A 46-year-old patient after the recovery froma case of influenza has suddenly started suffering from pain in the 36 tooth, the crown of which had been destroyed. The soft tissues surrounding the lower jaw are swollen. There are high fever up to 39°C and chills. Objectively: there is prominent swelling of the left lower jaw alveolar mucosa (both oral and vestibular surfaces). The 34, 35 and 37 intact teeth are mobile. Percussion is painful. The gingival pockets produce purulent exudate. Vincent’s symptom is observed. What diagnosis can be suspected?