The article describes complications following dental implant dislocation into the maxillary sinus and their management and attempts to elucidate the reasons for these complications and their prevention. This retrospective study presents 55 cases of dental implant migration into the maxillary sinus. Patients were 30 men and 25 women with average age of 58 years. Oroantral communication was found in 46 cases, primarily in cases without prior bone augmentation, in patients aged older than 60 years (mean), and medically compromised patients (ASA > 1). The dislocated implant and the infected tissue were removed from the sinus in most cases by Caldwell-luc intervention. The oroantral communication was closed by local and regional flaps. In most of the cases, the oroantral communication was closed by a single intervention. The conclusion was that oroantral communication and maxillary sinusitis are common findings following dental implant migration and dislocation into the maxillary sinus. The risk factors for these complications were dental implantation in the posterior maxilla without sufficient alveolar bone, implantation without prior maxillary sinus augmentation, and older and medically compromised patients. Successful closure of the communication is usually performed with local or regional flaps.