Impact of the distance of light curing on the degree of conversion and microhardness of a composite resin. (May 2014)

• Record Type: Journal Article
• Authors: Catelan, Anderson; de Araújo, Larissa Sgarbosa Napoleão; da Silveira, Bruna Cilene Martins; Kawano, Yoshio; Ambrosano, Gláucia Maria Bovi; Marchi, Giselle Maria; Aguiar, Flávio Henrique Baggio
• Is Part Of: Acta odontologica Scandinavica. Volume 73:Number 4(2015)
• Page Start: 298
• Page End: 301
• Publication Date: 2014-05
• Subjects: Dentistry -- Periodicals; 617.6005
• DOI: 10.3109/00016357.2014.946965
• Languages: English
• ISSNs: 0001-6357

Abstract

<abstract> <title>Abstract</title> <p> <bold> <italic>Objective.</italic> </bold> This study evaluated the impact of the distance between the light guide tip of the curing unit and material surface on the degree of conversion and Knoop microhardness of a composite resin. <bold><italic>Materials and methods.</italic></bold> Circular samples were carried out of a methacrylate micro-hybrid resin-based composite and light cured at 0, 2 and 4 mm distance. Monomer conversion rate was measured using a Fourier-transform Raman spectrometer and Knoop hardness number was obtained using a microhardness tester on the top and bottom surfaces. Data were statistically analyzed by analysis of variance and Tukey's test (<italic>α</italic> = 0.05). <bold><italic>Results.</italic></bold> Overall, the increase of curing distance reduced the microhardness (<italic>p</italic> ≤ 0.05), but did not influence the carbon double bond conversion rate (<italic>p</italic> &gt; 0.05) of the composite resin tested; and the top surface showed better properties compared to the bottom (<italic>p</italic> ≤ 0.05). <bold><italic>Conclusions.</italic></bold> The light curing at distance can reduce mechanical properties and could affect long-term durability of the composite restorations. Thus, the use of a curing device with high irradiance is recommended.</p> </abstract>