title: Bone level change at implant-supported fixed partial dentures with and without cantilever extension after 5 years in function.
abstract: OBJECTIVE
  The aim of this study was to retrospectively analyze whether the inclusion of cantilever extensions increased the amount of marginal bone loss at free-standing, implant-supported, fixed partial dentures (FPDs) over a 5-year period of functional loading.
  
  
  METHODS
  The patient material comprised 45 periodontally treated, partially dentate patients with a total of 50 free-standing FPDs supported by implants of the Astra Tech System. Following FPD placement (baseline) the patients were enrolled in an individually designed supportive care program. A set of criteria was collected at baseline to characterize the FPDs. The primary outcome variable was change in peri-implant bone level from the time of FPD placement to the 5-year follow-up examination. The comparison between FPDs with and without cantilevers was performed at three levels: FPD level, implant level, and surface level. Bivariate analysis was performed by the use of the Mann-Whitney U-test and stepwise regression analysis was utilized to evaluate the potential influence of confounding factors on the change in peri-implant bone level.
  
  
  RESULTS
  The overall mean marginal bone loss for the implant-supported FPDs after 5 years in function was 0.4 mm (SD, 0.76). The bone level change at FPDs placed in the maxilla was significantly greater than that for FPDs in the mandible (0.6 versus 0.2 mm; p<0.05). No statistically significant differences were found with regard to peri-implant bone level change over the 5 years between FPDs with and without cantilevers at any of the levels of comparisons. The multivariate analysis revealed that the variables jaw of treatment and smoking had a significant influence on peri-implant bone level change on the FPD level, but not on the implant or surface levels. The model explained only 10% of the observed variance in the bone level change.
  
  
  CONCLUSIONS
  The study failed to demonstrate that the presence of cantilever extensions in an FPD had an effect on peri-implant bone loss.
authors.affiliation: Department of Periodontology, Faculty of Odontology, The Sahlgrenska Academy at Göteborg University, SE 405 30 Göteborg, Sweden. wennstrom@odontologi.gu.se
authors.forename: Jan
authors.initials: J
authors.lastname: Wennström
authors.forename: Jose
authors.initials: J
authors.lastname: Zurdo
authors.forename: Stig
authors.initials: S
authors.lastname: Karlsson
authors.forename: Annika
authors.initials: A
authors.lastname: Ekestubbe
authors.forename: Kerstin
authors.initials: K
authors.lastname: Gröndahl
authors.forename: Jan
authors.initials: J
authors.lastname: Lindhe
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000209:etiology*; D015921:Dental Implants / Q000009:adverse effects; D017266:Dental Prosthesis / Q000009:adverse effects*; D017267:Dental Prosthesis Design / Q000009:adverse effects; D019094:Dental Prosthesis, Implant-Supported / Q000009:adverse effects; D003830:Denture, Partial, Fixed / Q000009:adverse effects; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013997:Time Factors
chemical_list: D015921:Dental Implants