Evaluate the response of the gingival tissues to the use of mouthwash with chlorhexidine and chlorhexidine + hyaluronic acid in terms of healing of the periodontal surgical wound.

Patients included in the study will undergo a thorough clinical examination aiming at collecting all the data desired: periodontal parameters of Probing Pocket Depth (PPD) and presence of recession of the gingival margin (Rec) will be recorded on six sites/tooth in the area selected for periodontal surgery by a single calibrated examiner using a University of North Carolina (UNC) 15-mm periodontal probe at a 0.3 N probing pressure. Surgery will be performed following a standardized protocol by a single operator.

After surgery, patients will be randomly assigned to study groups corresponding to mouth rinse prescription. The mouth rinse will be assigned by an experimenter not involved in the following steps of the study, in order to maintain the examiner blind. The patient will receive a non-labelled mouth rinse to avoid biases both of the examiner and the patient. The patient will also be given a diary for the registration of the number of rinses per day, to be returned to the examiner at T14. The mouth rinse protocol assigned to each study participant includes a 10 ml-rinse for 60 seconds twice-a-day (every 12 hours) for 14 days.

The patients will be allocated in one of the three distinct study groups as it follows:

• Group A: no administration of mouth rinses after surgery (control group)
• Group B: administration of a hyaluronic and 0.2% chlorhexidine mouth rinse (test group 1)
• Group C: administration of chlorhexidine 0.2% mouth rinse (test group 2).

Post-treatment photographs of surgical incision will be taken immediately after periodontal surgery and at 3 (T3), 7 (T7), and 14 (T14) days post-op, in order to allow the evaluation of the degree of wound healing. The degree of surgical healing will be evaluated using the Periodontal Wound Healing Index (Wachtel classification) on all the incisions, and a score from 1 to 5 will be assigned.

At T3, T7, and T14 the following clinical parameters will be recorded for each tooth in the surgical area: PPD, Rec, PI, and BOP. The clinical examinations will be performed by calibrated examiner blind to group allocation.

Inclusion Criteria:

• males or females of age range between 18 and 70 years,
• good health status,
• indication to perform periodontal surgery,
• patients willing to give informed consent,
• compliance to the study follow-up,
• plaque index (PI) score 0 and
• bleeding on probing (BOP) <25%

Exclusion Criteria:

• pregnancy or breast-feeding,
• therapy with oral contraceptives,
• indication to antibiotic therapy prior to surgical treatment,
• chronic infections,
• systemic diseases (including cardiovascular, pulmonary, cerebral, and metabolic diseases),
• previous therapy with the mouth rinses employed in the present study, and
• smoking habit (>20 cigarettes per day, and/or pipe or cigar smoking).

After surgery, patients will be randomly assigned to study groups corresponding to mouth rinse prescription. The mouth rinse will be assigned by an experimenter not involved in the following steps of the study, in order to maintain the examiner blind. The patient will receive a non-labelled mouth rinse to avoid biases both of the examiner and the patient