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盖髓、根管治疗等牙髓治疗中。虽然组织病理学研究证实氢氧化钙可诱导牙髓创面或根端形成硬组织，但氢氧化钙在牙髓矿化过程中的作用机制尚不清楚。本研究的目的是将氢氧化钙应用于体外培养的牙髓细胞和牙周韧带细胞，并观察氢氧化钙对牙髓硬组织形成的影响。牙齿裂开后，取出整个牙髓，并将其解剖成切面、颈部和根部。将每个切片进一步分成小块，在添加10%胎牛血清的改良Eagle‘s培养液中培养，以确定最适合实验的富含矿化细胞的部分。原代培养的增殖细胞形态多样，有多个细胞系。不同采收地点的细胞组成也不同。然而，在以后的传代中，并没有保留所有类型的细胞，建立一些纯化的细胞系的尝试以失败告终。由于正畸的原因，从拔除的牙齿中收集了人牙周膜细胞。取根中三分之一的小块，以与牛牙髓相同的方式进行培养。由于传代培养后的细胞失去了原代培养中的特征，本项目无法实现培养体系中体外矿化过程的模拟，需要进一步的测试来开发功能类似于牙髓或牙周韧带的细胞培养体系。在这种系统中，通过一个小管给药氢氧化钙，将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.