Macrophages mediate corticotomy-accelerated orthodontic tooth movement

Area of Science:

• Oral and Maxillofacial Surgery
• Orthodontics
• Immunology
• Cellular and Molecular Biology

Background:

• Surgical corticotomy is known to accelerate orthodontic tooth movement (OTM).
• The precise cellular and molecular mechanisms driving corticotomy-assisted OTM are not fully understood.
• Macrophages are implicated in bone remodeling and inflammation, suggesting a potential role in OTM.

Purpose of the Study:

• To investigate the role of macrophages in corticotomy-assisted orthodontic tooth movement (OTM).
• To elucidate the molecular signaling pathways involved in macrophage recruitment and polarization post-corticotomy.
• To determine the impact of macrophage depletion on corticotomy-enhanced OTM.

Main Methods:

• Orthodontic springs applied to induce OTM in rats/mice, with and without corticotomy.
• Macrophage depletion using liposome-encapsulated clodronate.
• Analysis of macrophage polarization (M1/M2 phenotypes) and signaling pathways (NF-κB, JAK/STAT3) via in vitro co-culture experiments.

Main Results:

• Corticotomy significantly enhanced OTM distance by inducing osteoclastogenesis and macrophage infiltration.
• Macrophages polarized from an M1 to an M2 phenotype during OTM, influenced by TNF-α.
• Depletion of macrophages markedly reduced corticotomy-enhanced OTM, confirming their critical role.

Conclusions:

• Corticotomy promotes OTM by orchestrating macrophage infiltration and polarization.
• Macrophage polarization involves sequential activation of NF-κB (M1) and JAK/STAT3 (M2) signaling pathways.
• These macrophage-mediated processes contribute to OTM by stimulating inflammatory cytokines and osteoclastogenesis.