Effects of a doubled orthodontic force magnitude on tooth movement and root resorptions. An inter-individual study in adolescents.
Effects of a doubled orthodontic force magnitude on tooth movement and root resorptions. An inter-individual study in adolescents.
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双倍正畸力大小对牙齿移动和牙根吸收的影响。
DOI：
10.1093/ejo/18.2.141
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发表时间：
1996
影响因子：
2.6
通讯作者：
Dan Lundgren
中科院分区：
文献类型：
--
作者：
P. Owman;Jüri Kurol;Dan Lundgren
本临床和组织学研究的目的是比较两种受控的、连续的50cn（约50g）和100cn（约100g）力对牙齿运动和牙根吸收的影响。患者32例，男14例，女18例，平均年龄13.1岁，分为4组，每组8例。试验期分别为4周和7周。在本研究中，设计为个体间研究，仅使用右侧上颌第一前磨牙。用固定矫治器在颊部移动试验牙。对16颗前磨牙连续每周施加50 cN的力，对其余16颗试验牙施加100 cN的力。在第一周，施加50 cN时，力平均下降22%，施加100 cN时，力平均下降27%。用三坐标测量机研究了牙模上牙齿的运动。4和7周后，50 cN组牙齿移动幅度在0.5 ~ 3.4 mm（4周）和2.7 ~ 7.1 mm（7周）之间；100 cN组牙齿移动幅度在1.0 ~ 2.9 mm（4周）和2.2 ~ 8.3 mm（7周）之间。在所有实验牙的组织学切片上都记录到了牙根吸收，在施用50 cN后比施用100 cN后7周更频繁。然而，当施加的力增加一倍至100 cN时，根吸收的严重程度（被吸收根的延伸和深度以及组织切片上的根面积大小）没有显著差异。在牙齿移动幅度和牙根吸收量方面，个体差异很大。
The aim of this clinical and histological study was to compare the effects of two controlled, continuous forces of 50 cN (approximately 50 g) and 100 cN (approximately 100 g) on tooth movement and root resorptions. The patients, consisting of 32 individuals, 14 boys and 18 girls (mean age 13.1 years), were divided into four groups of eight individuals. The experimental periods were 4 and 7 weeks. In this investigation, designed as an inter-individual study, only the maxillary first premolar on the right side was utilized. The test tooth was buccally moved by means of a fixed orthodontic appliance. A continuous, weekly controlled force of 50 cN was applied to 16 premolars and a force of 100 cN to the remaining 16 test teeth. The force declined on average 22 per cent during the first week when 50 cN was applied and 27 per cent when 100 cN was applied. Tooth movements were studied on dental casts using a coordinate measuring machine. After 4 and 7 weeks, the tooth movements ranged between 0.5 and 3.4 mm (4 weeks) and 2.7 and 7.1 mm (7 weeks) for 50 cN and between 1.0 and 2.9 mm (4 weeks) and 2.2 and 8.3 mm (7 weeks) for 100 cN, with no significant difference when the force magnitude was doubled. Root resorptions were registered in histological sections in all experimental teeth, more frequently after application of 50 cN compared with 100 cN after 7 weeks. However, the severity of root resorption (extension and depth of resorbed root contour and size of root area on histological sections) did not differ significantly when the applied force was doubled to 100 cN. Great individual variations were noted regarding both the magnitude of tooth movement and amount of root resorption.