Mucoderm® Versus CTG in the Treatment of Multiple Gingival Recessions Associated With Non-carious Cervical Lesion.

This is a prospective, parallel and controlled clinical trial assessing non-inferiority in root coverage and superiority in oral health-related quality of life. The population that will be evaluated in this is study will be enrolled at São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos.

Forty patients with multiple adjacent gingival recessions associated with non-carious cervical lesion will be enrolled and randomly allocated to one of the following groups:

• Test group (n=20): partial restoration of cervical lesion and modified coronally advanced flap for root coverage associated with porcine acellular dermal matrix (MCAF+PR+XMD)
• Control group (n=20): partial restoration of cervical lesion and modified coronally advanced flap associated with connective tissue graft (MCAF+PR+CTG).

The restorative treatment of non-carious cervical lesion will be performed one week prior the surgical procedures and will be conducted as follows. After local anesthesia, rubber dam isolation will be placed, and a coronal bevel will be performed at the incisal margin of the NCCL to reduce the step of lesions and to allow a correct and harmonious emergence profile of the restoration. Afterward, acid etching with 37% phosphoric acid will be performed and washed for 30 seconds with water-air-jet. The lesion will be dried with sterile cotton pellets to prevent dehydration, and the adhesive will be applied according to the manufacturer's instructions (Single Bond Universal, 3M ESPE). The adhesive will be light cured for 20 seconds, and the restoration will be made with resin composite (Filtek Z350 XT, 3M ESPE). The apical margin of the restoration will be determined to be 1 mm apical to the estimated position of the cementoenamel junction(CEJ) in order to rebuild only the anatomical part of the crown destroyed by the NCCL and 1 mm of the root surface, once the apical portion of the root surface will be covered by gingival tissue after periodontal surgery. After rubber dam removal, the restoration will be finished with ultrafine-grained burs, and 48 hours after the restoration procedure, polishing will be completed with diamond paste and felt discs.

All surgeries will be performed by the same expert periodontist (MPS). The surgical procedure for root coverage will be carried out according to Zucchelli's technique (Zucchelli et al., 2000). In brief description, following local anesthesia, oblique submarginal incisions in the interdental areas, which continued with the intrasulcular incision at the recession defects, will be carried out keeping a blade 15c (Swann-Morton® - Sheffield, England) mounted on No. 3 scalpel handle parallel to the long axis of the teeth to dissect in a split-thickness manner the surgical papilla. Each surgical papilla will be dislocated with respect to the anatomic papilla by the oblique submarginal interdental incisions. The envelope flap will be raised with a split-full-split thickness in the coronal-apical direction: gingival tissue apical to the root exposures will be raised in a full-thickness manner to provide that portion of the flap critical for root coverage with more thickness and the most apical portion of the flap will be elevated in a split-thickness manner to facilitate the coronal displacement of the flap. The portion of the root exposure with loss of clinical attachment will be instrumented with the use of curets. The remaining tissue of the anatomic interdental papilla will be de-epithelialized to create connective tissue beds to which the surgical papilla will be sutured through sling sutures to coronally cover 2 mm above the CEJ after the placement of the grafts. For the test group (MCAF+PR+XMD), a porcine acellular dermal matrix (Mucoderm®, Botiss, Berlin, Germany) will be trimmed with a scalpel in appropriate shape and size to cover the root surfaces and underlying bone. Lastly, for the control group (MCAF + PR + CTG), a connective tissue graft will be harvested from the palate according to Bruno's technique (Bruno JF, 1994).

After the surgery, the participants will be requested to take 500 mg of sodium dipyrone every 8 hours for 3 days in case of pain and to avoid brushing and flossing in the treated area for a period of 2 weeks. During this period, plaque control will be achieved using 0.12% chlorhexidine solution twice a day. The sutures will be removed after 10 days, and all of the patients will be recalled for prophylaxis and reinforcement of motivation and instruction for atraumatic toothbrushing during the study period.

Clinical, esthetics, and comfort of patients parameters will be assessed at 45 days, 2, 3 and 6 months after the surgical procedure.

Quantitative data will be recorded as mean ± standard deviation (SD), and normality will be 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), and dentin hypersensitivity (DH) values will be examined by two-way repeated measures ANOVA to evaluate the differences within and between groups, followed by a Tukey test for multiple comparisons when the Shapiro-Wilk p value was ≥ 0.05. Those presenting Shapiro-Wilk p values < 0.05 will be analyzed using a Friedman test (for intragroup comparisons) and Mann-Whitney tests (for intergroup comparisons). Patient's esthetics and discomfort measures using, respectively, visual analog scale (VAS) and postoperative diary (Tonetti et al. 2018) 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. A significance level of 0.05 will be adopted.