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Published on: December 20, 2024
Fracture analysis of one/two-piece clinically failed zirconia dental implants
Fei Zhang1, Mona Monzavi2, Maoyin Li3
1KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, B-3001 Leuven, Belgium`; KU Leuven, Department of Oral Health Sciences, BIOMAT - Biomaterials Research Group & UZ Leuven (University Hospitals Leuven), Dentistry, Kapucijnenvoer 7 block a, B-3000 Leuven, Belgium.
Objectives:
Analyzing factors that may have led to fracture of zirconia implants by macro/micro-fractography.
Methods:
Six one-piece and ten two-piece full-ceramic zirconia implants from two manufacturers, Z-Systems and CeraRoot, were retrieved after clinical failure. The time-to-failure ranged from 3 to 49 months. Optical and scanning electron microscopy (SEM) were used to analyze the fracture planes at the macro- and microscopic level. Treatment planning, surgical protocol, fracture-origin location and characteristic fracture features were assessed.
Results:
The fracture of all implants seemed to have been primarily due to overload in bending mode, while the fracture-initiation sites varied for the one- and two-piece implants. The fracture of all one-piece implants originated in the constriction region between two threads in the endosseous implant part. For two-piece implants, the abutment neck, internal abutment-implant connections and inner threads were found to be the main fracture-initiation sites. Surface defects at the root area for one-piece implants and damages at the abutment surface for two-piece implants were connected to the fracture origins. Importantly, the clinical failures of implants were often found to result from combined effects related to patient aspects, treatment planning/protocols, a high bending moment at the weakest link, implant-surface conditions and specific implant designs.
Significance:
This study provided information to be considered for future optimization of treatment planning and the surgical protocol for zirconia implants. Optimization of the surface conditions and the zirconia-starting powder were also suggested.
