title: Long-term results of mandibular implants supporting an overdenture: implant survival, failures, and crestal bone level changes.
abstract: OBJECTIVE
  The present study summarizes the long-term clinical observations of edentulous patients treated with mandibular implant-supported overdentures.
  
  
  METHODS
  From 1984 to 1997, edentulous patients were consecutively admitted to treatment with mandibular implant overdentures. The treatment plan was to connect the dentures to only two implants by means of single ball anchors or bars; in patients with special oral conditions, three implants would be placed. Regular maintenance care was provided at least one time per year. The cumulative implant survival rate was calculated. Implant failures were described according to clinical signs at the time of removal and related to the patient's specific history. Crestal bone measurements were performed using computer software.
  
  
  RESULTS
  In all, 147 patients with 314 implants were evaluated for 10 to 24 years. Of these, 101 patients were still available; of the 46 patients who were not evaluated, 26 had died or were not ambulatory. Thirteen implants failed during the observation period, resulting in a cumulative survival rate of 85.9% after 24 years. The reasons for removal of implants were peri-implantitis (two implants) and mobility (11 implants). Mean crestal bone loss was 0.54 ± 0.7 mm per implant site after an average observation time of 16.5 ± 3.9 years. The duration of loading had a statistically significant effect on bone loss.
  
  
  CONCLUSIONS
  The present data exhibit a satisfactory survival rate of implants. An individual analysis of implants with late failures did not reveal a typical failure pattern, but loss of implants without signs of infection was more frequent than loss of implants with signs of peri-implantitis.
authors.affiliation: Department of Prosthodontics, University of Bern, Switzerland.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ueda
authors.forename: Urs
authors.initials: U
authors.lastname: Kremer
authors.forename: Joannis
authors.initials: J
authors.lastname: Katsoulis
authors.forename: Regina
authors.initials: R
authors.lastname: Mericske-Stern
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016301:Alveolar Bone Loss / Q000209:etiology*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003779:Denture Design; D003781:Denture Retention; D003828:Denture, Overlay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007575:Jaw, Edentulous / Q000534:rehabilitation* / Q000601:surgery; D008137:Longitudinal Studies; D008297:Male; D008334:Mandible / Q000601:surgery*; D008875:Middle Aged; D010347:Patient Care Planning; D057873:Peri-Implantitis / Q000209:etiology; D011862:Radiography, Panoramic; D012984:Software; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants