torque removal evaluation of screw in one-piece and two-piece abutments tightened with a handheld screwdriver

introduction: some clinicians use a handheld screw driver instead of a torque wrench to definitively tighten abutment screws. the aim of this study was to compare the removal torque of one-piece and two-piece abutments tightened with a handheld driver and a torque control ratchet. methods: 40 iti implants were placed in acrylic blocks and divided into 4 groups. in groups one and two, 10 iti one-piece abutments (solid®) and in groups three and four, 10 iti two-piece abutments (synocta®) were placed on the implants. in groups one and three abutments were tightened by 5 experienced males and 5 experienced females using a handheld driver. in groups two and four abutments were tightened using a torque wrench with torque values of 10, 20 and 35 n.cm. insertion torque and removal torque values of the abutments were measured with a digital torque meter. results: the insertion torque values (itvs) of males in both abutments were significantly higher than those of females. itvs in both solid® and synocta® abutments tightened with a handheld screwdriver were similar to the torque of 20 n.cm in the torque wrench. removal torque values (rtvs) of solid® abutments were higher than those of synocta® abutments. conclusion: the one- piece abutments (solid®) showed higher rtvs than the two-piece abutments (synocta®). hand driver does not produce sufficient preload force for the final tightening of the abutment