Postoperative complications associated with free gingival graft (FGG) procedures are prolonged bleeding from the donor site, postoperative pain and delayed wound healing which increases the patients' morbidity. Hence, the aim of this study is to assess the effectiveness of different treatment modalities on palatal wound healing and patient's morbidity after FGG. Ninety patients requiring FGG were randomly will be assigned into six groups: group 1: Platelet rich fibrin (PRF) membrane, group 2: Essix retainer, group 3: topical ozone therapy, group 4: low-level laser therapy (LLLT), group 5: collagen fleece and group 6: untreated control group. Epithelization will be evaluated by means of bubble formation; sensitivity, edema, pain, changes in eating habits and burning sensation will be assessed by using visual analog scale (VAS) and also the presence of discomfort and bleeding will be evaluated in the postoperative first week and at 14 days, 1 and 3 months postoperatively.

Inadequate attached gingiva is one of the major mucogingival problems for many individuals. However, the width of the keratinized tissue required to prevent periodontal disease remains unclear. Recently, a consensus report highlighted that if an individual's plaque control is suboptimal, a minimum of 2 mm of keratinized tissue and 1 mm of attached gingiva is needed.

Palatal keratinized mucosa is the most favorable donor region for a free gingival graft (FGG) due to its anatomic properties such as being histologically identical to keratinized attached mucosa of alveolar ridge and its ideal tissue thickness. The FGG surgical wound heals within 2-4 weeks, and prolonged bleeding, pain, and delayed wound healing of either the donor or recipient sites, which increases the patient's risk of morbidity, are the most common postoperative complications following surgery. Although homeostatic agents, mechanical barriers, and bioactive materials have been found to be effective in preventing these complications, the most ideal treatment has not yet been determined.

Platelet-rich fibrin (PRF), a platelet concentrate, is a safe and cost-effectiveness procedure that does not require biochemical blood handling. PRF has been used in many fields as an autologous biomaterial with a great healing potential for regenerating soft tissue and bones without inflammatory reactions, and it may be used to promote hemostasis and wound healing due to the presence of many growth factors. Recent studies have concluded that using PRF membranes after harvesting FGG enhances wound healing, reduces a patient's discomfort, and decreases need to change eating habits; thus, it reduces patient morbidity.

An Essix® retainer (Clear Advantage Series, Ortho Technology, Florida, USA) is a thermoplastic material used for stabilization after orthodontic treatment. It has been reported that gingival wounds that heal by secondary intention should be sheltered during the period of epithelization to protect against topical irritants, trauma, acidic or highly seasoned foods, and toothbrush abrasion.

It has been suggested that hemostatic agents provide faster and continuous hemostasis and make a positive contribution to early soft tissue healing. Application of hemostatic agents to the palatal donor sites has been found to be highly beneficial for achieving hemostasis in comparison to pressure only. Collagen fleece is a hemostatic agent that is made from the natural collagen of porcine dermis. The structure of the collagen promotes the formation and stabilization of blood clots during the initial wound healing phase. Recently, collagen-based materials have been used to improve early wound healing with an open healing design in the palatal area.

Ozone is a natural gaseous molecule made up of three oxygen atoms. The use of ozone has been proposed in dentistry because of its a strong oxidation effect and its antimicrobial potential, biocompatibility, and healing properties. In a previous study, the application of ozonated oil was reported to improve epithelial healing and gingival health following topical application. Taşdemir et al. concluded that ozone therapy could enhance wound healing, and the patients receiving this therapy experienced less pain after FGG operations than patients that had not received it.

Lower-level laser therapy (LLLT) is known as 'soft laser therapy' or 'bio-stimulation'. In dentistry, LLLT is usually used to accelerate wound healing, enhance remodeling and repair of bone, and reduce pain. Application of LLLT has been shown to improve wound healing after FGG and gingivectomy.

In light of this aforementioned information, it has been hypothesized that applications of PRF, an Essix retainer, collagen fleece, ozone therapy, and LLLT can result in improved wound healing after harvesting FGG in comparison to spontaneous healing. Thus, the present study aimed to assess and compare the effectiveness of these methods on palatal wound healing and patient morbidity.

Inclusion Criteria:

• age >18,
• systemically healthy,
• non-smoker,
• full-mouth plaque and bleeding scores <20%,
• isolated gingival recession defects on the mandibular and maxillary anterior teeth with insufficient keratinized gingiva,

Exclusion Criteria:

• history of mucogingival surgery on the palatal area
• pregnancy
• systemic antibiotics taken for at least six months before the study
• having systemic diseases that could compromise wound healing