Three-dimensional retrospective analysis of root resorption and incisive canal changes following maxillary incisor retraction in class I and class II extraction cases: a comparison of clear aligners and fixed appliances

Abstract This study aimed to compare the effects of clear aligners and fixed appliances on root resorption, incisive canal (IC) morphology, and the spatial relationship between the maxillary central incisors (U1) and the IC following incisor retraction in dental/skeletal Class I and II extraction ca...

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Main Authors: Remsh Khaled Al-Rokhami, Karim Ahmed Sakran, Naseem Ali Al-Worafi, Maher Al-balaa, Ahmed Algahefi, Zhihua Li
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-10210-y
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author Remsh Khaled Al-Rokhami
Karim Ahmed Sakran
Naseem Ali Al-Worafi
Maher Al-balaa
Ahmed Algahefi
Zhihua Li
author_facet Remsh Khaled Al-Rokhami
Karim Ahmed Sakran
Naseem Ali Al-Worafi
Maher Al-balaa
Ahmed Algahefi
Zhihua Li
author_sort Remsh Khaled Al-Rokhami
collection DOAJ
description Abstract This study aimed to compare the effects of clear aligners and fixed appliances on root resorption, incisive canal (IC) morphology, and the spatial relationship between the maxillary central incisors (U1) and the IC following incisor retraction in dental/skeletal Class I and II extraction cases. Sixty-six adult patients (132 maxillary central incisors) with comparable baseline characteristics (based on the ABO Discrepancy Index) were retrospectively analyzed. Patients received either clear aligners (n = 33) or fixed appliances (n = 33) following first premolar extraction. Pre- and post-treatment CBCT measurements were recorded at three vertical reference planes (H1, H2, H3: 2 mm, 4 mm, and 6 mm above the labial cementoenamel junction), including IC width, cortical bone width (CBW), U1–IC distance, IC height, and U1 root length/width. Both groups showed reductions in IC width, CBW, and U1–IC distance, with greater changes in the fixed appliance group. U1–IC distance was significantly reduced in the fixed group at H1 (1.79 ± 0.76 mm vs. 1.24 ± 1.04 mm), H2 (1.78 ± 1.08 mm vs. 1.33 ± 0.86 mm), and H3 (1.61 ± 1.35 mm vs. 1.16 ± 0.90 mm) (P < 0.05). Root resorption was also significantly higher in the fixed group (1.81 ± 1.55 mm vs. 0.87 ± 0.77 mm, P < 0.001). Root–IC proximity patterns included 7.6% separation, 63.1% approximation, 15.9% contact, and 13.4% invasion, with contact and invasion more prevalent in the fixed group. Root resorption increased with IC proximity, peaking at 3.65 ± 1.97 mm in invasion cases. Regression analysis identified tooth movement, root length, and inter-root distance as predictors of U1–IC proximity, while root resorption was associated with treatment duration, U1 movement, IC height, and incisor inclination (U1–SN angle). These findings underscore the importance of individualized planning and appliance selection in cases requiring maximum anterior retraction to reduce the risk of root resorption and IC-related complications.
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spelling doaj-art-69402a6073df48b8a618a928d7ed1f912025-08-20T03:04:27ZengNature PortfolioScientific Reports2045-23222025-07-0115111110.1038/s41598-025-10210-yThree-dimensional retrospective analysis of root resorption and incisive canal changes following maxillary incisor retraction in class I and class II extraction cases: a comparison of clear aligners and fixed appliancesRemsh Khaled Al-Rokhami0Karim Ahmed Sakran1Naseem Ali Al-Worafi2Maher Al-balaa3Ahmed Algahefi4Zhihua Li5Department of Orthodontics, The Affiliated Stomatological Hospital of Jiangxi Medical College, Nanchang UniversityZhenjiang Stomatological HospitalDepartment of Orthodontics, School and Hospital of Stomatology, China Medical UniversityDepartment of Orthodontics, School and Hospital of Stomatology, Nanjing Medical UniversityDepartment of Orthodontics, The Affiliated Stomatological Hospital of Jiangxi Medical College, Nanchang UniversityDepartment of Orthodontics, The Affiliated Stomatological Hospital of Jiangxi Medical College, Nanchang UniversityAbstract This study aimed to compare the effects of clear aligners and fixed appliances on root resorption, incisive canal (IC) morphology, and the spatial relationship between the maxillary central incisors (U1) and the IC following incisor retraction in dental/skeletal Class I and II extraction cases. Sixty-six adult patients (132 maxillary central incisors) with comparable baseline characteristics (based on the ABO Discrepancy Index) were retrospectively analyzed. Patients received either clear aligners (n = 33) or fixed appliances (n = 33) following first premolar extraction. Pre- and post-treatment CBCT measurements were recorded at three vertical reference planes (H1, H2, H3: 2 mm, 4 mm, and 6 mm above the labial cementoenamel junction), including IC width, cortical bone width (CBW), U1–IC distance, IC height, and U1 root length/width. Both groups showed reductions in IC width, CBW, and U1–IC distance, with greater changes in the fixed appliance group. U1–IC distance was significantly reduced in the fixed group at H1 (1.79 ± 0.76 mm vs. 1.24 ± 1.04 mm), H2 (1.78 ± 1.08 mm vs. 1.33 ± 0.86 mm), and H3 (1.61 ± 1.35 mm vs. 1.16 ± 0.90 mm) (P < 0.05). Root resorption was also significantly higher in the fixed group (1.81 ± 1.55 mm vs. 0.87 ± 0.77 mm, P < 0.001). Root–IC proximity patterns included 7.6% separation, 63.1% approximation, 15.9% contact, and 13.4% invasion, with contact and invasion more prevalent in the fixed group. Root resorption increased with IC proximity, peaking at 3.65 ± 1.97 mm in invasion cases. Regression analysis identified tooth movement, root length, and inter-root distance as predictors of U1–IC proximity, while root resorption was associated with treatment duration, U1 movement, IC height, and incisor inclination (U1–SN angle). These findings underscore the importance of individualized planning and appliance selection in cases requiring maximum anterior retraction to reduce the risk of root resorption and IC-related complications.https://doi.org/10.1038/s41598-025-10210-yMaxillary central incisorsIncisive CanalClear alignersFixed appliancesTooth movement/RetractionRoot resorption
spellingShingle Remsh Khaled Al-Rokhami
Karim Ahmed Sakran
Naseem Ali Al-Worafi
Maher Al-balaa
Ahmed Algahefi
Zhihua Li
Three-dimensional retrospective analysis of root resorption and incisive canal changes following maxillary incisor retraction in class I and class II extraction cases: a comparison of clear aligners and fixed appliances
Scientific Reports
Maxillary central incisors
Incisive Canal
Clear aligners
Fixed appliances
Tooth movement/Retraction
Root resorption
title Three-dimensional retrospective analysis of root resorption and incisive canal changes following maxillary incisor retraction in class I and class II extraction cases: a comparison of clear aligners and fixed appliances
title_full Three-dimensional retrospective analysis of root resorption and incisive canal changes following maxillary incisor retraction in class I and class II extraction cases: a comparison of clear aligners and fixed appliances
title_fullStr Three-dimensional retrospective analysis of root resorption and incisive canal changes following maxillary incisor retraction in class I and class II extraction cases: a comparison of clear aligners and fixed appliances
title_full_unstemmed Three-dimensional retrospective analysis of root resorption and incisive canal changes following maxillary incisor retraction in class I and class II extraction cases: a comparison of clear aligners and fixed appliances
title_short Three-dimensional retrospective analysis of root resorption and incisive canal changes following maxillary incisor retraction in class I and class II extraction cases: a comparison of clear aligners and fixed appliances
title_sort three dimensional retrospective analysis of root resorption and incisive canal changes following maxillary incisor retraction in class i and class ii extraction cases a comparison of clear aligners and fixed appliances
topic Maxillary central incisors
Incisive Canal
Clear aligners
Fixed appliances
Tooth movement/Retraction
Root resorption
url https://doi.org/10.1038/s41598-025-10210-y
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