Survival and failure modes: platform-switching for internal and external hexagon cemented fixed dental prostheses.
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.
Department of Dentistry, Centro Universitário do Norte Paulista, São José do Rio Preto, SP, Brazil.
Rodolfo B
RB
Anchieta
Department of Operative Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Lucas S
LS
Machado
Department of Biomaterials and Biomimetics, New York University, New York, NY, USA.
Ronaldo
R
Hirata
Department of Biomaterials and Biomimetics, New York University, New York, NY, USA.
Paulo G
PG
Coelho
Department of Prosthodontics and Periodontology, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil. estevam.bonfante@fob.usp.br.
Estevam A
EA
Bonfante
D003442:Crowns; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D015203:Reproducibility of Results
D015921:Dental Implants
Weibull; dental implant; fatigue; fixed dental prostheses; fractography