Misfit is unavoidable in dental implant-supported prostheses due to machining process or inappropriate assembling, and the definition of an admissible misfit is still a controversial issue. This work aims to understand the behavior of the screws in dental implant-supported prostheses to estimate an admissible vertical misfit value in terms of screw fatigue failure. For that purpose, a finite element model of a dental implant-supported prosthesis was created and analyzed. Vertical misfits were introduced in different positions, the lower and upper screws were tightened to the bolting force values recommended by the manufacturer, and two different occlusal loads were analyzed. In addition, two different prosthesis materials were studied. Screw load variations were reported and a fatigue analysis was performed. As a result, it was observed that the screw tightening sequence closed small vertical misfits (equal to or less than 40 µm), whereas larger misfits (more than 40 µm) remained open. If the vertical misfit is closed by the end of the tightening sequence, it may be considered equivalent to the ideal fit situation in regard to screw fatigue failure. The prosthesis material had no significant influence on the fatigue behavior.
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http://dx.doi.org/10.1177/0954411918806325 | DOI Listing |
Sci Rep
December 2024
Department of Geophysics, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.
Accurate characterisation of seismic source mechanisms in mining environments is crucial for effective hazard mitigation, but it is complicated by the presence of anisotropic geological conditions. Neglecting anisotropic effects during moment tensor (MT) inversion introduces significant distortions in the retrieved source characteristics. In this study, we investigated the impact of ignoring anisotropy during MT inversion on the reliability of hazard assessment.
View Article and Find Full Text PDFSci Rep
December 2024
Earth Observatory of Singapore, Nanyang Technological University, Singapore, 639798, Singapore.
Coastal populations are susceptible to relative sea-level (RSL) rise and accurate local projections are necessary for coastal adaptation. Local RSL rise may deviate from global mean sea-level rise because of processes such as geoid change, glacial isostatic adjustment (GIA), and vertical land motion (VLM). Amongst all factors, the VLM is often inadequately estimated.
View Article and Find Full Text PDFJ Esthet Restor Dent
December 2024
Analysis of Techniques, Material and Instruments Applied to Digital Dentistry and CAD/CAM Procedures Research Group, University Complutense of Madrid, Madrid, Spain.
Objective: This clinical case describes a multidisciplinary retreatment of a patient with anterior fixed dental prostheses (FDPs) using minimally invasive restorations and a biologically oriented preparation technique (BOPT).
Clinical Considerations: A 56-year-old female patient, treated 30 years ago with a metal-ceramic FDP due to dental agenesis, presented a misfit prosthesis at the gingival margin, black spaces, and food retention at the pontics. Notably, tooth number 2.
Am J Dent
October 2024
Department of Dental Materials and Prosthesis, School of Dentistry of Ribeirao Preto, University of São Paulo (USP), Ribeirao Preto, SP, Brazil.
Purpose: To evaluate the marginal and internal misfit of fixed partial denture zirconia frameworks developed from conventional impression and intraoral scanning, before and after being subjected to the thermal cycle of the covering ceramic.
Methods: A three-elements fixed partial denture was prepared, molded, and poured with polyurethane. Group CI (n= 7) was impressed by the conventional technique with polyvinyl siloxane material, and the plaster models scanned on the inEosX5 bench scanner.
Clin Implant Dent Relat Res
December 2024
Department of Preventive Dental Sciences, College of Dentistry, Prince Sattam bin Abdulaziz University, Alkharj, Saudi Arabia.
Purpose: The objective of this study was to assess the surface micro-roughness and abutment adaptation of selective laser melting (SLM) implant abutments in comparison to cast and machined implant abutments.
Methods: Forty abutment specimens were divided equally into four groups according to the fabrication technique as follows (n = 10), Machined Ti alloy abutments (Control), Cast CoCr abutments, SLM-CoCr abutments, and SLM-Ti alloy abutments. Forty internal connection implants (Ø 4.
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