Photothermal Modulation of Gingival Fibroblasts via Polydopamine-Coated Zirconia: A Novel Approach for Promoting Peri-Implant Soft Tissue Integration

Achieving robust soft tissue integration around dental implants is crucial for long-term clinical success, as it forms a protective biological seal against bacterial invasion. However, the soft tissue attachment to implants is relatively deficient compared to natural teeth, particularly in the connective tissue region lacking sufficient gingival fibroblasts and perpendicular collagen fiber alignment. This study proposes an innovative strategy to enhance peri-implant soft tissue integration by modulating gingival fibroblast behavior via photothermal conversion. Zirconia surfaces were coated with polydopamine (PDA), a melanin-like polymer exhibiting near-infrared (NIR) absorption for photothermal conversion. Under NIR irradiation, the PDA coating enabled mild hyperthermia (42-43°C) on the zirconia surface through its photothermal effect. Remarkably, this mild photothermal stimulation significantly promoted human gingival fibroblast proliferation, adhesion, and collagen expression compared to unmodified zirconia in vitro. The upregulated collagen production was confirmed at both gene transcription and protein levels. By harnessing the photothermal properties of PDA coatings to modulate cellular behaviors beneficial for connective tissue formation, this pioneering approach provides a promising avenue to achieve improved soft tissue integration and long-term stability of dental implants. The findings highlight the innovative potential of combining biomaterial surface engineering with photothermal therapy concepts for applications in regenerative dentistry.