Characteristics of dental implants displaced into the maxillary sinus: comparison of intraoperative and postoperative displacement.

This study analyzed the characteristics of displaced implants and identified potential factors contributing to their intraoperative and postoperative displacement. 49 Patients referred from private practices with 50 implants were included. Clinical information regarding the displaced implants was investigated, and the sinus width, alveolar bone height, and bone quality were evaluated to determine their impact on the timing of implant displacement. Additionally, the patients' willingness and progress for prosthetic rehabilitation at the site of previous failure were assessed. When categorized by the timing of displacement, 23 cases (46 %) occurred during the implant installation process (intraoperative), and 27 cases (54 %) were discovered during follow-up (postoperative). The crestal approach for sinus elevation was the most frequently used in both groups (19 and 21 cases, respectively). Alveolar bone density was significantly lower in the intraoperative displacement group (p = 0.031). The bucco-palatal sinus width was significantly greater in the postoperative group compared to the intraoperative group (p = 0.007). Among the 42 patients assessed during follow up, six chose conventional prosthetic restorations and another six patients declined further treatment, citing concerns about potential failure. Lower bone density may also contribute to the incidence of intraoperative displacement. Additionally, a wider sinus may lead to late implant displacement, which has been reported to be related to delayed mineralization of the graft material. As patients may experience persistent complications from implant displacement, which subsequently affect their forthcoming prosthetic treatment, a thorough preoperative evaluation and careful selection of treatment are essential.