为啥感觉医生移动移动硬盘传输速度变慢慢了

来源：蜘蛛抓取(WebSpider) 时间：2017-05-16 19:24 标签： 移动硬盘读取速度变慢
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成人正畸牙移动速度是否慢于青少年
临床上经常会有成人正畸患者问：“我都这么大岁数了，时牙移动得肯定比小孩慢吧？”我记得以前似乎在Contemporary Orthodontics上读到过，成人患者正畸牙移动启动慢于青少年，而一旦启动，则速度不亚于青少年。也正是带着这个印象，我对这个问题的回答是“一样快”。然而，下面这个研究却显示，成人患者正畸牙移动速度确实慢于青少年，慢了近1/3，已经属于有临床意义的差距了。看来，今后我需要更改我的回答了。我推测造成这个差异的原因可能有两方面：1）青少年牙周膜更厚，且反应性更好，因而产生的破骨反应更强更快。2）成人牙槽骨骨密度更高，对骨吸收的抵抗更强。但另一方面，成人比青少年牙移动速度慢，却并不意味着成人患者的正畸疗程一定比青少年长。事实上，因为成人患者依从性更好，不掉托槽，一定程度上弥补了他们牙移动稍慢的劣势。这就是为什么青少年和年轻成人都是正畸最佳年龄群的原因。另，该研究还显示性别、牙位（包括上、下颌）对牙移动速度没有影响，尽管我们有时可能感觉女孩比男孩牙移动快、上牙比下牙移动快。———————————————————————————————————————Am J Orthod Dentofacial Orthop.&):616-21. doi: 10.1016/j.ajodo..Factors&related&to the&rate&of&orthodontically&induced&tooth&movement.Dudic A, Giannopoulou C, Kiliaridis S.SourceAssistant professor, Department of Orthodontics, University of Geneva, Geneva, Switzerland.AbstractINTRODUCTION:The purpose of this study was to investigate the variations of&orthodontically&inducedtooth&movement&in the maxillary and mandibular arches between patients and thefactors&such as age, sex, and presence of an interference that might influence the amount of&toothdisplacement.METHODS:By using a standardized experimental orthodontic&tooth&movement&in 30 subjects, 57 premolars were moved buccally during 8 weeks with the application of a 1-N force. Forty-four contralateral premolars not subjected to orthodontic&tooth&movement&served as the controls. Plaster models from before and after the experimental&tooth&movementwere digitized and superimposed to evaluate the amounts of&tooth&movement. Differences in&tooth&movement&between the experimental and control groups were tested by an unpaired t test. For the experimental teeth, subject-related&factors&(age and sex) and&tooth-related&factors&(location in the maxillary or mandibular dental arch, and the presence or absence of an intra-arch or interarch obstacle such as neighboring touching teeth or teeth interfering with the occlusion) were examined with analysis of variance. Multiple linear regression analysis was performed to determine correlations between&tooth&displacement, age, sex,&tooth&location, and presence of an interference.RESULTS:Each subject contributed at least 2 experimental premolars and 1 control premolar. The displacement of the&orthodontically&moved teeth was 2.42 mm (range, 0.3-5.8 mm). Younger subjects (&16 n = 19; number of teeth, 36) had significantly greater amounts of&tooth&displacement compared with older subjects (≥16 n = 11; number of teeth, 21): 2.6 ± 1.3 mm vs 1.8 ± 0.8 P &0.01. When an interarch or intra-arch obstacle was present, the amount of&tooth&movement&was significantly less (2.6 ± 1.3 mm vs 1.8 ± 0.8 mm) (P &0.05). Neither sex nor the location of the experimental teeth in the mandible or the maxilla had any effect.CONCLUSIONS:Younger patients showed greater&tooth&movement&velocity than did older ones. An interarch or intra-arch obstacle decreased the amount of&tooth&displacement.
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