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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Eliades, G.
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (10/10 displayed)
- 2017Comparative analysis of the mechanical properties of fiber and stainless steel multistranded wires used for lingual fixed retentioncitations
- 2016Viscoelastic properties of orthodontic adhesives used for lingual fixed retainer bondingcitations
- 2013Interactions of dentine desensitisers with human dentine: morphology and composition.citations
- 2010Surface characterization of zirconia dental implantscitations
- 2010A metallurgical characterization of ten endodontic Ni-Ti instruments: Assessing the clinical relevance of shape memory and superelastic properties of Ni-Ti endodontic instruments
- 2009Surface characterization and force relaxation of retrieved silk suturescitations
- 2007Surface characterization of precious alloys treated with thione metal primerscitations
- 2003Multi-technique characterization of retrieved bone cement from revised total hip arthroplastiescitations
- 2000Light intensity effects on resin-composite degree of conversion and shrinkage strain
- 2000Degree of cure of orthodontic adhesives with various polymerization initiation modes
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article
Light intensity effects on resin-composite degree of conversion and shrinkage strain
Abstract
Objective: The aim of this study was to investigate the relationship between the degree of conversion (DC) and shrinkage strain values of two representative resin-composites when irradiated by two light intensity levels, for different time periods. Methods: The DC of Z100 and Tetric Ceram was measured by FTIR spectroscopy immediately post-cure and shrinkage strain values were obtained continuously for 30 min from photoinitiation with the bonded-disk technique. All samples were photopolymerized at an initial temperature of 23°C with the Elipar Highlight unit under the following modes of variable light intensity (I) 40 s at 750 mW/cm2; (II) a two-step 'soft-start' irradiation mode of 10 s at 200 mW/cm2 plus 30 s at 750 mW/cm2; (III) 40 s at 200 mW/cm2; and (IV) 10 s at 200 mW/cm2. Temperature effects of the light and curing exotherm were not eliminated. Results: Mode II of irradiation did not reduce the DC for each material, relative to the values obtained with mode I (p > 0.05). The corresponding shrinkage strain values after 30 min were also not significantly different (p > 0.05). However, the effects of reduced light intensity levels for 10 s and 40 s (modes III and IV), were in agreement with previous findings implying reduced shrinkage strain levels. For both resin composites, data from all curing times and light-intensities gave a linear regression relationship (with r2 > 0.99) between the bonded-disk shrinkage strain versus DC values. Significance: For the materials and light-intensities studied, the correlation between DC and shrinkage strain values means that some reductions in the problems of shrinkage may be achieved by an acceptable reduction in DC. However, this must also be consistent with generating adequate curing performance in the resin-network. Nevertheless, DC is not the exclusive parameter describing network character and a fuller understanding of the latter is an important research goal. © 2000 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.