Nicoleta Ilie1, Julia Obermaier, Jürgen Durner. 1. Department of Operative/Restorative Dentistry, Periodontology and Pedodontics, Ludwig-Maximilians-University of Munich, Goethestr. 70, 80336, Munich, Germany, nilie@dent.med.uni-muenchen.de.
Abstract
OBJECTIVES: The aim of our study was to analyse whether the irradiation time and/or the modulation of irradiation time influence the degree of conversion (DC) and the amount of elutable substances from modern nano-hybrid resin-based composites (RBCs). MATERIALS AND METHODS: The DC was recorded in real time for 5 min by means of attenuated total reflectance-Fourier transform infrared spectroscopy (n = 5) on the lower surface of 2-mm-thick samples irradiated with continuous and modulated irradiation times for 20 s and 40 s. The modulated times comprise a short polymerisation (2 s or 5 s) followed by a rest period of 1 min and an additional polymerisation to complete 20 s and 40 s of polymerisation (2 s + 18 s, 5 s + 15 s, 2 s + 38 s and 5 s + 35 s). After storing the specimens in ethanol/water for 7 days at 37 °C, the eluates were analysed by gas chromatography-mass spectrometry. Results were statistically analyzed using a one-way ANOVA analysis (α = 0.05). RESULTS: The effect of irradiation time on DC is similar in all three analyzed materials, showing a significant increase in DC by increasing irradiation time from 20 s to 40 s, while the DC is not influenced within one irradiation time (20 s or 40 s) by the modulation of time. CONCLUSIONS: The type and amount of eluates are strongly dependent from the material and the irradiation protocol. CLINICAL RELEVANCE: An interrupt irradiation of RBCs is clinically feasible, reducing in general the amount of elutable substances at similar DC as the corresponding continuous polymerisation.
OBJECTIVES: The aim of our study was to analyse whether the irradiation time and/or the modulation of irradiation time influence the degree of conversion (DC) and the amount of elutable substances from modern nano-hybrid resin-based composites (RBCs). MATERIALS AND METHODS: The DC was recorded in real time for 5 min by means of attenuated total reflectance-Fourier transform infrared spectroscopy (n = 5) on the lower surface of 2-mm-thick samples irradiated with continuous and modulated irradiation times for 20 s and 40 s. The modulated times comprise a short polymerisation (2 s or 5 s) followed by a rest period of 1 min and an additional polymerisation to complete 20 s and 40 s of polymerisation (2 s + 18 s, 5 s + 15 s, 2 s + 38 s and 5 s + 35 s). After storing the specimens in ethanol/water for 7 days at 37 °C, the eluates were analysed by gas chromatography-mass spectrometry. Results were statistically analyzed using a one-way ANOVA analysis (α = 0.05). RESULTS: The effect of irradiation time on DC is similar in all three analyzed materials, showing a significant increase in DC by increasing irradiation time from 20 s to 40 s, while the DC is not influenced within one irradiation time (20 s or 40 s) by the modulation of time. CONCLUSIONS: The type and amount of eluates are strongly dependent from the material and the irradiation protocol. CLINICAL RELEVANCE: An interrupt irradiation of RBCs is clinically feasible, reducing in general the amount of elutable substances at similar DC as the corresponding continuous polymerisation.
Authors: Angela Di Pietro; Giuseppa Visalli; Sebastiano La Maestra; Rosanna Micale; Barbara Baluce; Giovanni Matarese; Luciano Cingano; Maria Elena Scoglio Journal: Mutat Res Date: 2007-11-22 Impact factor: 2.433