Calculated area of the last instrument used in each group and the difference in relation of the implant body area (without threads) and the external area of the implant with the threads.

Calculated area of the last instrument used in each group and the difference in relation of the implant body area (without threads) and the external area of the implant with the threads.各组末次使用器械的计算面积，以及种植体体部（无螺纹）面积与带螺纹种植体外表面面积的比值差异。