THE MECHANISM OF NOTCH1 SIGNALING PATHWAY INVOLVED IN ORTHODONTIC ALVEOLAR BONE REMODELING IN RATS

Jianyun Cao^1#, Xuebing Qiu^1#, Liangliang Cai², Lili Wu³, Haitao Dai^1*

¹Department of Stomatology, First Affiliated Hospital, School of Medicine, Shihezi University, Shihezi, 832000, China - ²Department of Stomatology, Hongxing Hospital, Division XIII Xinjiang Production and Construction Corps, Hami, 839000, China - ³Department of Stomatology, Second Division Yanqi Hospital, Yanqi, 841100, China

Objective: To analyze the mechanism of Notch1 signaling pathway involved in orthodontic alveolar bone remodeling in rats. 

Methods: 120 healthy adult SD rats were selected to establish the orthodontic tooth movement model, and were divided into four groups: group A (orthodontic tooth strength), group B (strength), group C (orthodontic tooth strength + DAPT solution injection), and group D (strength + DAPT solution injection). The orthodontic tooth movement distance between the first and second molars of each group of rats was measured. The changes in periodontal tissue were observed by HE staining. The morphology of osteoclasts was observed and counted by TRAP staining. The expressions of Notch1, Jagged1, RANKL, and OPG in the periodontal membrane of rats were observed by the immunohistochemical method. 

Results: From the first day of force application, the movement distance of orthodontic teeth in group A and group C increased with time. At 10 and 14 days of force application, the movement distance of orthodontic teeth in group A was significantly smaller than that in group C (P < 0.05). HE staining showed that the molar root and alveolar bone of rats in groups B and D were smooth, and the periodontal ligament had no change. Osteoclasts and bone absorption pits appeared in rats in groups A and C, and the width of periodontal ligament was significantly narrower than that in groups B and D. A. The number of trap positive cells in group C was significantly higher than those in group B and D (P < 0.05), and the number of trap positive cells in group C was significantly higher than that in group A (P < 0.05). The expression of Notch1, Jagged1, and RANKL in periodontal ligament in group A was significantly higher than that in group B, and the expression of OPG was significantly lower than that in group B (P < 0.05). The expression of RANKL in periodontal ligament in group C was significantly higher than that in group A, and the expression of Notch1, Jagged1, and OPG was significantly lower than that in group A (P < 0.05). 

Conclusions: The expression of Notch1 signaling pathway related proteins in the orthodontic alveolar bone of rats significantly changed, suggesting that Notch1 signaling pathway is involved in the absorption and remodeling of alveolar bone during orthodontic tooth movement in rats.