dandruff vs dermis

dandruff

noun
  • scaly white dead skin flakes from the human scalp; Pityriasis capitis 

verb
  • To fall or cover with white flakes, like dandruff. 

dermis

noun
  • The tissue of the skin underlying the epidermis. 

How often have the words dandruff and dermis occurred in a corpus of books? (source: Google Ngram Viewer )