Department of Orthodontics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea.
Am J Orthod Dentofacial Orthop. 2010 Feb;137(2):194-9. doi: 10.1016/j.ajodo.2008.03.031.
Survival analysis is useful in clinical research because it focuses on comparing the survival distributions and the identification of risk factors. Our aim in this study was to investigate the survival characteristics and risk factors of orthodontic mini-implants with survival analyses.
One hundred forty-one orthodontic patients (treated from October 1, 2000, to November 29, 2007) were included in this survival study. A total of 260 orthodontic mini-implants that had sandblasted (large grit) and acid-etched screw parts were placed between the maxillary second premolar and the first molar. Failures of the implants were recorded as event data, whereas implants that were removed because treatment ended and those that were not removed during the study period were recorded as censored data. A nonparametric life table method was used to visualize the hazard function, and Kaplan-Meier survival curves were generated to identify the variables associated with implant failure. Prognostic variables associated with implant failure were identified with the Cox proportional hazard model.
Of the 260 implants, 22 failed. The hazard function for implant failure showed that the risk is highest immediately after placement. The survival function showed that the median survival time of orthodontic mini-implants is sufficient for relatively long orthodontic treatments. The Cox proportional hazard model identified that increasing age is a decisive factor for implant survival.
The decreasing pattern of the hazard function suggested gradual osseointegration of orthodontic mini-implants. When implants are placed in a young patient, special caution is needed to lessen the increased probability of failure, especially immediately after placement.
生存分析在临床研究中很有用，因为它侧重于比较生存分布和确定风险因素。我们在这项研究中的目的是通过生存分析研究正畸微种植体的生存特征和风险因素。
这项生存研究共纳入 141 名正畸患者（2000 年 10 月 1 日至 2007 年 11 月 29 日接受治疗）。共放置了 260 个带有喷砂（大粒度）和酸蚀螺丝部分的正畸微种植体，位于上颌第二前磨牙和第一磨牙之间。将种植体的失败记录为事件数据，而将因治疗结束而移除的种植体和在研究期间未移除的种植体记录为删失数据。使用非参数寿命表法可视化危险函数，并生成 Kaplan-Meier 生存曲线以确定与种植体失败相关的变量。使用 Cox 比例风险模型确定与种植体失败相关的预后变量。
在 260 个种植体中，有 22 个失败。种植体失败的危险函数表明，放置后立即风险最高。生存函数表明，正畸微种植体的中位生存时间足以进行相对较长的正畸治疗。Cox 比例风险模型确定年龄增长是种植体生存的决定性因素。
危险函数的下降模式表明正畸微种植体逐渐骨整合。当在年轻患者中放置种植体时，需要特别小心，以降低失败的概率增加，尤其是在放置后立即。
