A 13-year-old girl has bleeding gums and her front teeth are mobile. These symptoms have been observed during the last month. Objectively: the gum mucosa in the area of the lower incisors and canines is swollen, hyperemic, bleeding when touched. There is class I teeth mobility, periodontal pockets are 3 mm deep. Orthopantomogram shows bone tissue destruction of the alveolar septums up to 1/3 of their height. Congestion of the lower jaw front teeth can be observed. Oral Hygiene Index equals 4,2. What specialist must be consulted first?