在治療嚴重的骨骼性安格式第二級咬合不整並合併有大的水平覆蓋(overjet)的成年患者，因缺乏下顎骨的成長，需要上顎齒列作較大量的後退，因此上顎後牙的錨定控制顎的格外重要，尤其是拔牙的病例；當然在上顎後臼齒的錨定控制有很多不一樣的作法，而本研究提出用J鉤(J Hook)來退後前牙齒列，主要目的也是要提供臨床上錨定控制的另一種選擇，並由患者治療前、後的側面測顱分析中得到在P值小於0.05為基準的獨立t-test檢驗下∠ANB，U1-SN，U6-FH，overjet，overbite的數值，在治療前後的改變有顎著的意義；而U6-Nv值卻沒有顎著的改變，來表示J-Hook用在治療成年人骨骼性安格式第二級咬合不整且合併有大的水平覆蓋上，由於擁有好的上顎臼齒的錨定控制，而使整個治療可以得到理想的前後咬合關係。

Maxillary molar anchorage control was the most important in the extraction case of severe Class Ⅱ malocclusion. This research will show, when using of J hook on treating anterior teeth retraction of Class II malocclusion, we will get a good maxillary first molar anchorage control and concurrently reduce large anterior overjet and overbite. Following the cephalometric value between pre-and post-treatment, it was found there is an obvious changes (p≦0.05) include∠ANB, U1-SN, U6-FH, overjet and overbite in using J hook treatment, but the same there is no obvious changes in horizontal changes of mesiobuccal cusp of upper first molar (U6-Nv). From the results, we can select the J hook to help treating the severe Class Ⅱ malocclusion with large overjet and overbite, especially in the extraction case.