hair extension vs periwig

hair extension

noun
  • A length of hair which is attached to one's normal hair to make it longer. 

periwig

noun
  • A wig, especially any kind of stylised wig as formerly worn by men and women. 

verb
  • To dress with a periwig, or with false hair; to bewig. 

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