, both for 24 h and 6 month aging. Conclusions: Blood contamination tested at any of the different stages of the bonding procedure showed a negative effect on the µTBS. Recovering adhesion of blood-contaminated dentin did not depend only on cleaning with distilled water. [ABSTRACT FROM AUTHOR]

Abstract Over the past years, significant effort has been dedicated to synthesizing low-shrinking formulations, however, development of dental composites with low volumetric shrinkage continues to be challenging. The purpose of this study was to synthesize a bisphenol allylic derivate (BPhADAC) and evaluate its inclusion in the formulation of a photopolymerizable dental composite resin, as a BisGMA diluent. Experimental (BisGMA/ BPhADAC) and control (BisGMA/TEGDMA) photopolymerizable composites were prepared. Double bond conversion, polymerization kinetics, volumetric shrinkage, water sorption, solubility, and flexural properties were investigated. The experimental composite showed higher degree of conversion values, less volumetric shrinkage and less water sorption than the control composite (p < 0.05). In addition, flexural strength between the materials was found to be similar. The overall properties prove that the allylic monomer BPhADAC could be potentially useful in the formulation of low-shrinking dental composite resins. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

This study evaluated the effectiveness of benzodioxole derivatives as coinitiators of radical polymerization in a model-dental adhesive resin. To compose the adhesive resin, a monomer mixture based on 50 wt % of Bis-GMA, 25 wt % of TEGDMA, and 25 wt % of HEMA was used. Camphorquinone (CQ) 1 mol % was used as a photoinitiator to initiate polymerization. 1,3-Benzodioxole (BDO) and piperonyl alcohol (PA) were used as coinitiators at 0.25, 0.5, 1, 2, 4, 8, and 16 mol % level. In addition, tertiary amine, ethyl 4-dimethylamino benzoate (EDAB) was used as coinitiator in the control group. Some physical, chemical, and mechanical properties of the polymer formed in the experimental adhesives were evaluated using the kinetics of polymerization, sorption and solubility, flexural strength, and elastic modulus tests. The results indicated that BDO and PA were effective coinitiators in the photoinitiator system based on CQ. Comparisons between the benzodioxoles derivative coinitiators and EDAB showed similar performance in the kinetics of polymerization and flexural strength. For water sorption and solubility evaluation, BDO and PA demonstrated significantly more sorption of water and less solubility than the EDAB control group. The findings suggest that BDO and PA were feasible alternatives to conventional amine as coinitiator. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

We evaluated the effect of activation mode (immediate or delayed light activation vs. no light activation) on diametral tensile strength (DTS), elastic modulus, ultimate tensile strength (UTS), and degree of conversion (DC) in dual-cured resin cements. Three resin cements were evaluated: Enforce, RelyX ARC, and Panavia F. The mixed cements were inserted into circular molds for the DTS test and into dumbbell-shaped molds for the UTS test. Inside the molds, the cements were light-activated either imme-diately or after 5 min (delayed light activation). If no light activation was performed, the materials were protected from light exposure (control). The DTS and UTS tests were performed until fracture. The elastic modulus was calculated using data from the DTS test, and DC was evaluated 24 h after manipulation using near-infrared spectroscopy. Data for each variable were individually analyzed by two-way ANOVA and the post-hoc Tukey test (a = 0.05). Regarding DTS, activation mode influenced only Panavia F specimens, which had the lowest DTS values in the absence of light activation. Activation mode did not influence the elastic modulus or UTS of any resin cement evaluated. Immediate light activation yielded higher DC values as compared with the absence of light activation. [ABSTRACT FROM AUTHOR]

This study evaluated the influence of ethanol/water ratios on the bond strength to dentin of experimental two-step, self-etch adhesive systems. Self-etch primers were prepared with constant 40 mass % of solvents. The ethanol/water ratios tested were 7:1 (P1), 3:1 (P2), and 1:1 (P3); primers with only ethanol (PE) or water (PW) as solvent were also tested. The bond strength to the dentin was investigated through a microtensile bond strength test. Resin-dentin beam-shaped specimens were obtained and tested after 24 h, 6 months, and 1 year of storage in water at 37°C. The hybridization morphology was analyzed using SEM. For bond strength at 24 h, PE = P1, P1 = P2, and P2, P3 and PW > PE. After 6 months, PE = P1 < P2, P3 and PW. After 1 year, no significant differences among the materials were detected. No significant differences among the periods were detected for PE. For P1, 24 h > 6 months = 1 year. For P2, P3 and PW, 24 h = 6 months > 1 year. For PE and P1, adhesive failures were predominant at 24 h, mixed or adhesive failures after 6 months, and premature debonding was predominant after 1 year. For P2, mixed failures were predominant at 24 h and 6 months, and premature debonding after 1 year. For P3 and PW, mixed failures were predominant at all storage periods. The SEM analysis revealed no clear differences in the hybridization patterns yielded by the water-based primers; PE showed formation of irregular resin tags. [ABSTRACT FROM AUTHOR]

This study evaluates the effect of zinc methacrylate (ZM) on the degree of conversion (DC), cytotoxicity and antimicrobial activity (AA) of an experimental resin. Tetraethyleneglycol dimethacrylate was used as the experimental resin and it was photo activated using camphoroquinone and ethyl 4-dimethylamine benzoate. Additionally, 1.0, 2.5, 5.0, 10, 20 and 30 wt% of ZM was added to the various experimental resins. The DC was accessed by Fourier Transform infrared spectroscopy. For cytotoxicity, immortalized mouse fibroblasts were exposed to the experimental resin extracts. An MTT assay was used to access the cytotoxicity. The AA against Streptococcus mutans UA159 was accessed by the agar diffusion method. An improvement in the DC in all concentrations of ZM was observed. The greater the amount of ZM on the experimental resin, the less the cytotoxicity was provoked. Three ZM concentrations showed AA that exhibited various inhibition growth zones with 10, 20 (10 mm) and 30 wt% (15 mm). [ABSTRACT FROM AUTHOR]

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Abstract: This study investigated the impact of immediate and delayed light activation on self-polymerization of a model dual-cured luting agent. The material presented the following components: base paste – 2,2-bis[4-(2-hydroxy-3-methacryloxyprop-1-oxy)phenyl]propane/triethylene glycol dimethacrylate (TEGDMA), camphorquinone, dimethyl-p-toluidine, butylated hydroxytoluene (BHT), glass fillers; catalyst paste – bisphenol-A ethoxylated dimethacrylate/TEGDMA, benzoyl peroxide, BHT, fillers. The pastes were mixed and seven polymerization scenarios tested: immediate light activation using low (5Jcm−2) or high (20Jcm−2) energy dose; delayed light activation (after 2min – short delay) using low or high dose; delayed light activation (after 10min – long delay) using low or high dose; and self-polymerization only. The degree of conversion (DC) and rate of polymerization (R p) were evaluated for 30min by real-time infrared spectroscopy. The lowest DC was detected for the self-polymerized and immediate–low dose groups, whereas the immediate–high dose and short delay–high dose groups showed the highest values. For the self-polymerized and immediate–high dose samples, R p max was detected after approximately 7s, whereas this took approximately 14s for the immediate–low dose group. R p max for the immediate–high dose group was higher than for the self-polymerized sample, which in turn was higher than for the immediate–low dose group. R p max for the short delay groups was higher than for the long delay groups. In conclusion, the extent of self-polymerization was influenced by the light dose reaching the material, which was dependent on high radiant exposure for optimal polymerization and the moment at which the light was applied; the short delay increased the DC for lower doses, while also generally decreasing the R p for all scenarios. [Copyright &y& Elsevier]

Objective. In this study we investigated the degree of conversion (DC) of a dual-cured resin luting agent beneath a ceramic of different thickness. Material and Methods. The luting material (RelyX) was photo-activated for 40s through ceramic disks (Empress Esthetic, 0.7, 1.4, or 2mm thick). Dual (DUC) and chemically cured (CC) control groups were obtained. A delayed exposure (DE) procedure was tested in which the material was light-activated after 5 min without using ceramic. DC (%) was measured using infrared spectroscopy at 40 s, 1, 2, 4, 6, 8, and 10min. Light irradiance and spectrum transmitted through ceramic were measured using a power meter and a spectrometer. Results. A decrease in irradiance was detected with increasing ceramic thickness, but no alteration in the emission profile was observed. At 10min, all groups showed DC higher than at 40s. No significant differences were detected for DUC compared with the groups indirectly activated through the ceramic disks. Generally, CC showed the lowest DC values. No significant effect in DC was detected for DE after 10min. A significant increase in DC was generally detected only up to 4min. Conclusions. The luting agent was dependent on light exposure and time to obtain improved DC. Neither the indirect activation nor the DE procedure significantly influenced the final DC. [ABSTRACT FROM AUTHOR]

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. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [ABSTRACT FROM AUTHOR]

This study investigates the in-depth polymerization of dual-cured resin cement (Enforce; Dentsply, shades A2, B1, and opaque). Cylindrical specimens are obtained by photo-activation through ceramic. Control samples are light-cured without using ceramic. Samples are tested after 15 min or 24 h. Knoop hardness readings are made at 100, 300, 500, and 700 µm depth. Hardness is generally dependent on the mode of activation and post-cure time. Shades A2 and B1 show higher hardness values than opaque resin. Hardness at 100 µm is higher than at 700 µm. A linear relationship between hardness and depth is observed. [ABSTRACT FROM AUTHOR]

The objective of this work was to synthesize two bio‐based monomers, using the resorcinol as raw material, and its effect as bisphenol A glycidyl dimethacrylate (Bis‐GMA) eluents on different chemical–physical and biological properties of experimental photopolymerizable composite resins. The acrylic 1,3‐phenylen diacrylic (1,3‐FDA) and methacrylic 1,3‐phenylen dimethacrylic (1,3‐FDMA) monomers were synthesized and fully characterized through FTIR and 1H‐NMR spectroscopies. Experimental photopolimerizable composites were formulated using Bis‐GMA/1,3‐FDA or Bis‐GMA/1,3‐FDMA as organic matrix. The materials were compared with a Bis‐GMA/TEGDMA resin‐based composite used as control. Polymerization kinetics was evaluated by means of FTIR spectroscopy. Polymerization stress was directly measured through a polymerization stress tester. The cell viability of the composites was evaluated using the MTT assay. One‐way analysis of variance and Tukey's test were used for statistical analysis. The materials formulated with the 1,3‐FDA monomer showed higher Rpmax values and lower polymerization stress values (p < 0.05), while the flexural strength, water sorption, and solubility remained similar to the TEGDMA composite. Conversely, the materials formulated with the 1,3‐FDMA monomer showed a lower degree of conversion and statistically lower flexural strength (p < 0.05). All materials exhibited a cellular viability close to 100%. Concerning the study conditions, the acrylic 1,3‐FDA monomer could be considered an alternative to TEGDMA in the formulation of photopolymerizable dental composite resins. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48576. [ABSTRACT FROM AUTHOR]

[Display omitted] • Antioxidants may act as polymerization inhibitors of resin formulations. • Incorporation of quercetin increased the yellowing index of the resin blend. • Incorporation of Gallic acid may reduce the mechanical strength of the resin. • Ascorbic acid did not function as a polymerization inhibitor. This study aimed to evaluate the physico-mechanical and biological properties of experimental adhesive resins modified with different antioxidants as radical polymerization inhibitors. The adhesive resins were formulated by mixing BIS-GMA, TEGDMA and HEMA (mass ratio of 50/25/25 wt%) and a tertiary initiation system (CQ + EDAB + DPHIHF – molar concentration of 1 %, 2 % and 1 %, respectively) together. Different antioxidants were added (1 mol%) to aliquots of the experimental resin, as follows: BHT (Butylated hydroxytoluene); HQ (hydroquinone); QC (quercetin); GA (gallic acid); and AA (ascorbic acid). An unmodified resin was used as control. The resin adhesives were tested with regard to sensitivity to ambient light, degree of conversion, cohesive strength, yellowing index, color stability; in addition, translucence and cytotoxicity (MTT assay) were analyzed. The data were analyzed using ANOVA and Tukey post-hoc tests (α = 5 %). The control and AA-based adhesive failed in the sensitivity to ambient light test. Adhesives modified with BHT and AA showed lower DC than the others. Color was considerably changed for the QC-containing adhesive. The presence of QC in the adhesive resulted in a higher yellowing index. When compared with the control, the addition of GA resulted in a reduction of the cohesive strength of the materials. All adhesives demonstrated similar cell viability and translucency. The use of alternative antioxidants as polymerization inhibitors rather than the synthetic types traditionally used showed potential application for the formulation of novel dental adhesive resins without significant impairment of the biological and physico-mechanical performance of the material. [ABSTRACT FROM AUTHOR]

Objectives This study evaluated the performance of phenylbis (2,4,6-trimethylbenzoyl)-phosphine oxide (BAPO) as an alternative photoinitiator in the polymerization kinetics (PK), flexural strength (σ) and elastic modulus (E) of a model dental resin. Methods A monomer mixture based on Bis-GMA and TEGDMA was used as model dental resin. Initially a screening was performed to evaluate BAPO concentrations (0.125, 0.25, 0.50, 1, 2, and 4mol%). Photoinitiator systems were formed with the combination of camphorquinone (CQ), ethyl-dimethylamino benzoate (EDAB), diphenyliodonium hexafluorophosphate (DPIHFP), and BAPO. Groups with unitary photoinitiator systems (BAPO and CQ), binary (BAPO+EDAB, BAPO+DPIHFP and CQ+EDAB), ternary (BAPO+CQ+EDAB, BAPO+CQ+DPIHFP, BAPO+EDAB+DPIHFP and CQ+EDAB+DPIHFP) and quaternary (BAPO+CQ+EDAB+DPIHFP) were formulated for evaluation. Real-time Fourier transform infrared spectroscopy was used to investigate the PK and test mini-bending to evaluate σ and E. Results When only CQ was used, a slow polymerization reaction was observed and a lower monomer conversion. When only BAPO was used as photoinitiator an increase in the polymerization rate was observed and conversion was higher than CQ+EDAB. The ternary system (BAPO+EDAB+DPIHFP) showed the highest polymerization and conversion rate, in short photo-activation time. Significance BAPO it is a potential photoinitiator for the photopolymerization of dental materials. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The purpose of this study was to evaluate the reactivity and polymerization kinetics behavior of a model dental adhesive resin with water-soluble initiator systems. Methods: A monomer blend based on Bis-GMA, TEGDMA and HEMA was used as a model dental adhesive resin, which was polymerized using a thioxanthone type (QTX) as a photoinitiator. Binary and ternary photoinitiator systems were formulated using 1mol% of each initiator. The co-initiators used in this study were ethyl 4-dimethylaminobenzoate (EDAB), diphenyliodonium hexafluorophosphate (DPIHFP), 1,3-diethyl-2-thiobarbituric acid (BARB), p-toluenesulfinic acid and sodium salt hydrate (SULF). Absorption spectra of the initiators were measured using a UV–Vis spectrophotometer, and the photon absorption energy (PAE) was calculated. The binary system camphorquinone (CQ)/amine was used as a reference group (control). Twelve groups were tested in triplicate. Fourier-transform infrared spectroscopy (FTIR) was used to investigate the polymerization reaction during the photoactivation period to obtain the degree of conversion (DC) and maximum polymerization rate (R p max) profile of the model resin. Results: In the analyzed absorption profiles, the absorption spectrum of QTX is almost entirely localized in the UV region, whereas that of CQ is in the visible range. With respect to binary systems, CQ+EDAB exhibited higher DC and values. In formulations that contained ternary initiator systems, the group CQ+QTX+EDAB was the only one of the investigated experimental groups that exhibited an value greater than that of CQ+EDAB. The groups QTX+EDAB+DPIHFP and QTX+DPIHFP+SULF exhibited values similar to those of CQ+EDAB with respect to the final DC; however, they also exhibited lower reactivity. Significance: Water-soluble initiator systems should be considered as alternatives to the widely used CQ/amine system in dentin adhesive formulations. [Copyright &y& Elsevier]

Objective: To evaluate the influence of Bis-EMA 30 on the resin-to-dentin microtensile bond strength (microTBS) and structural reliability of the experimental three-step etch-and-rinse adhesive systems.Methods: Five experimental primers containing different dimethacrylate monomer concentrations (0, 10, 20, 40, 60 wt% of the Bis-EMA 30, P0.P60) added to acid monomer and solvents (ethanol/water), and a resin bond (Bis-GMA/TEGDMA, 50/50 wt%) were formulated. The adhesive system Scotchbond MultiPurpose (SBMP, 3M ESPE) was tested as commercial reference. Sixty bovine incisors were randomly separated into six groups, and their superficial coronal dentin was exposed. After acid etching and rinsing, the excess water was removed from the surface with absorbent paper. Each experimental primer was actively applied (30 s), followed by a mild air stream (10 s). The experimental adhesive resin was applied and light activated for 20 s. Resin composite restorations were incrementally built up. The restored teeth were stored in distilled water at 37 degrees C for 24 h, and then sectioned to obtain sticks with a cross-sectional area of approximately 0.5 mm(2), after which 24 specimens per group were subjected to the microTBS test. Data (MPa) were analyzed by One-way ANOVA, Tukey test (alpha=0.05) and Weibull analysis.Results: The P40 group showed microTBS means similar to those of the control (SBMP), whereas both had statistically higher values when compared with the other groups (p<0.001). Moreover, P40 showed higher structural reliability, represented by the high Weibull modulus and characteristic strength values. The lowest microTBS was observed in the P0, P10 and P20 groups, which also had low structural reliability.Significance: Bis-EMA 30 is a promising monomer to be considered as a substitute for HEMA in adhesive system compositions. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To evaluate the influence of tetrahydrofuran (THF) on the resin-to-dentin microtensile bond strength (μTBS) after water storage, for 24h and 6 months, and to compare its behavior with that of traditional solvents. Methods: Seven versions of monomer/solvent mixtures (primers) were prepared using the following solvent and water combinations: (1) THF, (2) acetone, (3) ethanol, (4) water, (5) THF/water, (6) acetone/water and (7) ethanol/water. An experimental adhesive resin was also synthesized to compare adhesive systems with the different primers. Forty-two bovine incisors, randomly separated into seven groups, had their superficial coronal dentin exposed. After acid-etching and rinsing, the excess water was removed from the surface with absorbent paper. Each experimental primer was applied with agitation (30s) followed by a mild air stream (10s). The experimental adhesive resin was applied and light-activated (20s). Resin composite restorations were constructed incrementally. Restored teeth were stored in distilled water at 37°C (24h) and sectioned to obtain sticks with an area of 0.5mm2. Half the specimens were subjected to the μTBS test immediately after being cut and the other half were tested after 6 months of water storage. Data (MPa) were analyzed by two-way ANOVA (solvent type and storage time as factors) and Tukey–Kramer''s test at α =0.05. Results: Factors and interaction showed a statistical effect. After 6 months storage, acetone groups and primers containing THF showed similar μTBS to initial means. Significance: THF seems to be a promising solvent for use in dental adhesive systems, maintaining bond strength on dentin substrate after storage. [Copyright &y& Elsevier]