title: Implants placed in sites of previously failed implants: a systematic review.
abstract: OBJECTIVE
  The aim of this study was to systematically review the literature on implant placement in sites of previously failed implants and to assess survival and success rates of the replacement implants to investigate the effectiveness of the procedure.
  
  
  METHODS
  MEDLINE and Cochrane Oral Health Group databases were used to identify articles published between 1985 and 2011. Six articles were selected for a total of 334 patients (338 implants).
  
  
  RESULTS
  The survival rate ranged from 71% to 100%. The survival rate for implants placed for the second time (third attempt) in the sites of previously failed implants was 83.75%. No studies included in this review reported the cumulative success rate except for the prospective one, which reported a 93.7% success rate. The main limitations of the present systematic review have been the scarce number of patients and implants in the analyzed studies and the lack of large well-designed case-control long-term trials.
  
  
  CONCLUSIONS
  Survival rates of implants placed in the areas of previously failed implants are low, although they should not discourage clinicians from a second or even a third attempt.
authors.affiliation: *Adjunct Professor, Division of Periodontology and Graduate Master in Periodontics, School of Dentistry, Università Politecnica delle Marche, Ancona, Italy. †Research Fellow, Department of Medical, Oral and Biotechnological Sciences, Dental School, University of Chieti-Pescara, Chieti, Italy. ‡Full Professor, Department of Medical, Oral and Biotechnological Sciences, Dental School, University of Chieti-Pescara, Chieti, Italy. §Full Professor and Director, School of Dentistry, Università Politecnica delle Marche, Ancona, Italy. ‖Associate Professor and Director of the Graduate Master in Periodontics, School of Dentistry, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Quaranta
authors.forename: Vittoria
authors.initials: V
authors.lastname: Perrotti
authors.forename: Adriano
authors.initials: A
authors.lastname: Piattelli
authors.forename: Matteo
authors.initials: M
authors.lastname: Piemontese
authors.forename: Maurizio
authors.initials: M
authors.lastname: Procaccini
mesh_terms: D015921:Dental Implants / Q000009:adverse effects / Q000706:statistics & numerical data; D019232:Dental Restoration Failure / Q000706:statistics & numerical data; D006801:Humans; D012086:Reoperation / Q000009:adverse effects / Q000706:statistics & numerical data
chemical_list: D015921:Dental Implants