Human oral microbiome interactions with magnesium implants

Magnesium (Mg)-based barrier membranes demonstrate significant potential as biomaterials for guided bone regeneration, thereby potentially broadening the scope of clinical applications. However, the interaction between Mg-based implants and the human oral microbiome remains poorly understood. This in situ human study investigated the bidirectional interactions between pure Mg and the human oral microbiome using a personalized oral device. The results demonstrated that Mg-bacteria interactions induce spatially heterogeneous corrosion layers characterized by biomineralized precipitates and organic-matrix integration. Dynamic salivary flow and biofilm-mediated diffusion barrier synergistically promoted uniform electrochemical degradation and suppressed localized pitting corrosion. Although pure Mg exhibited antimicrobial effects under in vitro conditions, its in vivo bacteriostatic effect was attenuated by salivary sequestration of Mg-based surface and biofilm maturation. This led to inter-individual variability in microbial colonization of the biomaterial. Also, Streptococcus spp. were the dominant colonizers, and this pattern was influenced by acquired pellicle and salivary flow. These findings elucidate the critical role of the human oral microbiome in modulating Mg corrosion pathways, providing insights for the rational design of Mg-based implants for dental applications.