A retrospective study of edentulous patients rehabilitated according to the 'all-on-four' or the 'all-on-six' immediate function concept using flapless computer-guided implant surgery

Purpose: To report the outcome of an implant therapy protocol using 4 or 6 implants supporting immediately loaded fixed prostheses following 3D software planning and flapless guided surgery. Materials and methods: A total of 30 patients (24 women, 6 men), mean age of 53 years (range 35-84 years) were treated with 195 immediately loaded implants (97 NobelSpeedy Groovy and 98 Brånemark MKIII Groovy) supporting 25 maxillary and 17 mandibular fixed full-arch acrylic prostheses and followed for 1 year. The Procera Software v1.6 and v2.0 was used to plan implant position and to obtain a surgical template for the guided flapless implant placement. To perform immediate loading, the implants had to be inserted with torque of at least 35 Ncm. Provisional prostheses were made before surgery using software planning and were placed in the same session as the implants. Definitive restorations were delivered 6-12 months after surgery. Outcome measures were failures of the prosthesis and of the implants, marginal bone level changes, complications, clinical time and patient satisfaction. Results: Four patients with full edentulism and 26 with advanced periodontitis were enrolled in this study. A total of 195 implants were immediately loaded (128 implants were placed in the maxilla and 67 implants were placed in the mandible). Four implants out of 195 failed in three patients during the healing period: 2 in the maxilla (1 straight and 1 tilted), and 2 in the mandible (both of them tilted). Three of them were successfully replaced. One year after loading there were no dropouts and no failure of the definitive prosthesis occurred. In three cases, the surgical template fractured during surgery. In one patient, a new impression had to be taken to fit the provisional prosthesis onto the implants. Three patients were subjected to surgery and systemic antibiotics to treat apically infected implants. Conclusions: The 'all-on-four' and 'all-on-six' treatment protocol combined with computer-guided flapless implant surgery could be a viable and predictable treatment. Some complications occurred that were successfully treated. However, this technique could be sensitive to the experience of the surgeon and a learning curve is required. Schlagwörter: computerised tomographic scan, flapless surgery, full edentulism, guided surgery, immediate loading