Human non-decalcified histology of three dental implants 45 months under function—a case report

Fracture of an implant is a quite rare event but represents an important opportunity to evaluate the peri-implant bone tissue response to implant overload in human beings. This study aimed to evaluate bone tissue around three fractured titanium implants retrieved from a human maxilla, by histomorphometric and birefringence analyses. For this, the implants and the surrounding bone were removed after having been united to a tooth in function for 45 months, by a 4-mm internal diameter trephine bur, following an undecalcified section was obtained. The results showed a rate of 77.3% of bone-to-implant contact (BIC) and 80.3% of bone area filling within the limits of the implant threads. Under circularly polarized light microscopy investigation, the amount of the transverse collagen fibers was of 48.11%, and the amount of the longitudinal collagen fibers was of 51.89%. Within the limitation of this study, the possible cause of the implant fracture could be the association of overload, inadequate implant diameter, and fragile internal hexagon connection.