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The resistance to fracture and the phase stability of Y-TZP implant abutments were susceptible to hydrothermal and mechanical conditions. The surface microstructure of Y-TZP abutments did not change after aging conditions.
For a long time, different approaches to minimize the dimensional ridge alteration following tooth extraction have been described even though none of them was capable to avoid alveolar bone loss. The Socket-Shield Technique (SST) seems to be an alternative for alveolar bone preservation in dental extraction planning. This technique conventionally uses a flapless approach and the buccal root portion retention to prevent bone loss. This case report describes the SST with an early implant placement in a patient who presented the nonrestorable tooth # 15 due to the extensive cavity. After six months of the implant placement a porcelain-fused-to-metal crown was fabricated and screwed into the implant with a satisfactory esthetic and functional result. The SST is a non-invasive and effective approach to tooth extraction and rehabilitation, especially in the aesthetic zone. Approximately two-year follow-up shows a satisfactory aesthetic maintenance.
Yttria-stabilized tetragonal zirconia (Y-TZP) was introduced as ceramic implant abutments due to its excellent mechanical properties. However, the damage patterns for Y-TZP abutments are limited in the literature. Fractographic analyses can provide insights as to the failure origin and related mechanisms. The purpose of this study was to analyze fractured Y-TZP abutments to establish fractographic patterns and then possible reasons for failure. Thirty two prefabricated Y-TZP abutments on external hex implants were retrieved from a single-load-to failure test according to the ISO 14801. Fractographic analyses were conducted under polarized-light estereo and scanning electro microscopy. The predominant fracture pattern was abutment fracture at the connecting region. Classic fractographic features such as arrest lines, hackle, and twist hackle established that failure started where Y-TZP abutments were in contact with the retention screw edges. The abutment screw design and the loading point were the reasons for localized stress concentration and fracture patterns.
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