Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Nov 14;8(1):16788.
doi: 10.1038/s41598-018-34907-5.

Macrophages mediate corticotomy-accelerated orthodontic tooth movement

Yan Wang  1   2   3 , Hanwen Zhang  4 , Wen Sun  1 , Siyu Wang  1   2 , Shuting Zhang  1   2 , Linlin Zhu  1   2 , Yali Chen  1   2 , Lizhe Xie  1 , Zongyang Sun  5 , Bin Yan  6   7
Affiliations

Macrophages mediate corticotomy-accelerated orthodontic tooth movement

Yan Wang et al. Sci Rep. .

Abstract

Clinical evidence has suggested that surgical corticotomy of the alveolar bone can accelerate local orthodontic tooth movement (OTM), but the underlying cell and molecular mechanisms remain largely unclear. The present study examined the role of macrophages played in corticotomy-assisted OTM. Orthodontic nickel-titanium springs were applied to the left maxillary first molars of rats or mice to induce OTM with or without corticotomy. Corticotomy enhanced OTM distance by accelerating movement through induction of local osteoclastogenesis and macrophage infiltration during OTM. Further analysis showed that macrophages were polarized toward an M1-like phenotype immediately after corticotomy and then switched to an M2-like phenotype during OTM. The microenvironment of corticotomy induced macrophage infiltration and polarization through the production of TNF-α. More importantly, the amount of OTM induced by corticotomy was significantly decreased after mice were depleted of monocyte/macrophages by injection of liposome-encapsulated clodronate. Further experiments by incubating cultured macrophages with fresh tissue suspension obtained from post-corticotomy gingiva switched the cells to an M1 phenotype through activation of the nuclear factor-κB (NF-κB) signaling pathway, and to an M2 phenotype through activation of the JAK/STAT3 signaling pathway. Our results suggest that corticotomy induces macrophage polarization first by activating the NF-κB signaling pathway and later by activating the JAK/STAT3 signaling pathway, and that these processes contribute to OTM by triggering production of inflammatory cytokines and osteoclastogenesis.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Corticotomy increased the rate of OTM. Rats (male, 220–240 g, 8 wk old) (A–E) were divided into tooth movement only (TM) or corticotomy-assisted tooth movement (CO + TM). The rats (A–E) in each group were sacrificed at 3, 5, 7, 14, 21, 28 and 42 days for tissue collection and assessments. (A) Representative micro–computed tomography images and combined three-dimensional models established by mimics in rats from day 0 to day 42. Arrows represent the direction of force application. N = 5 or 6. Blue: TM; Red: CO + TM. (B) Semiquantification of orthodontic tooth movement (OTM) distance in rats from day 0 to day 42 (n = 5 or 6). (C) Average rate of orthodontic tooth movement (OTM) in rats on days 5 and 21 (n = 5 or 6). (D) The volume of interest (VOI) surrounding the left maxillary first molar was demarcated using the following boundaries: the mesial-most edge of the first molar, the mesial-most edge of the second molar, the lateral-most edge of buccal and palatal alveolar cortical plates, the apical edge of the first molar root tip, and the coronal-most edge of the first molar root furcation. (E) The bone mineral density (BMD) of the VOI was measured to assess the mineralization that occurred during tooth movement with or without corticotomy. Micro-computed tomography was performed from day 3 to day 42 after force was applied. *p < 0.05, **p < 0.01, ***p < 0.001 vs TM group. NS, not significant.
Figure 2
Figure 2
Corticotomy induced osteoclastogenesis and macrophage infiltration during OTM. Rats (male, 220–240 g, 8 wk old) (A–J) were divided into tooth movement only (TM) or corticotomy-assisted tooth movement (CO + TM). The rats (A–I) in each group were sacrificed at 3, 5, 7, 14, 21, 28 and 42 days or specified in each group for tissue collection and assessments. (A) Representative tartrate-resistant acid phosphatase (TRAP) staining of the compression side of the distobuccal roots. Large boxed areas show high-magnification views of the small boxed areas. The arrow represents the direction of force application. Scale bar: 50 μm. The surface of osteoclasts relative to the bone surface (Oc.S/B.S, %) (B) and the number of osteoclasts per mm of bone parameter (N.Oc/B.Pm, #/mm) (C) were determined in the dental alveolar bone of TRAP-stained mandibles. Data are the mean ± SD from five fields. (D,F) Representative images of the compression side of distobuccal roots immunostained against CD11b (D) or CD68 (F) after force was applied for 5, 7, 14, 21, 28 or 42 days. Large boxed areas show high-magnification views of the small boxed areas. The arrow represents the direction of force application. Scale bar: 50 μm. CD11b-positive areas (E) and CD68-positive areas (G) were calculated as a percentage of the total tissue area on the compression side for each subject. Real-time PCR analysis of CD11b (H) and CD68 (I) expression in gingiva after force was applied for 5 to 42 days with or without corticotomy surgery. Data for each gene were processed using the 2−ΔΔCt method and expressed relative to GAPDH. Data are mean ± SD of at least three independent experiments. (J) Flow cytometry analysis of the proportions of CD11b-positive cells in gingiva of rats after force was applied for 5 to 21 days with or without corticotomy surgery. Data are mean ± SD from three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 vs TM group. NS, not significant.
Figure 3
Figure 3
Corticotomy induced macrophage polarization at different stages of OTM. Rats (male, 220–240 g, 8 wk old) (A–G) were divided into tooth movement only (TM) or corticotomy-assisted tooth movement (CO + TM). The rats (A–L) in each group were sacrificed at 5, 7, 14, 21, 28 and 42 days or specified in each group for tissue collection and assessments. (A,B) Representative images on the compression side of distobuccal roots immunostained against CD86 (A) or CD163 (B) after force was applied for 5, 7, 14 or 21 days. Large boxed areas show high-magnification views of the small boxed areas. The arrow represents the direction of force application. Scale bar: 50 μm. CD86-positive areas (C) and CD163-positive areas (D) were calculated as a percentage of the total tissue area on the compression side. Flow cytometry analysis of proportions of CD11b+CD86+ cells (E) and CD11b+CD163+ cells (F) in gingiva of rats after force was applied for 5 to 21 days with or without corticotomy surgery. Data are mean ± SD of three independent experiments. Real-time PCR analysis of CD86 (G) and CD163 (H) expression levels in gingiva tissues of rats after force was applied for 5 to 42 days with or without corticotomy surgery. Real-time PCR analysis of expression levels of the M1 phenotype-related genes IL-1β (I) and TNF-α (J), as well as levels of the M2 phenotype-related genes Arg-1 (K) and CD206 (L) in gingiva tissues of rats after force was applied for 5, 14 and 21 days with or without corticotomy surgery. Data for each gene were processed using the 2−ΔΔCt method and expressed relative to GAPDH. Data are mean ± SD of at least three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 vs TM group. NS, not significant.
Figure 4
Figure 4
Corticotomy-induced OTM was decreased by macrophage depletion. Mice (male, 25–28 g, 8 wk old) (A–C) were divided into tooth movement only (TM) or corticotomy-assisted tooth movement (CO + TM). The mice (A–J) were sacrificed at 5, 7, 14 and 21 days. (A) Flow cytometry analysis of the proportions of F4/80-positive cells in gingiva of mice after force was applied for 5 to 21 days with or without corticotomy surgery. (B,C) Flow cytometry analysis of proportions of CD86-positive cells (B) and CD206-positive cells (C) in the F4/80-positive population in gingiva of mice after force was applied for 5 to 21 days with or without corticotomy surgery. Data are mean ± SD of three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001 vs TM group. NS, not significant. Both groups of TM and CO + TM mice were also injected intravenously with liposome-encapsulated clodronate (200 μL/mouse); these animals were labeled as the TM + LEC group and CO + TM + LEC group (D–J). Animals in the control group were intravenously injected with phosphate-buffered saline (200 μL/mouse) every 4 days starting 1 day before force application until 21 days after force application. Flow cytometry analysis of proportions of CD11b- and F4/80-positive cells in spleen (D) and gingiva (E) of mice after clodronate injection. (F,G) Flow cytometry analysis of proportions of CD86-positive cells (F) and CD206-positive cells (G) in the CD11b- and F4/80-positive population in gingiva of mice after clodronate injection. Data are mean ± SD of three independent experiments. ***p < 0.001, ****p < 0.0001 as indicated groups. Representative micro–computed tomography images (H) and semiquantification of OTM distance (I) in mice from day 0 to day 21 (n = 5 or 6). Arrows represent the direction of force application. ++++p < 0.0001 as CO + TM vs TM group. #p < 0.05, ###p < 0.001 as TM + LEC vs TM group. **p < 0.01, ****p < 0.0001 as CO + TM + LEC vs CO + TM group. (J) Average rate of orthodontic tooth movement (OTM) in mice on days 5 and 14 (n = 5 or 6). **p < 0.01, ***p < 0.001, ****p < 0.0001 as indicated groups.
Figure 5
Figure 5
Corticotomy induced macrophage polarization by activating NF-κB and JAK–STAT pathways. Bone marrow cells (BMCs) from 2-month-old mice were cultured for 7 days with conditioned medium from L929 cells (L929-CM) to generate bone marrow–derived macrophages (BMDMs). Mice (male, 25–28 g, 8 wk old) (A–H) were divided into tooth movement only (TM), corticotomy-assisted tooth movement (CO + TM) and blank with neither tooth movement nor corticotomy. Tissue suspension was prepared from fresh palatal gingiva after corticotomy had been applied for 5 to 21 days as described in Materials and Methods. Real-time PCR analysis of the expression of genes encoding TNF-α (A), IL-1β (B), Arg-1 (C) or CD206 (D) in BMDMs after 24-h incubation with fresh tissue suspension of palatal gingiva tissues. Data for each gene were processed using the 2−ΔΔCt method and expressed relative to GAPDH. Data are mean ± SD of at least three independent experiments. After incubation with fresh tissue suspension of palatal gingiva tissues, BMDMs were harvested and protein extracts were analyzed by Western blotting against p65 (E,F), phosphorylated STAT-3 (p-STAT3) and total STAT3 (T-STAT3) (G,H). Protein levels were calculated as a ratio to GAPDH and expressed relative to levels in the blank control. TM: tooth movement; CO + TM: tooth movement surgically assisted by corticotomy; Blank: blank group with no treatment. Data are mean ± SD of at least three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001 as indicated groups. NS, not significant.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Gil A.P.S., Haas O.L., Méndez-Manjón I., Masiá-Gridilla J., Valls-Ontañón A., Hernández-Alfaro F., Guijarro-Martínez R. Alveolar corticotomies for accelerated orthodontics: A systematic review. Journal of Cranio-Maxillofacial Surgery. 2018;46(3):438–445. doi: 10.1016/j.jcms.2017.12.030. - DOI - PubMed
    1. Al Makhmari SA, Kaklamanos EG, Athanasiou AE. Short-term and long-term effectiveness of powered toothbrushes in promoting periodontal health during orthodontic treatment: A systematic review and meta-analysis. American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics. 2017;152:753–766.e757. doi: 10.1016/j.ajodo.2017.09.003. - DOI - PubMed
    1. Lee YJ, Lee TY. External root resorption during orthodontic treatment in root-filled teeth and contralateral teeth with vital pulp: A clinical study of contributing factors. American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics. 2016;149:84–91. doi: 10.1016/j.ajodo.2015.06.027. - DOI - PubMed
    1. Owen KM, et al. Elevation of a full-thickness mucoperiosteal flap alone accelerates orthodontic tooth movement. American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics. 2017;152:49–57. doi: 10.1016/j.ajodo.2016.11.026. - DOI - PubMed
    1. Al-Naoum F, Hajeer MY, Al-Jundi A. Does alveolar corticotomy accelerate orthodontic tooth movement when retracting upper canines? A split-mouth design randomized controlled trial. Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons. 2014;72:1880–1889. doi: 10.1016/j.joms.2014.05.003. - DOI - PubMed

Publication types