Riggs' disease vs pyorrhoea

Riggs' disease and pyorrhoea both are nouns.

Word	Noun	Adjective	Verb	Adverb
Riggs' disease	Yes	No	No	No
pyorrhoea	Yes	No	No	No

As nouns, Riggs' disease and pyorrhoea are synonyms defined as:

Riggs' disease and pyorrhoea: chronic periodontitis; purulent inflammation of the teeth sockets

Other synonyms of Riggs' disease include pyorrhea, pyorrhea alveolaris.

Riggs' disease (noun)	pyorrhoea (noun)
chronic periodontitis; purulent inflammation of the teeth sockets	discharge of pus
	chronic periodontitis; purulent inflammation of the teeth sockets