More than a trend: the rationale for using bioactive materials in clinical practice.

The concept of bioactivity in restorative dentistry has evolved beyond the traditional expectation of inert materials designed solely to replace lost tooth structure. Contemporary restorative systems are increasingly engineered to interact with the dentin-pulp complex by modulating mineral dynamics, matrix stability, and cellular responses. However, misconceptions remain regarding what restorative "bioactivity" can realistically achieve in clinical practice. This review critically discusses the biological basis and clinical relevance of bioactive materials in restorative dentistry, emphasizing dentin-pulp preservation and the distinction between validated bioactivity and laboratory observations. Bioactivity may arise through physicochemical mechanisms, such as ion release, pH modulation, and mineral precipitation, which may contribute to mineral recovery and dentin-pulp preservation, although many proposed effects remain insufficiently validated clinically. In parallel, biological mechanisms involve modulation of odontogenic signaling, pulp cell differentiation, and extracellular matrix dynamics. Strategies targeting collagen stability, including cross-linking, protease inhibition, and intrafibrillar mineralization, may also improve hybrid-layer durability and interfacial longevity. Beyond dentin-focused interventions, pulp-directed bioactivity includes clinically established vital pulp therapy materials and emerging scaffold-based regenerative systems that remain largely investigational. However, important translational questions remain regarding the clinical functionality of current materials. Clinically relevant restorative bioactivity should not be defined by ion release or surface mineral deposition alone, but by the ability of materials to preserve dentin-pulp homeostasis and long-term restorative stability. Moving beyond the "bioactive" label requires evidence-based strategies that sustain dentin-pulp homeostasis rather than merely replacing lost structure.