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.