The All-on-4 concept for full-arch rehabilitation of the edentulous maxillae: A longitudinal study with 5-13 years of follow-up.

Background: Full-arch immediate function protocols such as the All-on-4 concept need long-term validation.

Purpose: To report the 5-13 year outcomes of the All-on-4 treatment concept for the rehabilitation of the edentulous maxilla.

Materials And Methods: This retrospective case series study involved 1072 patients (4288 maxillary implants) rehabilitated through the All-on-4 treatment concept. Primary outcome measures were cumulative prosthetic and implant success (life table analysis). Secondary outcome measures consisted in marginal bone loss (MBL) at 5 and 10 years, biological and mechanical complications. The estimation of risk indicators was performed through multivariable analysis for the outcome variables implant failure (Cox regression to estimate hazard ratios and 95% confidence intervals [95% CI]), MBL > 2.8 mm at 5 years, MBL > 3.0 mm at 10 years, biological and mechanical complications (binary logistic regression to estimate odds ratios [OR] with 95% CI).

Results: Eighteen patients deceased unrelated to the implant treatment (1.7%) and 219 patients (20.4%) were lost to follow-up. The prosthetic success rate was 99.2%; Implant cumulative survival and success rate was 94.7% and 93.9%, respectively, with up to 13 years of follow-up. Male gender (HR = 1.73), smoking (HR = 1.94), and mechanical complications (HR = 0.59) were significantly associated with implant failure. Average MBL at 5 and 10 years was 1.18 mm (95% CI: 1.16, 1.21) and 1.67 mm (95% CI: 1.58, 1.77) with age (OR = 0.97), male gender (OR = 0.58), smoking (OR = 1.73), and biological complications (OR = 2.1) associated with MBL > 2.8 mm at 5 years. The incidence of biological complications was 7.8% at implant level, with age (OR = 0.98) and smoking (OR = 1.53) significantly associated. The incidence of mechanical complications was 58.8% for the provisional prostheses and 7.3% for the definitive prostheses.

Conclusions: The high success rates registered for both implants and prostheses together with the low MBL confirm the All-on-4 treatment concept is predictable and safe in the long term outcome.