title: Early complete failures of fixed implant-supported prostheses in the edentulous maxilla: a 3-year analysis of 17 consecutive cluster failure patients.
abstract: BACKGROUND
  Clusters of implant failures in the edentulous maxilla seem to occur in some patients. To create groups for analysis with higher numbers of these patients implies large original groups for inclusion.
  
  
  OBJECTIVE
  The aim of this study was to retrospectively describe and compare a group of "cluster failure patients" with randomly selected patients treated in the edentulous maxilla.
  
  
  METHODS
  From a group of 1,267 consecutively treated patients in one clinic, all patients presenting failing fixed implant-supported prostheses within the first 3 years of follow-up were included. All patients were treated with turned titanium implants using two-stage surgery. A control group of equal number of patients were created for comparison. Data on patients were retrospectively retrieved from their records, and compared.
  
  
  RESULTS
  Seventeen patients (1.3%) met the inclusion criteria in the entire group. The bone resorption index revealed less bone quantity in the study group (p < .05) during implant placement, but there was no difference regarding primary implant stability at first-stage surgery. The distribution of short and long implants showed relatively higher number of short implants in the study group (p < .05), and more patients had a presurgical discussion on the risk of implant failure prior to treatment in this group (p < .05). Only 5 out of 102 implants (4.9%) were lost before prosthesis placement as compared to 38 and 25 lost implants during the following two years in the study group. Smoking habits and signs of bone loss related to periodontitis in the lower dentition were more frequent in the study group, but did not reach a significant level (p > .05).
  
  
  CONCLUSIONS
  The results indicate that bone quantity, reflected in fixture length, has a significant impact on increased implant failure risk. Other factors of interest as predictors for implant failures could be smoking habits and also possibly signs of periodontitis in the opposing dentition.
authors.affiliation: The Brånemark Clinic, Public Dental Health Service, Göteborg, Sweden. torsten.jemt@vregion.se
authors.forename: Torsten
authors.initials: T
authors.lastname: Jemt
authors.forename: Per
authors.initials: P
authors.lastname: Häger
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016301:Alveolar Bone Loss / Q000145:classification; D003758:Dental Implantation, Endosseous / Q000379:methods; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003781:Denture Retention; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007575:Jaw, Edentulous / Q000534:rehabilitation / Q000601:surgery*; D008297:Male; D008437:Maxilla / Q000601:surgery*; D008875:Middle Aged; D010518:Periodontitis / Q000150:complications; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D014025:Titanium / Q000737:chemistry
chemical_list: D015921:Dental Implants; D003764:Dental Materials; D014025:Titanium