The study received ethics approval but was never initiated. No participants were enrolled.

The gold standard for gingival recession treatment is the coronal repositioning of the flap associated with the subepithelial connective tissue graft. The porcine collagen matrix (PCR) has been used as a substitute for subepithelial connective tissue graft in periodontal plastic surgery and has achieved similar results. The PCR use has the advantage of avoiding possible pre and postoperative complications , as well as overcome the limitations presented by autograft . The different surgical techniques used for root coverage seek predictability and success . For this, besides the type of incision placements flap and graft are the most important because the healing benefits and outcome .

The aim of this study is to compare two surgical techniques for root coverage and evaluate which one provides better clinical outcomes and less morbidity . 20 adults , nonsmoking patients , showing multiple bilateral gingival recessions , class I or II Miller located in canine, first and second premolars are selected. Both techniques use the PCR as a graft . However, in one Quadrant partial flap will be held together with relaxing incisions through an intrasulcular incision, PCR will be positioned 1 mm apical to the cementoenamel junction (CEJ) and the flap will be positioned 1 mm coronal CEJ. In the opposite quadrant periosteal envelope that does not use relaxing incisions, avoiding any scars, will be performed with the PCR. The clinical parameters (gingival recession height and width, keratinized tissue thickness and width) will be evaluated 2 weeks after basic periodontal therapy and after 6 and 12 months to surgical procedures..

Inclusion Criteria:

-bilateral multiple gingival recession type Miller class I or II with at least one tooth with 3 mm of gingival recession height

Exclusion Criteria:

• diabetics
• pregnant women
• chronic use of medication
• periodontitis
• smokers

The participants and the outcomes Assessor are masked about the surgical technique that was performed. The surgical technique ir randomized in accordance with the arch side of each patient, so the investigator will open a envelope just before starting the incisions to know which technique will be performed.