Marit Øilo1, Dwayne Arola2. 1. Department of Clinical Dentistry, Faculty of Medicine and Dentistry, University of Bergen, Norway; Department of Materials Science and Engineering, University of Washington Seattle, WA, USA. Electronic address: marit.oilo@iko.uib.no. 2. Department of Materials Science and Engineering, University of Washington Seattle, WA, USA; Departments of Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA, USA; Departments of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA, USA.
Abstract
BACKGROUND: Promising results of initial clinical trials with yttria-stabilized zirconia have led to more extensive use of zirconia in dental implant superstructures. The applications have extended to abutments and complex individually designed crown-abutment one-piece structures. Little is known about their clinical success and the primary cause of failures. PURPOSE: The aim of this study was to identify the cause of fracture of retrieved implant-retained one-piece prostheses that failed during clinical use. METHODS: Nine fractured restorations were analyzed with fractographic methods and their fracture origins were identified. RESULTS: All but two of the fractures originated in an area of tight contact between the implant or titanium screw and the abutment base. Results of the evaluation showed that zirconia-based implant restorations with very thin walls in the region connecting the prosthesis to the implant are vulnerable to damage from the screw retaining process and fracture from non-axial loads. Two restorations failed due to veneer fractures. SIGNIFICANCE: The findings suggest that large crowns on narrow implants or implants with internal fixation should preferably not be made with zirconia abutments, or that a new design approach should be considered.
BACKGROUND: Promising results of initial clinical trials with yttria-stabilized zirconia have led to more extensive use of zirconia in dental implant superstructures. The applications have extended to abutments and complex individually designed crown-abutment one-piece structures. Little is known about their clinical success and the primary cause of failures. PURPOSE: The aim of this study was to identify the cause of fracture of retrieved implant-retained one-piece prostheses that failed during clinical use. METHODS: Nine fractured restorations were analyzed with fractographic methods and their fracture origins were identified. RESULTS: All but two of the fractures originated in an area of tight contact between the implant or titanium screw and the abutment base. Results of the evaluation showed that zirconia-based implant restorations with very thin walls in the region connecting the prosthesis to the implant are vulnerable to damage from the screw retaining process and fracture from non-axial loads. Two restorations failed due to veneer fractures. SIGNIFICANCE: The findings suggest that large crowns on narrow implants or implants with internal fixation should preferably not be made with zirconia abutments, or that a new design approach should be considered.
Authors: João P M Tribst; Amanda M O Dal Piva; Alexandre L S Borges; Lilian C Anami; Cornelis J Kleverlaan; Marco A Bottino Journal: Materials (Basel) Date: 2020-04-16 Impact factor: 3.623