Direct pulp capping using the final candidate peptides. Each peptide (No. 1: KLLETECPQ, No. 2: ELVRKDLQN, No. 3: NTDGAVNFQ, No. 4: NADKQLSFE) (100 µg/mL) was soaked in a gelatin sponge and used as a pulp-capping material. S100A8 or S100A9 (1 µg/mL) was used as a control. (A) Micro–computed tomography (CT) evaluation of tertiary dentin bridge formation. There were significant differences between No. 1 and No. 2, between No. 1 and phosphate-buffered saline (PBS), between mineral trioxide aggregate (MTA) and No. 2, and between MTA and PBS (Kruskal–Wallis test, P < 0.05). Grade 0: no dentin bridge formation; grade 1: dentin bridge formation covers one-third of exposed pulp; grade 2: dentin bridge formation covers two-thirds of exposed pulp; grade 3: dentin bridge formation completely covers exposed pulp. Green area indicates tertiary dentin formation. (B) Quantification of tertiary dentin formation at 4 wk after direct pulp capping (DPC). Different letters indicate significant differences between groups (Kruskal–Wallis test, P < 0.05). (C) Histological images (hematoxylin–eosin staining) of tertiary dentin formed by DPC. Dotted lines indicate boundaries between tertiary dentin and primary dentin. C, cavity; P, pulp; PD, primary dentin; TD, tertiary dentin.