J Adv Prosthodont.  2011 Dec;3(4):216-220. 10.4047/jap.2011.3.4.216.

Polymerization behavior and thermal characteristics of two new composites at five temperatures: refrigeration to preheating

• Jafarzadeh-Kashi TS
• Mirzaii M
• Erfan M
• Fazel A
• Eskandarion S
• Rakhshan V

• KMID: 2054756
• DOI: http://doi.org/10.4047/jap.2011.3.4.216

Abstract

PURPOSE
Heat of composite polymerization (HP) indicates setting efficacy and temperature increase of composite in clinical procedures. The purpose of this in vitro experimental study was to evaluate the effects of 5 temperatures on HP of two new composites.
MATERIALS AND METHODS
From each material (Core Max II [CM] and King Dental [KD]), 5 groups of 5 specimens each were prepared and their total HPs (J/gr) were measured and recorded, at one of the constant temperatures 0degrees C, 15degrees C, 23degrees C, 37degrees C and 60degrees C (2 x 5 x 5 specimens) using a differential scanning calorimetry (DSC) analyzer. The data were analyzed using a two-way ANOVA, a Tukey's test, an independent-samples t-test, and a linear regression analysis (alpha=0.05).
RESULTS
No polymerization reactions occurred at 0degrees C; then this temperature was excluded from statistical analyses. The mean HP of the remaining 20 KD specimens was 20.5 +/- 14.9 J/gr, while it was 40.7 +/- 12.9 J/gr for CM. The independent-samples t-test showed that there were significant differences between the HP of the two materials at the temperatures 15degrees C (P=.0001), 23degrees C (P=.0163), 37degrees C (P=.0039), and 60degrees C (P=.0106). Linear regression analysis showed statistically significant correlations between environment temperatures and HP of CM (R2=0.777).
CONCLUSION
Using CM is advantageous over conventional composite because of its better polymerization capacity. However due to its high HP, further studies should assess its temperature increase in vivo. Preheating KD is recommended. Refrigerating composites can negatively affect their polymerization potential.

Keyword

Dental Materials; Composite Resins; Polymerization; Differential Thermal Analysis; Differential Scanning Calorimetry (DSC)

MeSH Terms

Calorimetry, Differential Scanning
Composite Resins
Dental Materials
Differential Thermal Analysis
Hot Temperature
Linear Models
Polymerization
Polymers
Refrigeration
Composite Resins
Dental Materials
Polymers

Figure

• 

  Fig. 1 Mean (SD) HPs of the tested materials (J/gr) at different temperatures (℃).

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