dental orthopedics vs orthodontia

dental orthopedics and orthodontia both are nouns.

Word	Noun	Adjective	Verb	Adverb
dental orthopedics	Yes	No	No	No
orthodontia	Yes	No	No	No

As nouns, dental orthopedics and orthodontia are synonyms defined as:

dental orthopedics and orthodontia: the branch of dentistry dealing with the prevention or correction of irregularities of the teeth

Other synonyms of dental orthopedics include dental orthopaedics, orthodontics, orthodonture.

dental orthopedics (noun)	orthodontia (noun)
the branch of dentistry dealing with the prevention or correction of irregularities of the teeth	the branch of dentistry dealing with the prevention or correction of irregularities of the teeth