A 27-year-old patient has been referred by a prosthodontist for endodontic treatment of the 45 tooth. Objectively: the 45 tooth crown is destroyed; the lateral surface of the tongue and the buccal mucosa have patches of grayish macerated epithelium slightly rising above the mucosa surface at the points of direct contact with the 45 tooth. The uvula and palatine arches are stagnant-red in color; hard palate has papulae surrounded with red margin and covered in grayish epithelium. The submandibular, cervical, supraclavicular, and subclavicular lymph nodes are enlarged and painless. What is the provisional diagnosis?