Cellular Dynamics and Dentine Bridge Formation Following Direct Pulp Capping With <scp>MTA</scp> and Biodentine in a Murine Model

AIM: Formation of a mineralized dentine bridge is the hallmark of successful direct pulp capping (DPC). Mineral trioxide aggregate (MTA) and Biodentine are widely used capping materials, but in vivo evidence comparing their regenerative potential remains inconclusive. This study used a controlled murine model to compare dentine bridge formation and pulp response to MTA and Biodentine. METHODS: DPC was performed on maxillary first molars of mice using either MTA or Biodentine. Reparative dentine bridge formation was assessed by micro-computed tomography (bridge volume, mineral content, density); histology (morphology, collagen deposition); immunohistochemistry and RNAscope in situ hybridization (odontoblast activity); TUNEL assay and EdU labelling (apoptosis, proliferation, cell retention); and fluorochrome incorporation (dentine formation dynamics). RESULT: Both MTA and Biodentine supported dentine bridge formation. Biodentine induced significantly greater bridge volume and mineral content at 28 and 56 days, while mineral density was similar. Histological analysis showed more complete bridges with fewer tunnel defects in Biodentine-treated teeth. TUNEL assays indicated a trend toward lower apoptosis in Biodentine-treated pulps, while EdU labelling showed similar proliferation rates. Label-retaining cell analysis revealed reduced pulpal cell retention in MTA-treated teeth. Biodentine-treated samples displayed higher dentine sialophosphoprotein expression at Day 8, thicker predentin at Day 14, and more extensive collagen deposition at Day 28. Fluorochrome labelling confirmed earlier and more robust dentine deposition with Biodentine. CONCLUSIONS: In a controlled murine DPC model, Biodentine promoted greater dentine bridge formation and more favourable pulp regeneration than MTA. These effects may be explained by reduced apoptosis, greater pulpal cell retention, and enhanced odontoblast activity. The findings support Biodentine as a stronger stimulator of dentine regeneration and underscore the value of murine models for mechanistic studies of pulp healing.