Today, implant therapy is the treatment of choice for patients who are partially or completely edentulous. However, the resorption of the alveolar ridge of the posterior region of maxilla and pneumatization of the maxillary sinus lead to reduced bone volume, which limits the potential for implant therapy. In such patients, sinus floor elevation is necessary. Sinus floor elevation is a surgical procedure through which the floor of the maxillary sinus is transferred towards the cranial base, with simultaneous augmentation of the bone defect. CBCT is necessary to determine the anatomical position and bone volume of the implantation site determined earlier. Following the radiological assessment, anamnesis and clinical examination, the surgeon may plan the procedure. The decision between classical and modern operative techniques depends on the anatomy of the residual ridge and the individual preferences of the surgeon. After lifting the Schneiderian membrane apically in the direction of maxillary sinus, the defect created during this procedure is filled with bone graft materials. Implants can be placed immediately, or their placement may be delayed, depending on the technique used and the type of bone graft material. Impairment of ciliary function during the procedure, obliteration of the maxillary ostium, displacement of a foreign body into the sinus and previously existing sinusitis can all lead to the development of rhinosinusitis. Rhinosinusitis caused by these factors can be acute or chronic. Symptoms are almost always unilateral in this situation. The bacterial flora present in the maxillary sinus is similar to the bacterial flora in the oral cavity. Acute inflammation is characterized by a mixed bacterial flora, while anaerobic bacterial flora dominates in cases of chronic inflammation. The diagnosis of rhinosinusitis is based on medical examination and radiological evaluation. The treatment requires the use of medicaments and some surgical methods. Early recognition of symptoms and treatment prevent the loss of the placed implant. Complications of rhinosinusitis are very rare.