Supracrestal Complex Prosthetic Modification and Topical Oxygen Therapy for Peri-implant Mucositis Resolution in an Infrapositioned Implant: A Case Report With Three-Year Follow-Up

Long-term implant success depends on stable integration with peri-implant tissues and adequate bacteria control. However, implants placed in adolescents may later exhibit prosthesis infrapositioning and soft tissue complications due to continuous craniofacial growth. A 30-year-old healthy woman presented with long-standing inflammation around an implant-supported crown at site #23, placed at age 18. Clinical evaluation revealed deep probing depth (7 mm), bleeding on probing, and signs of cement-induced inflammation. The crown was infrapositioned and exhibited poor marginal adaptation, subgingival porcelain exposure, and residual cement. Despite these complications, crestal bone levels were preserved. The prosthesis was removed and replaced by a chairside-fabricated provisional crown composed of a highly polished composite. The subgingival portion of the provisional crown was thoroughly designed to allow for peri-implant soft tissue re-adherence and preservation and support of the peri-implant soft tissue topography, while the topical use of oxygen- and lactoferrin-releasing oral gel aimed at enhancing the soft tissue healing, reducing inflammation, and controlling the pathogenic bacteria. After healing, a final screw-retained implant crown was delivered, fulfilling biological, functional and aesthetic requirements. At the three-year follow-up, the peri-implant tissues were clinically healthy, with probing depths less than 3 mm and no bleeding. Inflammation was resolved, soft tissue architecture remained stable, and radiographic bone levels were unchanged. This case report illustrates the successful management of peri-implant complications linked to prosthesis infrapositioning and poor prosthetic design, following a biologically oriented approach that combined supracrestal complex management and topical oxygen therapy.