periodontia vs periodontics

periodontia and periodontics both are nouns.

Word	Noun	Adjective	Verb	Adverb
periodontia	Yes	No	No	No
periodontics	Yes	No	No	No

As nouns, periodontia and periodontics are synonyms defined as:

periodontia and periodontics: the branch of dentistry dealing with diseases of the gums and other structures around the teeth

periodontia (noun)	periodontics (noun)
the branch of dentistry dealing with diseases of the gums and other structures around the teeth	the branch of dentistry dealing with diseases of the gums and other structures around the teeth