The opportunity to connect implants and teeth has been discussed in the literature. A comparative retrospective study was performed to evaluate the prosthetic results obtained in our clinical experience with 31 free-standing and 30 tooth-connected posterior IMZ implant-supported fixed partial dentures. Complications such as the loosening and fracture of fixation screws and abutments, ceramic fractures, and natural tooth migration were observed. A significant difference in the incidence and types of such complications in the two groups was found: problems occurred more frequently and in a different pattern with the free-standing compared to tooth connected restorations. Possible explanations for this dissimilar behavior are discussed. Keywords: complications, free-standing, implant-supported fixed partial dentures, intramobile elements, proprioception, tooth-connected