Correction of metal artefacts around orthodontic mini-implants – a micro-CT study in the rat tail model

Abstract Micro-CT enables volumetric analysis of peri-implant tissue, but grey value alterations due to metal artefacts can impair analyses. This study aimed to assess to which extent peri-implant grey values are affected by metal artefacts at increasing distance to the implant, and whether mathemat...

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Main Authors: Robert Kerberger, Giulia Brunello, Nicole Rauch, Dieter Drescher, Bert van Rietbergen, Kathrin Becker
Format: Article
Language:English
Published: Nature Portfolio 2025-04-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-93411-9
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author Robert Kerberger
Giulia Brunello
Nicole Rauch
Dieter Drescher
Bert van Rietbergen
Kathrin Becker
author_facet Robert Kerberger
Giulia Brunello
Nicole Rauch
Dieter Drescher
Bert van Rietbergen
Kathrin Becker
author_sort Robert Kerberger
collection DOAJ
description Abstract Micro-CT enables volumetric analysis of peri-implant tissue, but grey value alterations due to metal artefacts can impair analyses. This study aimed to assess to which extent peri-implant grey values are affected by metal artefacts at increasing distance to the implant, and whether mathematical correction is possible. In nine rats, two Ti6Al4V orthodontic mini-implants (OMIs), 0.8 mm in diameter and 3.0 mm in length, were placed in a single tail vertebra. Micro-CT scans were performed before (T0) and after (T1) careful removal of the OMIs. Consecutive micro-CT scans were registered and differences in local grey values were computed at increasing distance to the implant (10.4 μm to 405.6 μm). Correction coefficient (CC) computation was performed using a smoothing spline fit, with the distance to the implant and the grey value difference as independent and dependent variable, respectively. To validate the effectiveness of the CC, the amount of calcified bone volume per total volume (BV/TV) was assessed within a standardized volume of interest (VOI) reaching up to 1 mm around the OMIs before and after the application of CC, and the T1-T0 differences between corrected and uncorrected scans were compared using the Wilcoxon signed-rank test. The grey value difference between uncorrected T0 and T1 scans was low in proximity to the implant (32.7%±6.11%) and improved at a distance of at least 100 μm (93.4%±4.46%). CC computation revealed a satisfactory fit (R2 = 0.989, RMSE = 0.031) and the difference in grey values was significantly lower after correction (p < 0.001). Most VOIs showed significant improvement, though overcorrection was observed in a few cases. Within the limitations of the study, metal artefacts decreased with increasing distance to the OMIs, and significant improvement was possible using the CC.
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spelling doaj-art-d72b42790d3149ce82d40c6e0c0dbef02025-08-20T03:07:40ZengNature PortfolioScientific Reports2045-23222025-04-0115111110.1038/s41598-025-93411-9Correction of metal artefacts around orthodontic mini-implants – a micro-CT study in the rat tail modelRobert Kerberger0Giulia Brunello1Nicole Rauch2Dieter Drescher3Bert van Rietbergen4Kathrin Becker5Department of Orthodontics and Dentofacial Orthopaedics, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu BerlinDepartment of Orthodontics and Dentofacial Orthopaedics, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu BerlinDepartment of Oral Surgery, University Hospital DüsseldorfDepartment of Orthodontics, University Hospital DüsseldorfOrthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of TechnologyDepartment of Orthodontics and Dentofacial Orthopaedics, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu BerlinAbstract Micro-CT enables volumetric analysis of peri-implant tissue, but grey value alterations due to metal artefacts can impair analyses. This study aimed to assess to which extent peri-implant grey values are affected by metal artefacts at increasing distance to the implant, and whether mathematical correction is possible. In nine rats, two Ti6Al4V orthodontic mini-implants (OMIs), 0.8 mm in diameter and 3.0 mm in length, were placed in a single tail vertebra. Micro-CT scans were performed before (T0) and after (T1) careful removal of the OMIs. Consecutive micro-CT scans were registered and differences in local grey values were computed at increasing distance to the implant (10.4 μm to 405.6 μm). Correction coefficient (CC) computation was performed using a smoothing spline fit, with the distance to the implant and the grey value difference as independent and dependent variable, respectively. To validate the effectiveness of the CC, the amount of calcified bone volume per total volume (BV/TV) was assessed within a standardized volume of interest (VOI) reaching up to 1 mm around the OMIs before and after the application of CC, and the T1-T0 differences between corrected and uncorrected scans were compared using the Wilcoxon signed-rank test. The grey value difference between uncorrected T0 and T1 scans was low in proximity to the implant (32.7%±6.11%) and improved at a distance of at least 100 μm (93.4%±4.46%). CC computation revealed a satisfactory fit (R2 = 0.989, RMSE = 0.031) and the difference in grey values was significantly lower after correction (p < 0.001). Most VOIs showed significant improvement, though overcorrection was observed in a few cases. Within the limitations of the study, metal artefacts decreased with increasing distance to the OMIs, and significant improvement was possible using the CC.https://doi.org/10.1038/s41598-025-93411-9Micro-CTPeri-implant bonePeri-implant artefactsMetal artefact correctionBone morphometryRat tail model
spellingShingle Robert Kerberger
Giulia Brunello
Nicole Rauch
Dieter Drescher
Bert van Rietbergen
Kathrin Becker
Correction of metal artefacts around orthodontic mini-implants – a micro-CT study in the rat tail model
Scientific Reports
Micro-CT
Peri-implant bone
Peri-implant artefacts
Metal artefact correction
Bone morphometry
Rat tail model
title Correction of metal artefacts around orthodontic mini-implants – a micro-CT study in the rat tail model
title_full Correction of metal artefacts around orthodontic mini-implants – a micro-CT study in the rat tail model
title_fullStr Correction of metal artefacts around orthodontic mini-implants – a micro-CT study in the rat tail model
title_full_unstemmed Correction of metal artefacts around orthodontic mini-implants – a micro-CT study in the rat tail model
title_short Correction of metal artefacts around orthodontic mini-implants – a micro-CT study in the rat tail model
title_sort correction of metal artefacts around orthodontic mini implants a micro ct study in the rat tail model
topic Micro-CT
Peri-implant bone
Peri-implant artefacts
Metal artefact correction
Bone morphometry
Rat tail model
url https://doi.org/10.1038/s41598-025-93411-9
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