title: Marginal Bone Stability Around Tapered, Platform-Shifted Implants Placed with an Immediately Loaded Four-Implant-Supported Fixed Prosthetic Concept: A Cohort Study.
abstract: OBJECTIVE
  To longitudinally evaluate marginal bone remodeling around tapered, platform-shifted implants placed for total arch rehabilitation with fixed hybrid prostheses.
  
  
  METHODS
  A retrospective cohort study was designed that evaluated radiographic data from patients undergoing implant surgical procedures with an immediately loaded four-implant-supported fixed prosthetic concept in a single clinic setting during a 36-month period. The primary outcome variable was the change in marginal bone levels during a 12- to 36-month follow-up postloading with the definitive prosthesis. All measurements were performed on matched and calibrated periapical radiographs obtained at: (1) the time of placement of the definitive prosthesis (baseline) versus (2) 12 to 36 months following definitive loading (follow-up). Other study variables, including duration of follow-up, implant position, maximum insertion torque, implant angulation, and implant diameter, were assessed for their association with changes in marginal bone levels.
  
  
  RESULTS
  One hundred sixty-nine patients (n = 856 implants) with a mean age of 59.5 ± 10.5 years were included in this study. Two implants failed, resulting in a 99.8% overall survival rate (mean follow-up: 15.2 ± 4.8 months, range: 12 to 36 months). The radiographic mean bone levels at baseline and follow-up were 1.16 ± 0.71 mm (n = 805) and 1.31 ± 0.93 mm (n = 805), respectively. The mean marginal bone loss from baseline to follow-up was 0.14 ± 0.59 mm (n = 805). The duration of follow-up had no effect on the extent of marginal bone loss (P = .154).
  
  
  CONCLUSIONS
  Within the limitations of this large-scale retrospective cohort study, it was concluded that the use of tapered, platform-shifted implants for total arch rehabilitation with the use of the All-on-Four protocol yields very favorable radiographic outcomes, at least after a minimum of 12 months in function.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Babbush
authors.forename: Ali
authors.initials: A
authors.lastname: Kanawati
authors.forename: Georgios A
authors.initials: GA
authors.lastname: Kotsakis
mesh_terms: D000328:Adult; D000368:Aged; D016301:Alveolar Bone Loss / Q000473:pathology; D016723:Bone Remodeling / Q000502:physiology*; D000069343:Bone-Implant Interface / Q000502:physiology*; D003724:Dental Arch / Q000601:surgery; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention / Q000592:standards*; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D057893:Immediate Dental Implant Loading / Q000379:methods; D008297:Male; D008875:Middle Aged; D009066:Mouth, Edentulous / Q000534:rehabilitation*; D012189:Retrospective Studies; D019415:Torque; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D015921:Dental Implants