title: Surface and mechanical analysis of explanted Poly Implant Prosthèse silicone breast implants.
abstract: BACKGROUND
  The recent events surrounding Poly Implant Prosthèse (PIP) breast implants have renewed the debate about the safety profile of silicone implants. The intentional use of industrial-grade instead of certified medical-grade silicone is thought to be responsible for reportedly higher frequencies of implant rupture in vivo. The differences in mechanical and viscoelastic properties between PIP and medical-grade silicone implant shells were investigated. Surface characterization of shells and gels was carried out to determine structural changes occurring after implantation.
  
  
  METHODS
  Breast implants were obtained from women at the Royal Free Hospital (London, UK). PIP implants were compared with medical-grade control silicone implants. Tensile strength, tear resistance and elongation at break were assessed using a tensile tester. Surfaces were analysed using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Spearman correlation analyses and Kruskal-Wallis one-way statistical tests were performed for mechanical data.
  
  
  RESULTS
  There were 18 PIP and four medical-grade silicone implants. PIP silicone shells had significantly weaker mechanical strength than control shells (P < 0·009). There were negative correlations between mechanical properties of PIP shells and implantation times, indicative of deterioration of PIP shells over time in vivo (r(s) = -0·75, P = 0·009 for tensile strength; r(s) = -0·76, P = 0·001 for maximal strain). Comparison of ATR-FTIR spectra of PIP and control silicones demonstrated changes in material characteristics during the period of implantation suggestive of time-dependent bond breakage and degradation of the material.
  
  
  CONCLUSIONS
  This study demonstrated an increased weakness of PIP shells with time and therefore supports the argument for prophylactic removal of PIP breast implants.
authors.affiliation: Department of Plastic and Reconstructive Surgery, Royal Free Hospital Hampstead NHS Trust, and University College London Centre for Nanotechnology and Regenerative Medicine, UCL Division of Surgery and Interventional Science, UCL, London, UK. larayildirimer@yahoo.de
authors.forename: L
authors.initials: L
authors.lastname: Yildirimer
authors.forename: A M
authors.initials: AM
authors.lastname: Seifalian
authors.forename: P E
authors.initials: PE
authors.lastname: Butler
mesh_terms: D000328:Adult; D000368:Aged; D018427:Breast Implants; D005260:Female; D006801:Humans; D016462:Mammaplasty / Q000295:instrumentation; D008875:Middle Aged; D011475:Prosthesis Failure; D020034:Silicone Gels / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013718:Tensile Strength; D014783:Viscosity
chemical_list: D020034:Silicone Gels