Bioactive glass granules as a bone adjunctive material in maxillary sinus floor augmentation

Bilateral sinus floor augmentation procedure was performed in 17 patients to study the effect of bioactive glass (BG) granules mixed with autologous bone (AB) chips on bone regeneration. The posterior part of 17 maxillary sinus was augmented with a 1:1 mixture of BG granules (phi 800-1000 microm) and AB chips harvested from the iliac crest (BG-AB group). The anterior parts of the same sinus and the contralateral sinus, serving as a control (AB group), were filled with AB chips alone. Trephine biopsies for histological, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analyses were taken from the posterior part of the sinus after 21-34 weeks at the time of insertion of dental implants. Additionally, six biopsies were taken from the BG-AB group and four biopsies were taken from the AB group in connection with abutment operation at 49-62 weeks.

Histological evaluation revealed lamellar bone growth in all the specimens. Although most of the BG granules were without bone contact in the majority of the patients in the BG-AB group, the bone lamellae were thicker than observed in the AB group. In the contact areas, bone was growing along the glass surface connecting the particles together. Histomorphometrical analysis carried out from the SEM images at 21-34 weeks revealed 26% and 25% bone in the BG-AB and the AB group, respectively. Corresponding figures for 49-62 weeks were 29% for the BG-AB group and 25% for the AB group. Bone-BG complex, i.e. the granules with intimate contact with bone, occupied 34% of the area measured at 21-34 weeks and 31% at 49-62 weeks. EDX analysis showed a tight contact and chemical bonding between the glass and bone. As a sign of dissolution, a few small Si-depleted areas were present in some BG granules at 21-34 weeks, while more and larger Si-free areas were observed in the granules at 49-62 weeks.

The results indicate that BG granules (S53P4) can be used together with AB chips for sinus floor augmentation procedure, thus decreasing the amount of bone needed. Further studies concerning especially the biomechanical properties of the BG-AB complex with dental implants are needed.