ABSTRACT
OBJECTIVE: This study aimed to investigate local and systemic effects of 2 concentrations of hyaluronic acid (HA) in rats. STUDY DESIGN: Fifty-four female Wistar rats were allocated to 3 treatment groups (25 mg/mL HA, 5.5 mg/mL HA, and 0.9% NaCl) and 3 subgroups of experimental time (7, 60, and 90 days). The rats were evaluated clinically and then killed. The tongue and right kidney were removed and stained by hematoxylin and eosin and picrosirius (tongue only). RESULTS: The clinical changes did not differ significantly between groups (Kruskal-Wallis: P > .05). Histologically there was significantly greater inflammatory response in the groups with HA compared with control (Kruskal-Wallis: P < .001). All kidney samples were normal. The 25 mg/mL HA group had higher collagen formation (analysis of variance mixed models: P = .016). CONCLUSIONS: HA causes moderate inflammatory reaction to 7 days and mild to 60 and 90 days, which is compatible with tissue repair, and a slightly increased collagen formation around the material was detected.