CBCT-Derived Volumetric Hard-Tissue Gain After Hydraulic Transcrestal Sinus Floor Elevation with or Without Cross-Linked Hyaluronic Acid: A Non-Randomized Prospective Clinical Study

Objectives: The aim of the study was to compare CBCT (Cone Beam Computed Tomography)-derived radiographic hard tissue gain after hydraulic transcrestal sinus floor elevation performed with versus without cross-linked hyaluronic acid (HA) and to assess associated clinical, radiographic, and patient-reported outcomes. Materials and Methods: This single-center, prospective clinical study enrolled 58 patients with 2–6 mm residual bone height in the posterior maxilla, assigned in a non-randomized parallel-group design to HA (n = 29) or No Graft (n = 29). The primary endpoint was CBCT-based 3D CBCT-derived radiographic hard-tissue volume gain at 12 months; secondary endpoints included vertical bone gain, marginal bone loss (MBL) at 12 and 24 months, implant stability quotient (ISQ), implant survival/success, complications, and patient-reported outcomes (VAS pain, OHIP-14). Analyses used ANCOVA and appropriate comparative statistics. Results: At 12 months, mean CBCT-derived radiographic hard-tissue volume gain was higher with HA (1210 +/− 610 mm3) than with No Graft (858 +/− 605 mm3; adjusted difference +352 mm3, 95% CI: 140–564; p = 0.002). ISQ at 12 months was greater with HA (p = 0.028), while MBL at 12/24 months did not differ significantly. Twenty-four-month implant survival was 98.1% (HA) vs. 94.3% (No Graft; p = 0.041). Complication rates were low and comparable; VAS pain at 72 h was modestly lower with HA. Conclusions: In this non-randomized prospective clinical study, cross-linked hyaluronic acid was associated with greater CBCT-derived radiographic hard-tissue volume gain and vertical radiographic gain after hydraulic transcrestal sinus floor elevation compared with clot stabilization alone. Clinical outcomes were favorable in both groups during the 24-month observation period. These findings support the interpretation of cross-linked hyaluronic acid as a potential space-maintaining adjunct in posterior maxillary sites with limited residual bone height; however, because no histological or histomorphometric assessment was performed, they should not be interpreted as proof of vital mature bone regeneration or superior bone quality.