由太平洋大学牙科学校发展的RPA卡环(rest,proximal plate,Akers clasp)目的在于克服使用RPI卡环(rest,proximal plate,I-bar clasp)时所发生的某些问题。作者首先在RPI卡环的设计特征中指出:当(牙合)力作用于基托时,RPI卡环和基牙脱离接触,并防止义齿(牙合)方移位,且复盖牙面小,显露金属少,无舌侧臂不与基牙舌侧面接触,该设计用于支撑牙齿及游离端缺 The RPA loop developed by the University of the Pacific School of Dentistry (rest, proximal plate, Akers clasp) aims to overcome some of the problems that occur when using an RPI ring (rest plate, I-bar clasp). The author first pointed out in the design features of the RPI ring: when the occlusal force acts on the base, the RPI clasp disengages from the abutment and prevents the displacement of the denture , Revealing less metal, no lingual arm does not come into contact with the flanks of the abutment tongue, which is designed to support teeth and free ends