Abstract：
The alveolar bone loss (ABL) and external apical root resorption (EARR) depict the safety of mesialization of mandibular second molars into the extraction space of mandibular first molars. The aim of this study was to evaluate the ABL and EARR after closure of mandibular first molar extraction space by mesialization of second molar on extraction side (ES) as compared to the contralateral non-extraction side (NES).
A retrospective cross-sectional study was carried out using the pre and posttreatment orthodontic records of young adults with complete set of permanent dentitions treated with extraction of unilateral mandibular first molar and non-extraction treatment on the contralateral side. All patients underwent mini-implant supported mesialization of second molar on ES. The ABL and EARR of second molar on ES and contralateral NES were measured on digital orthopantomograms. The ABL and EARR of second molars on ES and contralateral NES were compared using independent sample t-test.
A total of 36 subjects (14 males and 22 females) were included in the study. The mean treatment duration for molar mesialization was 28.75±8.05months. The mean crown and root movements of mandibular second molar on ES were 10.94±1.25mm and 9.04mm±1.14mm, as compared to 0.91±1.01mm and 0.77±0.83mm on contralateral NES, respectively. The mean ABL and EARR at mandibular second molar were found to be significantly greater on the ES than the contralateral NES (P<0.001 and<0.05, respectively). A total of seven patients (19.4%) experienced ABL≥1mm on ES as compared to none in the contralateral NES. EARR of>2mm of at least one root was found in seven patients (19.4%) in ES as compared to four (11%) in contralateral NES.
There was small but statistically significant difference in the ABL and EARR of mesialized mandibular second molar at first molar ES as compared to the contralateral NES. For majority of patients this difference was small but few isolated cases experienced severe ABL and EARR.
A retrospective cross-sectional study was carried out using the pre and posttreatment orthodontic records of young adults with complete set of permanent dentitions treated with extraction of unilateral mandibular first molar and non-extraction treatment on the contralateral side. All patients underwent mini-implant supported mesialization of second molar on ES. The ABL and EARR of second molar on ES and contralateral NES were measured on digital orthopantomograms. The ABL and EARR of second molars on ES and contralateral NES were compared using independent sample t-test.
A total of 36 subjects (14 males and 22 females) were included in the study. The mean treatment duration for molar mesialization was 28.75±8.05months. The mean crown and root movements of mandibular second molar on ES were 10.94±1.25mm and 9.04mm±1.14mm, as compared to 0.91±1.01mm and 0.77±0.83mm on contralateral NES, respectively. The mean ABL and EARR at mandibular second molar were found to be significantly greater on the ES than the contralateral NES (P<0.001 and<0.05, respectively). A total of seven patients (19.4%) experienced ABL≥1mm on ES as compared to none in the contralateral NES. EARR of>2mm of at least one root was found in seven patients (19.4%) in ES as compared to four (11%) in contralateral NES.
There was small but statistically significant difference in the ABL and EARR of mesialized mandibular second molar at first molar ES as compared to the contralateral NES. For majority of patients this difference was small but few isolated cases experienced severe ABL and EARR.
摘要：
背景：牙槽骨丢失（ABL）和外根尖根吸收（EARR）描述了下颌第二磨牙进入下颌第一磨牙拔牙空间的安全性。这项研究的目的是通过将拔牙侧（ES）的第二磨牙与对侧非拔牙侧（NES）进行中间化来评估下颌第一磨牙拔牙空间闭合后的ABL和EARR。
方法：使用治疗前和治疗后的年轻成年人的正畸记录进行了回顾性横断面研究，其中完整的永久性牙列接受了单侧下颌第一磨牙的拔除和对侧非拔除治疗。所有患者均接受了微型植入物支持第二磨牙在ES上的插入。第二磨牙在ES和对侧NES上的ABL和EARR在数字正像图上测量。采用独立样本t检验比较第二磨牙在ES和对侧NES上的ABL和EARR。
结果：共有36名受试者（14名男性和22名女性）被纳入研究。磨牙化合的平均治疗时间为28.75±8.05个月。下颌第二磨牙在ES上的平均牙冠和牙根运动分别为10.94±1.25mm和9.04mm±1.14mm，与对侧NES的0.91±1.01mm和0.77±0.83mm相比，分别。发现下颌第二磨牙的平均ABL和EARR在ES上明显大于对侧NES（分别为P<0.001和<0.05）。共有7名患者（19.4％）在ES上经历了ABL≥1mm，而对侧NES中没有。在ES中，有7名患者（19.4％）的至少一个根部的EARR>2mm，而在对侧NES中，有4名（11％）。
结论：与对侧NES相比，第一磨牙下颌第二磨牙的ABL和EARR差异很小，但具有统计学意义。对于大多数患者，这种差异很小，但很少有孤立病例经历严重的ABL和EARR。
方法：使用治疗前和治疗后的年轻成年人的正畸记录进行了回顾性横断面研究，其中完整的永久性牙列接受了单侧下颌第一磨牙的拔除和对侧非拔除治疗。所有患者均接受了微型植入物支持第二磨牙在ES上的插入。第二磨牙在ES和对侧NES上的ABL和EARR在数字正像图上测量。采用独立样本t检验比较第二磨牙在ES和对侧NES上的ABL和EARR。
结果：共有36名受试者（14名男性和22名女性）被纳入研究。磨牙化合的平均治疗时间为28.75±8.05个月。下颌第二磨牙在ES上的平均牙冠和牙根运动分别为10.94±1.25mm和9.04mm±1.14mm，与对侧NES的0.91±1.01mm和0.77±0.83mm相比，分别。发现下颌第二磨牙的平均ABL和EARR在ES上明显大于对侧NES（分别为P<0.001和<0.05）。共有7名患者（19.4％）在ES上经历了ABL≥1mm，而对侧NES中没有。在ES中，有7名患者（19.4％）的至少一个根部的EARR>2mm，而在对侧NES中，有4名（11％）。
结论：与对侧NES相比，第一磨牙下颌第二磨牙的ABL和EARR差异很小，但具有统计学意义。对于大多数患者，这种差异很小，但很少有孤立病例经历严重的ABL和EARR。
