Alena Knezevic1, Davor Zeljezic, Nevenka Kopjar, Zrinka Tarle. 1. Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb, Gunduliceva 5, 10000 Zagreb, Croatia. ma505ak@yahoo.com
Abstract
PURPOSE: This study determined the cytotoxic/genotoxic effect of different curing modes on cell culture. METHODS: A thin layer of lymphocyte cultures was cured applying three different curing modes of Bluephase C8 LED curing unit. Cultures were exposed to light directly or through a layer (2 mm) of polymerized resin composite sample. Cells were analyzed using trypan blue exclusion test, acridine orange/ethidium bromide dyeing technique, and alkaline comet assay. RESULTS: Only low intensity mode after direct exposure significantly increased the number of nonviable lymphocytes detected using trypan blue. All curing procedures significantly increased the number of apoptotic lymphocytes regardless whether the exposure occurred directly or through the composite. Low intensity mode in direct exposure significantly elevated DNA migration compared to other curing modes. 1 hour after exposure significant increase in tail length and intensity for all modes and procedures was detected. However, DNA damage measured for cultures cured by low intensity mode was higher compared to the other two modes; thus, despite of curing light intensity, longer curing time leads to greater cytotoxicity/genotoxicity in cell culture.
PURPOSE: This study determined the cytotoxic/genotoxic effect of different curing modes on cell culture. METHODS: A thin layer of lymphocyte cultures was cured applying three different curing modes of Bluephase C8 LED curing unit. Cultures were exposed to light directly or through a layer (2 mm) of polymerized resin composite sample. Cells were analyzed using trypan blue exclusion test, acridine orange/ethidium bromide dyeing technique, and alkaline comet assay. RESULTS: Only low intensity mode after direct exposure significantly increased the number of nonviable lymphocytes detected using trypan blue. All curing procedures significantly increased the number of apoptotic lymphocytes regardless whether the exposure occurred directly or through the composite. Low intensity mode in direct exposure significantly elevated DNA migration compared to other curing modes. 1 hour after exposure significant increase in tail length and intensity for all modes and procedures was detected. However, DNA damage measured for cultures cured by low intensity mode was higher compared to the other two modes; thus, despite of curing light intensity, longer curing time leads to greater cytotoxicity/genotoxicity in cell culture.