Light‐Emitting Diode Irradiation Promotes Donor Site Wound Healing of the Free Gingival Graft

Background: This study aims to evaluate the effect of light‐emitting diode (LED) light irradiation on the donor wound site of the free gingival graft. Methods: Rat gingival fibroblasts were chosen to assess the cellular activities and in vitro wound healing with 0 to 20 J/cm² LED light irradiation. Seventy‐two Sprague‐Dawley rats received daily 0, 10 (low‐dose LD]), or 20 (high‐dose HD]) J/cm² LED light irradiation on the opened palatal wound and were euthanized after 4 to 28 days; the healing pattern was assessed by histology, histochemistry for collagen deposition, and immunohistochemistry for tumor necrosis factor (TNF)‐α infiltration. The wound mRNA levels of heme oxygenase‐1 (HO‐1), TNF‐α, the receptor for advanced glycation end products, vascular endothelial growth factor, periostin, Type I collagen, and fibronectin were also evaluated. Results: Cellular viability and wound closure were significantly promoted, and cytotoxicity was inhibited significantly using 5 J/cm² LED light irradiation in vitro. The wound closure, reepithelialization, and collagen deposition were accelerated, and sequestrum formation and inflammatory cell and TNF‐α infiltration were significantly reduced in the LD group. HO‐1 and TNF‐α were significantly upregulated in the HD group, and most of the repair‐associated genes were significantly upregulated in both the LD and HD groups at day 7. Persistent RAGE upregulation was noted in both the LD and HD groups until day 14. Conclusion: LED light irradiation at 660 nm accelerated palatal wound healing, potentially via reducing reactive oxygen species production, facilitating angiogenesis, and promoting provisional matrix and wound reorganization.