The experimental findings of this study suggest that PFD may have a preventive and curative effect on harmful tracheal stenosis by inhibiting fibroblast proliferation and the fibrotic process and possibly through down‐regulating miR‐21‐5p and up‐regulating Smad7 and its mediated fibrotic and inflammatory responses. This evidence concerns the gene SMAD7 and polyostotic fibrous dysplasia.