患者，女，45岁，<img src="/Image1/0e/0e88feea35182bae1cb08823eb171304.jpg" />缺失，3年前曾单端固定桥修复，现因以<img src="/Image1/d2/d2e2e96daebe1457d1fff22ad1dbb3a5.jpg" />开面锤造冠为固位体的鞋端固定桥，固位体边缘与<img src="/Image1/d2/d2e2e96daebe1457d1fff22ad1dbb3a5.jpg" />颈缘有间隙，<img src="/Image1/d2/d2e2e96daebe1457d1fff22ad1dbb3a5.jpg" />牙龈区红肿、Ⅰ°松动，近中邻面龋坏有探痛就诊。且松动，可能的原因是（）<br>A:固位体与基牙不密合<br>B:<img src="/Image1/d2/d2e2e96daebe1457d1fff22ad1dbb3a5.jpg" />牙龈炎的表现<br>C:<img src="/Image1/d2/d2e2e96daebe1457d1fff22ad1dbb3a5.jpg" />设计不当，受力过大<br>D:制作不当<br>E:<img src="/Image1/d2/d2e2e96daebe1457d1fff22ad1dbb3a5.jpg" />牙髓炎的表现