CASE REPORT Peri-implant bone tissues around retrieved human implants after time periods longer than 5 years: a retrospective histologic and histomorphometric evaluation of 8 cases Giovanna Iezzi • Adriano Piattelli • Carlo Mangano • Jamil A. Shibli • Giovanni Vantaggiato • Massimo Frosecchi • Claudio Di Chiara • Vittoria Perrotti Received: 19 September 2011 / Accepted: 4 August 2012 Ó The Society of The Nippon Dental University 2012 Abstract Only rarely, it is possible to find in the litera- ture histological reports of human retrieved implants, especially after several years of functional loading. These implants can help us in understanding the reactions of peri- implant bone. The aim of this study was to perform a histologic and histomorphometric analysis of the peri- implant tissues behavior and of the bone–titanium interface in titanium dental implants retrieved from patients after time periods longer than 5 years. The archives of the Implant Retrieval Center of the Dental School of the University of Chieti-Pescara, Italy were searched for human dental implants, retrieved after a loading period of more than 5 years. A total of 8 implants were found: 3 of these had been retrieved after 5 years, 1 after 6 years, one after 10 years, 1 after 14 years, 1 after 18 years, 1 after 22 years. Only the bone to implant contact in the three best threads was evaluated. Compact, mature, lamellar bone, with few and small marrow spaces, was present around the implants. Osteons with Haversian canals were present inside some threads, in close proximity to the interface, at both cortical and trabecular regions. Other osteons had a direction perpendicular to the direction of the long axis of the implants. Numerous reversal lines were present. At higher magnification, no gaps or fibrous, connective tissues were present at the interface. The BIC of the three best threads for all implants varied from 94 to 100 %.In con- clusion, within the limitations of the present report histol- ogy showed that implants with different surfaces all presented the potential to maintain osseointegration over a long period, with a continuous remodeling at the interface, as indicated by the presence of reversal lines. Keywords Bone remodeling Á Human histology Á Implant surfaces Á Retrieved dental implants Introduction Retrieved implants are usually removed for failure [1]. Reasons for retrieval of osseointegrated and clinically stable implants are varied, i.e. fractures, psychological reasons, implants impossible to restore prosthetically, dysesthesia, or implants retrieved at autopsy [2–4]. In almost all of these cases, the retrieved implants have an excellent bone anchorage [2–4]. These implants can help us in under- standing the reactions of peri-implant bone [2–4]. The evi- dence quality of in vitro and experimental animal studies, performed for the evaluation of different implant macroge- ometries, surface topographies, loading conditions, implant insertion in different bone qualities and quantities, is G. Iezzi Á A. Piattelli (&) Á V. Perrotti Dental School, University of Chieti-Pescara, Via Dei Vestini 31, 66100 Chieti, Italy e-mail: apiattelli@unich.it G. Iezzi e-mail: gio.iezzi@unich.it C. Mangano Private Practice, Gravedona (Como), Italy J. A. Shibli Department of Periodontology, Dental Research Division, Guarulhos University (UnG), Guarulhos, SP, Brazil G. Vantaggiato Private Practice, Lecce, Italy M. Frosecchi Private Practice, Florence, Italy C. Di Chiara Private Practice, Venice, Italy 123 Odontology DOI 10.1007/s10266-012-0084-z