Yu Peng, Xu Yong-Xiang, Liu Yu-Shu
Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing, China.
National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing, China.
J Dent Sci. 2022 Jul;17(3):1212-1216. doi: 10.1016/j.jds.2021.12.004. Epub 2021 Dec 23.
BACKGROUND/PURPOSE: Bulk-fill resin-based composites (RBCs) are a new class of restorative materials, and polymerization shrinkage (PS) is concerned due to their single increment up to 4 mm. The aim of this study was to evaluate the PS and shrinkage stress (SS) of bulk-fill RBCs in vitro.
Three bulk-fill RBCs and three conventional non-bulk-fill RBCs were selected. The PS was determined with Acuvol volumetric shrinkage analyzer by calculating the specimen volume variation before and after light irradiation. The SS was investigated using universal testing machine method with a polymethyl methacrylate rod as a bonding substrate. The force generated during the polymerization process was detected by a load cell linked to a computer. SS was calculated by dividing the maximum stress force by the area of the rod.
The mean PS of various RBCs ranged from 1.72% to 2.13%. All PS results of bulk-fill RBCs were comparable to their conventional counterparts. Sonicfill 2 (SF2) and Harmonize (HM) showed the lowest PS (p < 0.05; Tukey HSD test). Medians of SS results ranged from 0.55 MPa to 0.67 MPa. All SSs of bulk-fill RBCs were comparable to their conventional counterparts. SF2 showed significantly lower SS than Tetric N-Ceram (TN) and Tetric N-Ceram Bulk Fill (TNB) (p < 0.0083; post hoc comparisons with Bonferroni adjustments). A moderate, positive correlation was observed between PS and SS with Pearson's correlation (r = 0.446, p = 0.013).
Both PS and SS are material dependent. A moderate, positive correlation between PS and SS is found with new bulk-fill RBCs and their conventional counterparts.
背景/目的：大体积充填树脂基复合材料（RBCs）是一类新型修复材料，因其单次充填厚度可达4毫米，故而聚合收缩（PS）备受关注。本研究旨在体外评估大体积充填RBCs的PS和收缩应力（SS）。
选取三种大体积充填RBCs和三种传统非大体积充填RBCs。使用Acuvol体积收缩分析仪通过计算光照前后试样体积变化来测定PS。采用万能试验机方法，以聚甲基丙烯酸甲酯棒作为粘结基底来研究SS。聚合过程中产生的力通过与计算机相连的测力传感器进行检测。SS通过将最大应力力除以棒的面积来计算。
各种RBCs的平均PS在1.72%至2.13%之间。所有大体积充填RBCs的PS结果与其传统对应物相当。Sonicfill 2（SF2）和Harmonize（HM）显示出最低的PS（p < 0.05；Tukey HSD检验）。SS结果的中位数在0.55兆帕至0.67兆帕之间。所有大体积充填RBCs的SS与其传统对应物相当。SF2显示出的SS显著低于Tetric N-Ceram（TN）和Tetric N-Ceram Bulk Fill（TNB）（p < 0.0083；采用Bonferroni校正的事后比较）。PS与SS之间观察到中等程度的正相关，Pearson相关系数为（r = 0.446，p = 0.013）。
PS和SS均取决于材料。新型大体积充填RBCs及其传统对应物的PS和SS之间存在中等程度的正相关。
