Dissolution Products from MTA Release Novel Growth Factors from Dentine

Mineral trioxide aggregate (MTA) has been shown to induce profound wound healing responses to the injured dental pulp following its application, however the biological mechanism of action is yet to be fully explained. Solubilisation of ionic components from these materials by local tissue fluids may lead to the creation of an environment in which the natural regenerative characteristics of the dentine-pulp complex are harnessed.  Objectives:   To determine i) The range of growth factors released by ionic dissolution products of white and grey MTA from dentine and ii) the composition of dentine following exposure to these products. Methods: Dissected powdered sound human dentine was exposed to solutions of EDTA (control), the soluble products of white and grey ProRoot MTA (Tulsa Dentsply, USA) over a period of 14 days, the solubilised dentine extracellular matrix (dECM) components were exhaustively dialyzed against water and lyophilised. Multiplex quantitative ELISA was performed on dECM components extracted by all agents. Treated dentine was analysed using Fourier transform infrared spectroscopy (FTIR) and synchrotron-based small angle X-ray scattering (SAXS). Results: A broad range of growth factors was released from dentine by all agents including several growth factors which have not previously been reported such as neurotropic growth factors and colony stimulating factors. FTIR demonstrated differential removal of the phosphate phase of dentine by each agent, yet it appeared that SAXS showed minor differences in crystalline structure following treatment. Conclusion: Analysis of treated dentine shows that the solubilisation of dECM components causes differing disruption of the mineral phase of dentine. This data suggests that ionic dissolution products of MTA liberate potent growth factors that may trigger the events leading to pulpal repair and yields differing blends with each material.