denticle vs serration

denticle

noun
  • A dentil. 

  • A pulp stone. 

  • Material serving as the dermis of sharks. 

  • A small tooth. 

serration

noun
  • A set of teeth or notches. 

  • One of the teeth in a serrated or serrate edge. 

  • The state of being serrated. 

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