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Survival and failure modes: platform‐switching for internal and external hexagon cemented fixed dental prostheses
Author(s) -
Anchieta Rodolfo B.,
Machado Lucas S.,
Hirata Ronaldo,
Coelho Paulo G.,
Bonfante Estevam A.
Publication year - 2016
Publication title -
european journal of oral sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.802
H-Index - 93
eISSN - 1600-0722
pISSN - 0909-8836
DOI - 10.1111/eos.12298
Subject(s) - connection (principal bundle) , weibull distribution , abutment , orthodontics , dentistry , mathematics , materials science , geometry , medicine , structural engineering , engineering , statistics
This study evaluated the probability of survival (reliability) of platform‐switched fixed dental prostheses (FDPs) cemented on different implant–abutment connection designs. Eighty‐four‐three‐unit FDPs (molar pontic) were cemented on abutments connected to two implants of external or internal hexagon connection. Four groups ( n = 21 each) were established: external hexagon connection and regular platform (ERC); external hexagon connection and switched platform (ESC); internal hexagon and regular platform (IRC); and internal hexagon and switched platform (ISC). Prostheses were subjected to step‐stress accelerated life testing in water. Weibull curves and probability of survival for a mission of 100,000 cycles at 400 N (two‐sided 90% CI) were calculated. The beta values of 0.22, 0.48, 0.50, and 1.25 for groups ERC, ESC, IRC, and ISC, respectively, indicated a limited role of fatigue in damage accumulation, except for group ISC. Survival decreased for both platform‐switched groups (ESC: 74%, and ISC: 59%) compared with the regular matching platform counterparts (ERC: 95%, and IRC: 98%). Characteristic strength was higher only for ERC compared with ESC, but not different between internal connections. Failures chiefly involved the abutment screw. Platform switching decreased the probability of survival of FDPs on both external and internal connections. The absence in loss of characteristic strength observed in internal hexagon connections favor their use compared with platform‐switched external hexagon connections.