Australian Dental Council (ADC) Practice Test

The presentation of a painless ulcerated lesion on the buccal mucosa with indurated margins and positive serology is highly indicative of a chancre, which is the primary lesion associated with syphilis.

Chancres are typically characterized by their painless and ulcerative nature, often with a clean base and well-defined, raised borders due to induration. The presence of positive serology supports the diagnosis of syphilis, as serological tests are commonly used to detect antibodies associated with the Treponema pallidum bacterium, the causative agent of syphilis.

In contrast, oral candidiasis usually presents as white lesions or patches that can be wiped off, and does not typically produce indurated margins. Herpes simplex virus infections present with painful vesicular lesions and tend to cluster rather than form a solitary ulcer with indurated edges. A dental abscess is often associated with localized pain, swelling, and possibly fever, which is not consistent with a painless sore on the mucosa. Therefore, the clinical features and laboratory findings point towards a diagnosis of syphilitic chancre.