Influence of the design of modern subperiosteal multivectorial anchored Implants on success and survival in complex patient cases

This study investigates factors relating to the success and survival of patient-specific subperiosteally multivectorial anchored implants (IPS-Implant) with a minimum of two coupling elements (CE) to anchor the prosthetic restoration in challenging patient situations. Construction parameters of the implants were analyzed. Implantation timepoint, complications, and complication severity using USPHS criteria (A-D) were obtained from patients records. CE-location, spacing, length and transmucosal height were evaluated for their influence. The medial plaque (mPI) and the gingival (GI) indices were evaluated in order to assess inflammations around the CE. Success and survival rates were analyzed via Kaplan-Meier analysis and log-rank tests. In fifteen patients (6 men, 9 women) aged 40 to 92 in total 49 CE were examined. Kaplan-Meier analysis revealed a 2-year success rate of 91.6% and survival rate of 97.5%, while long-term analysis showed a success rate of 53.9% and survival rate of 89.4% after 8.9 years in total. Only 3 CE got lost due to fracture of the supporting bone. 46 CE are still in clinical use. After 1.8 years in the earliest, in 18 cases, signs for inflammation were detected. 10 of these inflammations required medical care. Subperiosteal implants show good short-term results but often face soft-tissue complications over time. Neighboring natural teeth and distances between coupling elements < 10 mm increased the risk for complications. Implant design, surface finish, and prosthetic protection are crucial for long-term success, requiring further research.