Photopolymerization Kinetics of Methacrylate Dental Resins

Dickens, Sabine H.; Stansbury, Jeffrey W.; Choi, Kwok Pui; Floyd, Cynthia J.E.

doi:10.1021/ma021675k

Cited by 327 publications

(297 citation statements)

References 43 publications

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“…Two broad peaks can be observed around 45 and 105 °C, which suggest a heterogeneous polymeric network. 13,14 However, it can be seen that for the higher clay loadings (over 5%), the lower temperature peak tends to disappear, indicating that the heterogeneity of the resin is being reduced. Thus, the presence of the clay seems to turn the resins more homogeneous favouring the formation of crosslinked domains, and lowering the mobility of the polymeric chains.…”

Section: Photocalorimetry (Pca)mentioning

confidence: 99%

Effect of the loading of organomodified clays on the thermal and mechanical properties of a model dental resin

et al. 2016

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Experimental dental resins composed of triethyleneglycol dimethacrylate, urethane dimethacrylate, ethoxylated bisphenol-A-dimethacrylate and bisphenol A glycidyl methacrylate containing an organoclay as filler were prepared by photopolymerization. The addition of organoclay fillers results in slower polymerization rates (0.59 and 0.24 mol L -1 min -1 , for the formulations without and with 15% of organoclay, respectively) and lower degrees of conversion (0.50 and 0.35 for the formulations without and with 15% of organoclay), as determined by photocalorimetry. The influence of the organoclay on the thermal and mechanical properties of the resins was evaluated using thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) techniques. The (tan δ) and E´ curves indicate the formation of more rigid materials and the damping curve data indicates more homogeneous materials. An increase of storage modulus, E', was observed for composites with the higher organoclay filler contents. These effects are due to the higher viscosity of the systems with organoclay, resulting in a lower mobility of the radicals during the propagation step of polymerization, as well as to the scattering of the incident photopolymerizing radiation, which lowers the amount of initiation centres.

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Section: Photocalorimetry (Pca)mentioning

confidence: 99%

Effect of the loading of organomodified clays on the thermal and mechanical properties of a model dental resin

et al. 2016

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“…25,26 In this study, the round-bar glass-tubing molds were used in place of the widely used hour-glass shaped molds such as those made from Teflon, vinyl polysiloxane impression, or wax materials. 25,26 The advantages of the glass tubing molds included easy preparation of smooth surface beam specimens without the need for polishing, without air bubbles, and without evaporation of the solvent.…”

Section: Degree Of Conversion Of Model Adhesives Cured In the Presencmentioning

confidence: 99%

Relationship of solvent to the photopolymerization process, properties, and structure in model dentin adhesives

Spencer

Wang

et al. 2006

J Biomedical Materials Res

171

157

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The ratio of the double-bond content of monomer to polymer, i.e. degree of conversion (DC) has been used frequently as a convenient means of comparing the behavior and properties of dental composites and adhesives. The purpose of this investigation was to study the relationship of photopolymerization processes, bulk properties, and structure using model dentin adhesives cured in the presence of different ethanol content as an example. There was little difference in the DC of model BisGMA-based adhesives cured in the presence of ethanol concentrations ranging from 0 to 40 wt %, but there were substantial differences in the mechanical properties. Ultimate tensile strength (UTS) and modulus of elasticity decreased with an increase in ethanol content. Polymer structure was revealed by thermal behavior in the glass transition temperature (T g ) region; these measurements were obtained by modulated temperature differential scanning calorimetry (MTDSC) technology, which removes the competing irreversible effects associated with release of volatiles and residual curing. Glass transition temperature of model adhesives decreased substantially with an increase in ethanol content. The DC based on the quantity of remaining double bond has been used extensively to characterize and provide a relative assessment of the quality of dentin adhesives and dental composites. Since polymers differing in linearity, and therefore crosslink density, may have a similar degree of conversion, the measurement of monomer/polymer conversion does not necessarily provide complete representation of the quality or durability of the polymer structure.

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“…Moreover, it is hypothesized that TEGDMA underwent cyclization forming microgel regions within the forming polymer. High cyclization and microgel formation has been reported for TEGDMA [15] and has been suggested as the reason for certain curing characteristics of TEGDMA-rich formulation studied by differential scanning calorimetry [8]. If TEGDMA formed predominantly primary cycles within the TEGDMA-rich phase after phase separation, the PMDM/TEGDMA resin could have relatively high conversion of double bonds but low FS or WoF, since primary cycles of poly(TEGDMA) would reduce the number of unreacted double bonds but would not contribute as much to the mechanical strength as crosslinked TEGDMA.…”

Section: Discussionmentioning

confidence: 97%

“…The flexibility of TEGDMA is related to the ether linkages of the molecule, with only a slight hindrance to free rotation about the bonds [6,7]. While the structure of the "kinked" bisphenol A core imparts stiffness and strength, it hampers the polymerization and results in a higher amount of residual double bonds [8] and potentially leachable monomer [9] than, for example, an aliphatic core structure as in a urethane dimethacrylate. Work by Hammesfahr [10] indicated differences from various acidic monomer structures in dentin bond strength and cohesive (compressive) strength of compomer-type composite resin formulations.…”

Section: Introductionmentioning

confidence: 99%

Degree of cure and fracture properties of experimental acid-resin modified composites under wet and dry conditions

López-Suevos

Dickens

2008

Dental Materials

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Objective-Evaluate the effects of core structure and storage conditions on the mechanical properties of acid-resin modified composites and a control material by three-point bending and conversion measurements 15 min and 24 h after curing.Methods-The monomers pyromellitic dimethacrylate (PMDM), biphenyldicarboxylic-acid dimethacrylate (BPDM), (isopropylidene-diphenoxy)bis(phthalic-acid) dimethacrylate (IPDM), oxydiphthalic-acid dimethacrylate (ODPDM), and Bis-GMA were mixed with triethyleneglycol dimethacrylate (TEGDMA) in a 40/60 molar ratio, and photo-activated. Composite bars (Bariumoxide-glass/resin = 3/1 mass ratio, (2 × 2 × 25) mm, n = 5) were light-cured for 1 min per side. Flexural strength (FS), elastic modulus (E), and work-of-fracture (WoF) were determined in threepoint bending after 15 min (stored dry); and after 24 h under dry and wet storage conditions at 37 °C . Corresponding degrees of conversion (DC) were evaluated by Fourier transform infrared spectroscopy. Data was statistically analyzed (2-way analysis of variance, ANOVA, Holm-Sidak, p < 0.05).Results-Post-curing significantly increased FS, E and DC in nearly all cases. WoF did not change, or even decreased with time. For all properties ANOVA found significant differences and interactions of time and material. Wet storage reduced the moduli and the other properties measured with the exception of FS and WoF of ODPDM; DC only decreased in BPDM and IPDM composites.Significance-Differences in core structure resulted in significantly different physical properties of the composites studied with two phenyl rings connected by one ether linkage as in ODPDM having superior FS, WoF and DC especially after 24 h under wet conditions. As expected, post-curing significantly contributed to the final mechanical properties of the composites, while wet storage generally reduced the mechanical properties.

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Photopolymerization Kinetics of Methacrylate Dental Resins

Cited by 327 publications

References 43 publications

Effect of the loading of organomodified clays on the thermal and mechanical properties of a model dental resin

Effect of the loading of organomodified clays on the thermal and mechanical properties of a model dental resin

Relationship of solvent to the photopolymerization process, properties, and structure in model dentin adhesives

Degree of cure and fracture properties of experimental acid-resin modified composites under wet and dry conditions

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