A 13-year-old girl has presented with gingival hemorrhage and mobility of the front teeth over the last month. Objectively: gingival mucosa around the lower incisors and canines is edematous, hyperemic, bleeds on touch. There is grade l tooth mobility, periodontal pockets are 3 mm deep. Orthopantomogram shows the resorption of interalveolar septa by 1/3 of their height. There is crowding of the lower front teeth. Hygiene index is 4,2. The patient has to consult the following specialist: