Evaluation of Peri-Implant Bone Response in Implants Retrieved for Fracture After More Than 20 Years of Loading: A Case Series
Analysis of human retrieved dental implants is a useful tool in the evaluation of implant success and failure. More human histological data are needed from samples of long-term implant service. The aim of the present case series was a histological and histomorphometrical evaluation of the peri-implant bone responses in implants retrieved for fracture after more than 20 years loading. The archives of the Implant Retrieval Center of the Department of Medical, Oral and Biotechnological Sciences of the University of Chieti-Pescara, Italy were searched. A total of 5 implants, retrieved after a loading period of more than 20 years, were found: 2 had been retrieved after 20 years, 1 after 22 years, 1 after 25 years, and 1 after 27 years. All these implants were histologically processed. Compact, mature bone in close contact with the implant surface was observed in all specimens, with no gaps or connective tissue at the interface. Bone in different maturation stages was found around some implants. Primarily newly formed bone was observed in proximity of the implant surface, while mature compact bone with many remodeling areas and cement lines were detected in areas distant from the implant. Many primary and secondary osteons were present. Bone to implant contact percentage varied from 37.2% to 76%. In conclusion, histology and histomorphometry showed that even after many years of function, all implants presented more than adequate bone to implant contact and they appeared to be very well integrated in the peri-implant bone.
Figure 1. Orthopantomography showing a fractured implant located in the left mandible. It is possible to observe a peri-implant bone resorption in the most coronal portion of the implant. Figure 2. Orthopantomography showing a fractured implant located in the right mandible. The implant supported an overdenture.
Figure 3. Compact, mature bone at the interface of the implant. Bone remodeling areas are present. Acid fuchsin-Toluidine blue ×18. Figure 4. Compact mature bone at the interface. Connective tissue is present in the most coronal portion of the implant. Acid fuchsin-Toluidine blue ×18. Figure 5. Newly formed bone is present near the implant surface. Wide marrow spaces are present. Acid fuchsin-Toluidine blue ×18. Figure 6. Bone remodeling areas and osteons are present near the implant surface. No gaps are present at the interface. Acid fuchsin-Toluidine blue ×100. Figure 7. Newly-formed bone (NB) in direct contact to the implant surface. Not jet mineralized osteoid matrix (OM) can be observed. In the marrow spaces small and big sized blood vessels (V) are present. Acid fuchsin-Toluidine blue ×200. Figure 8. A rim of osteoblasts (arrows) depositing osteoid matrix directly on the implant surface. Acid fuchsin-Toluidine blue ×200. Figure 9. Blood vessels of different sizes are present within the marrow spaces. Osteoid matrix is present inside the marrow spaces. Secondary osteons are present abutting the implant surface. Acid fuchsin-Toluidine blue ×100. Figure 10. Wide marrow spaces are present. Lamellar bone is present. Acid fuchsin-Toluidine blue ×100.
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