explain vs make a dent

explain

verb
  • To make plain, manifest, or intelligible; to clear of obscurity; to illustrate the meaning of. 

  • To give a valid excuse for past behavior. 

  • To make something plain or intelligible. 

make a dent

verb
  • To make an impression; to have an effect on; to chip away at. 

  • Used other than figuratively or idiomatically: see make, a, dent. 

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