Objective. To analyze morphological and functional transformations of the mucous membrane and bone structures of the maxillary sinus during subantral augmentation using β-tricalcium phosphate.

Materials and methods. The experiment was conducted on 14 sheep (control and experimental groups of 7 animals each). All animals, kept under standard conditions with their usual diet, underwent subantral augmentation using an open technique according to the author's method (patent RU 2729651). In the experimental group, β-tricalcium phosphate granules were applied to the mucosa; in the control group, the defect was left to fill with a blood clot. Follow-up biopsies were performed under general anesthesia at 1, 2, and 3 months after surgery. The evaluation included a qualitative analysis of changes in the epithelium, lamina propria of the Schneiderian membrane, bone plate, and periosteum.

Results. The results demonstrate a biphasic response: initial necrosis and inflammation, followed by reparative processes such as epithelial metaplasia, lamina propria fibrosis, bioresorption of the material, and the formation of reticulofibrous bone tissue. In the experimental group, ramolithic cysts (bone cysts resulting from tissue necrosis) with osteogenesis were observed, confirming the osteoinductive properties of β-tricalcium phosphate. These changes highlight the importance of monitoring tissue responses to optimize implant procedures in the maxilla.

Conclusions. This study demonstrates that subantral augmentation using a bioresorbable composite material based on β-tricalcium phosphate induces a complex tissue response, including initial necrosis and inflammation of the mucosa and bone, followed by bioresorption and osseointegration.