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Light Curing (light + curing)

Distribution by Scientific Domains
Polymers and Materials Science50%
Medical Sciences50%

Terms modified by Light Curing

  • light curing unit
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    Selected Abstracts

    Resin composite shrinkage and marginal adaptation with different pulse-delay light curing protocols

    EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2005
    Ivo Krejci
    The aims of this study were, first, to measure shrinkage induced by different methods of pulse-delay light curing and, second, to verify their influence on the marginal adaptation of class V restorations in enamel and dentin. Eight groups, comprising seven groups (n = 6) with different pulse-delay parameters and a control group, were compared for dynamic linear displacement and force by using a fine hybrid composite. Based on these results, the pulse-delay curing procedure with the lowest shrinkage force was chosen and tested against the control group with respect to marginal adaptation in class V restorations (n = 8) before and after simultaneous thermal and mechanical loading. Statistically significant differences between groups were found for both shrinkage properties tested, with one pulse-delay group giving the lowest overall shrinkage values. However, the percentages of ,continuous margin' of this group, and of the control before and after loading, were not significantly different in dentin, whereas a significantly lower percentage of ,continuous margin' was detected in the pulse-delay group in enamel after loading. [source]

    Water sorption kinetics in light-cured poly-HEMA and poly(HEMA- co -TEGDMA); determination of the self-diffusion coefficient by new iterative methods

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007
    Irini D. Sideridou
    Abstract The present investigation is concerned with the determination of self-diffusion coefficient (D) of water in methacrylate-based biomaterials following Fickian sorption by two new methods: the Iterative and the Graphical methods. The D value is traditionally determined by means of the initial slope of the corresponding sorption curve and the so-called Stefan's approximation. The proposed methods using equations without approximations and data resulting from the whole sorption range reach to accurate values of D, even when the sorption curve does not present an initial linear portion. In addition to D, the Graphical method allows the extrapolation of the mass of the sorbed water at equilibrium (M,), even when the equilibrium specimen's mass fluctuates around its limited value (m,). The test of the proposed procedures by means of ideal and Monte Carlo simulated data revealed that these methods are fairly applicable. The obtained D values compared with those determined by means of the Stephan's method revealed that the proposed methods provide more accurate results. Finally, the proposed methods were successfully applied to the experimental determination of the diffusion coefficient of water (50°C) in the homopolymer of 2-hydroxyethyl methacrylate (HEMA) and in the copolymer of HEMA with triethylene glycol dimethacrylate (98/2 mol/mol). These polymers were prepared by light curing (, = 470 nm) at room temperature in presence of camphorquinone and N,N -dimethylaminoethyl methacrylate as initiator. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

    Evaluation of polymerization of light-curing hybrid composite resins

    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2006
    Yong Hoon Kwon
    Abstract The quality of polymerization of hybrid composite resins was tested to explore their feasibility for dental restorations. For this, microhardness, polymerization shrinkage, the coefficient of thermal expansion, and surface morphology were evaluated during or after light curing in conjunction with the thermocycling process. Each product had different microhardness values. The repeated thermal stimulus has no specific effect on the change of microhardness. The difference of microhardness between the thermocycled specimens and specimens stored only in distilled water was minor. The measured microhardness had a linear correlation with the filler content (vol %) of the tested specimens. The polymerization shrinkage had rapidly increased only during the light curing, and then it reached a plateau. Among the specimens, Z250 showed the least amount of shrinkage for all tested thicknesses. Regardless of the product, the shrinkage values increased as the specimens became thick. The coefficient of thermal expansion of the control specimens ranged between 42 and 55 ,m/°C in the temperature range of 30,80°C. The coefficient showed an inverse correlation with the filler content. Through the thermocycling process, Palfique Estelite showed randomly propagating cracks on the surface. Larger fillers showed a more apparent detachment than the smaller fillers. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source]

    Validation of two dual fluorescence techniques for confocal microscopic visualization of resin penetration into enamel caries lesions

    MICROSCOPY RESEARCH AND TECHNIQUE, Issue 7 2009
    Sebastian Paris
    Abstract Fluorescence confocal microscopy is a useful tool to analyze the infiltration of enamel caries lesions with low-viscosity resins (infiltrants) in vitro. The conventionally used staining technique, which comprises dye labeling of the resin, has been shown to be limited by chromatographic separation of the resin-dye-mixture during penetration. The aim of this study was to develop an improved dual staining technique and to compare validity and reproducibility of both methods. Human molars with proximal white spots were cut across the demineralizations. After varnishing the cut surfaces, paired lesion halves were infiltrated with an infiltrant using either one of two different staining techniques. For the conventional direct technique (A) the infiltrant was labeled with rhodamine isothiocyanate (RITC) prior to application. Using the new indirect technique (B) lesions were stained with RITC solution and subsequently infiltrated with pure infiltrant. After light curing, unbound dye was bleached by immersion in hydrogen peroxide. Remaining lesion pores were stained with sodium fluorescein solution. Penetration depths (PD) and lesion depths (LD) were evaluated by five examiners using confocal microscopy and compared with the results of scanning electron microscopic (SEM; PD) and microradiographic (TMR; LD) analysis. The indirect technique showed better correlation (intraclass coefficients) with SEM (0.990) and TMR (0.982) compared with the direct technique (SEM: 0.513; TMR: 0.702). Inter- and intrarater reliability was higher for technique B compared with technique A. The new indirect technique yields to more valid and reliable results to visualize infiltrant penetration into natural enamel caries lesions compared with the conventional method. Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc. [source]