Fucoidan inhibits tooth movement by promoting restorative macrophage polarization through the STAT3 pathway

Retention after treatment and effective anchorage control are two essential factors in orthodontics. Our study aimed to explore the effects of fucoidan on orthodontic tooth movement (OTM) and the involvement of macrophages. We established a murine OTM model to test the effect of fucoidan administration. We found that mice injected with fucoidan had a deceleration in OTM and a higher bone mineral density. Moreover, fucoidan increased the proportion of F4/80⁺ CD206⁺ macrophages and promoted the messenger RNA expression of Arg-1, CD206, and IL-10 at both in vivo and in vitro levels. In addition, macrophages showed lower expression of TNF-α, IL-1β, and IL-6 and a decrease in F4/80⁺ CD11c⁺ cells. Mechanistically, the level of phosphorylated STAT3 was elevated in unpolarized and restorative macrophages after treatment with fucoidan. Taken together, our findings suggest that fucoidan treatment inhibits OTM and enhances the stability of teeth after movement by promoting restorative macrophages through the STAT3 pathway.