Comparison of degree of conversion for light-cured and additionally heat-cured composites

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The purpose of this study was to compare the changes in the degree of conversion in the various layers of composites after additional heat curing. Four types of composites and three types of inlay ovens were used in this study. Composite was placed in a 4 mm thick Teflon mold and light cured from the top for 60 seconds. Twenty samples were prepared for each composite; 10 of these were additionally heat cured in an inlay oven as the manufacturer recommended. After light curing or light and heat curing, the samples were sectioned into four parts and assigned to groups A, B, C, or D according to their distance from the light source. These sections were then thinned to 50 to 70 mm, and these wafers were analyzed with a Fourier Transform Infrared spectrometer to determine the degree of conversion. A standard baseline technique was used to calculate the degree of conversion. When the composites were heat cured, significant increases in the degree of conversion were noted throughout the samples, but the amount of increase differed among materials. Thus the clinical performance of a heat-treated composite inlay may be different depending on materials.

Original languageEnglish
Pages (from-to)613-618
Number of pages6
JournalJournal of Prosthetic Dentistry
Issue number6
Publication statusPublished - 1996

Bibliographical note

Funding Information:
The increase in the degree of conversion (DC) after heat curing has been widely reported to vary by as much as 1% to 3%,3 3% to 18%,4 10% to 20%,5 and 20% to 30%.6 These differences may be due not only to the composition of monomer but also to the sensitivity of the technique applied. For composites, which contain inorganic filler, an attenuated total refractance technique with infrared (IR) spectrometry has been used.7,8 However, it was pointed out that the result can vary with IR spectrometry; thus the use of a Fourier Transform Infrared spectrometer (FX-6200, Analect Instruments, Irvine, Calif.) (FT-IR) with a thin film technique has been recommended for determining the DC in composites9 For this technique a thin, unfilled bonding agent is applied under the plastic matrix and a composite of a constant thickness is placed over the matrix. After illumination of the composite this bonding agent is used to measure the DC. However, with this technique, the thin unfilled This study was supported in part by the Non Directed Fund, Korea Research Foundation, 1995. “Assistant Professor, Department of Conservative

All Science Journal Classification (ASJC) codes

  • Oral Surgery


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