All-on-4 immediate-function concept with Brånemark System 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, Göteborg, 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 (Brånemark System TiUnite, 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 1 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 1 year. CONCLUSION: The high cumulative implant survival rate indicates that the immediate function concept for completely edentulous maxillae may be a viable concept.