Monomer conversion of pre-heated composite.
The potential for maximizing conversion of room-temperature, photoactivated resin composite in the oral environment is limited. Pre-heating composite prior to light-curing is hypothesized to increase monomer conversion and reduce the duration of light exposure. Composite temperature was controlled at between 3 degrees C and 60 degrees C prior to exposure with a conventional quartz-tungsten-halogen curing unit: 5, 10, 20, or 40 sec. Monomer conversion was calculated from infrared spectra at 0 mm (top) and 2-mm-deep surfaces 5 min after light initiation. A strong, positive correlation existed between temperature and monomer conversion: top r(2) = 0.999, 2 mm r(2) = 0.998. Conversion ranged from 31.6% (3 degrees C) to 67.3% (60 degrees C). The duration of light exposure, reduced by 50 to 75% with pre-heated composite, yielded the same or significantly higher conversion (p = 0.001) than with control (22 degrees C, 20 sec). Both hypotheses were accepted: Pre-heating composite prior to photoactivation provides greater conversion requiring reduced light exposure than with room-temperature composite.
Department of Dental Materials, School of Dentistry, University of São Paulo, São Paulo, SP, Brazil;
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M
Daronch
F A
FA
Rueggeberg
M F
MF
De Goes
D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D006244:Hardness; D006358:Hot Temperature; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D018709:Statistics, Nonparametric
D003188:Composite Resins; D011108:Polymers; D019279:Resin Cements