In this study the buccal fat pad derived stem cells (BFPSCs) will be harvested from buccal fat pad tissue of patients receiving maxillary sinus augmentation. In the test group the patients receive a combination of platelet rich fibrin (PRF) and freeze dried bone allograft (FDBA) (SureOss, Hansbiomed, Korea) loaded with BFPSCs. The results will be evaluated by cone beam computed tomography (CBCT)and hematoxylin and eosin staining in 6 months.

The buccal fat pad derived stem cells (BFPSCs) is harvested from buccal fat pad tissues. The BFPSCs will be loaded on freeze dried bone allograft (FDBA) (SureOss, Hansbiomed, Korea). Furthermore, twenty milliliters of the venous blood is obtained, placed and collected in a sterile tube, and centrifuged (GAC medical) for 14 minutes at 2800 rpm (approximately 400 g). Following centrifugation, three layers are separated in the tube: cellular plasma at the top, platelet rich fibrin (PRF) clot in the middle and red blood cells at the bottom of the tube. The PRF clot is separated by a sterile pincette.

The patients in the test group receives BFPSCs loaded on DFDBA with PRF for sinus augmentation and the control group receives combination of PRF and DFDBA (lacking any cells).The results will be evaluated by cone beam computed tomography (CBCT) in 6 months and microscopic evaluation of the biopsies by hematoxylin and eosine staining.

Inclusion Criteria:

1. patients with posterior maxillary edentulism
2. pneumatized sinus
3. less than 5mm bone height between the alveolar crest and sinus membrane

Exclusion Criteria:

1. smoking
2. history of malignancy
3. radiation
4. chemotherapy
5. pregnancy
6. systemic diseases contradicting dental and surgical treatments
7. conditions or drugs affecting bone remodeling or bone metabolism and connective tissue
8. allergy to collagen