The aim of this study is to evaluate the influence of therapy with low-intensity laser technique associated with connective tissue graft for root coverage in smokers and compare the results with non- smokers

This is a prospective, parallel and controlled clinical trial. The population evaluated in the study was selected at Science and Technology Institute - São José dos Campos, College of Dentistry.

The selected smokers patients will be randomly allocated by a computer generated list into:

Group CTG (n=15): patients who will receive only the connective tissue graft procedure to treat gingival recession and a simulation of laser therapy application (SHAM).

Group CTG+ LLLT (n=15): patients who will receive the connective tissue graft procedure to treat gingival recession plus 8 applications of low-level-laser therapy (LLLT) to treat gingival recession.

All surgeries will be performed by the same expert periodontist. Before the surgical procedure, all patients were enlightened about the causes and consequences of gingival recession and prevention techniques. Factors related to the origin of gingival recession, such as toothbrush trauma and inflammation caused by biofilm, will be controlled through instruction on standardized brushing technique to avoid the influence of other hygiene methods capable of promoting trauma on soft tissues. Standardized dental floss and toothbrushes were given to patients. The surgical technique adopted in the recession defects was the trapezoidal-type of coronally advanced flap (CAF) and the connective tissue graft (CTG) will be removed from palate mucosa . Briefly, a first incision on the palate will be performed perpendicularly to the long axis of the teeth, 2 to 3 mm apical to the gingival margin. The mesial-distal length of the incision will be determined by the length of the graft required to cover the recession. Because the selected recessions were in maxillary canines and premolars, the lengths of the graft varied minimally (10-12mm). The second incision will be made parallel to the first one (1-2 mm apically and parallel to the long axis of the teeth) to separate the subepithelium connective tissue from the epithelial layer. The incision is carried far enough apically to provide a 7- mm height of connective tissue to cover the denuded root surface. Afterward, another incision parallel to the long axis of the teeth starting from the first incision will be performed to separate the subepithelium connective tissue from the periosteum. Then, the connective tissue graft will be removed from the palate as atraumatically as possible. Single sutures will be made on the palate (4-0 silk) and the graft will be sutured on the receptor site. The irradiation will be performed with a Gallium aluminum arsenide laser (GaAlAs) that continuously emitted a wavelength of 660 nm. Thirty milliwatts will be used for 20 seconds and the total applied energy (fluence) will be 15 Joules per cm2 (3 Joules/ per point and an application time of 4 seconds per point).

Clinical, esthetics, and comfort of patients parameters were assessed at baseline, 3 and 6 months after the procedure.

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), and dentin hypersensitivity (DH) values were 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 were analyzed using a Friedman test (for intragroup comparisons) and Mann-Whitney tests (for intergroup comparisons). Patients' esthetics and discomfort measures using visual analog scale (VAS) were analyzed by T-tests. The frequency of complete root coverage was compared using χ2 tests. Intergroup root coverage esthetic score (RES) comparisons were performed with a T-test. A significance level of 0.05 was adopted.

Inclusion Criteria:

• Patients presenting Miller class I or II gingival recession in the maxillary canines or premolars
• Visible cemento-enamel junction (CEJ) with pulp vitality;
• Patients presenting no signs of active periodontal disease and full-mouth plaque and bleeding score ≤20%;
• Patients older than 18 years old; probing depth ˂3 mm in the included teeth;
• Patients who agreed to participate and signed an informed consent form.

Exclusion Criteria:

• Patients presenting systemic problems that would contraindicate the surgical procedure;
• Patients taking medications known to interfere with the wound healing process or that contraindicate the surgical procedure;
• Smokers or pregnant women;
• Patients who underwent periodontal surgery in the area of interest;
• Patients with orthodontic therapy in progress.