[Water sorption and hygroscopic changes of five core buildup composite resins].

Objective: To evaluate water sorption and hygroscopic dimensional changes of five core buildup composite resins, and to provide references for material modification on water sorption. Methods: Five commercial core buildup materials (group A: Smart Dentin Replacement(TM); group B: NanoFil; group C: ParaCore(TM); group D: LuxaCore Z; group E: EmbraceCore(TM) Resin Cement) were fabricated to disk-shaped specimens: (15.0±0.1) mm diameter, (2.0±0.1) mm thickness (n=10). Specimens were thoroughly irradiated with curing lights. The initial mass in air was recorded, and the initial mass in deionized water was recorded. Five specimens of each group were immersed in deionized water for 28 d. They were weighed as a function of different immersion time (1, 2, 3, 4, 5, 6, 7, 14, 28 d). The mass in air was recorded, and the displayed mass in deionized water was recorded. Archimedes' principle was applied to calculate the dimensional changes. The other five specimens of each group were stored in artificial saliva and were tested by the same methods. Results: All specimens gained weight and hygroscopic changes during 28 d immersion. When stored in deionized water, the apparent mass change of group A [(10.6±0.9) μg/mm(3)] and the dimensional change of group A [(0.39±0.10)%] were the lowest, while the mass change of group E [(48.0±0.2) μg/mm(3)] and the dimensional change of group E [(3.16±0.13)%] were the highest (P<0.05). In artificial saliva, the lowest apparent mass change was found in group A [(11.8±1.0) μg/mm(3)] while the highest change was found in group E [(47.4±3.5) μg/mm(3)] (P<0.05). The lowest dimensional change was found in group C [(0.37±0.09)%] and the highest was found in group E [(3.07±0.19)%] in artificial saliva (P<0.05). Conclusions: Water sorption and dimensional changes vary in immersion fluids with different osmotic pressure. Water sorption and dimensional changes of core buildup composite resins are highly correlated with test materials in both of the deionized water and artificial saliva.目的： 分析5种核树脂的吸湿变化，为改进核树脂的吸水性能提供参考。 方法： 将5种市售核树脂（Smart Dentin Replacement(TM)、NanoFil、ParaCore(TM)、LuxaCore Z、Embrace Core(TM) Resin Cement分为A、B、C、D、E组）制成直径为（15.0±0.1）mm、厚度为（2.0±0.1）mm的圆盘形试件各10个，充分固化后测量试件在空气中的初始质量和在去离子水中的初始质量。每组各5个试件浸泡于去离子水中28 d，分别测量浸泡1、2、3、4、5、6、7、14、28 d时试件在空气中的质量和在去离子水中的质量，计算得到各时间点各组试件在去离子水中的表观吸水量和体积变化量。每组5个试件浸泡于人工唾液中，重复上述方法得到试件在人工唾液中的表观吸水量和体积变化量。 结果： 所有试件浸泡28 d后均出现质量及体积增加。浸泡于去离子水中28 d，A组表观吸水量[（10.6±0.9）μg/mm(3)]和体积变化量[（0.39±0.10）%]均最小；E组表观吸水量[（48.0±0.2）μg/mm(3)]和体积变化量[（3.16±0.13）%]均最大，两组差异均有统计学意义（P<0.05）。浸泡于人工唾液中28 d，A组表观吸水量[（11.8±1.0）μg/mm(3)]最小，C组体积变化量[（0.37±0.09）%]最小；E组表观吸水量[（47.4±3.5）μg/mm(3)]和体积变化量[（3.07±0.19）%]均最大，组间差异均有统计学意义（P<0.05）。 结论： 5种核树脂浸泡于不同渗透压的溶剂中吸湿变化不同，但无论是浸泡于去离子水中还是人工唾液中，核树脂质量和体积的变化均与材料本身密切相关。.