[Implants in avascular iliac crest bone transplants. Prospective study of 176 implants]

Total and subtotal defects of the upper and lower alveolar ridge require bone grafts to make masticatory rehabilitation possible using alloplastic dental implants. The aim of this study was to establish the survival rate of dental implants inserted in avascular iliac bone grafts. Furthermore, we aimed to discover whether the prognosis of implants can be influenced by choosing one-stage or a two-stage procedure. In a prospective study, jaw defects in 40 patients were treated with avascular mono- or bicortical bone transplants taken from the right iliac wing. A total of 134 of 176 dental implants were inserted into an onlay osteoplasty. In 19 cases, 95 implants could have been inserted in a one-stage procedure, while in the other 13 cases 39 implants have been inserted in a two-stage procedure. One-stage insertion of implants was done in cases of definite primary stability only; otherwise, the two-stage method was preferred. After treatment, all patients were examined at least once every year. Both the rate of loss of implants and the time-dependent crestal bone loss were recorded. Of the 134 implants, 88% (i.e., 118 implants) were still in situ 6.8 years after abutment connection, and after 8.5 years 78% (i.e., 104 implants) were in situ. The interval of confidence was 95%. Projected over 8 years, 83 implants inserted in a one-stage procedure (i.e., 87%) were still functioning, while differently only 26 of the implants inserted in a two-stage procedure (i.e., 66%) were still functioning. The probability that implants stay in situ for a particular time corresponds to the results of former studies. The results of other studies with regard to one-stage or two-stage procedures could not be confirmed. The probability of total retention time for implants inserted in a two-stage procedure is lower than for those inserted in a one-stage procedure. The unfavorable starting point with the lack of primary stability of the implants in local bone within the two-stage procedure might be a reason for this.