The objective of this study will be to evaluate a new protocol for the surgical treatment of periodontal disease with two novelties: to make a single incision in the midline of the interproximal area to respect the vascular supply and preserve the granulation tissue with regenerative potential. The investigators will carry out a controlled and randomized clinical trial with a control group (n=25; modified Kirkland flap) and a test group (n=25; experimental surgical protocol: incision in the mid-interproximal area of the papilla and preservation of the granulation tissue). Clinical parameters will be taken at the time of surgery and 12 months follow-up: bleeding on probing (BoP), clinical attachment level (CAL), residual probing depth (rPD),Probing pocket depth reduction (PPDr), recession (REC), interproximal gingival recession (iGR), width of keratinized gingiva (KT), gain of supra-alveolar clinical attachment (SUPRA-AG), early wound healing index (EHI).