A 36-year-old man complains about acute headache, body temperature rise up to 39, 1°C, indisposition. Objectively: a slight face asymmetry because of soft tissue edema of the left infraorbital area. Crown of the 26 tooth is partly decayed. Percussion is acutely painful. Mucous membrane on the vestibular side in the area of the 25, 26 teeth is edematic, hyperemic. Breathing through the left part of nose is laboured, there are purulent discharges. X-ray picture showed a homogeneous shadow of the left part of maxillary sinus. What is the most probable diagnosis?