The aim of this study was to investigate the outcomes of direct pulp capping performed with two types of tricalcium silicate‐based materials (mineral trioxide aggregate/MTA and Biodentine/BD); nano‐hydroxyapatite (nHAP) crystals or calcium hydroxide (CH) in dogs. Following mechanical exposure, the pulps were randomly capped with one of the four materials. Histological analyses were performed to examine the outcomes after 7 days or 3 months. At 7 days, BD and nHAP showed significantly less inflammatory cell response than MTA and CH. At 3 months, the inflammatory cell response and tissue necrosis were significantly higher in the CH group. There was no significant difference between the tested materials in the calcific bridge formation after 7 days; however, a significant difference was noticed at the 3‐month period. Tricalcium silicate‐based cements and nHAP are potential alternatives to CH in vital pulp therapy following accidental pulp exposure.