Published reports on the clinical efficacy and remote results of treatment by dental implants of different types are reviewed. The authors assessed the incidence and causes of complications of implantations on the basis of a long (up to 12 years) follow-up of 865 patients to whom 1155 grafts were implanted. Methods for treating and preventing complications are developed. Implants have to be removed early (up to 1 year postoperation) because of errors in defining the indications to surgery and in the operative technique; in later periods the causes of implant removal are implant and denture fractures and bone resorption round the implant because of functional over-exercise.