A patient complains of pain and swelling in the right submandibular area. She has been treating the 45 tooth for a week. Objectively: body temperature is 38°C. There is a painful tense infiltration in the right submandibular region. The skin doesn't make a fold, its hyperemic and glossy. The mouth can be opened by 3 cm. Deglutition is painless. These clinical findings correspond with the following disease: