Background:
Posterior maxillary rehabilitation is often complicated by sinus pneumatization and reduced residual ridge height. Traditionally, multiple adjacent implant placements in such situations require an open lateral sinus elevation. Minimally invasive internal sinus lift techniques, particularly when combined with biologically active grafts, offer a promising alternative. This case highlights the novelty of performing closed sinus elevation at multiple adjacent sites in a subantral Class 3 case, supported by the use of platelet-rich fibrin (PRF)-based sticky bone to enhance osteogenesis.
Case Description:
A 43-year-old female patient (ASA I) presented with multiple missing posterior teeth in the right maxillary arch, impairing mastication. CBCT revealed sinus pneumatization with reduced alveolar bone height, classifying the case as subantral Class 3. Internal sinus elevation was performed using osseodensification burs. Sticky bone was prepared by combining autologous PRF with a xenograft (Bio-Oss, Geistlich Pharma, Switzerland) using a centrifugation protocol (2700 rpm for 12 minutes). Three implants (4.0 × 10 mm) were simultaneously placed at the first premolar, second premolar, and first molar sites.
Results:
Sinus membrane elevations of 3.58 mm, 4.45 mm, and 6.69 mm were achieved. Implants demonstrated primary stability of 30–40 Ncm and ISQ values of 62–74. Post-operative CBCT confirmed complete bony housing along the full implant length, indicating substantial bone gain and increased peri-implant bone density. After 3 months, osseointegration was achieved, and a cement-retained zirconia fixed partial denture was delivered.
Conclusion:
Closed sinus elevation across multiple adjacent implant sites in a subantral Class 3 case, combined with PRF-enriched sticky bone, enabled predictable vertical bone gain and complete implant housing without the need for open sinus augmentation. The incorporation of growth factor-rich PRF enhanced the osteogenic potential of the sinus membrane, supporting rapid healing and successful implant integration. This approach demonstrates a minimally invasive and biologically favorable strategy for managing posterior maxillary edentulism with reduced ridge height.
