This study evaluates the radiographic, histological and clinical comparisons of the completely autologous T-PRF or allograft effectiveness at the maxillary sinus elevation procedure.

Participants randomly divided into 2 groups and the test group had a Schneiderian membrane elevation with using balloon lifting technique and after that sinus was filled with T-PRF produced from the patients' blood and 4 months waiting period has been entered. At the end of the 4th month, the bone samples were received from the implant slots and sent to histological evaluation. After 3 months, implant stability was measured and recorded. In the control group, the same procedures were followed and sinus was filled with only allograft. Waiting period was changed to 6 months for this group.

Inclusion Criteria:

• Participants having been diagnosed to display a residual crest height of less than 5mm in posterior maxilla and non-smokers were included.

Exclusion Criteria:

• Participants with blood platelet disorders, infectious and metabolic diseases, ongoing chemotherapy or radiotherapy, history of chronic sinusitis associated with maxillary sinuses, taking any antibiotics and/or anti-inflammatory drugs were excluded.