Influence of misfit direction and abutment type on torque loss and fracture strength of implant-supported fixed dental prostheses
10.4047/jap.2025.17.6.380
- Author:
Vygandas RUTKŪNAS
1
;
Maisa HAIEK
;
Daniel KULES
;
Liudas AUŠKALNIS
;
Ieva GENDVILIENE
;
Ingrida MISCHITZ
;
Tan Fırat EYÜBOĞLU
;
Mutlu ÖZCAN
Author Information
1. Department of Prosthodontics, Institute of Odontology, Faculty of Medicine, Vilnius University, Vilnius, Lithuania
- From:The Journal of Advanced Prosthodontics
2025;17(6):380-391
- CountryRepublic of Korea
- Language:English
-
Abstract:
PURPOSE:. This study aimed to evaluate the effects of fatigue and misfit on the reverse torque, load-bearing capacity, and failure modes of cemented and screwretained two-implant-supported fixed dental prostheses (FDPs).
MATERIALS AND METHODS:. Eighty CAD-CAM zirconia frameworks with porcelain veneering were assigned to three groups based on engaging (E) and non-engaging (N) abutment configurations: N-N, N-E, and E-E. Misfit scenarios included a control cast and 100 μm horizontal or vertical misfits. Frameworks were mounted on implants as screw-retained or cement-retained 3-unit FDPs, forming seven test groups and one control group (n = 10). Reverse torque was measured before and after thermomechanical cycling, followed by maximum failure load (Fmax) testing and failure mode analysis. Fmax was evaluated using two-way ANOVA, and reverse torque using mixed-effects ANOVA accounting for engagement, misfit, and implant position (α = 0.05).
RESULTS:. No significant differences in Fmax were observed across zirconia specimen groups or engagement configurations under various misfit conditions (P > .05). Engagement configuration did not significantly impact fracture strength or reverse torque (P = .421). A significant difference was found in the horizontal misfit group compared to controls (P < .001). Reverse torque values differed between distal (13.5 ± 0.5 Ncm) and mesial implants (18.6± 0.5 Ncm) (P = .000), suggesting distal implants may be more prone to preload loss and mechanical issues.
CONCLUSION:. The engagement configuration of implants did not significantly affect reverse torque, fracture strength, or failure modes of cemented and screw-retained restorations, although horizontal misfit reduced load-bearing capacity.
