Er:YAG Laser Conditioning of Biofilm‐Fouled Titanium Supports Osteoblast Adhesive Retention and Osteogenic Maturation: Stage‐Specific Adhesion‐ and Osteogenesis‐Related Transcriptomic Signatures

Objectives To evaluate whether erbium‐doped yttrium aluminum garnet (Er:YAG) laser conditioning of clinically derived supragingival biofilm‐fouled sandblasted, large‐grit, acid‐etched (SLA) titanium reduces residual biofilm, improves apparent wettability, and supports early osteoblast adhesive retention and osteogenic maturation. Methods Supragingival plaque biofilms were generated on SLA titanium discs after 48 h of intraoral splint wear and treated with an Er:YAG laser under saline irrigation. Surface morphology, roughness, wettability, and residual biofilm were assessed by scanning electron microscopy, atomic force microscopy, water contact angle measurement, live/dead fluorescence imaging, and 16S ribosomal RNA gene quantitative polymerase chain reaction. MC3T3‐E1 cells were evaluated for spreading, adhesive retention, adhesion‐ and osteogenesis‐related gene expression, alkaline phosphatase activity, and mineralized matrix deposition. RNA sequencing (RNA‐seq) was performed at 4 h after cell seeding without detachment challenge and on Day 7 under osteogenic induction. Results Er:YAG treatment preserved local SLA roughness, reduced residual biofilm burden, and improved apparent wettability. Laser conditioning enhanced early osteoblast spreading and adhesive retention, accompanied by time‐dependent changes in Fn1, Col1a1 , and Ptk2 . 4‐h RNA‐seq showed limited exploratory transcriptional differences without a coordinated up‐regulated focal adhesion or PI3K‐Akt signature. On Day 7 under osteogenic induction, laser‐treated biofilm‐fouled surfaces showed higher Runx2, Alpl , and Spp1 expression and broader enrichment of extracellular matrix‐receptor interaction, focal adhesion, regulation of actin cytoskeleton, Rap1/Ras, PI3K‐Akt, and mTOR‐related pathways. These surfaces also showed higher alkaline phosphatase activity on Day 7 and greater mineralized matrix deposition on Day 14. Conclusions Within this supragingival‐biofilm model, Er:YAG conditioning preserved local SLA roughness, reduced residual biofilm burden, improved apparent wettability, enhanced early osteoblast adhesive retention, and supported osteogenic maturation. Integrated qRT‐PCR and RNA‐seq findings indicated stage‐specific extracellular matrix‐, focal adhesion‐, cytoskeleton‐, and osteogenesis‐related responses, with PI3K‐Akt‐mTOR representing an exploratory component of the osteogenic‐phase network rather than a continuous or causal mechanism.