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在临床牙冠较短的牙齿(例如(牙合)龈距仅3mm的后牙)上制作全冠是件颇具挑战性的工作。临床上可以用手术方式增长牙冠以增加牙体制备的垂直高度而得以改善。然而,患者常因为不舒适,或考虑到增加治疗时间及费用而拒绝手术治疗。相反,采取在牙体预备时使轴壁相互平行、制作沟及箱状洞等,均可增强固位及抗力。但是,这些措施对于牙冠较短的牙齿作用甚微。 (牙合)面洞是一种冠内固位形,可用于如下临床情况:①根管治疗后已作铸造或银汞合金核处理的牙。②髓腔凹窄的活髓牙。由于具有损伤牙髓的危险,髓腔较大的活髓牙禁止使用。 设计:①在进行常规的全冠牙体预备后,用6号圆钻预备一个(牙合)面洞,用柱形裂钻或平头锥形裂钻修整
Making a full crown on shorter clinical crowns (eg, posterior teeth with a gingival distance of only 3 mm) is a challenging job. Clinically, dental crowns can be surgically grown to increase the vertical height of dental preparation. However, patients are often denied surgery due to discomfort, or due to increased treatment time and costs. On the contrary, taken in the preparation of the teeth when the shaft wall parallel to each other, making grooves and box-shaped holes, etc., can enhance the retention and resistance. However, these measures have little effect on shorter crowns. (Occlusal) The hole is a crown-shaped retention, can be used for the following clinical conditions: â 'root canal treatment has been cast or amalgam nuclear treatment of teeth. ② Narrow pulp cavity live pulp teeth. Because of the danger of damaging the pulp, the vital pulp of the medullary cavity is forbidden to use. Design: ① After the conventional full crown preparation, prepare a (occlusal) face hole with No. 6 round diamond and trim it with a cylindrical or flathead cone