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

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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.