Flapless Periodontal Regeneration Using Hyaluronic Acid Versus Enamel Matrix Derivative

Inclusion Criteria: * Periodontitis stage III or IV, grade A or B (Tonetti et al., 2017): attachment loss ≥ 5mm, radiographic bone loss extending to to the middle third and beyond, tooth loss ≥4 due to periodontitis, probing depth (PD) ≥ 6mm. * Older adults ≥ 18 years. The number per sex shall be balanced. * Plaque index (PI) \< 1 following initial periodontal therapy and hygiene instructions. * Bleeding on probing (BoP) ≤ 10%. * Only patients with optimal compliance, assessed during etiological therapy, will be selected. * At least a 2-3 wall interproximal bone defect with a radiographically moderate or deep intrabony defect (≥3mm), PD≥ 6mm using a Williams probe on uniradicular teeth or mandibular molars without furcation involvement after non-surgical periodontal treatment. * Vital teeth or teeth with well-performed root canal treatment. * Absence of caries, prosthetic restoration or periapical infection in the tooth to be regenerated. * Absence of systemic pathology. * Negative history of pregnancy. * Signed informed consent. * The participant is willing and able to comply with the necessary visits for the treatments and evaluations scheduled during the clinical study. Exclusion Criteria: * The participant is pregnant, breastfeeding or plans to become pregnant in the next 6 months. * Smoking ≥10 cigarettes/day. * Daily alcohol intake \> 4U. * Chronic illness or reduced mental capacity that may influence compliance with the protocol. * Medications or drugs that alter the patient's healing or with concomitant oral manifestations that, in the opinion of the investigator, could interfere with the assessment of safety or efficacy. * Systemic diseases that may influence treatment such as diabetes mellitus or rheumatoid disease. * Allergies to drug compounds. * Antibiotic intake 3 months prior to the start of the study or systemic condition requiring antibiotic coverage at the time of periodontal treatment. * Periodontal treatment 6 months prior to the start of the study.