The primary objective of this study was to determine the torsion resistance of the Ball Head System (BHS) screw and screwdriver set at 0°, 20°, and 30° angulations. The secondary objective was to compare the BHS set with the 1.3-mm hexagonal screwdriver system (HexS) at 20° and analyze the condition of the BHS after 10 and 30 iterations with 30 N·cm torque at 30° angulation. A workbench made from type 4 plaster with 6 steel implant replicas (external hexagon, 4.1 mm) inserted at 0°, 20°, and 30° angulation was designed. An analogical torque meter was used. The deformations produced on the whole set were examined by field emission scanning electron microscopy. A descriptive analysis was performed. The maximum torque performance for BHS at 30° angulation was 54 ± 12 N·cm. Most screws could be removed despite the deformations produced. At 20° angulation, the BHS set achieved an average torque resistance of 67 ± 12 N·cm, whereas the HexS failed at 45 ± 2 N·cm. Although the iterations performed at 30 N·cm torque and 20° angulation produced some deformations on BHS sets; these could be tightened and unscrewed. The BHS allows tightening at a torque of up to 54 N·cm. Under the same conditions, BHS showed more torque resistance than HexS. Deformation of BHS sets was directly related to the number of iterations.
Keywords: angled screw channels; ball head screw; screw-retained prostheses; screwdriver; torsion resistance.