All-on-4 immediate-function concept with Branemark System (R) implants for completely edentulous maxillae: A 1-year retrospective clinical study

Background. Immediate implant function has become an accepted treatment modality for fixed restorations in totally edentulous mandibles, whereas experience from immediate function in the edentulous maxilla is limited. Purpose: The purpose of this study was to evaluate a protocol for immediate function (within 3 hours) of four implants (All-on-4, Nobel Biocare AB, Goteborg, Sweden) supporting a fixed prosthesis in the completely edentulous maxilla. Materials and Methods: This retrospective clinical study included 32 patients with 128 immediately loaded implants (Branemark System(R) TiUnite(TM), Nobel Biocare AB) supporting fixed complete-arch maxillary all-acrylic prostheses. A specially designed surgical guide was used to facilitate implant positioning and tilting of the posterior implants to achieve good bone anchorage and large interimplant distance for good prosthetic support. Follow-up examinations were performed at 6 and 12 months. Radiographic assessment of the marginal bone level was performed after I year in function. Results: Three immediately loaded implants were lost in three patients, giving a 1-year cumulative survival rate of 97.6%. The marginal bone level was, on average, 0.9 mm (SD 1.0 mm) from the implant/abutment junction after I year. Conclusion: The high cumulative implant survival rate indicates that the immediate function concept for completely edentulous maxillae may be a viable concept.