The aim of this study is to evaluate clinically the results of two types of matrix (Geistlich Mucograft® and Mucoderm®) associated with CAF technique for the treatment of gingival recessions.

This is a prospective, parallel and controlled clinical trial. The population that will be evaluated in the study will be selected at Institute of Science and Technology (ICT), São José dos Campos, College of Dentistry.

Seventy-five patients presenting gingival recession will be divided in 3 groups:

• Group CAF + XDM (25): Periodontal surgery for root coverage through coronally advanced flap technique plus xenogenous dermal matrix graft Mucoderm®.
• Group CAF + MC (25): Periodontal surgery for root coverage through coronally advanced flap technique plus xenogenous collagen matrix graft Mucograft®.
• Group CAF (25): Periodontal surgery for root coverage through coronally advanced flap alone.

All surgeries will be performed by a single operator (MPS) at the dental clinic of ICT. Two horizontal incisions will be made at right angles to the adjacent interdental papillae, without interfering with gingival margins of neighboring teeth. Two oblique vertical incisions will be extended beyond the mucogingival junction and a trapezoidal mucoperiosteal flap will be raised up to the mucogingival junction. After, a split-thickness flap will be extended apically, releasing the tension and favoring coronal positioning of the flap. The exposed root surface will be scaled and planed. After the root planning procedures are performed, the epithelial layer from incised papillae will be removed to expose the connective tissue. After this, the group in which the participant is inserted will be revealed to the surgeon. The grafts will be used according to the producers' instructions. In the CAF + MD group, the matrix will be placed without previous hydration with saline solution, whereas in the CAF + XDM group the matrix will be hydrated with sterile saline for 10 minutes. In both grafts groups, the matrix will be cut into the desired dimensions to cover the entire surface of the root and around the bone, being positioned at the CEJ level. The matrix will be sutured independently of the flap, with the porous surface in contact with the tooth and bone, while the smooth surface will be facing the flap. Then, the flap will be coronally positioned and sutured to completely cover the graft. After the surgical procedure, the patients will receive the appropriate postoperative recommendations and sutures will be removed after 10 to 14 days of the surgical procedure.

Clinical parameters will be assessed at baseline and 3 and 6 months postoperatively.

Quantitative data were recorded as mean ± standard deviation (SD), and normality was tested using Shapiro-Wilk tests. The probing depth (PD), relative gingival recession (RGR), clinical attachment level (CAL), keratinized tissue thickness (KTT), keratinized tissue width (KTW), aesthetic (A), postoperative discomfort (PD), dentin hypersensitivity (DH) and tissue edema (TE) values will be examined variance test. Patients' esthetics and discomfort measures using a visual analog scale (VAS) will be analyzed by T-tests. The frequency of complete root coverage will be compared using χ2 tests. Intergroup root coverage esthetic score (RES) comparisons will be performed with a T-test.

Inclusion Criteria:

• Patients presenting Miller class I or II gingival recession in the maxillary canines or premolars;
• Teeth included in the study should present pulp vitality and no associated with carious or cervical lesion;
• Patients presenting no signs of active periodontal disease and full-mouth plaque and bleeding score ≤ 20%;
• Probing depth ˂ 3 mm in the included and adjacent teeth, presenting no signs of bleeding or attachment loss;
• Patients older than 18 years old;
• Patients who agreed to participate and signed an informed consent form.

Exclusion Criteria:

• Patients with systemic problems (cardiovascular, blood dyscrasias, immunodeficiency, and diabetes, among others) that will contraindicate the surgical procedure;
• Patients taking medications known to interfere with the wound healing process or that contraindicate the surgical procedure;
• pregnant or lactating women;
• Smokers;
• Patients who underwent periodontal surgery in the area of interest;
• Patients with orthodontic therapy in progress.