A 5-year randomized trial to compare 1 or 2 implants for implant overdentures

J Dent Res. 2015 Jan;94(1):36-43. doi: 10.1177/0022034514554224. Epub 2014 Oct 27.


The hypothesis of this 5-y randomized clinical trial was that there would be no significant difference in the satisfaction of edentulous participants with removable complete overdentures attached to 1 or 2 mandibular implants. Secondary aims were to test changes in satisfaction between and within the groups from baseline to 5 y and differences between the groups in implant survival and prosthodontic maintenance over 5 y. Each of the 86 participants (mean age, 67 y) was randomly allocated to receive either 1 implant in the midline (group 1) or 2 implants in the canine areas (group 2) attached to a mandibular overdenture opposing a maxillary complete denture. Satisfaction was self-assessed by participants on a visual analog scale at baseline prior to implants, as well as at 2 mo and 1, 3, and 5 y with implant overdentures, whereas implant survival and prosthodontic maintenance were assessed by clinical examination. After 5 y, 29 participants in group 1 and 33 in group 2 were available, with most dropouts due to death. Satisfaction with the implant denture after 5 y was significantly (P < 0.001) higher than at baseline in both groups and remained with no significant difference (P = 0.32) between the groups. No implants failed in group 1 but 5 failed before loading in 4 participants in group 2. Most participants required maintenance or occasionally denture replacement, and although differences between the groups were not statistically significant, group 1 experienced almost twice as many fractured dentures usually adjacent to the implant attachment. We conclude that there were no significant differences after 5 y in satisfaction or survival of implants with mandibular overdentures retained by 1 implant or 2 implants. Additional research is required to confirm long-term treatment effectiveness of single-implant dentures and the implications of prosthetic maintenance with implant overdentures (ClinicalTrials.gov: NCT02117856).

Keywords: complete denture; dental implant; edentulous mandible; implant-supported dental prosthesis; single-implant denture; standard of care.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Dental Arch / surgery
  • Dental Implants*
  • Dental Implants, Single-Tooth*
  • Dental Prosthesis, Implant-Supported*
  • Dental Restoration Failure
  • Denture Rebasing
  • Denture Repair
  • Denture Retention
  • Denture, Complete, Lower
  • Denture, Overlay*
  • Female
  • Follow-Up Studies
  • Humans
  • Jaw, Edentulous / rehabilitation
  • Jaw, Edentulous / surgery
  • Male
  • Mandible / surgery
  • Patient Satisfaction
  • Self-Assessment
  • Survival Analysis
  • Treatment Outcome
  • Visual Analog Scale


  • Dental Implants

Associated data

  • ClinicalTrials.gov/NCT02117856