Boyd Robert L
Department of Orthodontics, Arthur A Dugoni School of Dentistry, University of the Pacific, San Francisco, CA 94115, USA.
J Dent Educ. 2008 Aug;72(8):948-67.
In this report, three patients were treated with a new treatment protocol for Invisalign to demonstrate that a variety of complex malocclusions can be successfully treated using this protocol, including correction of moderate crowding, correction of moderate Class II division 1, and deep overbite. Previous studies of Invisalign showed significant limitations for more complex orthodontic treatment, although a few recent case reports have shown successfully completed moderate to difficult orthodontic malocclusions. One reason for the discrepancy is that the earlier studies were done during the first four years of the appliance development (now ten years of clinical use), when significant problems existed with accomplishing bodily movement, torquing of roots, extrusions, and rotations of premolars and canines. The new protocol included new methods for anterior/posterior corrections, showing on the computer the effect of elastics for Class II treatment simulated as a one-stage anterior/posterior movement at the end of treatment. Staging for interproximal reduction (IPR) is now automatically staged when there is better access to interproximal contacts to avoid IPR where significant overlap between teeth is present to avoid performing IPR on surfaces that may be damaged by instruments such as burs, strips, and disks when cut on a sharp angle. Staging for tooth movements is now also done to enable combination movements to occur simultaneously for each tooth with the tooth that needs to move the most (the lead tooth) determining the minimum number of stages required. All other teeth move at a slower rate than the lead tooth throughout the duration of treatment. Attachments are now placed in the middle of the crown automatically for rotation and automatically sized in proportion to the clinical crown. Use of 1 mm thick (buccal-lingual dimension) horizontal beveled rectangular attachments is standard on premolars for retention of aligners during intrusive movements, such as leveling the lower curve of Spee in deep overbite for extrusions and for control of the tooth long axis during torquing movements. Staging of tooth movements now track linear and rotational velocities of teeth separately with the number of treatment stages determined by the lead tooth based on its rotational or linear maximum velocities at no more than two degrees of rotation per stage. Simultaneous movements are done for all teeth providing visible space (approximately 0.05 mm) between teeth during movements past other teeth using expansion instead of IPR as a primary way to increase space available for correction of crowding.
在本报告中，三名患者接受了一种针对隐适美的新治疗方案，以证明使用该方案可以成功治疗多种复杂错牙合畸形，包括中度牙列拥挤的矫治、中度安氏II类1分类错牙合的矫治以及深覆牙合的矫治。以往对隐适美的研究表明，其在更复杂的正畸治疗中存在显著局限性，尽管最近有一些病例报告显示成功完成了中度至重度正畸错牙合畸形的矫治。造成这种差异的一个原因是，早期研究是在矫治器研发的前四年进行的（现在已临床使用十年），当时在实现牙体移动、牙根转矩控制、牙齿伸长以及前磨牙和尖牙的旋转方面存在重大问题。新方案包括用于前后向矫治的新方法，在计算机上显示II类治疗中弹力牵引的效果，模拟为治疗结束时的一次性前后向移动。当更便于接触邻面接触点时，现在邻面去釉（IPR）会自动分阶段进行，以避免在牙齿有明显重叠的部位进行IPR，避免在使用车针、条带和圆盘等器械以锐角切割时可能受损的表面进行IPR。现在牙齿移动也进行分阶段，以使每个牙齿与需要移动最多的牙齿（主导牙）同时发生联合移动，主导牙决定所需的最少阶段数。在整个治疗过程中，所有其他牙齿的移动速度都比主导牙慢。附件现在自动放置在牙冠中部以进行旋转，并根据临床牙冠大小自动调整尺寸。在侵入性移动（如在深覆牙合中整平Spee曲线以进行牙齿伸长以及在转矩移动中控制牙长轴）期间，使用1毫米厚（颊舌径）的水平斜角矩形附件作为标准，用于在磨牙上固定矫治器。现在牙齿移动分阶段分别跟踪牙齿的线性和旋转速度，治疗阶段数由主导牙根据其旋转或线性最大速度确定，每个阶段旋转不超过两度。所有牙齿同时移动，在移动过程中，当经过其他牙齿时，通过扩展而不是IPR在牙齿之间提供可见间隙（约0.05毫米），作为增加可用于矫治牙列拥挤的间隙的主要方法。
