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(二)杆形卡: 杆形卡是从牙龈方向进入基牙倒凹区,产生一种推式的固位。所以杆形卡在就位时比较容易,而在取下时则比较困难。如果所有在一些因素都相同时(如卡环臂的长度、弹性、倒凹的深度等,则杆形卡的固位作用比圆周形卡大,而且更美观,缺点是容易使食物滞留,由于弹性较大所以稳定作用较差。杆形卡的设计要求:杆形卡的连接体不应压迫软组织,又不能越过软组织的倒凹区否则会引起食物滞留,连接体经过牙龈边缘时应与龈缘成90°角,尽可能少刺激牙龈。
(B) rod-shaped card: rod-shaped card is from the gingival direction into the abutment inverted concave area, resulting in a push-type retention. Therefore, the rod-shaped card in place is easier, and when it is more difficult to remove. If all the sticking effect of the rod-shaped card is larger and more aesthetically pleasing than that of the circumferential shape card when all the factors are the same (such as the length of the snap ring arm, the elasticity, the depth of the undercut, etc.), the disadvantage is that the food is liable to stagnate due to Greater flexibility so poor stability. Rod-shaped card design requirements: rod-shaped card connector should not be oppression of soft tissue, but also can not be crossed over the soft tissue of the undercut area or cause food retention, the body through the gingival margin should be gingiva Edge into a 90 ° angle, as little as possible to stimulate the gums.