Laser-induced modulation of root dentin surface for growth factor release and enhanced stem cell response

Growth factor release from dentin and subsequent cellular response are critical in endodontic regeneration procedures. This study evaluated the effects of Nd: YAG (1064 nm) and diode lasers (980 nm, 635 nm) at varying energy densities on dentin morphology, Transforming Growth Factor-beta 1 release, and the biological response of stem cells to promote pulp regeneration in immature permanent teeth. Dentin blocks from extracted human teeth were treated with 1.5% NaOCl followed by pulsed Nd: YAG or continuous-wave diode lasers (average energy densities of 24, 60 and 120 J/cm²). Controls included 1.5% NaOCl/17% EDTA group and untreated samples. TGF-β1 release was quantified via ELISA. Cell viability (24-72 h), alkaline phosphatase activity (7 days), and surface morphology were assessed. One-way or two-way ANOVA with post-hoc tests were applied (p < 0.05). SEM analysis revealed that all lasers partially disrupted the smear layer and increased surface roughness, while SHED cells on laser-treated dentin showed flattened morphology with extended filopodia, indicating favorable cell-surface interactions. All laser groups significantly increased TGF-β1 release compared to the negative control (p < 0.05), with Nd: YAG at 60 J/cm² producing the highest levels, exceeding even the positive control (p < 0.05). Laser-treated specimens were non-cytotoxic and significantly increased ALP activity compared to the negative control (p < 0.001), with Nd: YAG at 60 J/cm² showing the highest activity, statistically higher than the NaOCl/EDTA positive control (p < 0.05). Low to moderate energy Nd: YAG and diode lasers enhanced TGF-β1 release and ALP activity without cytotoxicity, matching or exceeding EDTA treatment. Thus, laser-assisted dentin conditioning is a promising adjunctive strategy for regenerative endodontics.