The treatment of black triangles in modern dentistry involves various approaches, both surgical and nonsurgical. Surgical methods aim to reconstruct or preserve gingival tissue using techniques such as soft tissue flaps or augmentation. Some invasive surgical methods proposed for papilla reconstruction and correction of black triangle recession include repeated interproximal curettage, Beagle's pedicle graft procedure, free epithelialized and de-epithelialized gingival grafts, and subepithelial connective tissue grafts. The success rate of surgical augmentation depends on the thickness of the gingiva biotype. Orthodontic treatment can also be used to reshape and decrease the embrasure space.

An alternative option is minimally invasive procedures for tissue re-volumizing and papilla anatomical-functional reconstruction. Hyaluronic acid (HA) has been used for minimally invasive papilla reconstruction, leveraging its volumizing filler effect.

Non-surgical strategies based on hyaluronan are gaining ground internationally. The immediate goal of minimally invasive treatment for interdental papilla loss and black triangle disease is mechanical protection and gingival restoration. Promoting tissue hydration, fibroblast vitality, and collagen deposition may offer a long-term regenerative medicine solution. Additionally, natural-origin, High Purification Technology Polynucleotides (PN HPTTM) are exploited for wound healing and counteracting connective tissue depletion.

PNs-based medical devices are widely used in Europe and other countries for various indications, including orthopedics (intra-articular administration), dermatology (intra-dermal injections), and vulvo-vaginal application.

PNs have minimal protein contaminants and allergic risks due to advanced purification techniques. Their hydrophilic nature provides hydration and acts as a volume enhancer. Recent in vitro studies demonstrate improved gingival fibroblast viability and collagen deposition with PNs.

The purpose of this clinical investigation is to assess the safety and clinical performance of RDM36 in the treatment of periodontal gingival contraction and in black triangles syndrome (BTS).

Inclusion Criteria:

1. Be able to provide written informed consent (ICF) for the study.
2. Males and females.
3. Be aged 18 years or older at the time of signing the informed consent.
4. Subjects have to show at least one anterior interdental papilla recession in the smile zone according to Jemt's classification (BTS).
5. The teeth near the interdental papilla recession must have the contact point.
6. Absence of periodontal diseases.
7. Subjects with adequate knowledge of domiciliary oral hygiene practices, as measured by the following parameters: FMPS (full mouth plaque score) and FMBS (full mouth bleeding score) values <10%.
8. Absence of plaque and bleeding on probing at the site of interest.
9. Absence of retentive factors at the site of interest.

Exclusion Criteria:

1. Subjects with active periodontitis.
2. Presence of an acute infection in the oral cavity or upper respiratory tract.
3. Pregnancy or breastfeeding or planning to conceive from the clinical evaluation for enrollment up to 120 days after the end of the treatment.
4. Subjects must not be Smokers more than 10 cigarettes per day.
5. Presence of bleeding disorders or taking medications that affect blood clotting (e.g., coumarin-type drugs or platelet aggregation inhibitors).
6. Presence of systemic diseases that could affect periodontal health.
7. Patients with autoimmune diseases.
8. Known or suspected allergy to seafood products.
9. Psychiatric or behavioral disorders or substance abuse that would interfere with the necessary cooperation for the study.
10. Presence of infra-bony defects associated with pocket or papilla contraction and visible on X-ray as well as detectable on probing.