The effect of DLC-coating deposition method on the reliability and mechanical properties of abutment's screws

Dimorvan Bordin, Paulo G. Coelho, Edmara T.P. Bergamo, Estevam A. Bonfante, Lukasz Witek, Altair A. Del Bel Cury

Research output: Contribution to journalArticle

Abstract

Objective: To characterize the mechanical properties of different coating methods of DLC (diamond-like carbon) onto dental implant abutment screws, and their effect on the probability of survival (reliability). Methods: Seventy-five abutment screws were allocated into three groups according to the coating method: control (no coating); UMS – DLC applied through unbalanced magnetron sputtering; RFPA-DLC applied through radio frequency plasma-activated (n = 25/group). Twelve screws (n = 4) were used to determine the hardness and Young's modulus (YM). A 3D finite element model composed of titanium substrate, DLC-layer and a counterpart were constructed. The deformation (μm) and shear stress (MPa) were calculated. The remaining screws of each group were torqued into external hexagon abutments and subjected to step-stress accelerated life-testing (SSALT) (n = 21/group). The probability Weibull curves and reliability (probability survival) were calculated considering the mission of 100, 150 and 200 N at 50,000 and 100,000 cycles. Results: DLC-coated experimental groups evidenced higher hardness than control (p < 0.05). In silico analysis depicted that the higher the surface Young's modulus, the higher the shear stress. Control and RFPA showed β < 1, indicating that failures were attributed to materials strength; UMS showed β > 1 indicating that fatigue contributed to failure. High reliability was depicted at a mission of 100 N. At 200 N a significant decrease in reliability was detected for all groups (ranging from 39% to 66%). No significant difference was observed among groups regardless of mission. Screw fracture was the chief failure mode. Significance: DLC-coating have been used to improve titanium's mechanical properties and increase the reliability of dental implant-supported restorations.

Original languageEnglish (US)
Pages (from-to)e128-e137
JournalDental Materials
Volume34
Issue number6
DOIs
StatePublished - Jun 2018

Keywords

  • Abutment screw
  • Biomechanics
  • Fatigue
  • Reliability
  • Screw design
  • Step-stress accelerated life-testing
  • Weibull

ASJC Scopus subject areas

  • Materials Science(all)
  • Dentistry(all)
  • Mechanics of Materials

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