The subperiosteal dental implantation implant was orginally described in the 1940s. The inadequate long-term results of subperiosteal implants are in contrast to the excellent results documented for endosseus oral implants. Consequently, subperiosteal implants and other soft-tissue-anchored implants should not be used presently. The present report documented twelve patient cases with complications after treatment with subperiosteal implants. Typical complications of SI are implant exposure, inflammation, infection, fistula formation and implant mobility. After removing the SI severe atrophic bone was seen. The placement of osseointegrated oral implants was mostly not possible without autogenous bone grafting. The present report is in conclusion with other studies, that a regular control of patients with subperiosteal implants is necessary. Subperiosteal implants should definitely be removed, if continuous periods of complication occur. The complete oral rehabilitation requires further surgical treatment in the field of preprosthetic surgery.