The most common oral manifestation of HIV infection is oral candidiasis, which occurs due to the immunosuppression caused by the virus, leading to an opportunistic fungal infection by Candida species. It presents as white, removable plaques on the oral mucosa and is often one of the earliest signs of HIV-related immunodeficiency. Oral candidiasis is highly prevalent in HIV-positive patients and serves as an important clinical marker of disease progression. Early identification aids in timely diagnosis and management of HIV infection.

Reference: Oral Pathology for the Dental Hygienist, Olga A. C. Ibsen, Joan Andersen Phelan, 7th Edition.