|
|
Posts Tagged ‘X-950-0000’
Monday, January 9th, 2012
Curing efficiency of dental resin composites formulated with camphorquinone or trimethylbenzoyl-diphenyl-phosphine oxide
Luis Felipe J. Schneider, Larissa Maria Cavalcante, Scott A. Prah, Carmem S. Pfeifer, Jack L. Ferracane. “Curing efficiency of dental resin composites formulated with camphorquinone or trimethylbenzoyl-diphenyl-phosphine oxide” Dental Materials. December 2011: Online
Summary:
This research presents trimethylbenzoyl-diphenyl-phosphine oxide (TPO) as an alternative to camphorquinone (CQ) photoinitiator systems for dental resins. An immediate advantage is the low color of TPO in comparison to the strong yellow color of CQ. Testing using a spectrophotometer and differential scanning calorimetry (DSC) revealed that TPO had higher reactivity than CQ. CQ exhibited higher absorbed power density, (PDabs) and better depth of cure.
Materials
Testing of each photoinitiator was performed using 50:50 formulations of 2,2-bis[4-2(2-hydroxy-3-
methacroyloxypropoxy)phenyl]propane (Bis-GMA, Esstech) and triethyleneglycol dimethacrylate (TEGDMA, Esstech).
LINK: http://dx.doi.org/10.1016/j.dental.2011.11.014
Sign up for our Monthly Email Update summarizing all new posts to Esstechinc.com, CLICK HERE.
Tags: bis-GMA, bisGMA, camphorquinone, composite, conversion, dental research, TEGDMA, X-801-0000, X-943-7446, X-950-0000
Posted in Research Paper | No Comments »
Thursday, December 1st, 2011
Micro-Raman spectroscopic analysis of the degree of conversion of composite resins containing different initiators cured by polywave or monowave LED units
Vesna Miletic a, Ario Santini b,
a Clinical Lecturer, University of Belgrade, School of Dentistry, Department of Restorative Odontology and Endodontics, Rankeova 4, Belgrade, Serbia
b Director of Biomaterials Research, The University of Edinburgh, Edinburgh Postgraduate Dental Institute, Lauriston Place, Edinburgh EH3 9HA, United Kingdom
Received 20 August 2011; revised 28 October 2011; Accepted 30 October 2011. Available online 6 November 2011.
Objectives
To determine the degree of conversion (DC) over 48 h post-curing of resin mixtures containing trimethylbenzoyl-diphenylphosphine oxide (TPO) initiator cured by a polywave or a monowave LED light-curing unit (LCU).
Methods
In resin mixtures based on equal weight percent (wt%) of BisGMA and TEGDMA the following initiators were added: 0.2wt% camphorquinone (CQ) + 0.8wt% ethyl-4-dimethylaminobenzoate (EDMAB) (Group 1); 1wt% TPO (Group 2) and 0.1wt% CQ + 0.4wt% EDMAB + 0.5wt% TPO (Group 3). Half of the samples in each group (n = 5) were cured using a polywave (bluephase® G2, Ivoclar Vivadent) or a monowave LED LCU (bluephase®, Ivoclar Vivadent). The DC was measured using micro-Raman spectroscopy within 5 min and then 1, 3, 6, 24 and 48 h post-irradiation. The data were analyzed using general linear model and two-way ANOVA for the factors ‘time’, ‘material’, ‘surface’ and ‘LCU’ at α=0.05.
Results
The initial DC values obtained upon light curing remained similar over a 48 h period. bluephase® G2 produced the highest DC in Group 2 followed by Group 3, and Group 1. bluephase® resulted in the highest DC in Group 1, followed by Group 2 and Group 3 (p < 0.05).
Conclusions
Unfilled resin materials containing both TPO- and CQ-amine initiators are effectively cured using bluephase® G2. Resin mixture with the same wt% of initiators is better cured when TPO is the only initiator, compared to CQ-amine only or combined TPO and CQ-amine system. After initial light cure, no additional conversion of uncured monomers was detected in an unfilled resin material over 48 h at 37 °C.
Materials
… Page 5 of 24 Ac ce pte d M an usc rip t 4 Materials and Methods The following materials were
used in the study: bisphenol A bis(2-bydroxy-3- methacryloxypropyl)ether (BisGMA), triethylene
glycol dimethacrylate (TEGDMA), camphorquinone (CQ) (Esstech Inc, Essington, PA …
Sign up for our Monthly Email Update summarizing all new posts to Esstechinc.com, CLICK HERE.
Tags: bisGMA, CQ, dental research, TEGDMA, X-943-7446, X-950-0000
Posted in Research Paper | No Comments »
Monday, July 11th, 2011
Development of an antimicrobial resin—A pilot study
Dental Materials. Volume 27, Issue 4, Pages 322-328 (April 2011)
Summary
To demonstrate that silver nanoparticles (AgNPs) could be synthesized in situ in acrylic dental resins.
Methods: Light-cure (LC; bisphenol A glycidyl methacrylate, tetraethyleneglycol dimethacrylate, bisphenol A ethoxylate dimethacrylate blend) and chemical-cure systems (CC; orthodontic denture resin) were used to synthesize AgNPs using different concentrations of Ag benzoate (AgBz).
Results: Rockwell hardness for LC resins showed that resins could be cured with up to 0.15% AgBz, while the hardness of CC resins were unaffected in the concentrations tested. UV–Vis spectroscopy and transmission electron microscopy confirmed the presence of AgNPs in both LC and CC resins. Generally, CC resins had better distribution of and much smaller AgNPs as compared to LC resins overall. In some samples, especially in LC resins, nanoclusters were visible. An in vitro release study over four-weeks showed that CC resins released the most Ag+ ions, with release detected in all samples. However, LC resins only released Ag+ ions when AgBz concentration was greater than 0.1% (w/w). AgNP-loaded CC resins made with 0.2 and 0.5% (w/w) AgBz were tested for antibacterial activity in vitro against Streptococcus mutans, and results showed 52.4% and a 97.5% bacterial inhibition, respectively. Further work is now warranted to test mechanical properties and to optimize the initiator system to produce commercially useful dental and medical resins.
Significance: Success in this work could lead to a series of antimicrobial medical and dental biomaterials that can prevent secondary caries and infection of implants.
LINK: http://www.demajournal.com/article/S0109-5641%2810%2900475-6/abstract
Sign up for our Monthly Email Update summarizing all new posts to Esstechinc.com, CLICK HERE.
Tags: bis-EMA, bis-GMA, bisEMA, bisGMA, composite, dental research, TEGDMA, Tetraethylene, X-945-7446, X-950-0000, X-970-0000
Posted in Research Paper | No Comments »
Monday, May 23rd, 2011
Efficiency of 4,4′-bis(N,N-diethylamino) benzophenone for the polymerization of dimethacrylate resins in thick sections
Walter F Schroeder, Silvana L Asmussen, Wayne D Cook, Claudia I Vallo
Article first published online: 2 MAY 2011, DOI: 10.1002/pi.3089, Copyright © 2011 Society of Chemical Industry
Abstract
The efficiency of 4,4′-bis( N, N-diethylamino)benzophenone (DEABP) for the polymerization of dimethacrylate monomers in thick sections ( 1– 2 mm) was studied. DEABP (λ max = 365 nm) represents a complete initiating system as it contains both ketone and amine functional groups. During irradiation, DEABP photobleaches at a fast rate causing deeper penetration of light through the underlying layers, but the photoinitiation efficiency (rate of polymerization per photon absorption rate) is relatively poor. As a result, irradiation of methacrylate monomers at 365 nm results in a slow average polymerization rate and a reduced monomer conversion for thick sections due to the light attenuation caused by the high absorptivity of DEABP and photolysis products. These results highlight the inherent interlinking of light attenuation and photobleaching rate in polymerization of thick sections.
Materials
Sign up for our Monthly Email Update summarizing all new posts to Esstechinc.com, CLICK HERE.
Tags: bis-GMA, polymerization, TEGDMA, X-943-7446, X-950-0000
Posted in Research Paper | No Comments »
Thursday, May 5th, 2011
BisGMA/TEGDMA ratio and filler content effects on shrinkage stress
Abstract
Objective
To investigate the contributions of BisGMA:TEGDMA and filler content on polymerization stress, along with the influence of variables associated with stress development, namely, degree of conversion, reaction rate, shrinkage, elastic modulus and loss tangent for a series of experimental dental composites.
Methods
Twenty formulations with BisGMA:TEGDMA ratios of 3:7, 4:6, 5:5, 6:4 and 7:3 and barium glass filler levels of 40, 50, 60 or 70 wt% were studied. Polymerization stress was determined in a tensilometer, inserting the composite between acrylic rods fixed to clamps of a universal test machine and dividing the maximum load recorded by the rods cross-sectional area. Conversion and reaction rate were determined by infra-red spectroscopy. Shrinkage was measured by mercury dilatometer. Modulus was obtained by three-point bending. Loss tangent was determined by dynamic nanoindentation. Regression analyses were performed to estimate the effect of organic and inorganic contents on each studied variable, while a stepwise forward regression identified significant variables for polymerization stress.
Results
All variables showed dependence on inorganic concentration and monomeric content. The resin matrix showed a stronger influence on polymerization stress, conversion and reaction rate, whereas filler fraction showed a stronger influence on shrinkage, modulus and loss tangent. Shrinkage and conversion were significantly related to polymerization stress.
Significance
Both the inorganic filler concentration and monomeric content affect polymerization stress, but the stronger influence of the resin matrix suggests that it may be possible to reduce stress by modifying resin composition without sacrificing filler content. The main challenge is to develop formulations with low shrinkage without sacrificing degree of conversion.
LINK: http://www.demajournal.com/article/S0109-5641%2811%2900020-0/abstract
Sign up for our Monthly Email Update summarizing all new posts to Esstechinc.com, CLICK HERE.
Tags: bis-GMA, bisGMA, composite, dental research, Shrinkage, stress, TEGDMA, X-943-7446, X-950-0000
Posted in Research Paper | No Comments »
Monday, March 7th, 2011
Preparation and characterization of light-cured methacrylate/montmorillonite nanocomposites
Veronica Mucci, Javier Perez, Claudia I Vallo
ABSTRACT
Polymer/clay nanocomposites were prepared from dimethacrylate monomers, commonly used in dental restorative resins, and an organically modified silicate (montmorillonite). The photopolymerization process was hardly affected by the presence of the silicate filler, and thus 2 mm thick samples containing 3 wt% clay were extensively cured. Transmission electron microscopy revealed that the montmorillonite platelets were either intercalated or exfoliated. Nevertheless, for all formulations, intermediate-sized aggregates of about 1 µm were present and their fraction increased as the amount of filler increased. The presence of the clay was found to have no major effect on the flexural modulus and compressive yield strength of the nanocomposites. Moreover, the water uptake of nanocomposites containing 3 wt% clay was about 10–15% higher than that of unfilled monomers. Modification of the clay surface with alternative organic cations is certainly necessary in order to achieve an optimal dispersion of the clay in the polymer matrix.
… The methacrylate monomers used for the preparation of the nanocomposites were 2,2-bis[4-(2-methacryloxyethoxy)phenyl]pro-pane (BisEMA; from Esstech, Essington, PA), triethylene glycoldimethacrylate and 1,6-bis(meth-acrylyloxy- …
Article first published online: 14 OCT 2010. DOI: 10.1002/pi.2935. Copyright © 2010 Society of Chemical Industry
LINK: http://onlinelibrary.wiley.com/doi/10.1002/pi.2935/full
Sign up for our Monthly Email Update summarizing all new posts to Esstechinc.com, CLICK HERE.
Tags: bis-GMA, composite, dental research, TEGDMA, X-943-7446, X-950-0000
Posted in Research Paper | No Comments »
Monday, February 28th, 2011
Hydrogen bonding interactions in methacrylate monomers and polymers
Marianela T. Lemon, Melissa S. Jones, Jeffrey W. Stansbury
Department of Craniofacial Biology, University of Colorado School of Dentistry, Aurora, Colorado 80045
ABSTRACT
It is well appreciated that hydrogen bonding affects a variety of monomer and polymer properties. This study focused on Bis-GMA and urethane dimethacrylate (UDMA) to help elucidate how the strength and nature of
specific noncovalent interactions involved with these different functional dimethacrylate structures are expressed in the monomers and polymers. Hydrogen bonding interactions in monomers and comonomer mixtures as well as in appropriate model compounds were examined by FT-IR under ambient conditions, at elevated temperatures and in dilution studies. The investigation of hydrogen bonding extended to monomer viscosity, photopolymerization reaction kinetics, and polymer mechanical properties.
CONCLUSION
The strength of hydrogen bonding was shown not only to be greater for Bis-GMA compared with UDMA, but there is also greater contribution from intermolecular interactions that enhance the hydrogen bonding effects. While UDMA-based polymers reach significantly higher levels of conversion compared with Bis-GMA materials, the stronger hydrogen bonding reinforcement associated with Bis-GMA appears to provide for comparable mechanical strength properties. Depending on the hydrogen bond donor functionality of a monomer as well as its neighboring functional groups, overall monomer structure and comonomers used, hydrogen bonding can favorably affect polymerization reactivity and mechanical properties, even in materials that form highly crosslinked polymeric networks.
Wiley Periodicals, Inc. J Biomed Mater Res 83A: 734–746,2007
Link: http://onlinelibrary.wiley.com/doi/10.1002/jbm.a.31448/abstract
Sign up for our Monthly Email Update summarizing all new posts to Esstechinc.com, CLICK HERE.
Tags: bis-GMA, bisGMA, dental research, Monomer, UDMA, urethane, X-850-0000, X-950-0000
Posted in Research Paper | No Comments »
Friday, September 10th, 2010
Effects of adhesive, base and diluent monomers on water sorption and conversion of experimental resins
Sabine H. Dickens, Glenn M. Flaim, Cynthia J.E. Floyd
Dental Materials Volume 26, Issue 7, Pages 675-681 (July 2010)
Objectives: To establish the relationship of resin composition and resin hydrophilicity (indicated by solubility parameters and logP) to water sorption (WS), solubility, and degree of double bond conversion (DC) of resin mixtures designed for adhesive restoratives by varying the concentration of pyromellitic glycerol dimethacrylate (PMGDM) and various co-monomers.
Methods: Sixteen resin mixtures were prepared with (30–70) mass fraction % PMGDM. At given PMGDM concentrations there were up to five compositions with increasing logP. Polymer disks (13mm×0.7mm) were exposed to 96% relative humidity (RH) to determine water sorption in humid atmosphere (WSH) and subsequently immersed in water for immersion water sorption (WSI) and solubility. DC was assessed by near infrared spectroscopy.
Results: WSI was somewhat higher than WSH, which ranged from (2.1 to 5.3) mass fraction %. Both data were positively correlated to PMGDM concentrations [Pearson correlation, p<0.02; R2=0.74, 0.73 (WSI)] and solubility (R2=0.64), but not to logP. When grouped by structural similarities, i.e., base resins with bisphenol A core (Group B), Group O containing diluent monomers, or Group U containing urethane dimethacrylate, WS within each group was inversely correlated to logP with R2=0.98, 0.81, 0.95, and WS/solubility correlation improved with R2=0.88, 0.92 and 0.75, respectively. Solubility ranging from 0.3% to 2.3% was inversely related to DC (r=−0.872). Conversion ranging from 41% to 81% was lower for resins with high base monomer concentrations and highest in mixtures with UDMA.
Significance: LogP was a good predictor of WS after grouping the resins according to functional, compositional and structural similarities. WS and conversion were reasonably well predicted from Hoy’s solubility parameters and other physical resin properties.
Link: http://www.demajournal.com/article/S0109-5641%2810%2900066-7/abstract
Tags: Adhesive Monomer, bis-GMA, bisEMA, bisGMA, EBPADMA, PMGDM, Remineralization, TEGDMA, UDMA, X-830-0050, X-850-0000, X-943-7446, X-950-0000, X-970-0000
Posted in Research Paper | 1 Comment »
Friday, September 10th, 2010
Contraction stress related to composite inorganic content
F. Gonçalvesa, Y. Kawanob, R.R. Bragaa
Dental Materials Volume 26, Issue 7, Pages 704-709 (July 2010).
Objectives: The role of inorganic content on physical properties of resin composites is well known. However, its influence on polymerization stress development has not been established. The aim of this investigation was to evaluate the influence of inorganic fraction on polymerization stress and its determinants, namely, volumetric shrinkage, elastic modulus and degree of conversion.
Methods: Eight experimental composites containing 1:1 BisGMA (bisphenylglycidyl dimethacrylate):TEGDMA (triethylene glycol dimethacrylate) (in mol) and barium glass at increasing concentrations from 25 to 60vol.% (5% increments) were tested. Stress was determined in a universal test machine using acrylic as bonding substrate. Nominal polymerization stress was obtained diving the maximum load by the cross-surface area. Shrinkage was measured using a water picnometer. Elastic modulus was obtained by three-point flexural test. Degree of conversion was determined by FT-Raman spectroscopy.
Results: Polymerization stress and shrinkage showed inverse relationships with filler content (R2=0.965 and R2=0.966, respectively). Elastic modulus presented a direct correlation with inorganic content (R2=0.984). Degree of conversion did not vary significantly. Polymerization stress showed a strong direct correlation with shrinkage (R2=0.982) and inverse with elastic modulus (R2=0.966).
Significance: High inorganic contents were associated with low polymerization stress values, which can be explained by the reduced volumetric shrinkage presented by heavily filled composites.
Link: http://www.demajournal.com/article/PIIS0109564110000801/fulltext
Tags: bis-GMA, bisGMA, dental research, esstech, polymerization, Shrinkage, stress, TEGDMA, X-950-0000
Posted in Research Paper | 1 Comment »
Tuesday, July 27th, 2010
Degree of conversion and color stability of the light curing resin with new photoinitiator systems
Dong-Hoon Shin, H. Ralph Rawls
Dental Materials, August 2009 (Vol. 25, Issue 8, Pages 1030-1038)
Objectives: This study investigated p-octyloxy-phenyl-phenyl iodonium hexafluoroantimonate (OPPI) as a photoinitiator, in combination with camphorquinone/amine photoinitiation systems, for use with di(meth)acrylate-based composite resins. The investigation determined if the inclusion of OPPI improved degree and rate of conversion, initial color and color stability of a representative composite resin dental material.
Methods: Camphorquinone (CQ) and OPPI were combined in various proportions with the amine co-initiator 2-dimethylaminoethyl methacrylate (DMAEMA) and used at two levels in which CQ+OPPI+DMAEMA=1wt.% or 3wt.% to photoinitiate a BisGMA/BisEMA/TEGDMA (37.5:37.5:25wt.%) monomer blend. Monomer mixture (GTE) was made by mixing 37.5wt.% BISGMA (lot # 568-21-07, ESSTECH, Essington, PA), 37.5wt.% BISEMA (lot # 474-32-02, ESSTECH), and 25wt.% TEGDMA (lot # 597-23-02, ESSTECH). A total of eight groups (four groups for each level of total photoinitiator, 1% and 3%) were tested according to the following proportion of components in the photoinitiator system: Each monomer was polymerized using a quartz-halogen curing unit (Demetron 400, Demetron Research Corp., Danbury, CT) with an intensity of 400mW/cm2 for 5s, 20s, 40s, 60s, 300s and their conversion levels (DC) were determined at each exposure time using a Fourier transform infrared spectrophotometer (FTIR). To examine color stability, experimental composite resins were made by mixing 3.2% silanated barium glass (78wt.%, average filler size; 1μm) with each monomer system, except both CQ only group and 1% CO group, which were found to cure insufficiently to be able to prepare useful specimens. Disk-shaped samples (10mm in diameter and 1.5mm in thickness) were made and stored under the conditions of dry or saline solution at room temperature (25°C) or 60°C water bath. Each CIELAB scale was determined with a colorimeter (CHROMA METER CR-400) at the time of baseline (day after curing), 1 week, 2 weeks, and 4 weeks later.
Results: The high level (3%) photoinitiated groups exhibited greater DC than the low level (1%) groups. In the 3% group, the COA group showed the fastest and the highest DC, while in the 1% group the CA and COA groups showed the greatest DC. In the color stability test, both CA groups were darker and more yellow than the CO and COA groups. Color was more stable in composite resins containing OPPI than those containing only the CQ and amine components. The least color change (greatest color stability) was found using 25°C saline solution aging, and the most change (least color stability) occurred using 60°C dry air aging.
Significance: This study suggests that OPPI can be used to replace the amine in a given CQ/amine photoinitiator system to accelerate cure rate, increase conversion, reduce initial color and increase color stability.
Link: http://www.demajournal.com/article/S0109-5641%2809%2900139-0/abstract
Tags: bis-EMA, bis-GMA, bisEMA, bisGMA, camphorquinone, conversion, CQ, dental research, esstech, TEGDMA, X-801-0000, X-943-7446, X-950-0000, X-970-0000
Posted in Research Paper | 1 Comment »
|
|
 |
Share This Post!