牙骨质根的物理特性：第 23 部分。每周 2 或 3 次再激活的连续或间歇正畸力对牙根吸收和牙齿移动的影响：一项微计算机断层扫描研究。
Physical properties of root cementum: part 23. Effects of 2 or 3 weekly reactivated continuous or intermittent orthodontic forces on root resorption and tooth movement: a microcomputed tomography study.
机构信息
Sydney Dental Hospital, Oral Health Services, and South Western Sydney Local Health District, Sydney, Australia.
出版信息
Am J Orthod Dentofacial Orthop. 2012 Feb;141(2):e29-37. doi: 10.1016/j.ajodo.2011.07.018.
INTRODUCTION
The force application period is a modifiable factor in root resorption. There is still ambiguity if the continuity of force application is advantageous in terms of root resorption and tooth movement. In this prospective randomized clinical trial, we compared the effects of 2 reactivation periods of controlled-intermittent and continuous forces on root resorption and tooth movement.
METHODS
Thirty-two patients were randomly divided into 2 groups: 2 weekly and 3 weekly reactivations. A split-mouth setup was used for the intermittent and continuous force comparisons. The intermittent force was designed with a pause of 3 days before each reactivation of the springs. A buccally directed tipping force (150 g) was generated with 0.017 × 0.025-in Beta III Titanium cantilever springs (3M Unitek, Monrovia, Calif). After the extractions, surface analysis was performed with microcomputed tomography (model 1172; SkyScan, Aartselaar, Belgium) and specially designed software (CHull2D) for direct volumetric analysis. Buccal premolar movement was also measured on the images of the study casts.
RESULTS
Continuous forces produced more resorption than intermittent forces on the total volumes in both groups. A significant difference was found for the 3-weekly group only (P <0.01) on the cervical-mesial (P <0.01) and cervical-buccal (P <0.05) compression regions. In the 2-weekly group, differences were evident in the middle-distal (P <0.05) and middle-lingual (P <0.05) tension regions. Continuous forces produced significantly more tooth movement than did the intermittent forces for both the 2-weekly (P <0.01) and the 3-weekly (P <0.001) regimens. Significant differences were not observed between the 2 intermittent force regimens regarding root resorption and tooth movement.
CONCLUSIONS
Intermittent force causes less root resorption and tooth movement than continuous force. Root resorption decreases irrespective of the timing of reactivation, when a pause is given. On the other hand, timing of reactivation might have critical importance on continuous force applications, since 2 weekly reactivations produced faster tooth movement with similar root resorption when compared with intermittent force.
简介
力的应用期是根吸收的一个可调节因素。在根吸收和牙齿移动方面，持续施加力是否有利仍存在不确定性。在这项前瞻性随机临床试验中，我们比较了两种间歇和连续力的再激活期对根吸收和牙齿移动的影响。
方法
32 名患者被随机分为两组：每周两次和每周三次再激活。使用间歇和连续力的分裂口设置进行比较。间歇力设计在每次弹簧再激活前有 3 天的暂停。使用 0.017×0.025 英寸 Beta III 钛悬臂弹簧（3M Unitek，Monrovia，加利福尼亚州）产生颊向倾斜力（150 克）。拔牙后，使用微计算机断层扫描（型号 1172；SkyScan，Aartselaar，比利时）和专门设计的软件（CHull2D）进行表面分析，以进行直接体积分析。在研究模型的图像上还测量了颊侧前磨牙的移动。
结果
在两组中，连续力比间歇力在总体积上产生更多的吸收。仅在每周 3 次组中发现了显著差异（P <0.01），在颈内近（P <0.01）和颈内颊（P <0.05）压缩区。在每周 2 次组中，中远端（P <0.05）和中舌（P <0.05）张力区存在差异。连续力比间歇力在每周 2 次（P <0.01）和每周 3 次（P <0.001）方案中均产生了更多的牙齿移动。两种间歇力方案在根吸收和牙齿移动方面均未观察到显著差异。
结论
间歇力比连续力引起的根吸收和牙齿移动少。当给予暂停时，无论再激活的时间如何，根吸收都会减少。另一方面，再激活的时间对于连续力的应用可能具有重要意义，因为与间歇力相比，每周两次的再激活产生了更快的牙齿移动和相似的根吸收。
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