Risk factors for periodontal ligament area reduction in maxillary central incisors following orthodontic treatment: a retrospective analysis using a deep learning-based CBCT-PDL segmentation network.

内容摘要

To analyze the relevant risk factors causing the reduction of periodontal ligament area (PDLA) of the maxillary central incisor by measuring the PDLA before and after orthodontic treatment using a previously validated cone-beam computed tomography-periodontal ligament (CBCT-PDL) deep learning segmentation network, providing a theoretical basis for orthodontic clinical treatment design. A retrospective analysis was performed on 63 patients who completed comprehensive orthodontic treatment in the Department of Stomatology, Beijing Friendship Hospital, Capital Medical University, between May 2021 and December 2022. Pre- and post-treatment CBCT images and clinical data were extracted from the hospital's dedicated imaging database. Using the CBCT-PDL segmentation network and orthodontic measurement and analysis software, PDLA and root length (RL) of 126 maxillary central incisors, were quantified before and after orthodontic treatment. Absolute and percentage changes in PDLA (&#x394;PDLA and &#x394;PDLA%, respectively) and RL (&#x394;RL and &#x394;RL%, respectively) were calculated. Statistical analyses were conducted, including Mann-Whitney U tests, Spearman correlation analysis, Generalized Linear Mixed Model and multiple linear regression, to identify the associated predictors of reduced PDLA in maxillary incisors from risk factors including gender, age, U1-NA angle, Angle's classification, sagittal skeletal pattern (ANB angle), vertical skeletal pattern, history of chronic periodontitis, tooth extraction status, and treatment duration. At the end of active orthodontic treatment, &#x394;PDLA and &#x394;PDLA% were significantly higher in the following subgroups compared with the reference group: patients with ANB angle&#x2009;>&#x2009;3&#xb0; [Maxillary right central incisor (T11) &#x394;PDLA: 9.49(13.37) mm, Maxillary left central incisor (T21) &#x394;PDLA: 11.02(14.45) mm, P&#x2009;<&#x2009;0.05; &#x394;PDLA%: T11 6.73(8.20) %, T21 7.05(8.66) %, P&#x2009;<&#x2009;0.05], tooth extraction treatment group [T11 &#x394;PDLA: 11.83(14.14) mm, T21 &#x394;PDLA: 11.82(16.67) mm, P&#x2009;<&#x2009;0.05; &#x394;PDLA%: T11 7.54 (10.13) %, T21 8.23(10.32) %, P&#x2009;=&#x2009;0.058], and treatment duration&#x2009;>&#x2009;2 years [T11 &#x394;PDLA: 9.34(14.83) mm, T21 &#x394;PDLA: 11.94(15.56) mm, P&#x2009;=&#x2009;0.059; &#x394;PDLA%: T11 7.00 (10.87) %, T21 8.37(8.73) %, P&#x2009;<&#x2009;0.05]. Additionally, the U1-NA angle&#x2009;>&#x2009;28.5&#xb0; subgroup showed marginally significantly higher &#x394;PDLA [11.46(25.13) mm, P&#x2009;=&#x2009;0.082], and patients with skeletal Class II malocclusion exhibited a marginally significantly higher &#x394;PDLA% [T11 7.53 (12.03) %, T21 6.91(9.24) %, P&#x2009;=&#x2009;0.059] relative to controls. Significant predictors of root resorption included adult age [T11 &#x394;RL: 0.63(1.30) mm, T21 &#x394;RL: 0.98(1.33) mm, P&#x2009;<&#x2009;0.05; T11 &#x394;RL%: 5.41(11.20) %, T21 &#x394;RL%: 8.16(10.20) %, P&#x2009;<&#x2009;0.05], and tooth extraction treatment [T11 &#x394;RL: 0.73(1.42) mm, T21 &#x394;RL: 1.12(1.41) mm, P&#x2009;<&#x2009;0.01; T11 &#x394;RL%: 6.33(12.03) %, T21 &#x394;RL%: 8.20(11.84) %, P&#x2009;<&#x2009;0.05]. Multiple linear regression revealed that &#x394;RL%, as a post-orthodontic outcome variable, was independently positively associated with &#x394;PDLA% (&#x3b2;&#x2009;=&#x2009;0.536, P&#x2009;<&#x2009;0.001). Among patient-related and treatment-related factors, the pre-treatment U1-NA angle significantly positively affected &#x394;PDLA% (&#x3b2;&#x2009;=&#x2009;0.257, P&#x2009;<&#x2009;0.01). Pre-treatment &#x2220;ANB (P&#x2009;=&#x2009;0.055) and treatment duration (P&#x2009;=&#x2009;0.082) demonstrated marginal statistical significance, while age and tooth extraction status exerted no significant effects (all P&#x2009;>&#x2009;0.05). Subgroup analyses identified adulthood, pre&#x2011;treatment &#x2220;ANB&#x2009;>&#x2009;3&#xb0;, pre&#x2011;treatment U1&#x2011;NA angle&#x2009;>&#x2009;28.5&#xb0;, tooth extraction, and treatment duration&#x2009;>&#x2009;2 years as associated risk factors for supporting tissue loss around the teeth. Multiple linear regression further confirmed the independent effects of pre&#x2011;treatment U1&#x2011;NA angle, &#x2220;ANB, and treatment duration on periodontal ligament area reduction. A comprehensive pre&#x2011;treatment evaluation of combined skeletal&#x2011;dental features is critical for individualized orthodontic risk stratification and clinical decision&#x2011;making.