title: Oral mucosa tissue response to titanium cover screws.
abstract: BACKGROUND
  Titanium is the most widely used metal in dental implantology. The release of particles from metal structures into the biologic milieu may be the result of electrochemical processes (corrosion) and/or mechanical disruption during insertion, abutment connection, or removal of failing implants. The aim of the present study is to evaluate tissue response of human oral mucosa adjacent to titanium cover screws.
  
  
  METHODS
  One hundred fifty-three biopsies of the supra-implant oral mucosa adjacent to the cover screw of submerged dental implants were analyzed. Histologic studies were performed to analyze epithelial and connective tissue as well as the presence of metal particles, which were identified using microchemical analysis. Langerhans cells, macrophages, and T lymphocytes were studied using immunohistochemical techniques. The surface of the cover screws was evaluated by scanning electron microscopy (SEM).
  
  
  RESULTS
  Forty-one percent of mucosa biopsies exhibited metal particles in different layers of the section thickness. Particle number and size varied greatly among specimens. Immunohistochemical study confirmed the presence of macrophages and T lymphocytes associated with the metal particles. Microchemical analysis revealed the presence of titanium in the particles. On SEM analysis, the surface of the screws exhibited depressions and irregularities.
  
  
  CONCLUSIONS
  The biologic effects seen in the mucosa in contact with the cover screws might be associated with the presence of titanium or other elements, such as aluminum or vanadium. The potential long-term biologic effects of particles on soft tissues adjacent to metallic devices should be further investigated because these effects might affect the clinical outcome of the implant.
authors.affiliation: Department of Oral Pathology, School of Dentistry, University of Buenos Aires, Buenos Aires, Argentina. olmedodg@gmail.com
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Olmedo
authors.forename: María L
authors.initials: ML
authors.lastname: Paparella
authors.forename: Martín
authors.initials: M
authors.lastname: Spielberg
authors.forename: Daniel
authors.initials: D
authors.lastname: Brandizzi
authors.forename: María B
authors.initials: MB
authors.lastname: Guglielmotti
authors.forename: Rómulo L
authors.initials: RL
authors.lastname: Cabrini
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000497:Alloys; D000535:Aluminum / Q000032:analysis; D003238:Connective Tissue / Q000187:drug effects / Q000473:pathology; D003343:Corrosion; D003722:Dental Alloys / Q000032:analysis / Q000494:pharmacology; D015921:Dental Implants; D003764:Dental Materials / Q000032:analysis / Q000494:pharmacology*; D004848:Epithelium / Q000187:drug effects / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000032:analysis; D007801:Langerhans Cells / Q000187:drug effects / Q000473:pathology; D008264:Macrophages / Q000187:drug effects / Q000473:pathology; D008297:Male; D008832:Microchemistry / Q000379:methods; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D009061:Mouth Mucosa / Q000187:drug effects* / Q000473:pathology; D010316:Particle Size; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D013601:T-Lymphocytes / Q000187:drug effects / Q000473:pathology; D014025:Titanium / Q000032:analysis / Q000494:pharmacology*; D014639:Vanadium / Q000032:analysis; D055815:Young Adult
chemical_list: D000497:Alloys; D003722:Dental Alloys; D015921:Dental Implants; D003764:Dental Materials; D014639:Vanadium; C031462:titanium alloy (TiAl6V4); D007633:Keratins; D000535:Aluminum; D014025:Titanium