Capodiferro S, Favia G, Scivetti M, De Frenza G, Grassi R
Department of Dental Sciences and Surgery, University of Bari-Italy, Bari, Italy.
Head Face Med. 2006 Jun 22;2:18. doi: 10.1186/1746-160X-2-18.
Osseointegrated endosseous implants are widely used for the rehabilitation of completely and partially edentulous patients, being the final prosthodontic treatment more predictable and the failures extremely infrequent. A case of fracture of an endosseous dental implant, replacing the maxillary first molar, occurring in a middle-age woman, 5 years after placement is reported.
The difficult management of this rare complication of implant dentistry together with the following rehabilitation is described. Additionally, the authors performed an accurate analysis of the removed fractured implant both by the stereomicroscope and by the confocal laser scanning microscope.
The fractured implant showed the typical signs of a fatigue-induced fracture in the coronal portion of the implant together with numerous micro-fractures in the apical one. Three dimensional imaging performed by confocal laser scanning microscope led easily to a diagnosis of "fatigue fracture" of the implant. The biomechanical mechanism of implant fractures when overstress of the implant components due to bending overload is discussed.
When a fatigue-induced fracture of an dental implant occurs in presence of bending overload, the whole implant suffers a deformation that is confirmed by the alterations (micro-fractures) of the implant observable also in the osseointegrated portion that is easily appraisable by the use of stereomicroscope and confocal laser scanning microscope without preparation of the sample.
骨结合式牙种植体广泛应用于全口和部分牙列缺失患者的修复，是最终的修复治疗中更可预测且失败率极低的方法。本文报道了一例发生在中年女性身上的上颌第一磨牙种植体折断病例，该种植体植入5年后出现折断。
描述了这种牙种植罕见并发症及其后续修复的棘手处理情况。此外，作者通过体视显微镜和共聚焦激光扫描显微镜对取出的折断种植体进行了精确分析。
折断的种植体在其冠部呈现出典型的疲劳性骨折迹象，根尖部分也有大量微骨折。共聚焦激光扫描显微镜进行的三维成像很容易诊断出种植体的“疲劳骨折”。文中讨论了由于弯曲过载导致种植体部件应力过大时种植体骨折的生物力学机制。
当牙种植体在存在弯曲过载的情况下发生疲劳性骨折时，整个种植体会发生变形，这可通过在骨结合部分观察到的种植体改变（微骨折）得到证实，使用体视显微镜和共聚焦激光扫描显微镜无需对样本进行处理即可轻松评估这些改变。
