%0 Journal Article
%T Photoactivation mode and irradiation distance influence on degree of conversion of a resin composite
%A N¨ªvea Regina FR¨®ES-SALGADO
%A Carlos FRANCCI
%A Yoshio KAWANO
%J Perspectives in Oral Sciences
%D 2009
%I 
%X Objective: To evaluate the degree of conversion of a resin composite varying irradiance ¡Á irradiation time and distance between light source and composite surface. Methods: For this analysis, Esthet-X (Caulk/Dentsply) A2 samples (cylindrical shaped, 5 mm diameter and2 mm height) were cured in accordance to the following protocols: 600 mW/cm2 for 40 s, 400 mW/cm2 for 60 s or 200 mW/cm2 for 20 s + 500 mW/cm2 for 40 s; distance light sourcecomposite of 0, 3 or 7 mm. There were nine experimental groups (n = 3). The degree of conversion was determined by FT-Raman spectrometer to provide the amount of remaining carbon double-bonds. Results were analyzed by three-way ANOVA and Tukey¡¯s test. Results: The distance of the light source and the analyzed face were significant (p < 0.05). The degreeof conversion averages (in %) were 59.13 ¡À 2.32, 58.61 ¡À 3.08 and 56.85 ¡À 2.24 for 0, 3 and 7 mm distances; only 0 and 7 mm showed statistical differences. Radiated and nonradiated faces demonstrated degree of conversion averages (in %) of 59.01 ¡À 2.56 and 57.40 ¡À2.67, respectively. Conclusions: It was concluded, therefore, that continuous or two-stepped irradiations provide similar degrees of conversion in resin composite. Increasing the distanceof the light source there is a reduction of the degree of conversion. This is especially important in deep restorations.
%K polymerization
%K degree of conversion
%K composite resin
%U http://poralsciences.up.edu.br/arquivos/poralsciences/File/PAGINAS%20POS%2011_17.pdf