The Prostacyclin Analog Iloprost Promotes Cementum Formation and Collagen Reattachment of Replanted Molars and Up-regulates Mineralization by Human Periodontal Ligament Cells

Abstract

Introduction: This study evaluated the use of the prostacyclin analog iloprost as a root surface treatment agent in promoting acellular cementum (AC) formation and collagen reattachment after tooth replantation in vivo. In addition, its effect on human periodontal ligament cell (hPDLC) mineralization was assessed in vitro.

Methods: First molars of 8-week-old Wistar rats were extracted. In 1 group, the root surfaces were treated with Hank's balanced salt solution (HBSS), and the other group's root surfaces were treated with 10^-6 mol/L iloprost before replantation. At day 30, maxillae were prepared for micro-computed tomographic imaging and histomorphometric analysis. The effect of iloprost on mineralization by hPDLCs was analyzed by mineralized nodule formation and quantitative polymerase chain reaction at 7 and 14 days.

Results: Micro-computed tomographic imaging demonstrated a significant higher bone volume in the iloprost groups, whereas the HBSS groups had extensive bone and root resorption. Histologic analysis revealed deposition of a thick AC layer along the root in the iloprost group with well-organized periodontal ligament fibers inserted into the cementum. The HBSS group demonstrated more osteoclasts than the iloprost group. In vitro, iloprost-treated hPDLCs had a significantly increased RUNX2, OSX, BSP, and ALP gene expression that coincided with an increased deposition of mineralized nodules. These effects were abrogated by a PGI₂ receptor inhibitor.

Conclusions: Our results revealed that iloprost promoted PDL regeneration in replanted molars. Furthermore, resorption of the roots was decreased, whereas AC deposition was stimulated. Iloprost-treatment increased hPDLC mineralization and was mediated by PGI2 receptor activation. These observations indicate that iloprost may be a promising root surface treatment agent.

Keywords: Acellular cementum regeneration; bone remodeling/regeneration; matrix mineralization; periodontal ligament; prostacyclin analog; tooth regeneration/transplantation.