Human bone reactions around implants with adverse interfacial bone strain over 20 years

Aims It has been accepted that bone damage and subsequent resorption occurs in cases of adverse interfacial bone strain. Fractured implants represents an important opportunity for evaluating the bone response to overstrain. The objective of the study was to analyze the bone morphology and morphometry around retrieved fractured implants in humans. Five fractured implants retrieved after 22.4 (± 2.8) years were used in the present study. The investigation was conducted in a transmitted brightfield and circularly polarized light Microscope. The parameters considered were the total bone area, total bone remodeling area, bone-remodeling rate (BRR), and bone transverse collagen fibers orientation (CFO). Findings For grouped samples, the BRR was 51.9% (± 10) while the transverse CFO was 13.0% (± 9.7). The interthread BRR was 58.1% (± 4.0) for level 1 and 40.4% (± 12.8) for level 2 with a significant decrease in BRR (p = 0.019) as a function of depth along the implant length. Conclusions Both bone level and bone quality attains stability to a certain level with respect to implant neck fracture following physiologic interaction between mechanical and biological inputs. The BRR significantly decrease as function of threads depth.