dental surgery vs dentistry

dental surgery and dentistry both are nouns.

Word	Noun	Adjective	Verb	Adverb
dental surgery	Yes	No	No	No
dentistry	Yes	No	No	No

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

dental surgery: the branch of dentistry involving surgical procedures
dentistry: the branch of medicine dealing with the anatomy and development and diseases of the teeth

Other hypernyms of dental surgery include dental medicine, odontology.

dental surgery (noun)	dentistry (noun)
the branch of dentistry involving surgical procedures	the branch of medicine dealing with the anatomy and development and diseases of the teeth