For the narrow zirconia post space preparation (subgroup ZN)
For a standardized post space preparation and to ensure the similar and precise dimensions of both glass-fiber post and custom-made zirconia post, the same calibration drill of group GN was also used in ZN subgroup.No. 1 white calibration drill of 1.3 mm diameter was used to prepare a narrow post space, in respect of adjusting the drill’s length to 10 mm [