title: Fracture strength and probability of survival of narrow and extra-narrow dental implants after fatigue testing: In vitro and in silico analysis.
abstract: 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.
authors.affiliation: Prosthodontics and Periodontology Department, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil; University of Guarulhos, Guarulhos, SP, Brazil; Department of Biomaterials and Biomimetics, New York University, College of Dentistry, New York, NY, USA. Electronic address: dimorvan_bordin@hotmail.com.
authors.forename: Dimorvan
authors.initials: D
authors.lastname: Bordin
authors.affiliation: Prosthodontics and Periodontology Department, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil; Department of Biomaterials and Biomimetics, New York University, College of Dentistry, New York, NY, USA.
authors.forename: Edmara T P
authors.initials: ETP
authors.lastname: Bergamo
authors.affiliation: Department of Biomaterials and Biomimetics, New York University, College of Dentistry, New York, NY, USA; Department of Prosthodontics and Periodontology, University of São Paulo - Bauru College of Dentistry, Bauru, SP, Brazil.
authors.forename: Vinicius P
authors.initials: VP
authors.lastname: Fardin
authors.affiliation: Department of Biomaterials and Biomimetics, New York University, College of Dentistry, New York, NY, USA.
authors.forename: Paulo G
authors.initials: PG
authors.lastname: Coelho
authors.affiliation: Department of Prosthodontics and Periodontology, University of São Paulo - Bauru College of Dentistry, Bauru, SP, Brazil.
authors.forename: Estevam A
authors.initials: EA
authors.lastname: Bonfante
mesh_terms: D003442:Crowns; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D007180:Incisor; D008422:Materials Testing; D011336:Probability; D015203:Reproducibility of Results; D013314:Stress, Mechanical
chemical_list: D015921:Dental Implants
keywords: Biomechanics; Fatigue; Narrow diameter dental implants; Reliability; Step-stress accelerated life-testing; Weibull