title: Microrelief suppresses large wrinkling appearance: an in silico study.
abstract: OBJECTIVE
  Extensive skin wrinkling during facial expressions is one of the considerable problems in aesthetic dermatology. Although a few in silico studies have been performed with the aim of revealing the mechanism of a wrinkled appearance, there have been few studies that take into account the influence of skin roughness (i.e. microrelief), which exists on human skin in vivo. In this study, finite element simulations were performed using multilayer skin models with microrelief to investigate how extensive wrinkling appears on human skin, especially focusing on the role of surface roughness in the wrinkling mechanism.
  
  
  METHODS
  Linear and post-buckling analyses were performed on soft elastic laminate models using the finite element method. A simplified multilayer model of human skin was employed to examine the contribution of skin's multilayer structure to the large-wrinkle mechanism. Microrelief was included in the model to assess its effect on the mechanism.
  
  
  RESULTS
  A large wrinkle was observed as dermal buckling following a number of buckling events on the stratum corneum. The existence of microrelief had an effect on the suppression of dermal buckling.
  
  
  CONCLUSIONS
  Skin's multilayer structure should play a major role in the appearance of large wrinkles on human skin via its post-buckling behavior. This study suggested that fine microrelief on the skin surface hampers large wrinkles. These findings should be valuable for the development of cosmetic or medical treatments to prevent unfavorable skin deformations.
authors.affiliation: Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Shiihara
authors.forename: M
authors.initials: M
authors.lastname: Sato
authors.forename: Y
authors.initials: Y
authors.lastname: Hara
authors.forename: I
authors.initials: I
authors.lastname: Iwai
authors.forename: N
authors.initials: N
authors.lastname: Yoshikawa
mesh_terms: D003198:Computer Simulation; D055119:Elastic Modulus / Q000502:physiology; D020342:Finite Element Analysis; D006244:Hardness / Q000502:physiology; D006801:Humans; D008954:Models, Biological; D015595:Skin Aging / Q000473:pathology* / Q000528:radiation effects*; D013499:Surface Properties; D013718:Tensile Strength / Q000502:physiology
keywords: buckling analysis; finite element method; mechanical property; multilayer structure; stratum corneum