影响藻酸盐印模材料凝固的因素是_________。
全口固定桥的基牙预备已完成，用缩合型硅橡胶取印模，并灌制一个主模型。桥体的金属支架戴在模型上很合适，但在所有基牙上不合适。这是印模材料的问题吗？如何解决？是什么原因造成这一问题？
Syneresis refers to()
A. the expansion ofa hydrocolloid impression material when it takes in water
B. the contraction of a hydrocolloid impression material when it exudes water
C. the fact that the sol and gel temperatures ofthe hydrocolloid differ
D. the inclusion ofpowder in a hydrocolloid impression material
Which of the following impression materials set by physical means()
A. agar
B. ZOE
C. alginate
D. addition silicone
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