Which disease of the oral soft tissues is associated with infection by bacteria?

Periodontitis is indeed a disease of the oral soft tissues that is directly associated with bacterial infection. This condition is characterized by inflammation of the supporting structures of the teeth, including the gums, periodontal ligament, and alveolar bone. The primary cause of periodontitis is the accumulation of plaque, a sticky film of bacteria, on the teeth and gums. When this plaque is not adequately removed through proper oral hygiene, it hardens into tartar, further fostering bacterial growth, which can lead to the destruction of the periodontal tissues.

In contrast, herpes simplex is caused by a viral infection, and oral candidiasis is the result of a fungal infection due to overgrowth of Candida species. Stomatitis can refer to inflammation of the oral mucosa and can be caused by various factors including viral, bacterial, fungal infections, or irritants, but it is not exclusively linked to bacterial infection as periodontitis is. This makes periodontitis uniquely associated with bacterial causes among the listed conditions.