periodontist
noun [ C ] medical specialized uk/ˌper.i.əʊˈdɒn.tɪst/ us/ˌper.i.oʊˈdɑːn.t̬ɪst/
牙周病医生
a dentist who specializes in the treatment of the gums (= the pink flesh in the mouth in which the teeth are fixed) and other tissues around the teeth