High concentrations of bioactive glass material (BioGran®) vs. autogenous bone for sinus floor elevation: Histomorphometrical observations on three split mouth clinical cases

In this study, high concentrations of bioactive glass (BG) particles were compared with autogenous bone in their capacity to augment maxillary bone when grafted in the human sinus floor using a split mouth design. Three female patients with severe maxillary atrophy underwent bilateral sinus floor elevation and bone grafting using 80-100% BG particles (300-355 μm in size) mixed with 20% to 0% iliac crest bone particles at one (experimental) side, and 100% iliac crest derived bone particles at the other (control) side. A total of 22 bone biopsies was taken at the time of fixture installation; that is, at 4, 6 and 15 months after grafting, and processed for histology and histomorphometry. At the control (autogenous bone) sides, trabecular bone amounted to 39% of the biopsy volume in the graft (site) at 4 months, almost 41% at 6 months, and 42% at 15 months. This bone contained viable osteocytes and was mostly of mature, lamellar type. At the experimental (BG particles) sides, the graft consisted of 27% of mostly woven (and some lamellar) bone at 4 months, 36% (woven and lamellar) bone at 6 months, and 39% (mainly lamellar) bone at 15 months. The grafted BG particles started to excavate at 4 months and their centers gradually filled with bone tissue. As a consequence, the volume of BG particles in the biopsy decreased from 29% at 4 months to 15% at 6 months and 8% at 15 months. The BG particles appeared to resorb within 1-2 years by dissolution rather than by osteoclastic activity. Parameters for bone turnover (% osteoid surface, % resorption surface) indicated that bone remodeling was very active at both experimental and control sides, during more than 6 months. These results suggest that mixtures of mainly (80-90%) BG particles and some (10-20%) autogenous bone are effective for bone regeneration in the augmented sinus offer 6 months healing time, while about 12 months healing time is needed for 100% BG particles.