Real-time analysis of temperature change in composite photopolymerization using non-contact infrared sensor / 대한치과재료학회지

ABSTRACT

The aim of this study was to investigate the effects of the radiant emittance of an LED light on temperature change during composite photopolymerization using a non-contact infrared sensor. A thermometer was prepared using a non-contact infrared sensor and a microcontroller. After preparing a disc-shaped composite specimen using a micro-hybrid conventional (Z250) or nano bulk-fill (BFP) composite, the temperature change of the prepared composite during photopolymerization was measured based on three photopolymerization protocols (Duty ratio/exposure time; 100%/20 s, 50%/40 s, and Increase (0→100%)/40 s) using a pulse width modulated (PWM) LED light. Subsequently, second light exposure, having the same protocol as the first, was performed on the photopolymerized composite. The first peak temperature rise of composite photopolymerization (ΔT total) and second peak temperature rise caused by the LED light (ΔT light ) were obtained from the temperature change vs. time curve.The net peak temperature rise caused by the curing heat of the composite (ΔT composite ) was obtained by subtracting the second curve from the first one. The peak time was defined as the time when ΔT composite occurred. ΔT total and ΔT composite of the 100%/20 s group were the highest and ΔT light of the 50%/40 s group was the lowest for both the composites (p<0.05). The temperature rise of Z250 was higher than that of BFP in all the groups except the ΔT composite of the Increase/40 s group (p<0.05). The peak time of the Increase/40 s group was the longest in both the composites, and the peak time of BFP was longer than that of Z250 in all the photopolymerization protocols (p<0.05). A real-time analysis of the temperature change during composite photopolymerization was effectively performed using the non-contact infrared sensor. Through this analysis, the polymerization kinetics of the composite could also be evaluated.