Investiation of the effect of temperature on polymerization shrinkage of flowable composite resin restorative material with micro computed tomography

The aim of this study is to determine which temperature will have more effect on polymerization shrinkage as a result of in vitro evaluation of polymerization shrinkage occurring in a newly developed flowable composite kept at different temperatures using the latest micro-computed tomography (micro-CT). At the same time, it is aimed to convey information about the properties of flowable composite resins to the literature and to contribute to the clinical applications and studies to be made from now on. The flowable composite resin (Clearfil Majesty Flow, Kuraray Noritake Dental INC, Okuyama JAPAN) samples used in this study were evaluated at 4 different temperatures (4°C ,20°C ,37°C ,55°C). After the flowable composites were kept at 4°C, 20°C, 37°C and 55°C for 30 minutes, 25 samples placed in standard polytetrafluoroethylene (PTFE) molds at a depth of 2mm were kept in the dark for two minutes at the same temperature and the samples were scanned in a micro-CT (Skyscan 1275, Bruker USA) device without polymerization. Then, to compensate for the heat loss during scanning, the samples were kept in the dark for two minutes at their current temperature and polymerized using a light device (BlueLEX GT-1200, Monitex Industrial Co., LTD, TAIWAN) for 20 seconds. The polymerized samples were scanned again in micro-CT. Data were statistically evaluated. When the average volume data of all groups before and after polymerization were compared, the least polymerization shrinkage at 4°C was observed. In our study, 4°C showed the least polymerization shrinkage, followed by 20°C and 37°C. The highest polymerization shrinkage was observed at 55 °C. In the tests performed to investigate the differences between the averages of polymerization shrinkage, no statistically significant difference was found between all temperatures in terms of polymerization shrinkage (p > 0.05).