Fracture strength and probability of survival of narrow and extra-narrow dental implants after fatigue testing: In vitro and in silico analysis

• Published in: Journal of the mechanical behavior of biomedical materials 2017-07, Vol.71, p.244-249
• Main Authors: Bordin, Dimorvan, Bergamo, Edmara T.P., Fardin, Vinicius P., Coelho, Paulo G., Bonfante, Estevam A.
• Format: Article
• Language: English
• Subjects: Biomechanics; Crowns; Dental Implants; Dental Prosthesis Design; Dental Restoration Failure; Dental Stress Analysis; Fatigue; Humans; Incisor; Materials Testing; Narrow diameter dental implants; Probability; Reliability; Reproducibility of Results; Step-stress accelerated life-testing; Stress, Mechanical; Weibull
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2017.03.022

To assess the probability of survival (reliability) and failure modes of narrow implants with different diameters. For fatigue testing, 42 implants with the same macrogeometry and internal conical connection were divided, according to diameter, as follows: narrow (Ø3.3×10mm) and extra-narrow (Ø2.9×10mm) (21 per group). Identical abutments were torqued to the implants and standardized maxillary incisor crowns were cemented and subjected to step-stress accelerated life testing (SSALT) in water. The use-level probability Weibull curves, and reliability for a mission of 50,000 and 100,000 cycles at 50N, 100, 150 and 180N were calculated. For the finite element analysis (FEA), two virtual models, simulating the samples tested in fatigue, were constructed. Loading at 50N and 100N were applied 30° off-axis at the crown. The von-Mises stress was calculated for implant and abutment. The beta (β) values were: 0.67 for narrow and 1.32 for extra-narrow implants, indicating that failure rates did not increase with fatigue in the former, but more likely were associated with damage accumulation and wear-out failures in the latter. Both groups showed high reliability (up to 97.5%) at 50 and 100N. A decreased reliability was observed for both groups at 150 and 180N (ranging from 0 to 82.3%), but no significant difference was observed between groups. Failure predominantly involved abutment fracture for both groups. FEA at 50N-load, Ø3.3mm showed higher von-Mises stress for abutment (7.75%) and implant (2%) when compared to the Ø2.9mm. There was no significant difference between narrow and extra-narrow implants regarding probability of survival. The failure mode was similar for both groups, restricted to abutment fracture. [Display omitted] •Narrow and extra-narrow dental implants have shown similar probability of survival.•Both implant diameters can be a reliable option to replace incisors and premolars.•Narrow and extra-narrow implants should be avoided in the posterior region.•Failures predominantly involved abutment fracture regardless implant diameter.•The stress peak concentration in the virtual model was comparable to the SSALT.