title: Comparative study of morphological and histological changes between differently structured expanded polytetrafluoroethylene implants in an animal model.
abstract: BACKGROUND
  Expanded polytetrafluoroethylene (e-PTFE) is a popular graft material used in augmentation rhinoplasty. New e-PTFE has thicker fibrils and is more compact than first developed e-PTFE. This study aimed to compare morphological and histological changes between differently structured e-PTFE implants in a rat model.
  
  
  METHODS
  Two types of e-PTFE were implanted in the cranial region of 30 adult male rats. En bloc specimens containing the implants and surrounding soft tissues were sampled 1, 3, and 6 months after implantation. We measured the three-dimensional size of the implants over time and evaluated histological changes using light and electron microscopy.
  
  
  RESULTS
  Grossly, no implants were extruded, and there was no evidence of wound infection. All first developed e-PTFE samples were fixed to surrounding tissues after 1 month, whereas new e-PTFE samples tended to migrate and were easily separated from surrounding tissues until 3 months after implantation. The first developed e-PTFE height diminution rate was 14.7% of the initial value after 6 months; however, new e-PTFE size was not changed. Diameter and height diminution rates for first developed e-PTFE were significantly greater than those for new e-PTFE after 6 months. Histologically, connective tissue in growth was observed in first developed e-PTFE after 1 month, and the internodal space decreased over time; however, connective tissue did not infiltrate into new e-PTFE until 6 months and the internodal space was not significantly changed.
  
  
  CONCLUSIONS
  First developed e-PTFE should be carefully trimmed in augmentation because of its potential to decrease in size over time, whereas new e-PTFE is more likely to show migration and instability.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Chuncheon Sacred Heart Hospital, Hallym University College of Medicine, Chuncheon, Republic of Korea.
authors.forename: Ji Heui
authors.initials: JH
authors.lastname: Kim
authors.forename: Jung Min
authors.initials: JM
authors.lastname: Lee
authors.forename: Hyung Woo
authors.initials: HW
authors.lastname: Ju
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Ah Young
authors.initials: AY
authors.lastname: Jun
authors.forename: Chan Hum
authors.initials: CH
authors.lastname: Park
mesh_terms: D000818:Animals; D003238:Connective Tissue / Q000254:growth & development / Q000601:surgery; D006801:Humans; D020007:Implants, Experimental; D008297:Male; D023421:Models, Animal; D011138:Polytetrafluoroethylene; D011475:Prosthesis Failure; D019919:Prosthesis Implantation; D060489:Prosthesis Retention / Q000706:statistics & numerical data*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012225:Rhinoplasty / Q000379:methods*; D012886:Skull / Q000601:surgery; D013997:Time Factors
chemical_list: D011138:Polytetrafluoroethylene