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Effect of the irradiance distribution from light curing units on the local micro-hardness of the surface of dental resins

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dc.title Effect of the irradiance distribution from light curing units on the local micro-hardness of the surface of dental resins en
dc.contributor.author Haenel, Thomas
dc.contributor.author Hausnerová, Berenika
dc.contributor.author Steinhaus, Johannes
dc.contributor.author Price, Richard B. T.
dc.contributor.author Sullivan, Braden
dc.contributor.author Moeginger, Bernhard
dc.relation.ispartof Dental Materials
dc.identifier.issn 0109-5641 Scopus Sources, Sherpa/RoMEO, JCR
dc.date.issued 2015
utb.relation.volume 31
utb.relation.issue 2
dc.citation.spage 93
dc.citation.epage 104
dc.type article
dc.language.iso en
dc.publisher Elsevier
dc.identifier.doi 10.1016/j.dental.2014.11.003
dc.relation.uri https://www.sciencedirect.com/science/article/pii/S0109564114006551
dc.subject Degree of conversion en
dc.subject Dental resin en
dc.subject FTIR en
dc.subject Hardness mapping en
dc.subject Irradiance distribution en
dc.subject Knoop micro-hardness en
dc.subject Light curing units en
dc.description.abstract Objective An inhomogeneous irradiance distribution from a light-curing unit (LCU) can locally cause inhomogeneous curing with locally inadequately cured and/or over-cured areas causing e.g. monomer elution or internal shrinkage stresses, and thus reduce the lifetime of dental resin based composite (RBC) restorations. The aim of the study is to determine both the irradiance distribution of two light curing units (LCUs) and its influence on the local mechanical properties of a RBC. Methods Specimens of Arabesk TOP OA2 were irradiated for 5, 20, and 80 s using a Bluephase® 20i LCU in the Low mode (666 mW/cm2), in the Turbo mode (2222 mW/cm2) and a Celalux® 2 (1264 mW/cm2). The degree of conversion (DC) was determined with an ATR-FTIR. The Knoop micro-hardness (average of five specimens) was measured on the specimen surface after 24 h of dark and dry storage at room temperature. Results The irradiance distribution affected the hardness distribution across the surface of the specimens. The hardness distribution corresponded well to the inhomogeneous irradiance distributions of the LCU. The highest reaction rates occurred after approximately 2 s light exposure. A DC of 40% was reached after 3.6 or 5.7 s, depending on the LCU. The inhomogeneous hardness distribution was still evident after 80 s of light exposure. Significance The irradiance distribution from a LCU is reflected in the hardness distribution across the surface. Irradiance level of the LCU and light exposure time do not affect the pattern of the hardness distribution - only the hardness level. In areas of low irradiation this may result in inadequate resin polymerization, poor physical properties, and hence premature failure of the restorations as they are usually much smaller than the investigated specimens. It has to be stressed that inhomogeneous does not necessarily mean poor if in all areas of the restoration enough light intensity is introduced to achieve a high degree of cure. en
utb.faculty University Institute
utb.faculty Faculty of Technology
dc.identifier.uri http://hdl.handle.net/10563/1004138
utb.identifier.rivid RIV/70883521:28610/15:43873062!RIV16-MSM-28610___
utb.identifier.obdid 43873482
utb.identifier.scopus 2-s2.0-84920896884
utb.identifier.wok 000349759400009
utb.identifier.coden DEMAE
utb.source j-scopus
dc.date.accessioned 2015-02-05T16:33:59Z
dc.date.available 2015-02-05T16:33:59Z
dc.description.sponsorship 17081X10, Bundesministerium für Bildung und Forschung
dc.description.sponsorship Federal Republic of Germany, Ministry of Education and Research [17081X10]; Operational Program Research and Development for Innovations; Czech Republic, within the framework of project Centre of Polymer Systems [CZ.1.05/2.1.00/03.0111]; European Regional Development Fund (ERDF); VOCO GmbH
utb.ou Centre of Polymer Systems
utb.contributor.internalauthor Haenel, Thomas
utb.contributor.internalauthor Hausnerová, Berenika
utb.contributor.internalauthor Steinhaus, Johannes
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