Abstract Aim To quantify the expression of insulin‐like growth factor‐1 (IGF‐1) and proliferating cell nuclear antigen (PCNA) in human pulp cells of teeth with complete or incomplete root development, to support the specific role of IGF‐1 in cell proliferation during tooth development and pulp reparative processes. Methodology Twenty six pulp samples were obtained from freshly extracted human third molars, equally divided in two groups according to root development stage (complete or incomplete root development). All samples were processed and immunostained to determine the expression of IGF‐1 and PCNA in pulp cells. Sections were observed with a light microscope at 80× and morphometric analyses were performed to calculate the area of PCNA and IGF‐1 immunostaining using digital image software. Mann–Whitney’s test was used to determine statistically significant differences between groups ( P < 0.05) for each peptide and the co‐expression of both. Results Expression of IGF‐1 and PCNA was observed in all human pulp samples with a statistically significant higher expression in cells of pulps having complete root development ( P = 0.0009). Conclusion Insulin‐like growth factor‐1 and PCNA are expressed in human pulp cells, with a significant greater expression in pulp cells of teeth having complete root development.