To cut the mainwire or not, that is the question.｜【Chris Chang Ortho】CC488

Abstract When closing the space of lower 1st molar, it’s recommended to bond lingual buttons on the adjacent teeth and attach power chains on their lingual and buccal sides for efficiency and prevention of side effects. The following two clinical cases are to demonstrate this method of space closure and a key differential tip in the application. The 1st case is a Class III malocclusion with anterior crossbite. During the correction of anterior crossbite, the space was partially closed. By the 12th month, the space of the 1st molar was completely closed. The protraction of posterior teeth simultaneously retracted anterior teeth, which resulted in an increase of overjet. In this case this side effect is helpful in correcting anterior crossbite. The 2nd case began with a normal overjet. At first all the same treatment protocols were followed. However, to address this undesired side effect of increased overjet in this case, we combined the use of Class II elastics and cutting the archwire between the 2nd molars and 3rd molars to reduce the posterior anchorage force. As such, the posterior protraction increased while the anterior retraction was reduced. 摘要 矯正治療期間要關閉下顎第一大臼齒的空間時，建議在要關閉空間前後的牙齒內側黏buttons，並在內外同時掛上橡皮筋，這樣的方式最有效率，也可減少副作用的產生。本次報告中分享了兩個案例來說明此關空間的方式，以及一個關鍵性執行上的差異。 第一個案例為安格氏三級咬合不正，在改正前牙錯咬的同時已關閉部分的缺牙空間，到第十二個月的時候，缺牙的空間已完全關閉。隨著後牙往前拉的過程中，前牙後退的副作用，有助於改善前牙錯咬的問題。 第二個案例起始的水平覆蓋量正常，一開始也使用同樣的方式處理，然後為了要改正在關空間的過程中，因下排牙齒前後牙對拉的關係導致水平覆蓋量愈來愈大。為了改善這個副作用，我們合併使用第二級牽引橡皮筋並切斷第二大臼齒與第三大臼齒之間的主線，減少後牙錨定，以增加後牙往前的量，減少前牙被拉進來的量。