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.

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.

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.

Histologic evaluation of a provisional implant retrieved from man 7 months after placement in a sinus augmented with calcium sulphate: a case report.

Little is known about the in vivo healing processes at the interface of implants placed in different grafting materials. For optimal sinus augmentation, a bone graft substitute that can regenerate high-quality bone and enable the osseointegration of load-bearing titanium implants is needed in clinical practice. Calcium sulphate (CaS) is one of the oldest biomaterials used in medicine, but few studies have addressed its use as a sinus augmentation material in conjunction with simultaneous implant placement. The aim of the present study was to histologically evaluate an immediately loaded provisional implant retrieved 7 months after simultaneous placement in a human sinus grafted with CaS. During retrieval bone detached partially from one of the implants which precluded its use for histologic analysis. The second implant was completely surrounded by native and newly formed bone, and it underwent histologic evaluation. Lamellar bone, with small osteocyte lacunae, was present and in contact with the implant surface. No gaps, epithelial cells, or connective tissues were present at the bone-implant interface. No residual CaS was present. Bone-implant contact percentage was 55% +/- 8%. Of this percentage, 40% was represented by native bone and 15% by newly formed bone. CaS showed complete resorption and new bone formation in the maxillary sinus; this bone was found to be in close contact with the implant surface after immediate loading.