A 由于牙槽嵴的吸收,基托组织面与组织间不密合 B
两侧后牙排列在牙槽嵴顶的外侧,咬合时以牙槽嵴为支点或上颌硬区为支点,造成基托左右翘动 C
前伸<img border="0" alt="" src="https://img.weimei168.com/uploads/upimg/20230104/2860011_0.jpg">、侧方<img border="0" alt="" src="https://img.weimei168.com/uploads/upimg/20230104/2860011_0_1.jpg">不平衡 D
牙尖早接触或牙尖干扰 E
以上都是