Five-year results of maxillary intramobile Zylinder implants

We retrospectively analysed the time-dependent function of 501 Intramobile Zylinder (IMZ) implants inserted between August 1983 and December 1994 to restore partially and fully edentulous maxillae. To ensure the independence of implants when calculating level of significance, we chose one implant per patient at random. This was done 500 times to obtain a representative result. The simplified success rate was 473/501 (92%) whereas the time-related survival probability was 76% after 60 months. In 31% (156/500) of the life-table calculations, implants placed in completely edentulous maxillae showed a significantly lower probability of survival than did those placed in partially edentulous patients (P mean: 0.17; SD: 0.19). Implants, that had been placed in the anterior and premolar regions of edentulous maxillae, had a survival probability of 60%, after 60 months. The survival probability of implants placed in the molar region was 100%, over the same observation period. The patient's age, sex, and the time of placement of the implant after tooth extraction had no significant influence on the implant's prognosis. The prognosis of implants inserted for partial edentulism meets the criteria proposed for a viable implant system. Our findings indicate that in complete edentulous maxillae, implants should be placed in the posterior rather than in the anterior region, even though this necessitates augmentation procedures such as sinus lift.