Alveolar bone remodeling following orthodontic closure of missing mandibular first molar spaces: a CBCT-based morphometric study

Xinmeng Shi^#^{1

2}, Shuo Wang^#³, Liyuan Chen^{1

2}, Tianhao Wu^{1

2}, He Zhang^{1

2}, Hangbo Liu^{1

2}, Shiying Zhang^{1

2}, Chang Li^{1

2}, Yuxin Liu⁴, Zeyu Wang⁴, Yongping Ma⁵, Danqing He^{6

7}, Yan Liu^{8

9}

Affiliations

¹ Department of Orthodontics, Peking University School and Hospital of Stomatology, 100081, Beijing, China.
² National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & Beijing Key Laboratory of Intelligent Biomanufacturing and Regeneration for Craniofacial Tissues & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, 100081, Beijing, China.
³ Department of Stomatology, School of Clinical Medicine, Beijing Tsinghua Changgung Hospital, Tsinghua Medicine, Tsinghua University, 102218, Beijing, China.
⁴ College of Stomatology, North China University of Science and Technology, Hebei, 063210, Tangshan, China.
⁵ Department of Stomatology, The No.2 Hospital of Baoding, Hebei, 071000, Baoding, China.
⁶ Department of Orthodontics, Peking University School and Hospital of Stomatology, 100081, Beijing, China. hedanqing@bjmu.edu.cn.
⁷ National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & Beijing Key Laboratory of Intelligent Biomanufacturing and Regeneration for Craniofacial Tissues & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, 100081, Beijing, China. hedanqing@bjmu.edu.cn.
⁸ Department of Orthodontics, Peking University School and Hospital of Stomatology, 100081, Beijing, China. orthoyan@bjmu.edu.cn.
⁹ National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & Beijing Key Laboratory of Intelligent Biomanufacturing and Regeneration for Craniofacial Tissues & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, 100081, Beijing, China. orthoyan@bjmu.edu.cn.

^# Contributed equally.

PMID: 41838310
DOI: 10.1186/s40510-026-00615-4

Alveolar bone remodeling following orthodontic closure of missing mandibular first molar spaces: a CBCT-based morphometric study

Xinmeng Shi et al. Prog Orthod. 2026.

. 2026 Mar 16;27(1):11.

doi: 10.1186/s40510-026-00615-4.

Authors

Affiliations

¹ Department of Orthodontics, Peking University School and Hospital of Stomatology, 100081, Beijing, China.
² National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & Beijing Key Laboratory of Intelligent Biomanufacturing and Regeneration for Craniofacial Tissues & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, 100081, Beijing, China.
³ Department of Stomatology, School of Clinical Medicine, Beijing Tsinghua Changgung Hospital, Tsinghua Medicine, Tsinghua University, 102218, Beijing, China.
⁴ College of Stomatology, North China University of Science and Technology, Hebei, 063210, Tangshan, China.
⁵ Department of Stomatology, The No.2 Hospital of Baoding, Hebei, 071000, Baoding, China.
⁶ Department of Orthodontics, Peking University School and Hospital of Stomatology, 100081, Beijing, China. hedanqing@bjmu.edu.cn.
⁷ National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & Beijing Key Laboratory of Intelligent Biomanufacturing and Regeneration for Craniofacial Tissues & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, 100081, Beijing, China. hedanqing@bjmu.edu.cn.
⁸ Department of Orthodontics, Peking University School and Hospital of Stomatology, 100081, Beijing, China. orthoyan@bjmu.edu.cn.
⁹ National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & Beijing Key Laboratory of Intelligent Biomanufacturing and Regeneration for Craniofacial Tissues & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, 100081, Beijing, China. orthoyan@bjmu.edu.cn.

^# Contributed equally.

PMID: 41838310
DOI: 10.1186/s40510-026-00615-4

Abstract

Background: Loss of the mandibular first molar is a common and detrimental clinical issue that often leads to alveolar bone resorption in the edentulous area, complicating future prosthetic or orthodontic interventions. This study aimed to evaluate the efficacy of orthodontic closure of missing mandibular first molar spaces and its impact on alveolar bone remodeling.

Methods: Fifteen patients (17 sites) who underwent orthodontic closure of mandibular first molar spaces were retrospectively analyzed using cone-beam computed tomography (CBCT). The mesiodistal and buccolingual angulations of the mandibular second molars were measured in sagittal and coronal planes, respectively. The alveolar bone height was reflected by the distance from the cemento-enamel junction to the alveolar bone margin (CEJ-BM) at six sites on both the second premolars and second molars. Moreover, CBCT before and after orthodontic treatment were superimposed, and changes of alveolar bone width were obtained at three levels (3 mm, 6 mm and 9 mm below the cemento-enamel junction plane) and at three sections (mesial, middle and distal) within the edentulous region. Changes in alveolar bone volume within the extraction site were also calculated. Statistical analysis was performed by paired t-test.

Results: Orthodontic space closure significantly improved second molar angulations in both the mesiodistal (p < 0.001) and buccolingual (p < 0.01) angulations. In 57.35% of measured sites, alveolar bone height increased, with significant elevations at the distobuccal, distolingual, and mesiobuccal sites of the second molar (p < 0.05). Alveolar bone width significantly increased at 3 mm and 6 mm below the CEJ plane after orthodontic closure (p < 0.05), accompanied by a notable increase in bone volume (before treatment: 2922.0 ± 479.0 mm³, after treatment: 3003.8 ± 489.6 mm³, p < 0.05).

Conclusions: Orthodontic closure of mandibular first molar spaces promotes alveolar bone remodeling, including improvements in angulation, bone height, width, and volume. This approach offers a biologically advantageous alternative for managing molar loss, enhancing both function and long-term periodontal support.

Keywords: CBCT; alveolar bone remodeling; mandibular first molar loss; orthodontic space closure.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: This research has been performed in accordance with the Declaration of Helsinki and has been approved by the Institutional Review Board at Peking University Hospital of Stomatology (approval No. PKUSSIRB-2024105218). Informed consent in the study has been obtained from participants. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

References

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Alveolar bone remodeling following orthodontic closure of missing mandibular first molar spaces: a CBCT-based morphometric study

Affiliations

Alveolar bone remodeling following orthodontic closure of missing mandibular first molar spaces: a CBCT-based morphometric study

Authors

Affiliations

Abstract

Conflict of interest statement

References

MeSH terms

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