Periimplant Bone Response in Human-Retrieved, Clinically Stable, Successful, and Functioning Dental Implants After a Long-Term Loading Period: A Report of 17 Cases From 4 to 20 Years.

OBJECTIVE: This study aimed at a histologic and histomorphometric analysis of the periimplant tissues and bone-titanium interface reactions in successfully osseointegrated, clinically stable, and immobile human titanium dental implants retrieved after a long loading period. MATERIALS AND METHODS: In the last 30 months (2013-2015), 21 implants, retrieved from individuals for different causes after a loading period ranging from 4 to 20 years, were sent to the Implant Retrieval Center, University of Chieti-Pescara, Italy. In 4 cases, almost all the bone had been lost during the retrieval, whereas in the remaining 17 cases, mineralized bone was still present. RESULTS: Around the majority of the implants, mature compact bone with few marrow spaces was found. The trabecular bone, constituted by a few thin bone trabeculae, was in a periimplant location around only a few implants. A high percentage of bone-implant contact (BIC) (comprised between 32 ± 4.1% and 83 ± 2.9%) was present. In almost all implants, the space within the threads was almost completely filled by compact lamellar bone or by a thin layer of bone. Close and tight contact between bone and implant surface was observed in all specimens with no gaps or connective tissue at the interface. CONCLUSIONS: All implants appeared to be well integrated in the surrounding mineralized bone, and all of them showed adequate bone-to-implant contact percentages.

Peri-implant bone tissues around retrieved human implants after time periods longer than 5 years: a retrospective histologic and histomorphometric evaluation of 8 cases.

Only rarely, it is possible to find in the literature 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 conclusion, within the limitations of the present report histology 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.

An in vitro investigation concerning the bacterial leakage at implants with internal hexagon and Morse taper implant-abutment connections.

PURPOSE: To evaluate, in vitro, the leakage observed in internal hexagon and Morse taper implant-abutment connections. MATERIALS: Ten specimens with internal hexagon and 10 with Cone Morse connection were used. The inner parts of 5 implants, per group, were inoculated with Pseudomonas aeruginosa (PS) suspension and 5 implants, per group, with Aggregatibacter actinomycetemcomitans (AA). The penetration of bacterial suspension into the surrounding solution was determined by observation of turbidity of the broth. RESULTS: In the internal hexagon implants, bacterial contamination was found in 2 of 5 implant-abutment assemblies seeded with the PS, and in the assemblies seeded with AA, the contamination was found in 3 samples, with a total of leaked assemblies in this group in 5 of 10. In the Cone Morse implants, bacterial contamination was found in 2 of 5 implant-abutment assemblies seeded with the PS, whereas in the assemblies seeded with AA, no contamination was found, with a total of leaked assemblies in 2 of 10. CONCLUSION: The data support a not significantly higher permeability to bacterial leakage and a lower infiltration rate of screw-retained abutment connections when compared to Cone Morse taper internal connections.

Histologic and histomorphometric report of three immediately loaded screw implants retrieved from man after a three-year loading period.

PURPOSE: The aim of the present study, in man, was an histologic and histomorphometric analysis of the peri-implant tissues in 3 immediately loaded screw implants retrieved, because of fracture, after a 3 year loading period. RESULTS: Mineralized tissue was present at the interface of all implants. The mean bone to implant contact percentage for the 3 implants was 56.3% +/- 5%. The histologic and histomorphometric data showed that mineralized tissues can be obtained in immediately loaded screw implants and that these mineralized tissues are maintained over a period of 3 years. The response of the osseous tissue was not disturbed by the stresses and strains transmitted at the interface. CONCLUSION: A high primary stability, obtained by the large threads of the screw-shaped implant, was probably a key factor in the long-term maintenance of a mineralized bone interface. The primary stability helps to resist micromotion, i.e., the relative movements between the implant surface and surrounding bone during functional loading.

Bone response to dental implants after a 3- to 10-year loading period: a histologic and histomorphometric report of four cases.

The aim of this study was to histologically and histomorphometrically analyze the peri-implant tissue reactions and the bone-titanium interface in loaded Ankylos implants retrieved after loading periods of longer than 1 year. The archives of the Implant Retrieval Center of the Dental School of the University of Chieti- Pescara were searched for Ankylos implants retrieved from humans after a loading period of longer than 1 year. A total of four implants were found: one had been retrieved after 3 years (Friadent plus surface), two after 3.5 years (Friadent plus surface), and one after 10 years (Deep Profile surface). All implants had been loaded; two had been loaded immediately. One implant was retrieved after fracture, one was retrieved after fracture of the superstructure, and the other two were retrieved because of bone resorption with or without infection. Compact bone with few small marrow spaces was present around the three implants retrieved after 3 and 3.5 years; trabecular bone was present around the implant retrieved after 10 years. The bone-implant contact of the three best threads was 35% for the implant retrieved after 10 years, 99% for the implant retrieved after 3 years, and 100% for the implants retrieved after 3.5 years. No untoward effects were present at the interface, and a high bone-implant contact was present around the implants with the microstructured surface. The data show that these implants had the potential to maintain osseointegration under long-term function with continuous and ongoing bone remodeling.

Machined and sandblasted human dental implants retrieved after 5 years: a histologic and histomorphometric analysis of three cases.

OBJECTIVE: Human retrieved implants with an intact bone-implant interface play a pivotal role in validating data obtained from in vitro studies and animal experiments. This study presents a histologic and histomorphometric analysis of peri-implant tissue reactions and of the bone-titanium interface in three machined and sandblasted dental implants retrieved after a 5-year loading period. METHOD AND MATERIALS: Three implants, with an intact bone-implant interface, were found in the Archives of the Implant Retrieval Center of the Dental School of the University of Chieti-Pescara, Chieti, Italy. The three implants had been used in a two-stage submerged procedure and loaded as part of a small prosthetic restoration. One implant had been retrieved because of an abutment fracture, while there was a fracture of the connecting screw in the other two. One implant was in the maxilla (sandblasted surface), and two were in the mandible (one with a machined surface and the other with a sandblasted surface). All implants had been processed for histology. RESULTS: All three implants presented mature, compact, lamellar bone at the interface. Many remodeling areas were present in the peri-implant bone, especially inside the implant threads. The bone was always in close contact with the implant surface. The bone-implant contact percentage of the machined implant was 92.7%, while the two sandblasted implants showed bone-implant contact percentages of 85.9% and 76.6%. CONCLUSION: The present histologic results confirmed that these implants with different surfaces maintained a good level of osseointegration over a 5-year loading period, with continuous remodeling at the interface, and showed high bone-implant contact percentages.