title: Estimation of Nasal Tip Support Using Computer-Aided Design and 3-Dimensional Printed Models.
abstract: OBJECTIVE
  Palpation of the nasal tip is an essential component of the preoperative rhinoplasty examination. Measuring tip support is challenging, and the forces that correspond to ideal tip support are unknown.
  
  
  OBJECTIVE
  To identify the integrated reaction force and the minimum and ideal mechanical properties associated with nasal tip support.
  
  
  METHODS
  Three-dimensional (3-D) printed anatomic silicone nasal models were created using a computed tomographic scan and computer-aided design software. From this model, 3-D printing and casting methods were used to create 5 anatomically correct nasal models of varying constitutive Young moduli (0.042, 0.086, 0.098, 0.252, and 0.302 MPa) from silicone. Thirty rhinoplasty surgeons who attended a regional rhinoplasty course evaluated the reaction force (nasal tip recoil) of each model by palpation and selected the model that satisfied their requirements for minimum and ideal tip support. Data were collected from May 3 to 4, 2014.
  
  
  RESULTS
  Of the 30 respondents, 4 surgeons had been in practice for 1 to 5 years; 9 surgeons, 6 to 15 years; 7 surgeons, 16 to 25 years; and 10 surgeons, 26 or more years. Seventeen surgeons considered themselves in the advanced to expert skill competency levels. Logistic regression estimated the minimum threshold for the Young moduli for adequate and ideal tip support to be 0.096 and 0.154 MPa, respectively. Logistic regression estimated the thresholds for the reaction force associated with the absolute minimum and ideal requirements for good tip recoil to be 0.26 to 4.74 N and 0.37 to 7.19 N during 1- to 8-mm displacement, respectively.
  
  
  CONCLUSIONS
  This study presents a method to estimate clinically relevant nasal tip reaction forces, which serve as a proxy for nasal tip support. This information will become increasingly important in computational modeling of nasal tip mechanics and ultimately will enhance surgical planning for rhinoplasty.
  
  
  METHODS
  NA.
authors.affiliation: Medical student, University of California, Irvine, School of Medicine2Beckman Laser Institute and Medical Clinic, University of California, Irvine, School of Medicine.
authors.forename: Eric
authors.initials: E
authors.lastname: Gray
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California, Irvine, School of Medicine3Department of Otolaryngology-Head and Neck Surgery, University of California, Irvine, School of Medicine.
authors.forename: Marlon
authors.initials: M
authors.lastname: Maducdoc
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California, Irvine, School of Medicine.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Manuel
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California, Irvine, School of Medicine3Department of Otolaryngology-Head and Neck Surgery, University of California, Irvine, School of Medicine.
authors.forename: Brian J F
authors.initials: BJ
authors.lastname: Wong
mesh_terms: D002983:Clinical Competence; D019245:Compressive Strength; D017076:Computer-Aided Design; D055119:Elastic Modulus; D006801:Humans; D008953:Models, Anatomic; D009666:Nose / Q000502:physiology* / Q000601:surgery; D010173:Palpation; D066330:Printing, Three-Dimensional; D012225:Rhinoplasty / Q000379:methods*; D012828:Silicones; D012984:Software; D014057:Tomography, X-Ray Computed
chemical_list: D012828:Silicones