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DOI

10.1016/j.jds.2012.09.006

First Page

8

Last Page

14

Abstract

Abstract Background/purpose This study investigated in seven patients the main causes of accidental fractures of various implant components. Materials and methods We used a scanning electron microscope and transmission electron microscope to observe the fracture interfaces of four fixtures, six abutment screws, and nine gold screws retrieved from patients with prosthetic problems. Results In all fixtures and some abutment screws, parafunctional force and a cantilever design ultimately resulted in movement of low-angle grain boundaries (LAGBs) at most fracture surfaces. Fractographic observations showed that overloading deformed the grain sizes, and the no precipitates were present on the high-angle grain boundaries (HAGBs) or matrices of some abutment screws and most gold screws. Conclusion To avoid implant fracture, certain underlying mechanical risk factors should be noted such as patients with a habit of bruxism, bridgework with a cantilever design, or two implants installed in a line in the posterior mandible.

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