A ll‐on‐4® Treatment Concept for the Rehabilitation of the Completely Edentulous Mandible: A 7‐Year Clinical and 5‐Year Radiographic Retrospective Case Series with Risk Assessment for Implant Failure and Marginal Bone Level

Background Studies are needed to evaluate long‐term outcomes of the A ll‐on‐4® treatment concept ( N obel B iocare AB ) for rehabilitation of edentulous mandibles by assessing marginal bone levels and risk indicators for implant failure. Purpose To evaluate 7‐year clinical outcomes and 5‐year radiographic outcomes of the A ll‐on‐4 treatment concept. Materials and Methods This retrospective case series included patients admitted for implant rehabilitations in the mandible, who were followed for 7 years clinically and 5 years radiographically. Primary outcome measures were cumulative prosthetic and implant survival using patient as the unit of analysis ( K aplan‐ M eier product limit estimator). Secondary outcome measure was marginal bone level ( MBL ) at 5 years. Variables associated with implant failure were analyzed using the C ox proportional hazards regression model to calculate hazard ratios ( HRs ) with 95% confidence intervals ( CIs ). Binary logistic regression was used to compute odds ratio ( OR ) with 95% CIs for variables associated with MBL ≥2.8 mm at 5 years. Results A total of 324 patients (194 women, 130 men, average age = 58.9 years) were rehabilitated with 1,296 implants supporting 324 full‐arch fixed immediately loaded mandibular prostheses. Sixty‐four patients (19.8%) were lost to follow‐up. Prosthetic survival was 323/324 (99.7%), and 14 patients lost 18 implants, with an estimated cumulative survival rate of 95.4% at 7 years. Variables associated with implant failure were smoking ( HR  = 5.28; 95% CI: 1.33, 20.91]) and the learning curve effect (0.69 <  HR  < 0.33 for more experienced levels). Mean MBL at 5 years was 1.81 mm (95% CI : 1.70, 1.92), and smoking was associated with MBL ≥2.8 mm ( OR  = 2.4; 95% CI: 1.02, 5.62). Conclusions The high implant and prosthetic survival rates and excellent MBL outcome confirm the predictability and safety of the A ll‐on‐4 treatment concept over a longer term than previously reported.