Effect of light curing protocol on degree of conversion of composites. (November 2014)

• Record Type: Journal Article
• Authors: Catelan, Anderson; Mainardi, Maria do Carmo Aguiar Jordão; Soares, Giulliana Panfiglio; Lima, Adriano Fonseca de; Ambrosano, Gláucia Maria Bovi; Lima, Débora Alves Nunes Leite; Marchi, Giselle Maria; Aguiar, Flávio Henrique Baggio
• Is Part Of: Acta odontologica Scandinavica. Volume 72:Number 8(2014)
• Page Start: 898
• Page End: 902
• Publication Date: 2014-11
• Subjects: Dentistry -- Periodicals; 617.6005
• DOI: 10.3109/00016357.2014.920108
• Languages: English
• ISSNs: 0001-6357

Abstract

<abstract> <title>Abstract</title> <p> <bold> <italic>Objective.</italic> </bold> To evaluate the degree of conversion (DC) of two light-cured composites with different protocols of light curing. <bold><italic>Materials and methods.</italic></bold> One hundred and ninety two specimens (<italic>n</italic> = 8) were prepared (5 mm × 2 mm) according to experimental groups: two composite resins (Filtek Supreme and four seasons); three light curing protocols [20 s with the tip of the light curing unit (LCU) device touching composite surface (C); 20 s with the tip of the LCU at 8 mm distant from composite surface (D); and tip of the LCU at 8 mm distant from composite surface and polymerization time required to obtain a radiant exposure of 16 J/cm<sup>2</sup> (DS)]. Four LCUs (Bluephase 16i, Ultralume LED 5, XL 3000 and Optilux 501C) were used. DC of the bottom and top surface of specimens were measured using a FTIR spectrometer. Data were statistically analyzed by 3-way split splot ANOVA and Tukey's test (alpha = 0.05). <bold><italic>Results.</italic></bold> The results showed that DC of the top surface was higher than the bottom at all experimental conditions (<italic>p</italic> < 0.0001). Overall, the curing at 8 mm of distance did not affect conversion rate on the top surface (<italic>p</italic> > 0.05), but bottom surfaces showed DC reduction (<italic>p</italic> < 0.05). The highest monomer conversion values were observed for C and DS situations. <bold><italic>Conclusion.</italic></bold> The distance between the LCU and material surface and radiant exposure can affect the DC. Polymerization at distance should be performed with curing units with higher light power and/or extended exposure time.</p> </abstract>