10-MDP in dentin bonding: a novel role in pulp protection via modulation of dental pulp stem cell behavior

10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-containing adhesives applied to deep dentin cavities near the pulp have demonstrated clinical success without pulp capping. 10-MDP has been reported to exhibit cytotoxic effects on the pulp. However, within the dentin bonding interface, 10-MDP predominantly exists in the form of calcium salts. This study aimed to investigate whether 10-MDP calcium salts exert pulp-protective effects by modulating the biological behavior of dental pulp stem cells (DPSCs).

Tooth-on-a-chip models were fabricated to evaluate the effects of 10-MDP, HEMA, or their mixture on DPSCs cultured on dentin substrate. 10-MDP calcium salts were synthesized using CaCl₂ and 10-MDP to replicate those formed in dentin surface. The proliferation, migration, apoptosis, odontogenic differentiation, and matrix metalloproteinase (MMP) expression of DPSCs treated with 10-MDP calcium salts, as well as the reactive oxygen species (ROS) levels, mitochondrial morphology, and mitochondrial membrane potential, were determined.

DPSCs incubated with HEMA and 10-MDP mixture showed higher cell viability than when incubated with HEMA alone in tooth-on-a-chip models. 10-MDP calcium salts promoted DPSC proliferation, migration and odontogenic differentiation while suppressing MMP expression. Furthermore, 10-MDP calcium salts reduced ROS levels, maintained mitochondrial morphology and membrane potential in DPSCs, and did not affect apoptosis.

10-MDP calcium salts exerted beneficial effects on pulp by promoting the odontogenic differentiation, inhibiting the MMP expression, and maintaining mitochondrial dynamics of DPSCs.

The application of 10-MDP-containing adhesive has the potential to protect pulp for the formation of 10-MDP calcium salts.