The healing effect of calcium hydroxide on pulp and periodontal tissue-a study on cell behavior

氢氧化钙已广泛应用于根管治疗、盖髓术等。尽管组织病理学证实氢氧化钙可诱导牙髓创面或根端硬组织形成，但氢氧化钙在矿化过程中的作用机制尚不清楚。本研究的目的是通过将氢氧化钙应用于从小牛下切牙收集的牙髓细胞或牙周膜细胞的培养中来产生体外矿化，然后研究氢氧化钙对体内硬组织形成的影响。在使牙齿破裂后，将整个牙髓取出并解剖成切部、颈部和根部切片。将每个切片进一步分成小块，并在补充有10%胎牛血清的改良Eagle培养基中培养，以确定富含能够矿化的细胞的最适合实验的部分。原代培养中增殖的细胞表现出不同的形态，表明有几种细胞系。收获部位的细胞组成也存在差异。然而，在以后的传代中，并不是所有类型的细胞都被保留下来，并且试图建立一些纯化的细胞系的尝试以失败告终。以与牛牙髓相同的方式培养来自根的中三分之一的小块。由于后期传代培养的细胞失去了原代培养的特征，本项目无法实现体外培养体系的矿化过程模拟，需要进一步的试验来开发类似于牙髓或牙周膜功能的细胞培养体系。在该系统中通过小管给药氢氧化钙可探讨其在矿化中的作用。

Calcium hydroxide has been widely used in endodontic therapy such as pulp capping and root canal treatment. Although it is histopathologically demonstrated that calcium hydroxide induces the formation of hard tissue at pulp wound surface or root end, the mechanism of calcium hydroxide activity in the mineralization process is yet unclear. The purpose of this study was to generate in vitro mineralization by applying calcium hydroxide to cells in culture collected from either dental pulp or periodontal ligament, and then to figure out the effect of calcium hydroxide on hard tissue formation in vivo.The dental pulp cells were obtained from calf lower incisors. After cracking the teeth, the whole pulp was removed and dissected into incisal, cervical and radicular sections. Each section was further divided into small pieces and cultured in modified Eagle's medium supplemented with 10% fetal bovine serum to determine the most suitable portion for the experiment that is rich with cells capable of mineralization. The proliferated cells in the primary culture showed various forms indicating several cell lines. Also there was a difference in the cell composition by the harvest site. However in later passages, not all type of the cells was kept and the attempt to establish some purified cell lines ended in failure.Human periodontal ligament cells were collected from extracted teeth due to orthodontic reasons. Small pieces from the mid-third of the roots were cultured in the same manner as the bovine dental pulp. As the cells in later subcultures lost the features seen in the primary culture, simulation of in vitro mineralization process in culture system could not be achieved in this project.Further tests will be required to develop a cell-culture system similar to those seen in dental pulp or periodontal ligament in function. Administration of calcium hydroxide through a small tube in such system would probe into its role in mineralization.