Lithium carbonate accelerates the healing of apical periodontitis

Apical periodontitis is a disease caused by bacterial invasions through the root canals. Our previous study reported that lithium chloride (LiCl) had a healing effect on apical periodontitis. The aim of this report is to investigate the healing properties and mechanism of lithium ion (Li + ) for apical periodontitis using rat root canal treatment model. 10-week-old male Wistar rat’s mandibular first molars with experimentally induced apical periodontitis underwent root canal treatment and were applied lithium carbonate (Li 2 CO 3 ) containing intracanal medicament. Base material of the medicament was used as a control. Subject teeth were scanned by micro-CT every week and the periapical lesion volume was evaluated. The lesion volume of Li 2 CO 3 group was significantly smaller than that of the control group. Histological analysis showed that in Li 2 CO 3 group, M2 macrophages and regulatory T cells were induced in the periapical lesion. In situ hybridization experiments revealed a greater expression of Col1a1 in Li 2 CO 3 group compared with the control group. At 24 h after application of intracanal medicament, Axin2-positive cells were distributed in Li 2 CO 3 group. In conclusion, Li 2 CO 3 stimulates Wnt/β-catenin signaling pathway and accelerate the healing process of apical periodontitis, modulating the immune system and the bone metabolism.