不同年龄段牙髓组织比例及牙髓干细胞分布的实验研究

目的通过观察不同年龄段前磨牙及第三磨牙牙髓占牙齿的比例，及干细胞分布情况，评估牙齿组织工程l临床适宜的选材标本。方法临床收集不同年龄段因正畸或其他原因拔除的无龋坏、无牙周疾病等的健康前磨牙及第三磨牙，分别称重牙齿及牙髓并计算比例。扫描电镜观察牙髓表面形态。脱钙后病理切片观察．牙髓组织内成牙本质细胞层完整与否，观察细胞与纤维成分比例；阿尔新蓝一希尔红染色，偏振光显微镜观察有无双折射现象：免疫组化染色观察．间充质干细胞特异性标记物STRO-1以及成牙本质相关蛋白牙本质涎蛋白DSP的表达情况．评估牙髓干细胞在牙髓组织中的分布情况。结果随着年龄的增长．前磨牙及第三磨牙牙髓占牙齿比例逐渐缩小．11～20岁年龄段与31～40岁、41～50岁，以及50岁以上年龄段比较．有统计学差异。扫描电镜下可见摘除的牙髓组织类似树桩．有些区域比较平滑，有些区域表面有不规则突起。牙髓组织内存在双折射。STRO-1阳性表达细胞在牙髓组织中散在分布．在血管周围较密集。DSP表达则主要集中在牙本质区域及成牙本质细胞内，牙髓内仅有少量表达。结论随着年龄的增长．牙髓逐渐萎缩，牙髓干细胞的分布集中于血管周围．在牙髓组织内散在分布．未分化的牙髓干细胞不表达成牙本质相关蛋白DSP。

Experimental Study on Dental Pulp Tissue Proportion and Stem Cell Distribution of Dental Pulp Tissue in Different Age Groups

Objective To investigate the pulp/tooth ratio and distribution of stem cells of dental pulp tissue in premolars and third molars from different age groups and assess the selection of clinical specimens for dental tissue engineering. Methods Healthy premolars and third molars of different ages were collected during removal due to orthodontic or other reasons. Both the teeth and pulp tissues were weighed and dental pulp/tooth ratio were calculated. The surface morphology of the extracted dental pulp tissue was observed under SEM. After fixed and decalcified, premolars and third molars were embedded and cut for HE staining. Then the slides were observed under the microscope to check the integrity of odontoblast cell layer and the cell/fiber distribution. Alcian blue/Sims red staining was used and slides were observed under the polarized light microscope to check birefringence. Immunohistochemical staining was used to observe specific mesenchymal stem cell markers STRO-1 and dentin sialoprotein-DSP expression to assess the distribution of dental pulp stem cells in dental pulp tissue. Results The pulp/tooth ratio was gradually reduced with age. SEM showed the ＂stump-like＂ pulp tissue with relatively smooth in some regions and irregular protrusions in other regions. There were birefringence in the pulp tissue. STRO-1 positive cells were scattered in dental pulp tissue, and concentrated around blood vessels. DSP expression was mainly concentrated in the region of dentin and odontoblasts. Conclusion The pulp tissue shrinks with age. Dental pulp stem cells are scattered in the pulp tissue and distributed mainly around the blood vessels. Undifferentiated dental pulp stem cells do not express odontoblast-related.