Collagen Scaffolds in Regenerative Endodontic Procedures: Current Evidence, Limitations, and Future Perspectives.

Predictable pulp-dentin regeneration continues to represent a major challenge in regenerative endodontic procedures (REPs). Although collagen-based scaffolds are widely investigated for their excellent biocompatibility, their ability to deliver consistent clinical and histological outcomes requires critical evaluation. This review summarizes recent advances in the application of collagen scaffolds for REPs. Clinical studies demonstrate that these scaffolds support high tooth survival rates and promote vitality recovery, root wall thickening, and apical closure. However, consistent root lengthening remains elusive. Histologically, the newly formed mineralized tissue from collagen scaffolds within REPs tends to be cementum-like or bone-like rather than reparative dentin, a pattern closely associated with the physicochemical properties of collagen, including pore size, porosity, concentration, stiffness, viscosity, and viscoelasticity. We conclude that while collagen scaffolds represent a "promising platform" for REPs due to their biocompatibility and clinical performance, current evidence indicates that they do not consistently achieve true pulp-dentin regeneration. We therefore propose targeted modification and advanced tissue engineering strategies to direct genuine regeneration. This review offers a framework for the rational design of next-generation collagen constructs toward more predictable regenerative outcomes.