title: Dental implants placed in previously failed sites: survival rate and factors affecting the outcome.
abstract: OBJECTIVE
  The purpose of the present study was to evaluate the survival rate of dental implants in previously failed implant sites. In addition, factors that might affect the outcome of these redo procedures were also explored.
  
  
  METHODS
  Patients that had failed dental implants, which were replaced with the same implant type at the same site, were included. Data on the failed implants were collected. The same parameters, along with the interval between retrieval and re-implantation, were collected for the second set of implants. Descriptive statistics were used to describe the patients and implants. Life table analysis of these implants was tabulated for both implant sets. The effect of systemic, environmental and local factors on the survival of the redo dental implants was evaluated.
  
  
  RESULTS
  Fifty-six patients with a total of 79 redo implants were included in this study. Implants were followed for 7-78 months (mean 29.9+/-2). Thirteen implants failed that resulted in an overall survival rate of 83.5%. Successful implants had greater diameter (4.05+/-0.52 mm) than failed implants (3.72+/-0.56 mm); however, these differences were only marginal (P=0.06). Conversely, smoking habits, implants length and location, mode of placement and spontaneous exposure did not have a significant effect on the outcome of this procedure.
  
  
  CONCLUSIONS
  Redo of dental implants has a lesser survival rate compared with previous reports for implants in pristine sites. These results were not associated with most implant- and/or patient-related factors. Thus, a possible negative effect that is associated with the specific implant's site might account for this phenomenon.
authors.affiliation: Unit of Periodontology, Department of Oral and Dental Medicine, Rambam Health Care Campus, Haifa, Israel. machtei@rambam.health.gov.il
authors.forename: Eli E
authors.initials: EE
authors.lastname: Machtei
authors.forename: Dan
authors.initials: D
authors.lastname: Mahler
authors.forename: Orit
authors.initials: O
authors.lastname: Oettinger-Barak
authors.forename: Otman
authors.initials: O
authors.lastname: Zuabi
authors.forename: Jacob
authors.initials: J
authors.lastname: Horwitz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D020878:Device Removal; D006801:Humans; D015993:Life Tables; D008875:Middle Aged; D010518:Periodontitis / Q000150:complications; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants