title: Corrosion at the marginal gap of implant-supported suprastructures and implant failure.
abstract: OBJECTIVE
  Late failure, which occurs after successful osseointegration, is usually attributed to prosthodontic determinants. Corrosion of metallic suprastructures and incorrectly handled materials are often primary causes of late implant failure. In this study, 6 implants whose failure was related to suprastructure metal corrosion and adjacent bone were investigated.
  
  
  METHODS
  Six implants as well as their suprastructures were analyzed for surface corrosion using light and scanning microscopy. Metal alloys and soldering compounds were analyzed using energy-dispersive x-ray analysis. Bone adhering to the implants was removed and analyzed for metal content using atom absorption spectroscopy.
  
  
  RESULTS
  Extensive corrosion lesions and areas of oxidation were detected on all 6 of the implants and inner crown surfaces. Bone tissue collected from 5 of the implants showed higher contents of metal ions in comparison to physiologic baseline values detected in healthy bone.
  
  
  CONCLUSIONS
  In spite of the high gold content of the suprastructure, corrosion occurred. Bonding oxides necessary for the process of fusing porcelain to gold will initiate corrosion. Apparently, once corrosion is initiated it rapidly progresses at the gap crevices, and toxic metal ions are released. These toxic ions diffuse into the peri-implant bone, causing bone structure breakdown and hastening osseodisintegration.
  
  
  CONCLUSIONS
  Biocompatible metals, alloys, and ceramics should be used for implant-supported suprastructures. It is also essential that gaps between the implant and its suprastructure be avoided by cementing the suprastructure or sealing the gap.
authors.affiliation: Department of Periodontology, Endodontology and Cariology, School of Dental Medicine, University of Basel, Switzerland. joseph.guindy@unibas.ch
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Guindy
authors.forename: Harold
authors.initials: H
authors.lastname: Schiel
authors.forename: Fre
authors.initials: F
authors.lastname: Schmidli
authors.forename: Jakob
authors.initials: J
authors.lastname: Wirz
mesh_terms: D000293:Adolescent; D000328:Adult; D000539:Alveolar Process / Q000737:chemistry; D003343:Corrosion; D003442:Crowns / Q000009:adverse effects; D003722:Dental Alloys / Q000009:adverse effects*; D003758:Dental Implantation, Endosseous / Q000009:adverse effects; D015921:Dental Implants / Q000009:adverse effects*; D019094:Dental Prosthesis, Implant-Supported / Q000009:adverse effects*; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D008297:Male; D008670:Metals / Q000032:analysis; D008875:Middle Aged
chemical_list: D003722:Dental Alloys; D015921:Dental Implants; D008670:Metals