Methods: 18 internal hexagonal implants (6 for each type of abutment) were divided into three groups, 2-piece abutment (group 1), 1-piece abutment (group 2), and Screw abutment (group 3). Abutments were tightened by digital torque gauge and after 15 minutes, the reverse torque values were recorded.
Results: The mean reverse torque values of studied groups were as follows respectively: 20.65±1.92 N.cm, 37.88±4.28 N.cm, 30.76±3.92 N.cm, which showed a significant difference between three groups. The samples in group 3 showed the highest reverse torque values after group 2 and both were significantly higher than group 1 (P=0.000).
Conclusions: More surface area in implant -abutment connection causes more adaptation between adjacent surfaces and may increase the cold weld probability. Consequently, it may reduce screw abutment loosening.