title: Involvement of upper cheek sagging in nasolabial fold formation.
abstract: BACKGROUND
  Nasolabial folds are a well-known feature of aging, but the mechanism of their formation remains unclear.
  
  
  OBJECTIVE
  To clarify the mechanism of nasolabial fold formation, we established grading criteria for severity and explored the influence of dermal elasticity and subcutaneous adipose mass. We also investigated the involvement of facial morphological changes, such as wrinkling and sagging.
  
  
  METHODS
  Faces of 108 healthy Japanese female volunteers (age range: 20-60) were photographed at the angle of 45°, and a six-grade photograph-based grading scheme for nasolabial fold severity was established and evaluated. In 70 Japanese female volunteers (middle-aged: 30-50), dermal elasticity was measured with a Cutometer MPA 580® and subcutaneous adipose layer thickness was measured by ultrasound using a Prosound alpha 5®.
  
  
  RESULTS
  Nasolabial fold severity was significantly and positively correlated with age in subjects in their twenties to sixties (R = 0.777, P < 0.001). Nasolabial folds were drastically reduced, or disappeared, when the facial position was changed (subjects lay down instead of sitting) to reduce sagging; only 13.8% of subjects showed fixed wrinkles at the positions of the nasolabial folds after the facial position change. Nasolabial fold severity in middle-aged volunteers was significantly and negatively correlated with dermal elasticity parameters, i.e., net elasticity excluding viscoelastic creep (Ur/Ue), overall elasticity including creep and creep recovery (Ua/Uf), ratio of elastic recovery to total deformation (Ur/Uf), and the negative value of the amount of deformation that did not recover to the original state [-Uf-Ua)], all of which were significantly and negatively correlated with age. Subcutaneous adipose layer thickness was significantly and negatively correlated with dermal elasticity parameter Ua/Uf, and also significantly and positively related to nasolabial fold severity (R = 0.285, P < 0.017).
  
  
  CONCLUSIONS
  Nasolabial fold severity increases with decreasing dermal elasticity and with increment of the subcutaneous adipose layer. These changes might induce sagging formation in the upper cheek area, promoting fold formation at the border between the inner and outer nasolabial areas.
authors.affiliation: Shiseido Research Center, Yokohama-shi, Kanagawa, Japan. tomonobu.ezure@to.shiseido.co.jp
authors.forename: Tomonobu
authors.initials: T
authors.lastname: Ezure
authors.forename: Satoshi
authors.initials: S
authors.lastname: Amano
mesh_terms: D000328:Adult; D002610:Cheek / Q000033:anatomy & histology* / Q000502:physiology*; D055119:Elastic Modulus / Q000502:physiology; D005260:Female; D006801:Humans; D060052:Nasolabial Fold / Q000033:anatomy & histology* / Q000502:physiology*; D015595:Skin Aging / Q000473:pathology* / Q000502:physiology*; D055815:Young Adult