title: Implant-retained prostheses: ball vs. conus attachments - A randomized controlled clinical trial.
abstract: OBJECTIVE
  To evaluate implant survival, peri-implant tissue conditions, prosthodontic maintenance requirements and patient satisfaction of two differently retained implant-supported mandibular overdentures (IOD) after the 3 years of observation.
  
  
  METHODS
  Twenty-five patients with edentulous mandibles received two implants each. Twelve patients were randomly selected to receive ball attachments, whereas 13 patients received prefabricated coni. Implant survival, peri-implant parameters (modified Plaque Index, Bleeding on Probing, modified Gingival Index, probing depth and marginal bone loss) and patient satisfaction were assessed. Additionally, prosthodontic maintenance was monitored. Clinical and radiographic follow-ups were performed 1, 2 and 3 years after prosthetic delivery. The Kaplan-Meier method was used to calculate complication rates.
  
  
  RESULTS
  After a mean observation period of 29.6 months, an implant survival rate of 100% could be observed. There were no significant differences in the peri-implant parameters. During the observation period, six patients with conus attachment refused to further participate in follow-ups due to dissatisfaction with their treatment and had to be regarded as dropouts. Based on the Kaplan-Meier method, inacceptable retention was calculated for 80% and 75% of the patients in the ball and the conus groups, respectively. Patient satisfaction was 64% for the ball- and 100% for the conus-retained IODs, the latter only respecting five of initially 13 patients.
  
  
  CONCLUSIONS
  The evaluated treatment method revealed high implant survival rates, but the prosthetic reconstruction required intensive maintenance. Therefore, a trend toward the reduced patient satisfaction was observed, and the promoted economy of the evaluated attachment systems should be questioned. For the conical attachment, the recommendation of the manufacturer is to use four interforaminal implants to support a removable prostheses.
authors.affiliation: Private Practice, Riegel, Germany.
authors.forename: Sandy
authors.initials: S
authors.lastname: Cepa
authors.affiliation: Private Practice, Much, Germany.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Koller
authors.affiliation: Center for Dental Medicine, Department of Prosthetic Dentistry, Medical Center - University of Freiburg, Freiburg, Germany.
authors.forename: Benedikt Christopher
authors.initials: BC
authors.lastname: Spies
authors.affiliation: Clinic for Transplantation Immunology and Nephrology, STCS Statistics and Data Management, University Hospital Basel, Basel, Switzerland.
authors.forename: Susanne
authors.initials: S
authors.lastname: Stampf
authors.affiliation: Center for Dental Medicine, Department of Prosthetic Dentistry, Medical Center - University of Freiburg, Freiburg, Germany.
authors.forename: Ralf-Joachim
authors.initials: RJ
authors.lastname: Kohal
mesh_terms: D000368:Aged; D019094:Dental Prosthesis, Implant-Supported; D003781:Denture Retention / Q000379:methods*; D003828:Denture, Overlay; D005260:Female; D006801:Humans; D007575:Jaw, Edentulous / Q000601:surgery; D008297:Male; D008334:Mandible / Q000601:surgery; D017060:Patient Satisfaction; D016896:Treatment Outcome
keywords: SynCone; ball attachment; dental implants; implant-retained mandibular overdentures; randomized controlled clinical trial