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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Influence of Diamondlike Carbon Coating of Screws on Axial Tightening Force and Stress Distribution on Overdenture Bar Frameworks with Different Fit Levels and Materials

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Author(s):
Fernandes dos Santos, Mateus Bertolini [1] ; Bacchi, Atais [2] ; Xediek Consani, Rafael Leonardo [3] ; Correr-Sobrinho, Lourenco [3]
Total Authors: 4
Affiliation:
[1] Univ Fed Pelotas, Sch Dent, Pelotas, RS - Brazil
[2] Merid Fac, Sch Dent, Passo Fundo, RS - Brazil
[3] Univ Estadual Campinas, Piracicaba Dent Sch, Sao Paulo - Brazil
Total Affiliations: 3
Document type: Journal article
Source: INTERNATIONAL JOURNAL OF ORAL & MAXILLOFACIAL IMPLANTS; v. 30, n. 5, p. 1019-1027, SEP-OCT 2015.
Web of Science Citations: 3
Abstract

Purpose: The aim of this study was to evaluate the axial tightening force applied by conventional and diamondlike carbon (DLC)-coated screws and to verify, through three-dimensional finite element analysis (FEA), the stress distribution caused by different framework materials and prosthetic screws in overdenture frameworks with different misfit levels. Materials and Methods: The axial tightening force applied by the screw was evaluated by means of a titanium matrix connected to a load cell. Conventional titanium or DLC-coated screws were tightened with a digital torque wrench, and the load values were recorded. The values were applied in an FEA to a bar-clip attachment system connected to two 4.0 x 11-mm external-hexagon titanium implants placed in an anterior edentulous arch. DLC-coated and conventional screws were modeled with their respective axial forces obtained on the experimental evaluation for three bar framework materials (titanium, nickel-chromium, and cobalt-chromium) and three levels of misfit (100, 150, and 200 mu m). Von Mises stresses for prosthetic components and maximum principal stress and microstrains (maximum principal strains) for bone tissue were measured. Results: The mean force applied by the conventional screw was 25.55 N (+/- 1.78); the prosthetic screw coated with a DLC layer applied a mean force of 31.44 N (+/- 2.11), a statistically significant difference. In the FEA, the DLC screw led to higher stresses on the framework; however, the prosthetic screw suffered lower stress. No influence of screw type was seen in the bone tissue. Conclusion: Titanium frameworks reduced the stress transmitted to the bone tissue and the bar framework but had no influence on the screws. Higher misfit values resulted in an increased stress/strain in bone tissue and bar framework, which was not the case for retention screws. (AU)

FAPESP's process: 12/19374-5 - Influence of different prosthetic screws and framework material in the compensation of misfit in ill-fitted overdenture retaining bars with two implants.
Grantee:Mateus Bertolini Fernandes dos Santos
Support Opportunities: Scholarships in Brazil - Post-Doctoral