逆行性牙髓炎的患牙能否保留，主要取决于（）
A.牙槽骨吸收程度
B.牙龈炎症程度
C.牙周袋深度
D.牙疼痛程度
E.牙髓无活力
参考答案：C
解析：1.逆行性牙髓炎的患牙能否保留，主要取决于该牙牙周病变的程度和牙周治疗的预后。 2.特征①牙髓无活力或活力异常。②牙周袋和根分叉病变局限于个别牙。③与根尖病变相连的牙槽骨破坏，呈烧瓶形，邻牙的牙周组织基本正常或病变轻微。
| 完形填空。 | ||||
| There was a woman in Detroit, who has two sons. She was worried about them, especially the younger one, Ben, __1__ he was not doing well in school. Boys in his class made jokes about him because he seemed so __2___. The mother decided that she would, herself, have to get her sons to do better in school. She told them to go to the Detroit Public Library to read a __3___ a week and do a report about it for her. One day, in Ben's __4___, the teacher held up a rock and asked if anyone knew it. Ben put up his hand and the teacher let him ___5__. "Why did Ben raise his hand?" they wondered. He __6__ said anything; what could he possibly want to say? Well, Ben not only _7___ the rock; he said a lot about it. He named other rocks in its group and even knew __8___ the teacher had found it. The teacher and the students were __9__. Ben had learned all this from doing one of his book __10___. Ben later went on to the __11__ of his class. When he finished high school, he went to Yale University and at last became one of the best doctors in the United States. After Ben had grown up, he _12__ something about his mother that he did not know as a _13___. She, herself, had never learned how to __14__. | ||||
|