数字化成型的金属修复体表面性状及其戴用时长对生物学效应影响的研究

With the promotion and application of digital technology in the dentistry, increasingly digital molding methods such as selective laser melting(SLM) and CAD/CAM appear in the molding methods of dental alloys in addition to the traditional lost wax casting process. So far the accumulation and metabolism of metal ions released from metallic dental prosthesis that processed by different molding methods still remains unknown.Our previous studies have proved that metallic ions released from dental casting alloys can accumulate in oral mucosa and peripheral blood, which might cause apoptosis-based cell death via the mitochondrial pathway and trigger the autophagic regulator. However, whether different molding methods affect the biocompatibility of dental alloys needs to be further studied . The present study aims to (1) observe the surface characteristics of the dental digitization molding alloys as well as the type and concentration of metal ions released from the cobalt-chromium alloys and commercial pure titanium processed by lost wax casting process, selective laser melting(SLM) and CAD/CAM ,and evaluate biological effects and mechanism by different concentration solution of single metal ions on dog gingival fibroblasts cells (2) establish a beagle canine maxillary mental plate model, and investigate the concentration and biological change of metal ions in the palatal mucosa, peripheral blood, liver and kidney with and without removal of the plate. The findings would extremely valuable in comparative analyzing the effect and outcome of the metal ions in the oral local region and the whole body by different dental digitization molding alloys as well as wearing duration, in order to provide an experimental evidence for alloys choosing of different molding methods in dental clinic.

金属修复体传统的制作方法为失蜡铸造法，如今选择性激光熔融和数字化切削等数字化成型方法也已广泛应用于临床。迄今不同成型方法的金属修复体金属离子在局部和全身蓄积和代谢情况仍知之甚少。前期研究发现铸造牙科合金可影响口腔粘膜、血中金属离子蓄积，并引起以凋亡为主的细胞死亡，激活自噬相关因子，但数字化成型方法是否影响金属离子析出情况与生物相容性还有待研究。为此，本项目拟：（1）研究不同数字化成型的牙科合金表面性状、对细胞的生物学效应及其机制（2）构建比格犬上颌金属支架修复模型，研究戴用及摘除后不同数字化成型的金属修复体后对犬粘膜、血清及肝肾中金属离子种类和浓度及生物学变化的影响。从而对比分析不同数字化成型的金属修复体表面性状及其戴用时长对金属离子在口腔局部与全身中的变化及转归，及其引起局部与全身病理变化的机制。此外，本项目的研究结果也将为临床诊疗过程中不同加工方式金属修复体的应用提供参考依据。

前期研究发现铸造牙科合金可影响口腔粘膜、血中金属离子蓄积，并引起以凋亡为主的细胞死亡，激活自噬相关因子，但数字化成型方法是否影响金属离子析出与生物相容性还有待研究。本课题通过扫描电镜、金相显微镜、能谱仪和质谱仪研究选择性激光熔融钴铬SLM Co-Cr和数字化切削纯钛CAD/CAM Ti表面性状及离子释放水平。SLM Co-Cr酸蚀后电镜下见晶胞细小致密，晶界分明，偶见晶间腐蚀，表面检出元素主要为Co、Cr、W、Mn、Nb，金相显微镜下呈卵石般紧密堆叠，大量二相粒子散布于晶界内部及边缘；而CAD/CAM Ti电镜下见少量散在点腐蚀，表面检出元素主要为Ti与O，金相显示出均一、有序排列的α-Ti相。两种金属在无血清浸提液中均有不同程度的离子析出，CAD/CAM Ti的离子析出水平显著低于SLM Co-Cr。通过构建三维口腔粘膜组织模型，评估两种材料对口腔粘膜细胞凋亡和自噬的影响，表明SLM Co-Cr引起三维模型显著的早期凋亡水平升高，但对晚期凋亡水平无显著影响。而CAD/CAM Ti组的凋亡水平则与对照组无统计学差异。同时，两种材料均引起了三维组织模型自噬水平升高，但两种材料间的差异无统计学意义。此外，本项目组成功构建比格犬金属支架修复模型，分别采用SLM CO-CR、CAD/CAM TI支架持续刺激比格犬腭粘膜6个月，检测各时间点犬腭粘膜、血液与肝肾中金属离子种类与浓度和生物学的变化。研究发现这两种材料释放的金属离子可在口腔粘膜、全血、血浆和毛发中发生一过性蓄积，高峰点分别为1个月、2个月、1个月和2周。SLM Co-Cr和CAD/CAM Ti都可诱导口腔粘膜的凋亡和组织病理学变化，且在1个月时影响最显著。然而这两种材料未引起口腔粘膜的自噬水平和肝肾中的金属离子及生物学作用的显著变化。.由于受到新冠肺炎疫情影响，目前根据前述得出的各组血清中TMC高峰期去除金属支架，检测各时间点比格犬腭粘膜、血清与肝肾中金属离子种类与浓度和生物学的变化情况这部分实验尚在进行中。争取通过以上研究揭示摘除金属修复体后，口腔局部组织、血液与肝肾等脏器中金属离子蓄积情况及生物学行为的改变。

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