endodontics vs dentistry

endodontics and dentistry both are nouns.

Word	Noun	Adjective	Verb	Adverb
endodontics	Yes	No	No	No
dentistry	Yes	No	No	No

As nouns, dentistry is a hypernym of endodontics; that is, dentistry is a word with a broader meaning than endodontics:

endodontics: the branch of dentistry dealing with diseases of the dental pulp
dentistry: the branch of medicine dealing with the anatomy and development and diseases of the teeth

Other hypernyms of endodontics include dental medicine, odontology.

endodontics (noun)	dentistry (noun)
the branch of dentistry dealing with diseases of the dental pulp	the branch of medicine dealing with the anatomy and development and diseases of the teeth