Growth factor release from dentine matrix by pulp capping agents promote pulp tissue repair-associated events

Aim: To characterise growth factor release from dentine by pulp capping agents and to determine the effects of liberated dentine extracellular matrix (dECM) components on pulp cells in the key wound healing processes of migration and cell growth.

Methodology: Powdered human dentine was exposed to solutions of calcium hydroxide, white and grey Mineral Trioxide Aggregate (MTA) (ProRoot, (Dentsply Tulsa, Tulsa, OK, USA) over 14 days. The solubilised dECM components were dialysed and lyophilised and characterised using multiplex quantitative ELISA. Following dECM component extraction dentine was analysed using Fourier transform infrared spectroscopy (FTIR). Primary rat dental pulp cells (RDPCs) were exposed to dECM components (0.1 - 100 μg/mL) released by calcium hydroxide, white and grey MTA and cell growth and chemotactic responses were assessed. Statistical differences between the experimental and control groups were determined using one way ANOVA

Results: A broad range of growth factors, many not previously reported in dentine, were liberated by these pulp capping agents, including: SCF, M-CSF, GM-CSF, IGFBP-1, NGF, GDNF. White and grey MTA liberated more growth factors than calcium hydroxide. FTIR analysis of dentine exposed to pulp capping agents showed partial depletion of amide bands I, II and III, with little alteration in phosphate peaks compared to untreated dentine. dECM components released by white and grey MTA induced significantly more cell growth at low-to-moderate concentrations (p≤0.05) examined in this study, and significantly enhanced cell chemotaxis at all concentrations compared with controls (p≤0.05).

Conclusions: White and grey MTA solubilise a broad range of bioactive molecules from dentine, which can induce proliferation and chemotaxis in pulp cells.