Parker R J, Harris E F
Am J Orthod Dentofacial Orthop. 1998 Dec;114(6):677-83. doi: 10.1016/s0889-5406(98)70200-8.
External apical root resorption is a multifactorial problem encountered in all disciplines of dentistry, but it is most commonly seen in cases treated orthodontically. Specific tooth movements that are most likely to exacerbate external apical root resorption are poorly understood. Purpose of the present investigation was twofold: (1) to quantify apical and incisal movements of the maxillary central incisor in the sagittal and vertical planes from cephalograms and (2) to use stepwise multivariate linear regression analyses to see which tooth movements and skeletodental relationships are most predictive of external apical root resorption. The sample consisted of 110 adolescents with similar pretreatment malocclusions (Class I crowded or bimaxillary protrusive) and treatment planned similarly (extraction of four first premolars) by experienced private practitioners. Each of three practitioners used a different orthodontic appliance; the sample was divided proportionately into cases treated with Tweed standard edgewise technique, Begg lightwire technique, and Roth-prescription straightwire technique. Lateral cephalograms were analyzed at the start, middle, and end of treatment. There was no statistical difference in average external apical root resorption between sexes or among techniques. Measures of tooth movement were highly predictive, explaining up to 90% of the variation in root resorption. Apical and incisal vertical movements and increase in incisor proclination were the strong predictors of external apical root resorption for each regression model. Incisor intrusion with increase in lingual root torque together were the strongest predictors of external apical root resorption. In contrast, distal bodily retraction, extrusion, or lingual crown tipping had no discernible effect.
根尖外吸收是牙科各领域都会遇到的多因素问题，但在正畸治疗病例中最为常见。人们对最有可能加剧根尖外吸收的特定牙齿移动了解甚少。本研究的目的有两个：（1）通过头影测量量化上颌中切牙在矢状面和垂直面的根尖和切端移动；（2）使用逐步多元线性回归分析，以确定哪些牙齿移动和骨骼牙关系最能预测根尖外吸收。样本包括110名青少年，他们具有相似的治疗前错牙合畸形（I类拥挤或双颌前突），并由经验丰富的私人执业医生制定了相似的治疗计划（拔除四颗第一前磨牙）。三位医生分别使用了不同的正畸矫治器；样本按比例分为使用Tweed标准方丝弓技术、Begg细丝弓技术和Roth处方直丝弓技术治疗的病例。在治疗开始、中期和结束时对头侧位片进行分析。性别之间或技术之间的平均根尖外吸收没有统计学差异。牙齿移动的测量具有高度预测性，可解释高达90%的牙根吸收变化。根尖和切端垂直移动以及切牙倾斜度增加是每个回归模型中根尖外吸收的强预测因素。切牙舌向根转矩增加的同时切牙压低是根尖外吸收最强的预测因素。相比之下，远中整体后移、伸长或牙冠舌向倾斜没有明显影响。
