Laser-induced modulation of root dentin surface for growth factor release and enhanced stem cell response.
Mokhtari Hadi H, Fakhri Elaheh E, Sadrhaghighi AmirHouman A, Eslami Hosein H et al.
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.