Sinus floor augmentation with autogenous iliac bone block grafts: a histological and histomorphometrical report on the two-step surgical technique

In thirteen patients, screw-type endosseous implants were inserted 6 months after sinus floor elevation and augmentation with autogenous iliac bone block grafts. Bone biopsies were harvested at graft positioning (baseline), at implant placement (6 month) and at abutment connection (1 year). Histological evaluation suggested a decrease in the volume of mineralized tissue and in the vitality of the grafts 6 months after graft insertion, followed by an increase at abutment connection. Histomorphometric analysis of the bone specimens showed that, at implant placement, bone content was reduced by 5.2% on average, while 12 months after grafting it had increased by 4.8% compared to the amount of mineralized tissue contained in the graft at baseline. The results suggest that in sinus floor augmentation procedures with autogenous iliac bone blocks, a two-step surgical technique allows implant insertion when graft healing is entering a phase of greater density and vitality.