Department of Orthodontics and Craniofacial Developmental Biology, Graduate School of Biomedical Sciences, Hiroshima University, Japan.
Eur J Orthod. 2012 Jun;34(3):350-6. doi: 10.1093/ejo/cjr018. Epub 2011 Aug 2.
The purpose of this study was to clarify the prevalence and degree of root resorption induced by orthodontic treatment in association with treatment factors. The files of 243 patients (72 males and 171 females) aged 9-51 years were randomly selected from subjects treated with multi-bracket appliances. The severity of root resorption was classified into five categories on radiographs taken before and after treatment. The subjects were divided into extraction (n = 113 patients, 2805 teeth) and non-extraction (n = 130 patients, 3616 teeth) groups and surgical (n = 56 patients, 1503 teeth) and non-surgical treatment (n = 187 patients, 4918 teeth) groups. These subjects were also divided into two or three groups based on the duration of multiloop edgewise archwire (MEAW) treatment, elastic use, and total treatment time: 0 month (T1; n = 184 patients, 4831 teeth), range 1-6 months (T2; n = 37 patients, 994 teeth), more than 6 months (T3; n = 22 patients, 596 teeth); range 0-6 months (n = 114 patients, 3016 teeth) more than 6 months (n = 129 patients, 3405 teeth); range 1-30 months (n = 148 patients, 3913 teeth) and more than 30 months (n = 95 patients, 2508 teeth). The prevalence of overall and severe root resorption evaluated by the number of subjects and teeth was compared with a chi-square test. A Student's t-test for unpaired data was used to determine any statistically significant differences. The prevalence of severe root resorption based on the number of teeth was significantly higher in the group with extractions (P < 0.01). Longer use of a MEAW appliance and elastics also produced a significantly higher prevalence of root resorption (P < 0.05). On the other hand, the prevalence of severe root resorption was not significantly different between the subjects treated with or without surgery, but there was a significant increase when treatment time was prolonged (P < 0.05). A significant difference was found in the amount of root movement of the upper central incisors and the distance from their root apices to the cortical bone surface (P < 0.05). These are regarded as essential factors in the onset of root resorption. These results indicate that orthodontic treatment with extractions, long-term use of a MEAW appliance and elastics, treatment time, and distance of tooth movement are risk factors for severe root resorption.
本研究旨在阐明正畸治疗相关的治疗因素诱导的牙根吸收的发生率和程度。从接受多曲方丝弓矫治器治疗的患者中随机选择 243 名患者（72 名男性和 171 名女性，年龄 9-51 岁）的档案。在治疗前后的 X 光片上，将牙根吸收的严重程度分为五类。将患者分为拔牙组（n = 113 例，2805 颗牙齿）和非拔牙组（n = 130 例，3616 颗牙齿）以及手术组（n = 56 例，1503 颗牙齿）和非手术组（n = 187 例，4918 颗牙齿）。这些患者还根据多圈方丝弓（MEAW）治疗、弹性使用和总治疗时间的持续时间分为两组或三组：0 个月（T1；n = 184 例，4831 颗牙齿）、1-6 个月（T2；n = 37 例，994 颗牙齿）、6 个月以上（T3；n = 22 例，596 颗牙齿）；0-6 个月（n = 114 例，3016 颗牙齿）6 个月以上（n = 129 例，3405 颗牙齿）；1-30 个月（n = 148 例，3913 颗牙齿）和 30 个月以上（n = 95 例，2508 颗牙齿）。通过患者和牙齿的数量比较整体和严重的牙根吸收的发生率，并进行卡方检验。采用未配对数据的学生 t 检验确定任何具有统计学意义的差异。基于牙齿数量的严重牙根吸收的发生率在拔牙组显著更高（P < 0.01）。更长时间使用 MEAW 矫治器和弹性装置也会导致更高的牙根吸收发生率（P < 0.05）。另一方面，手术组和非手术组之间严重牙根吸收的发生率没有显著差异，但治疗时间延长时则显著增加（P < 0.05）。上中切牙的牙根移动量和根尖到皮质骨表面的距离之间存在显著差异（P < 0.05）。这些被认为是牙根吸收发生的重要因素。这些结果表明，拔牙、长时间使用 MEAW 矫治器和弹性装置、治疗时间和牙齿移动距离是严重牙根吸收的危险因素。
