Analysis of hard tissue regeneration and Wnt signalling in dental pulp tissues after direct pulp capping with different materials.

AIM

To investigate the involvement of Wnt signalling and cell cycle regulation in hard tissue formation after pulp capping with several materials in a rat molar pinpoint exposure model.

METHODOLOGY

Thirty-two rat molar pulps were mechanically exposed and assigned to 4 groups according to the pulp capping materials used Ca(OH) , mineral trioxide aggregate (MTA), Biodentine™ and an untreated control group. After 4 weeks, the teeth were collected for microcomputed tomography to quantify reparative dentine formation. Histological analysis was then performed to evaluate the quality of the reparative dentine and the dental pulp tissue inflammatory reaction. Cyclin D1 and β-catenin expression was examined using immunofluorescence staining. The Kruskal-Wallis followed by Dunn's multiple comparison test was performed to determine significant differences.

RESULTS

The exposed dental pulps treated with Ca(OH) , MTA and Biodentine™ exhibited reparative dentine formation near the exposure site. Fibrous tissues adjacent to the exposure site were observed in the untreated group. The microcomputed tomography evaluation of MTA and Biodentine™ groups revealed significantly greater reparative dentine formation compared with the control group (P = 0.0032 in the MTA group and P = 0.05 in the Biodentine group). From histological evaluations, the Biodentine group exhibited significantly greater reparative dentine formation grading compared with the control group (P = 0.0152). The pulp tissues treated with Ca(OH) and Biodentine™ exhibited a lower inflammatory score compared with those of the untreated control (P = 0.0291 in the Ca(OH) and P = 0.0110 in the Biodentine group). Ca(OH) , MTA and Biodentine™ induced cyclin D1 expression in the dental pulp tissues adjacent to the reparative dentine. Moreover, the Biodentine™-treated defects demonstrated β-catenin expression in the pulp tissue adjacent to the newly formed reparative dentine, which was not observed with the other materials.

CONCLUSION

All test materials promoted dentine bridge formation and stimulated cyclin D1 expression. The favourable outcome after direct pulp capping with Biodentine™ involved Wnt/β-catenin signalling. However, Wnt/β-catenin signalling did not participate in the mechanism by which Ca(OH) and MTA promoted reparative dentine formation.