The goal of this study is to evaluate the use of a gel containing cross-linked hyaluronic acid (xHyA) at the palatal donor site following soft tissue harvesting procedures. The main questions it aims to answer are: 1) Does the use of xHyA improve post-operative patient morbidity?; 2) Does the use of xHyA improve palatal donor site healing? Researchers will compare xHyA topically applied at the palatal donor site to a negative control to see if xHyA works to minimize participants' morbidity and improve clinical healing.

Participants will be equally distributed into two groups, half of them receiving xHyA. Participants will fill a visual analogue scale for subjective analyses during the first 2 post-operative weeks and will visit the dental clinic at 3, 7, 14 and 60 post-operative days for checkups and clinical examinations.

The aim of the present study is to evaluate the effects of topical cross-linked high molecular weight hyaluronic acid (xHyA) gel on postoperative patient discomfort and wound healing of palatal donor sites after free gingival graft (FGG) surgery.

Twenty patients requiring FGG are randomly assigned into two groups: negative control and a test group receiving xHyA gel in a single application. All surgical interventions are performed by the same surgical team. Anaesthesia of the palatal region is achieved with local infiltrations of mepivacaine 2% with epinephrine 1:100,000. The donor area is delimited by the distal line angle of the canine and the distal line angle of the second molar. A distance ≥ 2 mm from the gingival margin is respected. A half-thickness incision is made and a rectangular FGG with a thickness of ≈1.5 mm and dimensions of ≈20 × 5 mm in length x height respectively is harvested with a 15C scalpel under periodontal probe (PCP-UNC 15, Hu-Friedy Mfg. Co., LLC, Chicago, IL, USA) guidance maintaining a uniform thickness. A 1-minute moderate finger compression with a wet gauze is used to achieve initial haemostasis. Following soft tissue harvesting, in both groups a collagen sponge is placed to protect the palatal donor site, stabilized with cross-mattress sutures. In the test group, xHyA is injected over the exposed connective tissue and into the collagen sponge. In the negative control, the collagen sponge is left dry. In the immediate post-operative period, in order not to disturb the stabilization of the clot and the effects of the topical xHyA, participants are given instructions not to eat, drink, or rinse for about 4 hours. From the day after the surgery, participants are allowed to rinse passively with an ozone-based mouthwash (CollutO3, Innovares S.r.l., Reggio Emilia, Italy) for about 30 seconds twice daily for 2 post-operative weeks. Patients are placed on a soft diet with cold foods for the first week and are advised to avoid any mechanical or thermal trauma. Patients are also instructed not to brush and floss the upper teeth of the sector homolateral to the palatal donor area for one week. Nonsteroidal anti-inflammatory drugs (ibuprofen 600 mg every 6-8 hours up to 3 times a day) to be used as needed are prescribed for pain relief. Palatal sutures are removed after 7 days.

Inclusion Criteria:

• Good general health (ASA 1 or 2)
• No local contraindications to implant surgery procedures (mucosal inflammation, active periodontal disease, erosive mucosal conditions, bone lesions, history of local radiation therapy and bruxism along with inadequate oral hygiene or lack of motivation for home care)
• Presence of two adjacent implants either submerged or prosthetically loaded
• Premolar and/or molar sectors of either the mandible or the maxilla
• Presence of < 2 mm of keratinized mucosa width at the buccal aspect of the said adjacent implants

Exclusion Criteria:

• Smokers (> 10 cigarettes/day)
• Subjects with known allergies to penicillin or collagen
• Poor oral hygiene
• Uncontrolled systemic pahologies
• Active periodontal infection
• No medical history of head and neck radiation therapy
• No medical history of antiresorptive agents or steroids therapies
• Pregnant or lactating women
• Physical or mental disabilities affecting oral hygiene

No individual participant data (IPD) or additional supporting documents will be shared. Data will remain confidential and stored securely at the Implant Center for Edentulism and Jawbone Atrophies, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, in accordance with institutional ethical approval.

Statistician