Release of Growth Factors into Root Canal by Irrigations in Regenerative Endodontics

Introduction: The aim of this study was to investigate the release of growth factors into root canal space after the irrigation procedure of regenerative endodontic procedure. Methods: Sixty standardized root segments were prepared from extracted single root teeth. Nail varnish was applied to all surfaces except the root canal surface. Root segments were irrigated with 1.5% NaOCl + 17% EDTA, 2.5% NaOCl + 17% EDTA, 17% EDTA, or deionized water. The profile of growth factors that were released after irrigation was studied by growth factor array. Enzyme-linked immunosorbent assay was used to validate the release of transforming growth factor (TGF)-beta 1 and basic fibro-blast growth factor (bFGF) at 4 hours, 1 day, and 3 days after irrigation. The final concentrations were calculated on the basis of the root canal volume measured by cone-beam computed tomography. Dental pulp stem cell migration on growth factors released from root segments was measured by using Transwell assay. Results: Total of 11 of 41 growth factors were detected by growth factors array. Enzyme-linked immunosorbent assay showed that TGF-beta 1 was released in all irrigation groups. Compared with the group with 17% EDTA (6.92 +/- 4.49 ng/mL), the groups with 1.5% NaOCl + 17% EDTA and 2.5% NaOCl + 17% EDTA had significantly higher release of TGF-beta 1 (69.04 +/- 30.41 ng/mL and 59.26 +/- 3.37 ng/mL, respectively), with a peak release at day 1. The release of bFGF was detected at a low level in all groups (0 ng/ mL to 0.43 +/- 0.22 ng/mL). Migration assay showed the growth factors released from root segments induced dental pulp stem cell migration. Conclusions: The root segment model in present study simulated clinical scenario and indicated that the current irrigation protocol released a significant amount of TGF-beta 1 but not bFGF. The growth factors released into root canal space induced dental pulp stem cell migration.