Methods:(1)DC of Realseal SE, either self or dual cured (n=5 in each group), were calculated according to the Raman spectra obtained 2min, 10min, 20min, 45min, 4 days, 1 week, 2 weeks and 3 weeks after mixing. (2)Thirty extracted teeth with single canal were instrumented and divided randomly into 2 groups in terms of different canal drying methods: a) Paper points; b) Paper points followed by 95% ethanol. Serial cross sections (2mm, 5mm and 8mm from the apex) were obtained 1 week after obturation with Resilon/Realseal SE. DC of Realseal SE in each section was investigated by using micro-Raman spectroscopy.
Results: DC of Realseal SE increased with time (P<0.01). Significant increase in DC of Realseal SE was observed in one week with little change afterwards, ranging from 73% to 75%. DC of Realseal SE in canals dried by paper points and ethanol (82%~84%) was significantly higher than that of paper points (74%~76%) (P<0.01). However, DC of Realseal SE at different levels of sections were not sifnificantly different (P>0.05).
Conclusions: DC of Realseal SE showed time-dependent increase after mixing and became stable till one week. Root canals dried by paper points and 95% ethanol favored the conversion of Realseal SE. Furthermore, chemical-cured Realseal SE achieved similar DC to the dual-cured one.