The current research includes a diagnostic study of stomatitis that occurs by dentures, mentioning the most important causes of inflammation and classifying them according to its type, severity, impact on the patient, and appropriate treatment methods. In order to treat this disease and maintain oral and dental health, some necessary steps must be followed. These steps are to clean the dentures and keep them in the liquid designated for them during bedtime at night. In addition, food and drink also have a direct effect that may lead to stomatitis, so the research included an accurate diagnosis of the disease in order to find out which of the treatments is appropriate for the condition that occurred and at what stage of the disease according to the development and severity of the condition. The morphological and microscopic diagnosis reveals to us the type of microorganisms that cause stomatitis, which is often fungal, represented by Candida species, which causes inflammation of the mucous membrane.