Calcium Hydroxyapatite for Gingival Phenotype Enhancement: A Translational Review and Clinical Decision-Making...

Soft-tissue deficiencies, including interdental papilla loss and thin gingival phenotypes, remain challenging to manage predictably in periodontology. While hyaluronic acid fillers provide transient volumetric improvement, calcium hydroxyapatite (CaHA) is a biostimulatory injectable biomaterial capable of inducing extracellular matrix remodeling and sustained soft-tissue reinforcement. This review evaluates the biological rationale and available evidence supporting CaHA and explores its potential role in periodontal soft-tissue management. A narrative review was conducted in accordance with the Scale for the Assessment of Narrative Review Articles (SANRA) recommendations. A structured search of PubMed, Scopus, and Google Scholar identified studies published from 2020 to 2025 investigating injectable CaHA in soft-tissue applications. Evidence from dermatology, aesthetic medicine, biomaterials, and histological research was synthesized to assess the biological mechanisms, tissue responses, and translational relevance of CaHA to gingival tissues. CaHA demonstrates a dual mechanism combining immediate volumization with delayed biostimulation through fibroblast activation, neocollagenesis, and extracellular matrix remodeling. Evidence from extraoral applications consistently reports increased tissue thickness, improved mechanical properties, and sustained clinical effects. Preliminary reports in periodontal contexts suggest potential for interdental papilla augmentation in mild defects; however, available data remain limited by small sample sizes, short follow-up, and lack of standardized protocols or histological validation. Current evidence supports the biological plausibility of CaHA as an adjunctive approach for soft-tissue reinforcement rather than defect correction. Its potential role appears most relevant in thin gingival phenotypes and mild papillary deficiencies, where increased tissue thickness and stability are desired. However, the available evidence is derived predominantly from non-periodontal studies, and the absence of controlled periodontal investigations precludes routine clinical use. Accordingly, the application of CaHA in periodontology should currently be regarded as experimental until validated by dedicated preclinical and clinical studies.