Retrospective cohort assessment of survival and complications of zygomatic implants in atrophic maxillae

To report on zygomatic implant (ZI) survival rate and associated complications through a longitudinal retrospective cohort assessment.A total of 940 ZIs (rough: 781, machined: 159; immediate loading: 454, delayed loading: 486) and 451 standard implants (rough: 195, machined: 256; immediate loading: 58, delayed loading: 393) were placed in 302 adult patients with atrophic maxilla from December 1998 till September 2020. Following data collection reported complications were grouped based on their origin as infectious/ non-infectious biological and mechanical. Statistical analysis was performed to identify risk factors and preceding complications leading to implant loss (p0.05).The survival rate of ZI was found to be 89.9% and the average time between implant placement and an eventual loss was 4.8 years. The mean ZI follow-up period was 7.9±4.9 years. Amongst the infectious biological complications, sinusitis was the most reported (n=138) occurring at a mean follow-up time-point of 4.5 years, whereas infraorbital nerve hypoesthesia occurred more frequently in the non-infectious biological category (n=8, meantime: 0.3 years). The prosthetic screw fracture was the most reported complication of mechanical origin (n=29, meantime: 4 years). Furthermore, sinusitis, standard implant loss, zygomatic/peri-zygomatic region infection, and oroantral communication were significantly associated with ZI loss.ZI placement offered a high survival rate for the rehabilitation of severely atrophied maxilla with most losses occurring within the first five years at follow-up. The most frequently observed complication was sinusitis which tends to develop several years following implant placement.