A 44-year-old patient consulted a surgeon about constant acute pain in the upper jaw region on the left that is getting worse during teeth joining. The pain was noted 3 days ago. Objectively: the face is symmetrical, mouth opening is unlimited. The crown for the 26 tooth is half-destroyed. Probing of the carious cavity is painless. Percussion of the 26 tooth provokes acute pain. Mucous membrane of the alveolar process is edematic, hyperaemic at the level of the 26 tooth. The 26 tooth had been treated before. What is your provisional diagnosis?