Sayahpour Babak, Lau Diana, Eslami Sara, Buehling Sarah, Kopp Stefan, Jamilian Abdolreza, Chhatwani Sachin
Department of Orthodontics, Center for Dentistry and Oral Medicine (Carolinum), Goethe University Frankfurt, Theodor-Stern-Kai 7, 60596, Frankfurt, Germany.
Dental Practice, Darmstädter Straße 44, 63225, Langen, Germany.
J Orofac Orthop. 2025 May;86(3):1-9. doi: 10.1007/s00056-023-00501-2. Epub 2023 Oct 17.
This study aimed to evaluate the effects of lower premolar extraction on posttreatment stability one year following fixed orthodontic treatment with passive self-ligating brackets (Damon system, Ormco, Orange, CA, USA).
All patients were treated with fixed orthodontic appliances using passive self-ligating brackets (Damon). For retention, removable Hawley retainers were used. Two groups of patients were included in the study. Each group consisted of 23 patients: group Ex consisted of 10 male and 13 female patients (13.4 ± 1.6 years old) with extraction of lower first premolars and group NonEx consisted of 11 male and 12 female patients (13.4 ± 3.9 years old) without dental extractions. The patients' dental models and photographs were assessed at T0 (pretreatment), T1 (the end of active orthodontic treatment: 3.3 ± 1.0 years in the Ex and 2.3 ± 0.8 years in the NonEx group) and at T2 (1 year posttreatment). All lower casts were scanned and the following dental parameters were recorded and compared between the two groups: intercanine width (ICW), anterior arch width (AAW), intermolar width (IMW), Little's irregularity index (LII) and gingival recessions.
An increase in ICW (group Ex: 1.20 ± 2.51 mm and group NonEx: 0.84 ± 1.48 mm) by the end of active treatment (T1; P < 0.05), as well as a relapse regarding the ICW (group Ex: -0.1 ± 0.47 mm and group NonEx: -67% ± 0.38 mm) one year post-treatment (T2) were recorded in the samples. Relapse in the non-extraction group was statistically and clinically significant, whereas ICW values remained relatively stable in the extraction group during the posttreatment period (T1-T2). The irregularity index decreased during treatment (group Ex: -8.79 ± 6.36 mm and group NonEx: -5.24 ± 2.99 mm) and relapsed in both groups (group Ex: 0.57 ± 90 mm and group NonEx: 0.27 ± 0.53). The rate of relapse in LII was correlated to the relapse rate of ICW. A reduction of IMW was recorded in the Ex group (-1.89 ± 1.82 mm) during active treatment (P < 0.05), which remained stable 1 year posttreatment. AAW increased in both groups (group Ex: 2.77 ± 1.77 mm and group NonEx: 1.77 ± 2.04 mm) throughout active treatment and remained stable at T2.
Intergroup comparison revealed that ICW remained stable 1 year posttreatment in the Ex group, whereas high relapse of ICW was recorded in the NonEx group. Furthermore, risk of a relapse of LII appears to be higher in cases with a relapse of the ICW.
本研究旨在评估使用被动自结扎托槽（美国加利福尼亚州奥兰治奥美科公司的Damon系统）进行固定正畸治疗后一年，拔除下前磨牙对治疗后稳定性的影响。
所有患者均使用被动自结扎托槽（Damon）进行固定正畸矫治。保持器采用可摘式霍利保持器。本研究纳入两组患者。每组由23例患者组成：Ex组包括10例男性和13例女性患者（年龄13.4±1.6岁），拔除了下第一前磨牙；NonEx组包括11例男性和12例女性患者（年龄13.4±3.9岁），未拔牙。在T0（治疗前）、T1（主动正畸治疗结束时：Ex组为3.3±1.0年，NonEx组为2.3±0.8年）和T2（治疗后1年）对患者的牙模和照片进行评估。对所有下颌模型进行扫描，并记录两组之间的以下牙齿参数并进行比较：尖牙间宽度（ICW）、前牙弓宽度（AAW）、磨牙间宽度（IMW）、利特尔不规则指数（LII）和牙龈退缩情况。
在主动治疗结束时（T1），样本中记录到ICW增加（Ex组：1.20±2.51mm，NonEx组：0.84±1.48mm）（P<0.05），并且在治疗后1年（T2）记录到ICW复发（Ex组：-0.1±0.47mm，NonEx组：-67%±0.38mm）。非拔牙组的复发在统计学和临床上均具有显著性，而在治疗后期间（T1-T2），Ex组的ICW值保持相对稳定。不规则指数在治疗期间下降（Ex组：-8.79±6.36mm，NonEx组：-5.24±2.99mm），且两组均出现复发（Ex组：0.57±90mm，NonEx组：0.27±0.53）。LII的复发率与ICW的复发率相关。在主动治疗期间，Ex组记录到IMW减小（-1.89±1.82mm）（P<0.05），治疗后1年保持稳定。在整个主动治疗期间，两组的AAW均增加（Ex组：2.77±1.77mm，NonEx组：1.77±2.04mm），并在T2时保持稳定。
组间比较显示，Ex组在治疗后1年ICW保持稳定，而NonEx组记录到ICW的高复发率。此外，ICW复发的病例中，LII复发的风险似乎更高。
