2019 Volume 32 Issue 1 Pages 48-56
Purpose : In Japan, there are few reports about following a protocol for the immediate function of four implants supporting a fixed prosthesis in the completely edentulous maxilla (the “All-on-4” concept). The purpose of this study was to evaluate the outcomes after 3 or more years of following the “All-on-4” concept in the completely edentulous maxilla.
Materials and Methods : This retrospective clinical study included 150 patients with 662 maxillary implants rehabilitated according to the All-on-4 concept. Clinical examinations were performed to investigate the risk factors (number of implants per case, implant systems, implant lengths, primary implant stability, implant orientation, medical history and smoking habit) of implant failure.
Results : Seventeen implants were lost, giving an estimated survival rate of 97.4% at the implant level. Implant survival rates of the left posterior position (95.3%) were significantly lower than those of the right anterior position (98.4%). Smokers showed significantly lower implant survival rates (94.8%) compared to nonsmokers (98.8%).
Conclusion : The high implant survival rate of the All-on-4 concept indicates that it is an effective treatment for the completely edentulous maxilla with small residual alveolar bone volume in the molar region.
