engleski

The pulsed exicemer laser composite photopolymerization

The objective of this study was to evaluate the degree of conversion and polymerization shrinkage of two hybrid and two microfilled composite materials cured by pulsed excimer laser (XeCl Lambda Physik LPX 100/3002) and standard curing unit. The laser was set at 468 nm wavelenght and the duration of laser pulse was 20 ns with the energy of 10 mJ. Conventional halogen lamp used was Heliolux GTE (Vivadent, Liechtenstein) with 500 mW/cm2 output. The tested materials were Tetric and Helioprogress (Vivadent, Liechtenstein), Valux Plus (3M, USA) and Visiodispers (ESPE, Germany). Degree of conversion measurements were perfomed by Perkin Elmer FTIR Spectrometer at the surface of the material and at 3.0 mm depth. The degree of conversion values varied from 59.8 to 84.3%. Statistical analysis (ANOVA p<0.05) showed significantly higher curing values in the case of pulsed laser for all the materials and shades tested. Polymerization shrinkage measurements where perfomed by pycnometer and significantly lower values were obtained in case of pulsed laser curing. Polymerization shrinkage values varied from 0, 8 to 3.2%. The saturation effect in the material illuminated by pulsed laser light may be responsible for the increased degree of conversion and the relaxation of the molecules between nanopulses may lead to the reduced net polymerization shrinkage. (This study was supported by the Ministry of Science and Technology of Republic of Croatia).

pulsed laser; composite; polymerization

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