Effect of primary tooth root resorption on the isolation of dental pulp stem cells from primary teeth / 中国组织工程研究

ABSTRACT

BACKGROUND: Mesenchymal stem cells are derived from a variety of tissues, such as bone marrow, pulp, placenta, umbilical cord and adipose tissue. Mesenchymal stem cells from deciduous pulp have strong stemness and biological activity, no rejection, and strong immunoregulation, which are one of excellent cell sources for biotherapy. It is easy and suitable for large-scale production of mesenchymal stem cells from deciduous pulp, thereby laying a good foundation for the industrialization of dental pulp stem cells. OBJECTIVE: To investigate the effect of primary tooth root resorption on the isolation and expansion of dental pulp stem cells, in order to further determine the proper period for tooth extraction for pulp stem cell isolation. METHODS: Totally 173 primary teeth from 173 pupils aged 7-9 years were extracted for the isolation and expansion of dental pulp stem cells. Before tooth extraction, we took X-ray periapical film or orthopantomography of the primary teeth, in accordance with the World Health Organization (WHO) professional inspection standard. Root resorption in primary teeth could be divided into five kinds root resorption 1/3, root resorption 1/2, root resorption 2/3, complete root resorption, and natural loss of primary teeth. Collected teeth after tooth extraction were placed into a medium within 7 seconds, and stored at in a refrigerator of 2-4 ℃. Then, the teeth were sent to the Oral Stem Cell Bank in Beijing within 24 hours by a professional cold-chain logistics for the isolation, expansion and preservation of dental pulp stem cells. Statistical analysis of the test results was performed. RESULTS AND CONCLUSION: For 32 primary teeth with root resorption 1/3, dental pulp stem cells were successfully extracted from 30 teeth, with a success rate of 94%, and ectopic eruption of permanent teeth was found in 12 cases, with an average eruption time of (2.19±0.18) months. For 35 primary teeth with root resorption 1/2, dental pulp stem cells were successfully extracted from 32 teeth, with a success rate of 92%, and ectopic eruption of permanent teeth was found in 11 cases, with an average eruption time of (1.89±0.13) months. For 59 primary teeth with root resorption 2/3, dental pulp stem cells were successfully extracted from 54 teeth, with a success rate of 92%, and ectopic eruption of permanent teeth was found in 8 cases, with an average eruption time of (1.42±0.12) months. For 37 primary teeth with complete root resorption (the bottom of the pulp was intact), dental pulp stem cells were successfully extracted from 34 teeth, with a success rate of 92%, and ectopic eruption of permanent teeth was found in 2 cases, with an average eruption time of (1.03±0.15) months. For 10 naturally exfoliated primary teeth, dental pulp stem cells were not extracted, and ectopic eruption of permanent teeth was found in 4 cases, with an average eruption time of (0.65±0.23) months. To conclude, the primary teeth naturally exfoliated have no dental pulp with no stem cells; the success rate of extraction is relatively high in primary teeth that have mobility I-II, root resorption 2/3 or complete root resorption but with the complete bottom of the pulp. Moreover, it has no effect on permanent tooth eruption, and it is the best time for collection of primary teeth.