title: Biofilm formation on bone-anchored hearing aids.
abstract: OBJECTIVE
  To investigate microbiological biofilm contamination of retrieved bone-anchored hearing aids.
  
  
  METHODS
  Nine failed, retrieved bone-anchored hearing aids and 16 internal screws were examined by scanning electron microscopy. A fixture from a failing implant, which had been removed and disassembled under aseptic conditions, was cultured. Finally, an internal screw from a new, unimplanted fixture was examined by scanning electron microscopy.
  
  
  RESULTS
  Debris was seen on the fixture and abutment of all bone-anchored hearing aids, and on the heads of the 16 internal screws. On eight screws, biofilm extended down the shaft to the threads, where it was several micrometres thick. Culture of a failing fixture yielded staphylococcus. The new, unimplanted fixture internal screw showed evidence of scratching and metallic debris on the threads, which may interfere with close fitting of the screw and subsequently facilitate microleakage.
  
  
  CONCLUSIONS
  There may be a link between internal microbial contamination and failure of bone-anchored hearing aids.
authors.affiliation: Dept of Otolaryngology, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital, Queen Elizabeth Medical Q2 Centre, Birmingham, UK.
authors.forename: P
authors.initials: P
authors.lastname: Monksfield
authors.forename: I L C
authors.initials: IL
authors.lastname: Chapple
authors.forename: J B
authors.initials: JB
authors.lastname: Matthews
authors.forename: M M
authors.initials: MM
authors.lastname: Grant
authors.forename: O
authors.initials: O
authors.lastname: Addison
authors.forename: A P
authors.initials: AP
authors.lastname: Reid
authors.forename: D W
authors.initials: DW
authors.lastname: Proops
authors.forename: R L
authors.initials: RL
authors.lastname: Sammons
mesh_terms: D000328:Adult; D018441:Biofilms; D001863:Bone Screws / Q000382:microbiology*; D002648:Child; D006310:Hearing Aids / Q000009:adverse effects / Q000382:microbiology*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D016348:Osseointegration; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections / Q000453:epidemiology*; D013210:Staphylococcus / Q000302:isolation & purification; D053441:Suture Anchors / Q000382:microbiology*; D014025:Titanium
chemical_list: D014025:Titanium