Backround: No data on the adjunctive effects of hyaluronic acid (HA) in a post-surgery, chlorhexidine (CHX) - based plaque control regimen are available. Also, contrasting evidence is available regarding the efficacy of CHX-based formulations containing anti-discoloration system (ADS). The aim of the present study was to evaluate the post-surgery gingival healing as well as plaque, gingival inflammation, and staining levels following the use of a 0.2% chlorhexidine (CHX) solution with or without anti-discoloration system (ADS) and 0.2% hyaluronic acid (HA).

Methods: Patients undergoing flap surgery at sites with an intact or reduced but healthy periodontium participated in a parallel-arm RCT. After surgery, patients used the assigned mouthrinse (CHX+HA+ADS or CHX) for 21 days. At day 7 and 21, the Gingival Healing Index (GHI) was used to assess the quality of flap closure at the interdental papilla. Plaque index (PlI), Gingival Index (GI), Angulated bleeding score (AngBS), tooth and tongue staining were also assessed.

INCLUSION CRITERIA

Patients were included in the study if positive for each of the following patient related criteria:

• 18 years or older;
• able and willing to provide a written informed consent;
• willing to grant the sufficient compliance with the experimental procedures.

Patients were included in the study if positive for each of the following surgery-related criteria (verified as part of their overall treatment plan):

• indication to at least one session of oral surgery (including periodontal surgery, endodontic surgery, tooth extraction, and implant surgery) requiring the elevation of an envelope or triangular, full-thickness gingival/mucosal flap;
• indication to flap extension to the interdental papilla between either the canine and first premolar or first and second premolar to enhance surgical visibility (teeth in this area were identified as the experimental teeth);
• intact (i.e., no clinical attachment loss) or reduced periodontium with probing pocket depths ≤ 3 mm and no diastema at experimental teeth;
• indication to the repositioning of the surgical flap at the pre-surgical level on the experimental teeth at suturing (i.e. no coronal advancement or apical displacement of the flap).

EXCLUSION CRITERIA

Patients were excluded from the study (at either recruitment or during the experimental phase) if positive for one or more of the following patient-related criteria:

• pregnancy or lactation;
• genetic defects (e.g. Down's syndrome) with an established impact on periodontal status;
• diabetes mellitus;
• immune system disorders (e.g. HIV/AIDS);
• heavy smokers (≥ 10 cigarettes/day);
• severe blood disorders, with a documented qualitative and/or quantitative deficit of polymorphonuclears and/or platelets;
• assumption of medications affecting the gingiva and/or the oral mucosa (e.g. diphenylhydantoin, calcium channel blockers, cyclosporin A, immunostimulants/immunomodulators),
• assumption of oral contraceptives;
• use of systemic or local antibiotics in the previous 4 weeks before study initiation and throughout the entire experimental phase;
• documented allergy to CHX and/or HA.

Patients were excluded from the study if the experimental teeth were positive for one or more of the following criteria:

• dental treatment within the last two months;
• presence of untreated caries or endodontic lesions;
• presence of root fractures;
• tooth alterations (i.e. amelogenesis imperfecta, tetracycline staining) impairing staining evaluations;
• presence of inadequate restorations;
• orthodontic appliances;
• indication to mucogingival surgery.

The patient, the clinical operators as well as the clinical examiner were kept blinded with respect to treatment allocation until the termination of the study. To ensure blindness, CHX and CHX+HA+ADS mouthrinses were provided in identical, masked containers numbered according to the randomization sequence.