[The second edition of oral rare diseases list].

The low prevalence and complex clinical characteristics of oral rare diseases make their diagnosis and treatment difficult in clinical practice. The publication of "The first edition of oral rare diseases list" in 2020 provides the important references for the diagnosis and treatment of such diseases. In order to further expand and improve the scope of oral rare diseases, this second version of oral rare diseases list has newly included 9 groups and 454 types of diseases with different degrees or kinds of oral craniofacial features, and provides the Chinese and English disease names and online Mendelian Inheritance in Man classification numbers,as well as short descriptions. We also revised eight items in the first edition. The whole contents have been reviewed by the committee members of the Society of Oral Genetic Diseases and Rare Diseases, Chinese Stomatological Association. The diseases on the first and second list together forms the whole system of oral rare diseases.