title: Viscoelastic properties of rabbit vocal folds after augmentation.
abstract: BACKGROUND
  Vocal fold function is closely related to tissue viscoelasticity. Augmentation substances may alter the viscoelastic properties of vocal fold tissues and hence their vibratory capacity.
  
  
  OBJECTIVE
  We sought to investigate the viscoelastic properties of rabbit vocal folds in vitro after injections of various augmentation substances.
  
  
  METHODS
  Polytetrafluoroethylene (Teflon), cross-linked collagen (Zyplast), and cross-linked hyaluronan, hylan b gel (Hylaform) were injected into the lamina propria and the thyroarytenoid muscle of rabbit vocal folds. Dynamic viscosity of the injected vocal fold as a function of frequency was measured with a Bohlin parallel-plate rheometer during small-amplitude oscillation.
  
  
  RESULTS
  All injected vocal folds showed a decreasing dynamic viscosity with increasing frequency. Vocal fold samples injected with hylan b gel showed the lowest dynamic viscosity, quite close to noninjected control samples. Vocal folds injected with polytetrafluoroethylene showed the highest dynamic viscosity followed by the collagen samples.
  
  
  CONCLUSIONS
  The data indicated that hylan b gel in short-term renders the most natural viscoelastic properties to the vocal fold among the substances tested. This is of importance to restore/preserve the vibratory capacity of the vocal folds when glottal insufficiency is treated with injections.
authors.affiliation: Department of Logopedics and Phoniatrics, Huddinge University Hospital, Karolinska Institute, Stockholm, Sweden. stellan.hertegard@klinvet.ki.se
authors.forename: Stellan
authors.initials: S
authors.lastname: Hertegård
authors.forename: Ake
authors.initials: A
authors.lastname: Dahlqvist
authors.forename: Claude
authors.initials: C
authors.lastname: Laurent
authors.forename: Assunta
authors.initials: A
authors.lastname: Borzacchiello
authors.forename: Luigi
authors.initials: L
authors.lastname: Ambrosio
mesh_terms: D000818:Animals; D003094:Collagen / Q000494:pharmacology* / Q000627:therapeutic use; D004548:Elasticity / Q000187:drug effects; D006820:Hyaluronic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use; D019736:Prostheses and Implants; D011817:Rabbits; D014827:Vocal Cords / Q000187:drug effects* / Q000601:surgery*
chemical_list: C048470:glutaraldehyde-cross-linked collagen; C445362:hylan-B gel; D006820:Hyaluronic Acid; D003094:Collagen