【名词&注释】
接触面(interface)、体外受精(in vitro fertilization)、同源人工授精(artificial insemination by husband)、异源人工授精(artificial insemination by donor)、固位体(retainer)、无性生殖(asexual reproduction)、双端固定桥(rigidly fixed bridge)
[单选题]双端固定桥(rigidly fixed bridge)两端固位力不相等时会引起
A. 基牙疼痛
B. 基牙下沉
C. 固位体磨耗
D. 固位体松动、脱落
E. 固位体变形