A Guide to Esthetic Treatment After Whitening
Linda Greenwall in Tooth Whitening Techniques, 2017
The manufacturers of composite materials have responded to requests for providing lighter and whiter shades of composites to match the new shades of whiter teeth. To do so, manufacturers have had to make some changes to the composite formulations. It may be that to achieve bright white or translucent shades of resins, some manufacturers find it necessary to use less camphorquinone or another photoinitiator altogether (Neumann et al. 2005). Photoinitiators such as 1-phenyl-1,2-propanedione (PPD) are photosensitizers of potential value in reducing color problems associated with visible light-cured dental resins. In combination with camphorquinone, they act synergistically to produce a more efficient photoinitiation reaction. Other composite-related factors in the whitener shade composites include shade, translucency, and filler particle size, load, and distribution. Light-related factors include light intensity, spectral distribution, and exposure time. In a study by Gomes et al. (2006), different light-emitting diode (LED) lights were used to polymerize a whitening shade resin composite, and compared with a conventional Optilux 501 light. It was hypothesized that the LED lights would not be able to effectively polymerize this specific resin composite. According to the results, the hardness values of LED 2 were similar to the values observed when the halogen light was used. There appears to be a good correlation between decreasing degree of conversion and decreasing hardness, fracture toughness, and abrasive wear resistance. To compensate for the lower hardness values found, the duration of exposure can be increased, within practical limits determined by the properties of the material and light source, providing enhanced opportunity for creation of free radicals.
Methods for Characterization of Bioactivity Using Confocal Microscopy *
Mary Anne S. Melo in Designing Bioactive Polymeric Materials for Restorative Dentistry, 2020
Ethoxylated bisphenol-A dimethacrylate (EDMA, degree of ethoxylation ≈ 6), was obtained from Esstech, Inc. Camphorquinone (CQ) and ethyl 4-N,N-dimethylaminobenzoate (4E) were purchased from Aldrich Corp. All reagents were used as received. The resin monomer was activated with a redox photoinitiator system consisting of 0.2% CQ and 0.8% 4E (by mass), and stored in the dark until use. Sodium chloride crystals were ground into small particles using a mortar and pestle and then separated into defined size ranges using brass sieves.
The Modification Of Arginine
Roger L. Lundblad in Chemical Reagents for Protein Modification, 2020
The modification of arginyl residues with glyoxal has also been proposed.11 Specificity of reaction is a problem with reaction also at primary amine groups and sulfhydryl groups. For example, reaction of glyoxal with bovine serum albumin at pH 9.0 resulted in modification of greater than 80% of the arginine residues with approximately 30% modification of lysine residues.11 Glass and Pelzig12 have examined the reversible modification of arginyl residues with glyoxal in some detail. Several products are formed from the reaction of glyoxal and arginine at alkaline pH. One of these derivatives is markedly stable in strong acid (12 M HCl) at ambient temperature but is rapidly degraded to form free arginine in the presence of O-phenylenediamine (0.16 M) at pH 8.1 to 8.3. More alkaline conditions resulted in more rapid decomposition of the glyoxal-arginine derivative and ninhydrin-positive compounds other than arginine were formed. Reaction of arginine with glyoxal in borate buffer also yields the product described above. The same research group has reported on the reversible modification of arginine residues with camphorquinone-10-sulfonic acid and derivatives such as camphorquinone-10-sulfonylnorleucine.13 The synthesis of the parent compounds and various derivatives is reported. The sulfonic acid function provides a basis for the attachment of a “tag” such as norleucine which can be used for determining the extent of modification.14 Reaction with arginine occurs in 0.2 M sodium borate, pH 9.0. Under these conditions, reaction of camphorquinone-sulfonic acid with an amino acid analysis standard showed a greater than 90% loss of arginine and a 25% loss of cystine. Loss of cystine was not observed in the proteins studied (soybean trypsin inhibitor, ribonuclease S-peptide). The arginine derivative is stable for 24 h in trifluoroacetic acid and under other mild acid conditions. The derivative is stable to 0.5 M hydroxylamine, pH 7.0, conditions under which the cyclohexanedione derivative of arginine decomposes8 but arginine is regenerated in 0.2 Mo-phenylenediamine, pH 8.5 (approximately 75% after 4 h; complete after 16 h).
Monowave and polywave light-curing of bulk-fill resin composites: degree of conversion and marginal adaptation following thermomechanical aging
Published in Biomaterial Investigations in Dentistry, 2021
Sheila Celia Mondragón Contreras, Ana Luiza Barbosa Jurema, Evaniele Santos Claudino, Eduardo Bresciani, Taciana Marco Ferraz Caneppele
In some bulk-fill RCs, camphorquinone (CQ), which is the most common photoinitiator in conventional RCs, is also used [12]. First and second-generation light-emitting diode (LED) light-curing units (LCUs) show one emission peak (monowave, MW) that matches the absorption spectrum of CQ (430–500 nm) [16]. However, such LCUs may not provide adequate cure of RCs containing alternative initiators. Tetric N-Ceram Bulk Fill (TB) contains Ivocerin, a photoinitiator characterized by high quantum efficiency and high absorption capacity. This germanium-based initiator system has a greater photo-curing activity than CQ. The absorption peak of Ivocerin is set in the violet spectrum (380–420 nm) and slightly extends to the blue spectrum range (420–455 nm), where almost 50% of its peak absorbance occurs at 440 nm. Ivocerin is a photoinitiator with higher photopolymerization reactivity [17]. The third-generation LED LCUs are considered to be broad-spectrum devices. They have two or more emission peaks (polywave, PW) with narrower wavelengths; violet to activate alternative photoinitiators and blue to activate CQ [18].
Controlled release of bioactive IL-2 from visible light photocured biodegradable elastomers for cancer immunotherapy applications
Published in Pharmaceutical Development and Technology, 2022
Mohamed A. Shaker, Jules J. E. Doré, Husam M. Younes
Tricarballylic acid (99%), 1,10-decanediol (98%), stannous 2-ethyl hexanoate (95%), 4-dimethylamino pyridine (DMAP) (99%), acryloyl chloride (ACRL) (96%), triethylamine (TEA) (99%), sodium sulfate (≥99%) and camphorquinone (97%) were purchased from Aldrich-Sigma chemical company, USA. Ethyl ether (99%), acetone (99%), and chloroform (99%) were purchased from Caledon chemical company, Canada. Recombinant murine interleukin 2 (rmIL-2) and rmIL-2 ELISA kits were purchased from Peprotech Inc., Canada. Trehalose dihydrate, bovine serum albumin, and ABTs liquid substrate system for ELISA were purchased from Sigma-Aldrich, USA. Chemicals used in calorimetric assays, including phenol (99%), sulfuric acid (95-98%), and Pierce BCA protein assay kit was purchased from Thermo-Fisher Scientific, Canada. Dulbecco’s phosphate buffer saline, GIBCO® RPMI medium 1640, penicillin, and streptomycin were obtained from Invitrogen, Canada. Rat T-STIM with Concanavalin A was purchase from BD biosciences, Canada. MTT cell Proliferation Kits were purchased from Roche, Canada. All chemicals were used as received without any further purification.
Antibacterial activity and physicochemical properties of a sealer containing copaiba oil
Published in Biofouling, 2023
Lara Rodrigues Schneider, Andressa da Silva Barboza, Juliana Silva Ribeiro de Andrade, Daniela Coelho dos Santos, Carlos Enrique Cuevas-Suárez, Evandro Piva, Angela Diniz Campos, Rafael Guerra Lund
The formulation of dual-cure experimental endodontic sealers (Figure 1) was based on the following monomers: Exothane 8, ethoxylated bisphenol A diglycidyl ether dimethacrylate with 30 ethylene oxide units (Bis-EMA 30), triethylene glycol dimethacrylate (TEGDMA), polyethylene glycol dimethacrylate (PEG 400), silica particles as the filler, camphorquinone (CQ), ethyl 4-dimethylaminobenzoate (EDAB), Ytterbium trifluoride (YT3) as the radiopacifier, benzoyl peroxide, sulfinic acid derivatives, and antioxidant BHT. The copaiba oil was incorporated at concentrations of 0% (negative control group – C0), 0.5% (C0.5), 1% (C1), and 2% (C2). The RealSeal™ (SybronEndo, Orange, USA) and AH Plus (Dentsply De Trey Gmbh, Konstanz, Germany) were the commercial reference sealers used in this study. Commercial reference samples were prepared according to the manufacturer’s recommendations, with the mixing tip. An experimental dual-cure endodontic sealer consisting of a paste-paste system was prepared through manipulation with a spatula for 10 s. The samples for all the tests were obtained after 2 h of curing and they were photoactivated for 20 s with a dental light-emitting diode (LED) unit (Radii™ Curing Light, SDI Limited, Bayswater, Victoria, Australia).
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