dressing gown vs surgical gown

dressing gown

noun
  • An item of clothing often made from cotton or another absorbent material, in the form of a long open robe with a belt to tie it around the middle and fasten it securely; often worn over pyjamas. 

surgical gown

noun
  • A protective plastic gown worn by a surgeon when performing surgery. 

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