endodontia vs endodontics

endodontia and endodontics both are nouns.

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

As nouns, endodontia and endodontics are synonyms defined as:

endodontia and endodontics: the branch of dentistry dealing with diseases of the dental pulp

endodontia (noun)	endodontics (noun)
the branch of dentistry dealing with diseases of the dental pulp	the branch of dentistry dealing with diseases of the dental pulp