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The effect of clockwise and counterclockwise twisting moments on abutment screw loosening
Author(s) -
Yao KuangTa,
Kao HungChan,
Cheng ChengKung,
Fang HsuWei,
Yip ShingWai,
Hsu MingLun
Publication year - 2012
Publication title -
clinical oral implants research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.407
H-Index - 161
eISSN - 1600-0501
pISSN - 0905-7161
DOI - 10.1111/j.1600-0501.2011.02282.x
Subject(s) - clockwise , abutment , perpendicular , materials science , implant , bending moment , orthodontics , dentistry , torque , structural engineering , mathematics , composite material , geometry , engineering , medicine , physics , rotation (mathematics) , surgery , thermodynamics
Objectives Abutment screw loosening is one of the most common complications of dental implants. When occlusal loading is applied, bending and twisting moments are counteracted by the implant‐abutment connection held with the abutment screw. Restorations in different quarters of the oral cavity might bear clockwise or counterclockwise twisting moments that result from a regular chewing pattern. The aim of this study was to investigate the effect of different directional twisting moments on abutment screws. Methods Twenty 3i implants were divided into four groups of C, R, L, and O. Each assembly consisted of an implant, abutment, and superstructure. For group C, a cyclic load of 10–100 N for 10 6 cycles was applied centrally and perpendicular to the long axis of the implant, whereas for groups R and L, the same load conditions were applied eccentrically in clockwise and counterclockwise directions, respectively. Group O was left unloaded. The difference between the initial torque and post‐load reverse torque was defined as the total torque loss. The data were analyzed by Kruskal–Wallis test. The surface of the abutment hexagon corners were examined with SEM after loading. Results No abutment screw loosening was found after loading. Total torque loss of groups C, R, L, and O were 10.50 ± 0.58, 9.56 ± 1.01, 9.98 ± 1.81, and 9.58 ± 0.94 Ncm, respectively. There were no statistical differences among the four groups. SEM observations showed marked burnishing at the hexagonal corners on the compression sides of the R and L groups. Conclusions Within the limitations of this study, there was little effect of twisting moment direction on the total torque loss of an internal hexagon connection implant system. This could be attributed to the anti‐twisting mechanism of the internal hexagon connection.