This study evaluated,over a 4-month study period,the amount of apical root resorption occurring in maxillary central incisors following their retraction when employing either micro-implant or J-hook headgear anchorage...This study evaluated,over a 4-month study period,the amount of apical root resorption occurring in maxillary central incisors following their retraction when employing either micro-implant or J-hook headgear anchorage.The prospective randomised clinical trial was conducted in Orthodontic Clinic,College of Stomatology,China from 2008-2009.Subjects are patients requiring fixed appliances on waiting list (n=20).In female Han Chinese patients aged from 16-26 years,standardized periapical radiographs from 10 randomly assigned patients with maxillary protrusions comprising the micro-implant group,and from 10 similar patients comprising the J-hook headgear group,were assessed for maxillary central incisor apical root resorption.Measurements before and after orthodontic therapy were also obtained from lateral cephalometric radiographs to calculate incisor horizontal retraction and vertical intrusion distances.Estimated retraction force vectors were calculated in horizontal and vertical directions for both treatment groups.Data analysis employed t-tests and the Pearson correlation test,with α=0.05 for statistical significance.The results showed that when compared with the J-hook group,significantly more apical root resorption shortening of the maxillary central incisors was observed in the micro-implant group (1.27 mm difference,95% CI=0.70-1.84,P<0.001),which was associated with a significantly larger retraction distance (P=0.004) and a smaller vertical force component (P<0.0001).We are led to conclude that continuous activation of the nickel-titanium coil springs used in the micro-implant group resulted in significantly more apical root resorption shortening and maxillary central incisor retraction than when intermittent J-hook retraction was employed.The employment of continuous duration orthodontic forces presents a risk for increased apical root resorption that requires careful radiographic monitoring.展开更多
目的探讨以"挂钩"的方式顺行置入双J管在腹腔镜肾盂成形术中的应用。方法 2014年10月~2016年5月对28例肾盂输尿管连接部梗阻行腹腔镜肾盂成形术,在完成肾盂输尿管连接部后壁的缝合后,双J管以"挂钩"的方式顺行置入...目的探讨以"挂钩"的方式顺行置入双J管在腹腔镜肾盂成形术中的应用。方法 2014年10月~2016年5月对28例肾盂输尿管连接部梗阻行腹腔镜肾盂成形术,在完成肾盂输尿管连接部后壁的缝合后,双J管以"挂钩"的方式顺行置入输尿管内,双J管远端进入膀胱内,撤出导丝及推管,腹腔镜弯钳将双J管近端放置肾盂内,完成肾盂输尿管连接部的前壁缝合。结果 28例双J管均以顺行方式顺利置入,围手术期无并发症发生。镜下置管时间2 min 30 s^4 min 45 s,平均3 min 5 s。术后4~6周拔除双J管,复查泌尿系超声或静脉肾盂造影,肾积水较术前减轻(术前中度17例,重度11例;术后中度9例,轻度13例,无肾积水6例)。结论顺行"挂钩"法置入双J管安全、操作简便,利用双J管自身的优势,不需要额外辅助器械,为腹腔镜肾盂成形手术中置入双J管提供一种新的思路。展开更多
目的分析J钩高位牵引时牵引钩高度变化对切牙牙周膜应力和初始位移的影响,探讨J钩牵引过程中的力学机制,为临床正畸提供客观的理论依据。方法建立上颌牙齿及矫治器的三维有限元模型;牵引钩高度分2、4、6、8、10、12 mm 6种高度;于牵引...目的分析J钩高位牵引时牵引钩高度变化对切牙牙周膜应力和初始位移的影响,探讨J钩牵引过程中的力学机制,为临床正畸提供客观的理论依据。方法建立上颌牙齿及矫治器的三维有限元模型;牵引钩高度分2、4、6、8、10、12 mm 6种高度;于牵引钩顶端加载与矢状面颊向30°及与牙合平面向上30°,力大小为1.5 N;描绘出上颌切牙牙周膜应力图和初始位移图。结果当牵引钩高度增加时,中切牙最大主压应力变大,牵引钩高度小于4 mm时表现为舌倾压低,牵引钩高度大于8mm时表现为唇倾压低;侧切牙最大主压应力值先变小后增大,在牵引钩高度为4 mm时最小、12 mm时最大,舌倾伸长趋势增加。结论 J钩高位牵引时随着牵引钩高度增加,中切牙从舌倾压低变为唇倾压低;侧切牙舌倾伸长趋势增加。展开更多
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘This study evaluated,over a 4-month study period,the amount of apical root resorption occurring in maxillary central incisors following their retraction when employing either micro-implant or J-hook headgear anchorage.The prospective randomised clinical trial was conducted in Orthodontic Clinic,College of Stomatology,China from 2008-2009.Subjects are patients requiring fixed appliances on waiting list (n=20).In female Han Chinese patients aged from 16-26 years,standardized periapical radiographs from 10 randomly assigned patients with maxillary protrusions comprising the micro-implant group,and from 10 similar patients comprising the J-hook headgear group,were assessed for maxillary central incisor apical root resorption.Measurements before and after orthodontic therapy were also obtained from lateral cephalometric radiographs to calculate incisor horizontal retraction and vertical intrusion distances.Estimated retraction force vectors were calculated in horizontal and vertical directions for both treatment groups.Data analysis employed t-tests and the Pearson correlation test,with α=0.05 for statistical significance.The results showed that when compared with the J-hook group,significantly more apical root resorption shortening of the maxillary central incisors was observed in the micro-implant group (1.27 mm difference,95% CI=0.70-1.84,P<0.001),which was associated with a significantly larger retraction distance (P=0.004) and a smaller vertical force component (P<0.0001).We are led to conclude that continuous activation of the nickel-titanium coil springs used in the micro-implant group resulted in significantly more apical root resorption shortening and maxillary central incisor retraction than when intermittent J-hook retraction was employed.The employment of continuous duration orthodontic forces presents a risk for increased apical root resorption that requires careful radiographic monitoring.
文摘目的探讨以"挂钩"的方式顺行置入双J管在腹腔镜肾盂成形术中的应用。方法 2014年10月~2016年5月对28例肾盂输尿管连接部梗阻行腹腔镜肾盂成形术,在完成肾盂输尿管连接部后壁的缝合后,双J管以"挂钩"的方式顺行置入输尿管内,双J管远端进入膀胱内,撤出导丝及推管,腹腔镜弯钳将双J管近端放置肾盂内,完成肾盂输尿管连接部的前壁缝合。结果 28例双J管均以顺行方式顺利置入,围手术期无并发症发生。镜下置管时间2 min 30 s^4 min 45 s,平均3 min 5 s。术后4~6周拔除双J管,复查泌尿系超声或静脉肾盂造影,肾积水较术前减轻(术前中度17例,重度11例;术后中度9例,轻度13例,无肾积水6例)。结论顺行"挂钩"法置入双J管安全、操作简便,利用双J管自身的优势,不需要额外辅助器械,为腹腔镜肾盂成形手术中置入双J管提供一种新的思路。
