Histological effects of chitosan, chitosan-carried hyaluronic acid, and photobiomodulation on palatal wound healing in rats: an in vivo study.

OBJECTIVES

To compare the histological effects of topical chitosan (CS), a hyaluronic acid-chitosan gel (HA/CS), and photobiomodulation (PBM) on palatal wound healing in rats.

METHODS

Sixty male Wistar rats were randomized to control, CS, HA/CS, or PBM groups (n = 15/group). Standardized 5-mm full-thickness palatal wounds were created. Gels were applied three times daily; PBM (660 nm, 150 mW, 4.2 J/cm², 14 s) was administered on days 0, 1, 3, 5, 7, 10, and 13. Five independent animals/group were assessed on days 3, 7, and 14. The animal was the experimental unit, and re-epithelialization was the prespecified primary outcome. Ordinal scores were compared at each endpoint using Kruskal-Wallis and Bonferroni-adjusted Dunn tests.

RESULTS

HA/CS had higher re-epithelialization scores than control on days 3 (adjusted p = 0.003) and 7 (adjusted p = 0.024), and than PBM on day 3 (adjusted p = 0.015). PBM exceeded control on day 7 (adjusted p = 0.024). All day-14 animals had the maximum epithelial score. HA/CS had higher fibroblast scores than control on day 3; all interventions had higher fibroblast and angiogenesis scores than control on days 7 and 14. Collagen scores exceeded control with CS and HA/CS on day 3 and HA/CS on days 7 and 14.

CONCLUSIONS

The tested HA/CS formulation showed favorable early epithelial and selected stromal findings. Day-14 epithelial scores showed a ceiling effect. HA-specific effects and HA-CS synergy cannot be established.