title: Clinical outcome and peri-implant findings of four-implant-supported distal cantilevered fixed mandibular prostheses: five-year results.
abstract: OBJECTIVE
  This retrospective study evaluated implant and prosthodontic survival/success rates of four-implant-supported distal cantilevered mandibular fixed prostheses over more than 5 years of clinical use.
  
  
  METHODS
  Patients with mandibular edentulism treated with four-implant mandibular prostheses with distal extensions were evaluated. Cumulative implant survival/success rates, peri-implant conditions, and prosthodontic maintenance efforts were assessed. Relationships between the degree of distal implant tilting, length of cantilevers, and implant-generated supporting zone were evaluated.
  
  
  RESULTS
  Thirty-eight patients with 152 implants (90.5% of the original sample) were available for follow-up after 5 to 7 years (mean follow-up, 66.5 ± 3.1 months). The cumulative survival and success rates for included implants were 100% and 98.6%, respectively. Denture cantilever length (mean, 14.7 ± 2.3 mm; range, 9 to 20 mm) and implant-generated supporting zone (mean, 318.9 ± 48.1 mm(2); range, 225 to 410 mm(2)) showed significant positive and negative correlations, respectively, with the inclination of tilted distal implants toward the occlusal plane (76 ± 7.2 degrees; range, 65 to 90 degrees). Peri-implant marginal bone resorption (1.5 ± 0.4 mm) and pocket depths (1.8 ± 0.8 mm) were similar for anterior and posterior implants and were not influenced by degree of tilting or cantilever length. Plaque and calculus conditions were poorer for anterior implants than for posterior implants. No dentures fractured; however, fractures of resin tooth veneer material, denture rebasing, and a strong need for cleaning as a result of resin discoloration were seen.
  
  
  CONCLUSIONS
  Fixed four-implant rehabilitations with distal cantilevers of a defined length with or without distally tilted implants showed high success rates. Inferior hygiene in the anterior mandible regions may be a result of reduced cleansability and variations in anatomical landmarks. Resin veneering proved advantageous for repair or modification but disadvantageous for discoloration.
authors.affiliation: Dental School, University of Vienna, Vienna, Austria. krennmair@aon.at
authors.forename: Gerald
authors.initials: G
authors.lastname: Krennmair
authors.forename: Rudolf
authors.initials: R
authors.lastname: Seemann
authors.forename: Michael
authors.initials: M
authors.lastname: Weinländer
authors.forename: Stefan
authors.initials: S
authors.lastname: Krennmair
authors.forename: Eva
authors.initials: E
authors.lastname: Piehslinger
mesh_terms: D000328:Adult; D000368:Aged; D015921:Dental Implants; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure / Q000706:statistics & numerical data; D003779:Denture Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007575:Jaw, Edentulous / Q000534:rehabilitation*; D008297:Male; D008334:Mandible; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D015921:Dental Implants