J Korean Acad Conserv Dent.  2002 Mar;27(2):135-141. 10.5395/JKACD.2002.27.2.135.

Effect of light intensity on the polymerization rate of composite resin using real-time measurement of volumetric change

Affiliations
  • 1Department of Conservative Dentistry, College of Dentistry, Seoul National University, Korea.
  • 2Department of Chemical Engineering, Chung-Ang University, Korea.
  • 3Department of Conservative Dentistry, College of Dentistry, Chonbuk National University, Korea.

Abstract


OBJECTIVES
The aim of this study is to evaluate the effect of light intensity variation on the polymerization rate of composite resin using IB system (the experimental equipment designed by Dr. IB Lee) by which real-time volumetric change of composite can be measured.
METHODS
Three commercial composite resins [Z100(Z1), AeliteFil(AF), SureFil(SF)] were photopolymerized with Variable Intensity Polymerizer unit (Bisco, U.S.A.) under the variable light intensity (75/150/225/300/375/450mW2) during 20 sec. Polymerization shrinkage of samples was detected continuously by IB system during 110 sec and the rate of polymerization shrinkage was obtained by its shrinkage data. Peak time(P.T.) showing the maximum rate of polymerization shrinkage was used to compare the polymerization rate.
RESULTS
Peak time decreased with increasing light intensity(p<0.05). Maximum rate of polymerization shrinkage increased with increasing light intensity(p<0.05). Statistical analysis revealed a significant positive correlation between peak time and inverse square root of the light intensity (AF:R=0.965, Z1:R=0.974, SF:R=0.927). Statistical analysis revealed a significant negative correlation between the maximum rate of polymerization shrinkage and peak time(AF:R=-0.933, Z1:R=-0.892, SF:R=-0.883), and a significant positive correlation between the maximum rate of polymerization shrinkage and square root of the light intensity (AF:R=0.988, Z1:R=0.974, SF:R=0.946). DISCUSSION AND CONCLUSIONS: The polymerization rate of composite resins used in this study was proportional to the square root of light intensity. Maximum rate of polymerization shrinkage as well as peak time can be used to compare the polymerization rate. Real-time volume method using IB system can be a simple, alternative method to obtain the polymerization rate of composite resins.

Keyword

Composite Resin; Volumetric Shrinkage; Rate of Polymerization; Light Intensity; IB system
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