MTA induces mineralization of human periodontal ligament cells

Objectives: The use of MTA has been expanded not only to endodontic applications, but to direct pulp capping, repair of root and furcation perforations, and root apexification technique. However, it has been unclear how MTA contributes to such healing. Therefore, we aimed to clarify the effects of MTA on human periodontal ligament fibroblasts (HPLF). Methods: Two HPLF populations were isolated and generated from the healthy premolars of a 22-year-old female, and a 14-year-old male who visited Kyushu University Hospital for extraction, and cells were maintained in 10%FBS/αMEM (Gibco-BRL, Grand Island, NY). All procedures were performed in compliance with the regulations of Kyushu University. White ProRoot MTA (DENTSPLY Tulsa Dental, Johnson City, TN) was mixed with sterile water according to the manufacturer's instructions, dispensed into plastic lids of 1.5ml micro-centrifuge tubes, and placed in a humidified incubator (37°C) for 24hr. MTA discs (φ9mm) were then rinsed with αMEM, placed in 24-well culture plates (1disk/well), and subjected to the cultures with HPLF. Results: SEM observation showed attachment of HPLF onto MTA discs within 24hr, but the cell proliferation was restricted until at least 7d. However, MTA up-regulated expression of bone-related genes osteopontin, osteocalcin, and collagen XII and down-regulated periostin expression in HPLF within 7d, and induced its mineralization around MTA after 4wk of culture. MTA furthermore, released Calcium into culture media time-dependently. CaCl₂ treatment also stimulated expression of osteopontin and osteocalcin, and decreased periostin expression in HPLF, but showed no effect on collagen XII expression. Conclusion: The present study indicated that MTA restricted proliferation of HPLF, but included the biocompatibility against HPLF and induced their osteogenic differentiation. These results suggest that MTA contributes to the tissue healing through the release of Calcium.