The Effects of Matrix Trioxide Aggregate (MTA) on the Adhesion, Migration and Apoptosis of Dental Pulp Cells

Purpose: Matrix trioxide aggregate (MTA) has been used for direct pulp-capping as well as perforation repair due to its potent ability to induce hard tissue regeneration. Pulp exposure, usually caused by tooth fracture and carious tooth treatment, involves the physical damage of pulp extracellular matrix. Therefore, when cells invade the damaged space from surrounding tissue, the existence of an adhesive substrate to aid cell proliferation and differentiation of invading cells is the key factor influencing the prognosis of pulp-capping treatment. In this study, we examined the effects of MTA on the adhesion, proliferation and apoptosis of human dental pulp cells (hDPCs) by comparison with composite resin (CR) and glass ionomer cement (GIC).<br> Materials and methods: Ninety-six-well plates were coated with MTA, CR, GIC and fibronectin. Cells were suspended in serum-free medium and then seeded onto coated wells. After 1.5-hr incubation at 37°C, the wells were rinsed to remove non-adherent cells. The number of adherent cells was quantified using the Cell Titer Glo Luminescent Cell Viability Assay Kit. For proliferation assay, these cells were seeded onto MTA, CR and GIC and attached cells were quantified. After 1.5-hr incubation, serum-free medium was replaced with 10% serum medium and cells were cultured onto these substrates for 72 hrs. The ability to induce apoptosis was evaluated by caspase 3/7 activity.<br> Result: MTA facilitated the adhesion of hDPCs, while CR and GIC did not. However, the adhesive effect of MTA was much weaker than that of fibronectin. hDPCs could attach onto MTA but not CR or GIC, even 72 hrs after seeding, although the number of attached cells gradually decreased during the culture period. These observations suggest that MTA could be used as a substrate for the adhesion, but not a scaffold for the proliferation, of hDPCs. A drastic increase of caspase 3/7 activity was observed when hDPCs were cultured onto CR and GIC. In contrast, MTA did not induce it.<br> Conclusions: Compared with CR and GIC, MTA is a good substrate for hDPC adhesion. These differential adhesive effects may be explained by the differential abilities for inducing pro-apoptotic signals in hDPCs. However, the effect of MTA as a cell adhesion substrate was much weaker than that of fibronectin. More importantly, MTA was unable to induce the proliferation of hDPCs on it. Thus, the co-addition of MTA with other adhesive and migratory proteins such as fibronectin may induce better wound healing and pulp tissue regeneration in vivo.