Effect of green propolis extracts on experimental aged gingival irritation in vivo and in vitro.

Objectives: Tooth bleaching has become one of the most frequently requested esthetic procedures in dental practice. A side effect of bleaching is gingival irritation. This study examined the efficacy of propolis to treat gingival irritation caused by bleaching in vivo and in vitro.

Methods: Gingival irritation was mimicked by a mild burn injury to oral mucosa in young (10 week old) and aged (18 month old) mice. Propolis ointment was immediately applied to the burn area. After 24 h, gingiva was collected to determine the efficacy of propolis by hematoxylin and eosin staining and real-time polymerase chain reaction (PCR).

Results: Topical application of propolis ointment reduced the infiltration of inflammatory cells at irritated sites and promoted the repair of the mucosal epithelium in young and aged mice. It also suppressed the expression of IL-1β and TNF-α and increased keratin 1 and 5 expression in the irritated gingiva. Propolis suppressed an increase in IL-1β and TNF-α upon stimulation with HO in young and SA-β-gal-expressing senescent human gingival fibroblasts (HGFs) cultures.

Conclusions: Propolis may be effective for mucosal repair in gingival irritation as it suppresses the expression of proinflammatory cytokines and promotes keratin expression.