For a long time (on average more than seven years), from the time of HIV infection until the onset of AIDS, patients may have no symptoms. During this period, the vast majority of patients and others are unaware that they are infected, but these patients can still transmit HIV. According to international studies and the clinical experience of many people, it is suggested that within one to four years before the onset of AIDS, most AIDS patients will first develop oral symptoms in the form of a variety of oral lesions, which is an important indication for the detection and diagnosis of HIV infection. Oral lesions closely related to HIV infection include the following: Candidiasis albicans, erythematous and pseudomembranous. Most of them occur in the gingival mucosa as the specific site of damage; sometimes white spots or plaques can be seen on the red area of the lesion. The lesions can also occur in any part of the mouth and appear as white or yellow spots or plaques, which can be wiped away, leaving red areas with bleeding. Many epidemiologic investigations have shown that oral candidiasis has a fairly high prevalence in HIV-infected populations, occurring at various stages of HIV infection, up to 96%. Oral candidiasis is often the initial manifestation of HIV infection and is most common in oral damage; for the vast majority of cases, it is an early sign of immunosuppression following HIV infection, indicating the possibility of other opportunistic infections presenting. It has been suggested that oral Candida infections and hairy white spots can be used as indicators to detect or predict AIDS. Hairy white spots are white or gray lesions that occur on the edges of both sides of the tongue; the lesions may also extend to the belly and back of the tongue and cannot be erased. Hairy leukoplakia is a common oral manifestation second only to candidiasis in terms of prevalence in HIV-infected and AIDS patients, and is a marker of HIV-associated disease that is almost exclusively seen in the HIV-infected and AIDS population, with a very marked specificity. Therefore, the presence of hairy white spots should be highly emphasized. Periodontal Disease Gingival inflammation, gingival ulceration, gingival necrosis, and tooth loosening can occur, as well as painful bleeding and malignant changes in the gums. It is reported that 19% to 29% of HIV-infected or AIDS patients have periodontitis. Kaposi’s sarcoma A single or multiple red, light blue, or purple plaque or mass, with or without ulceration, found first on the palate and gums. Kaposi’s sarcoma is rare in the general population, but with the AIDS epidemic, Kaposi’s sarcoma is appearing in large numbers in people at risk for AIDS. In the United States, people with AIDS are at least 20,000 times more likely to develop Kaposi’s sarcoma than the general population. The prevalence of Kaposi’s sarcoma in oral manifestations of HIV-infected and AIDS patients is second only to candidiasis and trichoplasmosis in terms of prevalence.” Several epidemiologic data show that oral damage can occur in all HIV-positive or AIDS patients, from infants to adults. The populations that usually have the highest incidence are adults such as male homosexual patients, heterosexuals, and intravenous drug users. With the expansion of infection, oral manifestations can also occur in HIV-positive children and HIV-infected individuals who receive blood products. Because oral lesions are so closely associated with HIV-infected patients and AIDS patients; AIDS patients often present to the dentist with oral symptoms. Therefore, as a dentist, you should have knowledge in this area in order to detect and diagnose infected patients and take necessary treatment measures to prevent the spread of AIDS.