Evaluation of the Effect of Smoking on Palatal Donor Site Tissue Profile in the Success of Connective Tissue Grafts

This single-center prospective clinical study investigates how smoking affects palatal donor site tissue biology and, in turn, the success of connective tissue grafts used in root coverage surgery. A total of 24 systemically healthy patients with Cairo Type 1 (recession type 1 \[RT1\]) gingival recession will be enrolled: 12 smokers and 12 non-smokers. All participants will receive a coronally advanced flap combined with a subepithelial connective tissue graft (CAF + CTG) harvested from the palatal donor site. Both donor and recipient sites will be assessed at baseline and postoperatively (2 weeks, 1 month, and 3 months) using ultra-high frequency ultrasonography (UHFUS) to measure tissue thickness, echogenicity, structural integrity, and vascularization. Residual connective tissue fragments obtained during routine graft preparation will undergo histological, histochemical, and immunohistochemical analysis (including COL1A1, COL1A2, COL3A1, α-SMA, CD31, Factor XIIIa, and IL-33). Smoking status will be biochemically confirmed via salivary cotinine enzyme-linked immunosorbent assay (ELISA). Clinical outcomes (recession depth, clinical attachment level, keratinized tissue height, percentage of root coverage) and patient-reported outcome measures (PROMs) will be compared between groups. Primary Hypothesis: Smoking negatively affects palatal donor site biology, impairing the clinical and ultrasonographic healing outcomes of CAF + CTG procedures.

Inclusion Criteria: 1. Aged 18 years or older. 2. Systemically healthy, with no systemic disease that could directly affect status or wound healing. 3. Presence of an isolated facial recession on non-molar maxillary teeth: greater than 2 mm, less than 5 mm (up to a maximum of 5 mm). 4. Recession classified as Cairo Type 1 (RT1 = Miller Class I and II), meaning gingival recession without interproximal attachment loss. 5. No previous soft tissue surgery at the surgical site. 6. Good oral hygiene (full-mouth bleeding on probing below 10%). 7. No soft tissue graft previously harvested from the palatal donor site. 8. Able to comply with all study-related procedures, including attendance at all follow-up visits. Exclusion Criteria: 1. Untreated periodontitis or peri-implantitis. 2. Any systemic disease that could potentially impair wound healing, such as diabetes or connective tissue disorders. 3. Pregnancy or breastfeeding. 4. Previous or concurrent use of medications affecting mucosal healing (e.g., steroids or high-dose anti-inflammatory drugs). 5. Coagulation or bleeding disorders. 6. Cleft palate. 7. Active orthodontic treatment with fixed or removable appliances. 8. A history of malignancy, radiotherapy, or chemotherapy for malignancy within the past 5 years. 9. Antibiotic therapy within the past 6 months. 10. Previous connective tissue graft harvested from the palatal donor site. 11. Any other surgical procedure at the palatal donor or recipient site (e.g., apical resection or crown lengthening).