The study aims to investigate the radiological and histomorphometric results of the use of PLGA-coated biphasic calcium phosphate granules in sinus floor elevation, to analyze the underlying molecular processes by immunohistochemical staining, and to evaluate the handling of the biomaterial and the in situ hardening properties.

A randomized clinical study is designed to include patients in need of two-stage sinus floor elevation. Patients are assigned to receive either PLGA-coated biphasic calcium phosphate particles (group I) or the equivalent but non-coated particles (group II). CBCT scans are performed before and 6 months after the procedure to assess the bone height gain. At the time of implant placement, bone core biopsies are obtained at the site of implant placement. Histological sections are subjected to histomorphometric and immunohistochemical evaluation of differentiation markers.

Inclusion Criteria:

• Partially edentulous patients.
• Kennedy class I or II in the upper jaw, from first premolar to second molar.
• Less than 5 mm of residual crestal bone.
• Need for the replacement of teeth with dental implants.

Exclusion Criteria:

• Sinus pathology (sinusitis, mucocele, cysts).
• Smokers.
• Previous long-term (>3 months) use of drugs known to affect bone metabolism, such as bisphosphonates.