Transdentinal effects of flavonoid-based primers applied to caries-affected dentin on pulp cells

To examine the transdentinal response of odontoblast-like cells (MDPC-23), dental pulp stem cells (DPSC), and macrophages to flavonoid-based primers applied to caries-affected dentin.

Primers were prepared from 20 mM of Naringin, Kaempferol, or Baicalein in 20% ethanol. Caries-affected dentin discs (N = 56) were produced using a microcosm biofilm model and mounted in artificial pulp chambers with MDPC-23 cells seeded on the pulp side. Occlusal surfaces (n = 8) were etched with 35% phosphoric acid, rinsed, and blot-dried, followed by application of ultrapure water (negative control, NC), 20% ethanol (solvent control, SC), flavonoid primers, or 29% hydrogen peroxide (positive control, PC). After 24 h, cell viability and morphology (scanning electron microscopy, SEM) were evaluated. Extracts obtained by transdentinal diffusion were applied to DPSC and MDPC-23 cells for up to 7 days to assess cell viability and mineralization, and to macrophages (RAW 264.7) for reactive oxygen species (ROS) production. Data were analyzed using ANOVA and Sidak's test (α = 5%).

None of the flavonoid primers reduced MDPC-23 viability, while PC and phosphoric acid showed significant differences from NC. SEM images revealed altered cell morphology in acid-etched groups. After 7 days, primers slightly increased DPSC viability, maintained MDPC-23 viability, promoted mineralization, and reduced ROS.

Flavonoid-based primers applied to caries-affected dentin were non-cytotoxic, stimulated mineralization in pulp cells, and lowered oxidative stress in macrophages.

Flavonoid primers could support pulp health during dentin pretreatment, providing a conservative strategy for managing caries-affected dentin and reducing the risk of pulp irritation.