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Effect of Engaging Abutment Position in Implant‐Borne, Screw‐Retained Three‐Unit Fixed Cantilevered Prostheses
Author(s) -
Dogus Sitki M.,
Kurtz Kenneth S.,
Watanabe Ikuya,
Griggs Jason A.
Publication year - 2011
Publication title -
journal of prosthodontics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.902
H-Index - 60
eISSN - 1532-849X
pISSN - 1059-941X
DOI - 10.1111/j.1532-849x.2011.00714.x
Subject(s) - statistical significance , cantilever , mathematics , orthodontics , dentistry , materials science , implant , abutment , statistical analysis , fracture (geology) , composite material , structural engineering , medicine , surgery , statistics , engineering
Purpose: To investigate the effects of internally connected engaging component position in screw‐retained fixed cantilevered prostheses. Materials and Methods: Twenty‐one three‐unit fixed dental prostheses (FDPs) were cast in high‐palladium alloy in three groups. In group A, engaging components were incorporated into the units away from the cantilevered segment; proximal units received nonengaging components. In group B, these positions were reversed. Control specimens were fabricated using all nonengaging components. Specimens were attached to internally connected 3.5 (diameter) × 13 mm (length) implants, torqued to 32 Ncm, and embedded into epoxy resin. Specimens were tested in cyclic fatigue with a 2 Hz sine wave and 0.1 min/max load ratio. Load amplitude started at 1.8 N and increased by 1.8 N every 60 cycles until fracture. Log‐rank statistic, ANOVA, Spearman's correlation, and LIFETEST procedures were used to evaluate level of statistical significance within the results. Results: In the control group, the mean number of cycles to fracture was 31,205 ± 2639. Mean axial force at fracture was 932 ± 78 N. In group A, these numbers were 38,160 ± 4292 and 1138 ± 128 N, and in group B, 31,810 ± 3408 and 949 ± 101 N. Statistical significance levels for number of cycles to fracture were: Control versus group A, p = 0.0117, and groups A versus B, p = 0.0156 (statistically significant). Control versus group B, p = 0.357 (not statistically significant). Log‐rank statistic for the survival curves is greater than would be expected by chance; there was a statistically significant difference between survival curves ( p = 0.012). The location and mode of failure were noteworthy (always in the abutment screw). Conclusions: The position of the engaging component had significant effects on the results. Within the limitations of this investigation, it can be concluded that using an engaging abutment in a screw‐retained fixed cantilevered FDP provides a mechanical advantage, and engaging the implant furthest from the cantilever when designing a screw‐retained cantilever FDP increased resistance to fracture of the distal abutment screw.