Materials and methods Forty patients seeking treatment for open gingival embrasures next to an implant restoration will be included. Patients will be randomly assigned to test group (n=20; injection of hyaluronic acid, Hyadent Barrier Gel, BioScience, Germany; CE certificated for Europe) or control group (n=20; injection of saline solution as a placebo control medium). The following clinical parameters will be assessed at baseline and after 1, 3, and 6 months: Modified papilla index score, distance between papilla tip and contact point, area and volume of black triangle, tissue texture and colour, probing depth, clinical attachment level, presence of plaque and/or bleeding on probing, aesthetic satisfaction of the patient and the examiner and sensation during injection. At baseline and after 6 months the distance between contact point and most cervical region of the alveolar bone crest will be assessed on periapical radiographs.