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Fractographic Failure analysis of a Procera AllCeram Using Stereo and Scanning Electron Microscopy



Susanne Scherrer, George D. Quinn, Janet Quinn


Objectives: Presentation of a methodological approach using stereo and scanning electron microscope examination to failure analysis of an alumina all-ceramic premolar crown (Procera AllCeram).Methods: The recovered part of a fractured Procera Alumina crown was examined utilizing first a stereomicroscope and second a scanning electron microscope (SEM). The stereomicroscope analysis was performed at low magnifications with oblique lightening in order to enhance spatial relationships and gross detection of crack features. A preliminary fracture surface map of the stereo observations was drawn which was used as a guide for the SEM analysis that followed. Specific sites of interest identified under the stereo microscope were analyzed by SEM at high magnifications searching for small fracture features such as wake hackle and twist hackle within the veneering ceramic in order to confirm the direction of crack propagation.a compression curl indicating the end of the fracture event as well as larger hackle lines distributed over the cracked surface. The higher magnifications with the SEM analysis of the sites of interest showed the presence of wake and twist hackle, indicators of the crack propagation direction. A general map of the fracture events could be reconstructed starting with a primary veneer edge chip at the mesial margin. Hackle and wake hackle of the crack front emanating from this margin were driven by hoop stresses and propagated through the full crown thickness towards the distal end of the restoration were the compression curl was located. Additional occlusal surface damage in form of veneer chipping containing arrest lines and twist hackle in opposite direction as the main crack path were observed but occurred as a secondary event without penetrating the alumina core material. Significance: Stereo and SEM are complementary analysis techniques useful for the mapping and interpretation of the fracture surface.
Dental Materials


dental restoratives, mechanical properties, microstructure


Scherrer, S. , Quinn, G. and Quinn, J. (2008), Fractographic Failure analysis of a Procera AllCeram Using Stereo and Scanning Electron Microscopy, Dental Materials, [online], (Accessed July 22, 2024)


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Created August 23, 2008, Updated October 12, 2021