There are many causes of white milia on adult gums, such as wisdom tooth pericoronitis, periodontal abscess, alveolar bone growth, apical periapical inflammation and so on. 1. Wisdom tooth pericoronitis: Wisdom tooth pericoronitis will invade the adjacent tissues, so it will lead to local bleeding, pus, and pain, which will lead to the phenomenon of white rice grains on adult gums. 2. Periodontal abscess: gingivitis, chronic periodontitis can form a periodontal abscess, which can lead to the phenomenon of white grains of rice on the adult gums. 3. Alveolar bone hyperplasia: white grains of rice on the adult gums may belong to the alveolar bone hyperplasia, due to alveolar bone hyperplasia, resulting in tooth protrusion, in order to adapt to the biting force, so the formation of white hard lumps. 4. apical periodontitis: teeth suffer trauma, caries or other factors, can lead to pulp necrosis, inflammation further spread to the root tip, the formation of local pus, if the pus can not be discharged in a timely manner, it can lead to the phenomenon of adult gums grow white grains of rice. There are many reasons for the growth of white rice particles on the adult gums, after the emergence of symptoms, it is recommended to go to the hospital in a timely manner to improve the examination, under the guidance of the doctor to take standardized treatment, do not treat privately, so as not to lead to adverse consequences.