Failure probability, stress distribution and fracture analysis of experimental screw for micro conical abutment

Antonio Braulino de Melo Filho, João Paulo Mendes Tribst, Nathália de Carvalho Ramos, Julio Nogueira Luz, Maria Aparecida Neves Jardini, Alexandre Luiz Souto Borges, Mauro Pedrine Santamaria, Renata Marques de Melo

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


The aim of this study was to evaluate the failure probability of two types of abutment screws after compressive load and to analyze the stress distribution with finite element method. Sixty (60) single-tooth implant restorations were assembled on titanium implants (e-fix, A.S. Technology – Titanium Fix). The groups were divided into Conventional screw (Screw neck 1.5 ø mm) and Experimental screw (Screw neck constricted with 1.2 ø mm). Specimens were subjected to single load to failure with compressive test according ISO 14801. The fractured specimens were subjected to stereomicroscopy for measurement of remaining screws inside the implant and characterization of fracture origin. Representative specimens were analyzed by scanning electronic microscopy. For finite element method (FEM), an identical 3D model of the two in vitro test groups were used with similar conditions (30º, 100 N load). The stress in the abutment screw was analyzed by von-Mises criteria. The results of strength means were 4132.5 ± 76 MPa and 4528.2 ± 127.2 for conventional and experimental groups, respectively. During microscopy, the mean (mm) of the remaining screw piece inside the implants were 0.97 ± 0.23 and 1.32 ± 0.12 for conventional and experimental groups, respectively. In FEM, the conventional group showed stress concentered in an unfavorable region (peak of 39.23 MPa), while the experimental group showed more stress areas but less concentration than the conventional group (36.6 MPa). In using the tested experimental geometry, the abutment screw can have its strength improved, and the origin of failure can be more favorable to clinical resolution.

Original languageEnglish
Pages (from-to)157-163
Number of pages7
JournalBrazilian Dental Journal
Issue number2
StatePublished - Mar 1 2019

Bibliographical note

Funding Information:
The authors acknowledge the Research Foundation of the State of São Paulo (FAPESP - Grant 13/17733-0)

Publisher Copyright:
© 2019, Associacao Brasileira de Divulgacao Cientifica. All rights reserved.


  • Abutment screw loosening
  • Dental implant
  • Finite element analyses
  • Weibull analysis

ASJC Scopus subject areas

  • Dentistry (all)


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