title: All-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.
abstract: BACKGROUND
  Studies are needed to evaluate long-term outcomes of the All-on-4® treatment concept (Nobel Biocare AB) for rehabilitation of edentulous mandibles by assessing marginal bone levels and risk indicators for implant failure.
  
  
  OBJECTIVE
  To evaluate 7-year clinical outcomes and 5-year radiographic outcomes of the All-on-4 treatment concept.
  
  
  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 (Kaplan-Meier product limit estimator). Secondary outcome measure was marginal bone level (MBL) at 5 years. Variables associated with implant failure were analyzed using the Cox 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 All-on-4 treatment concept over a longer term than previously reported.
authors.affiliation: Oral Surgery Department, Maló Clinic, Lisbon, Portugal.
authors.forename: Paulo
authors.initials: P
authors.lastname: Maló
authors.affiliation: Research and Development Department, Maló Clinic, Lisbon, Portugal.
authors.forename: Miguel
authors.initials: M
authors.lastname: de Araújo Nobre
authors.affiliation: Oral Surgery Department, Maló Clinic, Lisbon, Portugal.
authors.forename: Armando
authors.initials: A
authors.lastname: Lopes
authors.affiliation: Oral Surgery Department, Maló Clinic, Lisbon, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Ferro
authors.affiliation: Oral Surgery Department, Maló Clinic, Lisbon, Portugal.
authors.forename: Inês
authors.initials: I
authors.lastname: Gravito
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003758:Dental Implantation, Endosseous / Q000009:adverse effects / Q000379:methods*; D019094:Dental Prosthesis, Implant-Supported / Q000379:methods*; D019232:Dental Restoration Failure / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007575:Jaw, Edentulous / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011861:Radiography, Dental; D011862:Radiography, Panoramic; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult
keywords: immediate function; long-term survival; tilted implants