根面龋最易找到的细菌是
A．乳杆菌
B．螺旋体
C．放线菌
D．范永菌
E．变形链球菌
参考答案：C
解析： 放线菌是人口腔正常菌丛中最常见的革兰阳性丝状菌，粘性放线菌促进变形链球菌定殖于根面，对根面菌斑形成根面龋的发生可能有重要的协同作用；乳杆菌使口腔的正常菌群，它可能不是龋病发生的初始致病菌，但参与龋病的发展，可能是导致牙本质龋、根面龋发展的致龋菌之一；变形链球菌有强的致龋性，它不仅是冠部龋病的主要致病龋，也是根部的主要致病龋。综上所述，答案为C。
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