Objective: Titanium-prepared platelet-rich fibrin (T-PRF) is activated with titanium, which results in a more mature and aggregated form than PRF. In our previous studies, we established that the fibrin carpet formed with titanium had a firmer network structure, and longer resorption time in the tissue than the fibrin carpet formed with glass. The purpose of this randomized controlled clinical trial is to compare the effects of autogenous T-PRF and CTG.

Materials and methods: A total 114 Miller Class I/II gingival recessions with abrasion defects will be treated either T-PRF (63 teeth) or CTG (51 teeth) using a modified tunnel technique. Clinical periodontal indexes, keratinized tissue (KTW), gingival thickness (GT) and recession depth (RD) will be recorded before surgery and at 6 and 12-month follow-up examinations. The Visual Analog Scale and healing index scores will be assessed.

A total of 34 patients will be informed in detail about the risks and benefits of each step of the study, and their signed consents will be obtained.

These clinical assessments will be done:

1. Plaque Index and Gingival Index In case of multiple gingival recessions, plaque index and gingival index will be obtained from the three dental points as mesial, distal and vestibule midpoints; plaque index will be calculated according to Sillnes&Löe criteria, whereas gingival index will be calculated according to Löe&Silness criteria.
2. Periodontal Pocket Depth In case of multiple gingival recessions, the distance between the pocket base and free gingival margin will be measured separately for each tooth with the assistance of periodontal Williams probe through the midpoint of vestibule.
3. Recession Width Periodontal probe will be horizontally placed on the enamel-cement border and the measurement will be recorded.
4. Recession Depth The defect distance will be measured vertically from the enamel-cement conjunction of the tooth to the very apical aspect of the gingival margin using periodontal probe and recorded in millimeters.
5. Clinical Attachment Level The clinical attachment level (CAL) will be measured by periodontal probe through the midpoint of vestibule as the distance between gingiva base and enamel-cement border and recorded in millimeters.
6. Keratinized Tissue Width The distance between gingival margin and alveolar mucosa will be measured in millimeters. A solution consisted of 10% potassium iodide and 5% iodine will be applied onto the gingiva and alveolar mucosa with a cotton pellet. This solution stains the glycogen-rich alveolar mucosa darker than the keratinized tissue and allows keratinized gingival mucosa to be exposed more clearly.
7. Gingival Thickness This measurement will be performed in the relevant area by No. 15 endodontic spreader under topical anesthesia. The spreader will be placed perpendicular to the gingiva through approximately 1.5 mm apical aspect of the gingival margin, pushed forward until obtaining bone support, and fixed with a disc. The distance between the disc and the tip of endochuck will be measured by a digital caliper with a sensitivity of 0.1 mm.
8. Measurement of CTG Thickness Fat and glandular tissue and band-shape epithelium on the CTG, which will be derived from the maxillary palate, will be removed by a scissor. The graft, which will be placed onto a sterile, metal smooth surface, will be fixed through its mesial, distal and middle aspects by a No. 15 endodontic spreader with the assistance of a disc and then measured by digital caliper. The mean graft thickness will be calculated as the arithmetic mean of the values measured.
9. Measurement of T-TRF Membrane Thickness Two thrombocyte rich platelets taken from the tubes that have been centrifuged will be separated from the serum at room temperature in sterile gauze and will be turned into membranes. They will be measured by digital caliper as two-layer similar to the measurement of connective tissue thickness, and the values will be recorded..

VAS Assessment On the postoperative Day 1, 3 and 7, the patients will be asked to complete a chart where they can rate subjective complaints of pain, burning sensation and discomfort in the surgery site between 0 (none) and 100 (very severe).

Wound Healing Index While removing the sutures two weeks after surgery, the physician will evaluate wound healing according to the Huang criteria separately for each tooth; Score 1: Problem-free wound healing without gingival edema, erythema, suppuration, or dehiscence of the flap margins.

Score 2. Problem-free wound healing with mild gingival edema, erythema, patient discomfort and flap dehiscence without suppuration.

Score 3. Poor wound healing with severe gingival edema, erythema, suppuration, patient discomfort and flap dehiscence.

Calculation of Root Surface Coverage Ratio This ratio is presented as percentage (%) and evaluated in the 6th and 12th months.

Preoperative recession depth - Postoperative recession depth X 100 % Preoperative recession depth

Inclusion Criteria:

Eligibility criteria included the following:

• Absence of systemic disease that would likely hinder periodontal surgery or unfavourably influence wound healing
• Having multiple gingival recessions including at least two adjacent Miller class I or II teeth among mandibular or maxillary incisors and premolars. Molars were excluded.
• The teeth undergoing treatment were vital with no restoration or decay in the tooth neck (collum dentis) and with a completely or partially fixable enamel-cement border
• The relevant teeth in the arch were rotation-free with no mobility
• The presence of periodontal pockets not exceeding 3 mm in the teeth undergoing treatment; the teeth had no occlusal trauma; and the patients were older than 18 years of age

Exclusion Criteria:

• Receiving medicines that would likely cause gingival hypertrophy
• Smokers
• Presence of blood-borne diseases
• Presence of any systemic disease likely to influence coagulation, and receiving any anticoagulant medicines