中文摘要：

目的 研究3种基底材料的吸水膨胀性,探讨其在潮湿环境下的尺寸稳定性.方法 将牙本质、自凝塑料及光固化树脂三种基底材料分别制成8mm×8mm×2mm的立方体片.每种材料6个试件,浸泡于蒸馏水中,并测量浸泡前和浸泡7d、28 d、3个月后的体积,分别计算浸泡前后各时间点材料的吸水膨胀率,采用SPSS13.0软件对数据进行单因素方差分析.结果 经过7d、28 d、3个月浸泡后,牙本质体积膨胀率分别为1.08％、3.24％、3.65％;自凝塑料为2.93％、5.81％、7.69％;光固化树脂为1.65％、4.63％、6.13％.每个时期的吸水膨胀率从大到小依次为自凝塑料、光固化树脂和牙本质.28 d时三种材料与其各自7d时的体积膨胀率相比均有明显增高（P＜0.05）,而各组材料在其28 d和3个月时的体积变化率相比均无统计学差异（P＞0.05）.3个月时三种材料均已基本达到体积稳定.结论 牙本质的吸水膨胀率最小,在全瓷材料的实验研究中把新鲜离体牙作为其基底材料可能是较好的选择.

英文摘要：

Objective The study was to investigate the volume expansion of human dentin, self-curing polymethyl methacrylate（PMMA） resin and light-cured resin resulting from water sorption and evaluate their di- mension stability in wet environment. Methods Three materials were tested in the study： human dentin, self- curing PMMA resin and light-cured resin. Six specimens with the size of 8mm × 8mm × 2mm of each material were prepared. The volume of the specimen was measured before it was immersed in water and after 7 days＇, 28 days＇ and 3 months＇ water storages at 37℃ respectively. The percentage of volume expansion of the specimen was calculated and the data were analyzed with one-way ANOVA analysis by SPSS 13.0 software. Results The per- centages of volume expansion after 7 days, 28 days and 3 months of water storage were 1.08%, 3.24% and 3.65% respectively for the human dentin; 2.93%, 5.81% and 7.69% for the PMMA, and 1.65%, 4.63% and 6.13% for the light-cured resin. The percentages of volume expansion in descending order were： the PMMA resin, the light-cured resin and the human dentin in each period. For all of the three materials, there was significant difference （P 〈0.05） between the percentage of volume expansion after 7 days＇ water storage and that after 28 days＇ water storage. While there was no significant difference between the percentage of volume expansion after 28 days＇ water storage and that after 3 months＇ water storage （P 〉0.05） .The dimensions of the three materials tended to be stable after three months＇ storage. Conclusion The percentage of volume expansion of human dentin was the minimum and it may be a better choice to select the freshly extracted teeth as the base material in the study of all-ceramic materials.