We evaluated the bone augmenting capacity of bioactive glass particles, size range 300-355 microns (BG-particles), in human sinus floor elevations using histomorphometrical methods. A total of 10 patients underwent bilateral grafting, using a 1:1 mixture of autogenous bone particles (from iliac crest) and BG-particles at one side (experimental side), and bone particles only at the other side (control side, split mouth design). A total of 72 bone biopsies were taken at the time of fixture installation; that is, 3 patients at 4 months, 3 at 5 months and 3 at 6 months after grafting and 1 patient at 16 months (when she presented again). In each case 6 biopsies were taken, 3 left and 3 right. Histomorphometry showed that in grafts at control sides, trabecular bone was present after 4 months, comprising almost 41% of the tissue volume. This bone contained viable osteocytes and was of mature lamellar type and showed a mature histological appearance. Bone volume continued to increase slightly, to 42% at 5 months, 44% at 6 months and 45% at 16 months. The graft volume at experimental sides consisted at 4 months for 28% of woven and some lamellar bone, and increased to 35% at 5 months and 38% at 6 months, when mainly lamellar bone was found. At 16 months a lamellar bone volume of 45% was found. The BG-particles transformed and became excavated with time, starting at 4 months, and their centers gradually filled with bone tissue. All BG-particles had disappeared by resorption at 16 months after grafting and had been replaced by bone tissue. Parameters of bone turnover (% osteoid surface, % resorption surface, mineral apposition rate as measured by tetracycline labeling) indicated that bone remodeling was very active at both sides, during more than 6 months, despite the mature histological appearance of the bone tissue. From these histological observations, we conclude that a 1:1 mixture of autogenous bone/BG-particles seems a promising alternative to autogenous bone only, when low amounts of bone tissue are available for sinus augmentation.

Although the number of patients examined was limited, the data suggest that deproteinized cancellous bovine bone, preferably combined with autogenous bone particles, is a suitable material for sinus floor elevation in the severely atrophic human maxilla.

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 microm 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.