The effect of DLC-coating deposition method on the reliability and mechanical properties of abutment's screws.
Dent Mater 2018;
34:e128-e137. [PMID:
29653724 DOI:
10.1016/j.dental.2018.03.005]
[Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 01/20/2018] [Accepted: 03/12/2018] [Indexed: 12/26/2022]
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 200N 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 100N. At 200N 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.
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