Subgingival instrumentation will be performed following the MINST technique in conjunction with a microsurgical dental mirror and an atraumatic gingival retractor without applying any product previously. Teeth will be instrumented until no residual calculus could be detected and no debris or biofilm flushed out of the pocket after irrigation with sterile saline solution. Following this, it will be dried and the root will be conditioned applying EDTA with a thin blunt tip for 2 minutes to remove the dentin mud layer from the root surfaces. Subsequently, the defect area will be carefully rinsed with water-spray and by 5-s passage of ultrasonic instrument's fine tip in the site with no contact to the root surface. A sterile gauze will be placed in the vestibule in the proximity of a selected site and a thorough drying of the site will be performed with an air-spray. Once bleeding control is achieved, EMD will be applied with a blunt tipped sterile syringe (25G), until overflowing.

Subgingival instrumentation will be performed following MINST and EDT+EMD or NaOCl+HA application will be simulated by inserting the manufacturer's syringes within the pocket, but the defects won't receive any adjunct.

The probing depth will be measured in six areas (disto-buccal, mediate-vestibular, mesio-buccal, disto-palatal, mid-palatal, and mesio-palatal) of each tooth with a Williams PQ-OW 208 396 probe. It will be use with a pressure of 20 grams that is equivalent to the pressure of dropping the weight of the probe without exerting additional pressu

The "Full mouth bleeding score" (FMBS) will be calculated based on scores of 0 (no bleeding) or 1 (bleeding) after probing depths are checked. The usual thing is to measure 4 points for each tooth, but the investigators have modified the index and value 6 points per tooth (disto-buccal, mid-buccal, mesio-buccal, disto-palatal, mid-palatal and mesio-palatal).

The investigators consider that the score is 1 when there is a red dot in the bleeding diagram of the periodontogram and 0 when there is a blank box.

The plaque will be quantified as follows:

Score 0 = no plaque Score 1 = A film of plaque adhered to the free gingival margin and the adjacent area of the tooth. The plaque can be seen in situ only after the application of a plaque revealer or by using the probe on the surface of the tooth.

Score 2 = Moderate accumulation of soft deposits in the pocket, tooth or gingival margin, which can be seen without magnification.

Score 3 = Abundance of soft material inside the bag and / or on the tooth and the gingival margin.

The evaluation will be carried out in 4 points per tooth (disto-buccal, mesio-buccal, disto-palatal, mesio-palatal).

The duration of the procedure will be timed, starting with the application of local anaesthesia and ending after the application of the bioactive material.

- The presence or absence of bleeding, swelling, suppuration, tooth hypersensitivity and interference with daily activities will be assessed by dichotomous question. In case of a positive answer, 5-point Likert scale will be used (far too little, too little, about right, too much, far too much).

Visual analog scale (VAS) will be used to evaluate the intensity of the discomfort and pain (Mounssif and cols., 2023). It consists of a horizontal line of 100 millimeters, with the extreme expressions of a symptom at each end. The left end represents absence or lower intensity, while the right end represents the highest intensity (Tonetti and cols., 2004). Patients are asked to mark on the line the point that indicates the intensity, and it is measured with a millimeter ruler. The intensity is expressed in millimeters. The assessment will be:

• Mild pain if the patient scores pain as less than 30.
• Moderate pain if the rating is between 40 and 70.
• Severe pain if the rating is 80 or higher.

- Oral health impact profile (OHIP-14, Spanish version). The OHIP-14 scores can range from 0 to 56 and are calculated by adding the ordinal values for each of the 14 domains. Scores for individual domains can range from 0 to 5 (Montero-Martín and cols., 2009).

Patients will be asked to describe their perception of the outcome in terms of improvement in gingival bleeding, redness, gingival swelling, and hygiene capability. These parameters will also be measured using a Visual Analog Scale (VAS), where zero indicates no improvement and 100 indicates maximum improvement.

Finally, the perception and satisfaction level with the aesthetic result of the treatment will be evaluated by selecting one of the following options: very satisfied, satisfied, neutral, moderately satisfied, or dissatisfied (Wismeyer and cols., 1995).