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The International Journal of Oral & Maxillofacial Implants



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Int J Oral Maxillofac Implants 30 (2015), No. 6     23. Nov. 2015
Int J Oral Maxillofac Implants 30 (2015), No. 6  (23.11.2015)

Page 1256-1261, doi:10.11607/jomi.3868, PubMed:26574850

Torque Loss of Different Abutment Sizes Before and After Cyclic Loading
Moris, Izabela Cristina Maurício / Faria, Adriana Cláudia Lapria / Ribeiro, Ricardo Faria / Rodrigues, Renata Cristina Silveira
Purpose: The aim of this study was to compare 3.8- and 4.8-mm abutments submitted to simulations of masticatory cycles to examine whether abutment diameter and cemented vs screw-retained crowns affect torque loss of the abutments and crowns.
Materials and Methods: Forty implant/abutment sets were divided into the following groups (n = 10 in each group): (1) G4.8S included 4.8-mm abutment with screwretained crown; (2) G4.8C included 4.8-mm abutment with cemented crown; (3) G3.8S included 3.8-mm abutment with screw-retained crown; and (4) G3.8C included 3.8-mm abutment with cemented crown. All abutments were tightened with torque values of 20 Ncm, and 10 Ncm for screw-retained crowns. Torque loss was measured before and after cycling loading (300,000 cycles).
Results: Torque loss of screwretained crowns significantly increased after cycling in abutments of groups G3.8S (P ≤ .05) and G4.8S (P = .001). No difference was noted between the abutments before cycling (P = .735), but G3.8S abutments presented greater torque loss than the other groups after cycling (P = .008). Significant differences were noted in the abutment torque loss before and after cycling loading only for the G3.8C group (P ≤ .05).
Conclusion: The abutment diameter affects torque loss of screw-retained crowns and leads to failure during the test; mechanical cycling increases torque loss of abutment screw and screw-retained crowns.

Keywords: abutment, cycling loading, dental implants, torque