Immediately loaded blade implants. A histological and histomorphometrical evaluation after a long loading period. A restrospective 20 years analysis (1989-2009)

ABSTRACT Introduction: Although the presence of mineralized tissues at the interface with blade implants has been reported, the view that blade implants cannot integrate still persists. Blades are the immediately loaded implants with the longest clinical history, so their histological evaluation may give results applicable to root-form implants. The aim of the present retrospective study was a histological evaluation of the peri-implant tissues in immediately loaded human blade implants retrieved after a long loading history. Materials and method: The archives of the Implant Retrieval Center were retrospectively searched (1989-2009) to look for retrieved human blade implants. Only the blade implants that corresponded to the following inclusion criteria were analysed: 1) presence of healthy peri-implant soft tissues, with no bleeding on probing; 2) absence of mobility; 3) absence of pain upon percussion; 4) no signs of bone or soft tissue pathology at implant retrieval; 5) absence of a peri-implant radiolucency and radiographical presence of mineralized tissues; 6) fabrication and insertion of an interim implant-supported prosthesis on the day of implant surgery. Out of 85 retrieved blade implants found, only 31 met all the inclusion criteria and were retrieved for different causes, after a loading history varying from 2 to 23 years. Results: Histologically, bone was in close and tight contact with the implants surface and no gaps or connective fibrous tissues were present at the implant-bone interface. The peri-implant bone was compact, mature, with the presence of small marrow spaces and Haversian canals. Many osteons were in contact with the implant surface. Most Haversian systems ran perpendicular to the major axis of the blades. In some fields it was possible to observe the presence of a few osteoblasts. Remodeling areas were present. Mean bone to implant contact percentage was, for all 31 implants, 43 % +/- 5.2 %. Discussion and Conclusions: The present report showed that immediately loaded blade implants can achieve and maintain osseointegration under more than 20 years function.