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Polymerization Kinetics of Pre-heated Composite
1 Department of Dental Materials, School of Dentistry, University of São Paulo, São Paulo, SP, Brazil; Correspondence: * corresponding author, frueggeb{at}mcg.edu Temperature affects the polymerization behavior of dimethacrylate-based materials. This study describes the influence of pre-polymerization temperature and exposure duration on polymerization kinetics of a commercial dental photo-activated composite at the top and at 2-mm depth. We used the temperature-controlled stage of a diamond-attenuated-total-reflectance unit to pre-set composite temperature between 3° and 60°C. Composite was light-exposed by a conventional quartz-tungsten-halogen curing unit for 5, 10, 20, or 40 sec. Real-time conversion, maximum conversion rate (Rpmax), time to achieve Rpmax, and conversion at Rpmax were calculated from infrared spectra. Composite pre-warming enhanced maximal polymerization rate and overall monomer conversion (top significantly greater than 2 mm). Time when Rpmax occurred did not change with temperature, but occurred sooner at the top than at 2-mm depth. Conversion at Rpmax increased with temperature, allowing more of the reaction to occur prior to vitrification than at room temperature.
Key Words: resin composite kinetics polymerization rate monomer conversion curing temperature
Journal of Dental Research, Vol. 85, No. 1,
38-43 (2006) |
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