Polydopamine-ECM Coated Titanium to Promote Cementogenesis on Dental Implants

Abstract

Titanium dental implants integrate directly with the surrounding bone, a phenomenon known as osseointegration. Unlike natural teeth, which are supported by periodontal ligaments (PDL), osseointegrated implants have weaker mechanical barriers against bacterial infiltration, heightened inflammation, reduced blood flow, and limited proprioception. Current methods to regenerate peri-implant ligaments involve costly, invasive, and time-intensive procedures. Polydopamine (PDA) is a biocompatible polymer known for its excellent adhesive properties. Periodontal ligament fibroblasts (PDLFs) play a pivotal role in periodontal tissue maintenance. Recent evidence suggests fibroblasts can induce a cementogenic phenotype by altering titanium surface topography and depositing cementum-like tissue. This study investigates PDA's efficacy in immobilizing ECM produced by PDLFs on titanium, hypothesizing enhanced cementogenesis on PDA-coated titanium surfaces. We assessed ECM immobilization efficiency, optimized decellularization protocols to retain ECM, and evaluated PDLF differentiation into a cementogenic phenotype. PDLFs cultured on PDA-coated titanium underwent decellularization after 10 days, followed by recellularization for 14 days. Cell interactions and gene expression were assessed using immunofluorescence microscopy, scanning electron microscopy (SEM), and RT-qPCR. Results demonstrated increased cell numbers on PDA-coated surfaces without affecting attachment or proliferation. Decellularization effectively removed cellular material, preserving key ECM proteins like Collagen I and CEMP-1. Gene expression analysis revealed significant upregulation of cementogenic markers (CP23, CAP, CEMP1, BSP) and downregulation of osteogenic markers (ALP, SOST), especially prominent on PDA-ECM surfaces. Our findings support that PDA-ECM-coated titanium surfaces promote cementogenic differentiation of PDLFs, potentially enabling peri-implant cementum-like tissue formation and periodontal ligament regeneration.