Effects of different subgingival instrumentation on periodontitis-affected root surface properties and human gingival fibroblast responses: An in vitro study.

OBJECTIVE: To assess the effects of four subgingival instrumentation on the physicochemical properties of root surfaces and the subsequent adhesion of human gingival fibroblast (hGF), and to investigate hGF behavior under bacterial stimulation. DESIGN: Specimens were assigned to manual subgingival scaling (Group M), ultrasonic subgingival scaling (Group U), manual scaling combined with erythritol-based air polishing (Group ME), and ultrasonic scaling combined with erythritol-based air polishing (Group UE). Root surface morphology and roughness were examined via scanning electron microscopy (SEM) and white light interferometry (WLI). HGFs and Streptococcus mitis (S. mitis) were inoculated onto the root specimens from each group. The proliferation, adhesion, morphology, and spreading area of hGFs were evaluated using CCK-8, Ki67 immunofluorescence staining, laser scanning confocal microscopy (LSCM), and ImageJ analysis. S. mitis adhesion and viability were assessed by SEM and live/dead staining. Following S. mitis stimulation, hGF morphology and IL-1β secretion were evaluated by LSCM and ELISA, respectively. RESULTS: Root surfaces treated with erythritol-based air polishing exhibited lower roughness, reduced S. mitis adhesion and viability compared with scaling alone. HGFs cultured on air-polished root surfaces showed enhanced proliferation and spreading, as evidenced by increased Ki67 expression and larger spreading areas. Following S. mitis stimulation, Group UE demonstrated reduced bacterial adhesion and significantly lower IL-1β secretion. CONCLUSION: Erythritol-based subgingival air polishing combined with scaling exhibited lower root surface roughness, reduced S. mitis adhesion, and higher hGF attachment and proliferation compared with scaling alone, suggesting that it may create a more favorable root surface microenvironment.