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Posts Tagged ‘conversion’
Thursday, May 24th, 2012
One of Esstech’s own, Jim Duff, had the opportunity to speak with Dr. Bicuspid’s Assistant Editor, Rob Goszkowski about EXOTHANE Elastomers.
These unique materials continue to gain popularity for their low volumetric shrinkage, low shrinkage stress and high conversion! Click the following link to read the whole article.
http://www.drbicuspid.com/index.aspx?d=1&sec=sup&sub=rst&pag=dis&ItemID=310631
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Tags: conversion, EXOTHANE, EXOTHANE Elastomers, low-shrink, polymerization
Posted in Announcements | No Comments »
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
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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, July 28th, 2011
Click on the following link for a pdf download of our poster.
Physical Properties of a New Low Shrink Resin
A. JOHNSTON1, F. RUEGGEBERG2, H.R. RAWLS3, H. SLAFF1, T. BARCLIFT1, and J. DUFF1, 1Esstech Inc, Essington, PA, 2Medical College of Georgia, Augusta, GA, 3University of Texas Health Science Center at San Antonio, San Antonio, TX
Introduction:
The improvement of aesthetic restorative dental composites can be pursued on many fronts. A composite is made from multiple components but, generally, it is a blend of finely ground glasses and reactive monomers. The monomers cure to provide a continuous polymer matrix for retaining the glass. Together they present a hard surface with the capability to survive in the oral environment. Failure of these composites is a complex phenomenon. While clinical failure can occur when the adhesive force between the composite and the vital dental tissue is compromised, failure also occurs when stresses overcome the cohesive strength of the continuous phase of the mixture. Catastrophic material failure can occur as wear against complementary dentition that slowly erodes the surface. Those cracks through the polymer phase lead to composite failure. To improve the composite properties, a new monomer has been introduced, FIT 852 Resin™, that can provide greater toughness in the polymer, greater extent of cure in the polymer, lower shrinkage stress and no change in composite material manufacture.
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Tags: composite, conversion, dental research, esstech, low-shrink, Shrinkage, urethane, X-852-0000
Posted in Research Paper | No Comments »
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 »
Friday, May 21st, 2010
Bis-GMA co-polymerizations: Influence on conversion, flexural properties, fracture toughness and susceptibility to ethanol degradation of experimental composites
Carmem S. Pfeifer, Laura R. Silva, Yoshio Kawano, Roberto R. Braga
Dental Materials Volume 25, Issue 9, Pages 1136-1141 (September 2009)
Objectives
The aim of this study was to evaluate the influence of monomer content on fracture toughness (KIc) before and after ethanol solution storage, flexural properties and degree of conversion (DC) of bisphenol A glycidyl methacrylate (Bis-GMA) co-polymers.
Results
The 30B:70T composite presented the highest KIc value (in MPa m1/2) at 24h (1.3±0.4), statistically similar to 30B:35T:35U and 30B:70U, while 30B:70E presented the lowest value (0.5±0.1). After ethanol storage, reductions in KIc ranged from 33 to 72%. The 30B:70E material presented the lowest reduction in FT and 30B:70U, the highest. DC was similar among groups (69–73%), except for 30B:70U (52±4%, p<0.001). 30B:70U and 30B:35T:35U presented the highest FS (125±21 and 122±14MPa, respectively), statistically different from 30B:70T or 30B:70E (92±20 and 94±16MPa, respectively). Composites containing UDMA or Bis-EMA associated with Bis-GMA presented similar FM, statistically lower than 30B:35T:35U.
Tags: bis-EMA, bis-GMA, bisEMA, bisGMA, composite, conversion, dental research, esstech, mechanical properties, TEGDMA, UDMA, urethane, X-850-0000, X-943-7446, X-950-0000, X-970-0000
Posted in Research Paper | No Comments »
Tuesday, April 20th, 2010
Preparation and Evaluation of Dental Resin Luting Agents with Increasing Content of Bisphenol-A Ethoxylated Dimethacrylate
Rafael R. Moraes, Mário A.C. Sinhoreti, Lourenço Correr-Sobrinho, Fabrício A. Ogliari, Evandro Piva, and Cesar L. Petzhold
Journal of Biomaterials Applications, Jan 2010; vol. 24: pp. 453 – 473.
Abstract: Resin luting agents in which bisphenol-A glycidyl dimethacrylate (Bis-GMA) and/or triethylene glycol dimethacrylate (TEGDMA) are replaced with increasing amounts of bisphenol-A ethoxylated dimethacrylate are prepared. Degree of conversion (DC), diametral tensile strength (DTS), Young’s modulus (YM), Knoop hardness (KHN), film thickness (FT), water sorption (Wsp ), and solubility are evaluated. Regression analyses investigate the substitution of each monomer. The most appreciable differences are detected when TEGDMA is replaced: decreased DC, DTS, and Wsp, and increased YM, KHN, and FT. For substitution of Bis-GMA, the only significant differences are reduced Wsp and increased YM. An ideal formulation of resin cement would make use of the three monomers.
…Bis-GMA, TEGDMA, and/or Bis-EMA (Esstech Inc., Essington, PA, USA) were tested…photo-curable, 0.4 wt% of camphor- quinone (Esstech) and 0.8 wt% of N,N-dimethyl-p-toluidine…silanated strontium glass fillers (Esstech), 0.7 and 2 mm in size, to a constant…
This version was published on January 1, 2010.
Link: http://jba.sagepub.com/cgi/content/abstract/24/5/453
Tags: bis-EMA, bisGMA, borosilicate, camphorquinone, conversion, CQ, dental research, EBPADMA, HEMA, Methacrylate, strontium, TEGDMA, V-124-1110, X-943-7446, X-950-0000, X-970-0000
Posted in Research Paper | No Comments »
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