Authors

Di Wu*, Dong Liu**, #

Departments

*Department of Stomatology, Jinan children’s Hospital, Jinan City, Shandong Provine, 250022 - **Department of Stomatology, Shengli Oilfield Central Hospital, Dongying City, Dongying City, Shandong Province, 257034

Abstract

Objective: To investigate the effects of human growth hormone on orthodontic tooth movement, root resorption and local expression of nuclear factor κB receptor activating factor ligand (RANKL), osteoprotegerin (OPG), and insulin-like growth factor 1 (IGF-1) in rats. 

Methods: 24 healthy male Wistar rats with an SPF grade of more than 5 weeks were randomly selected as normal group. The remaining 22 rats were randomly divided into control group (n = 11) and observation group (n = 11). The rats in the normal group were fed normally, the rats in the observation group were injected with 0.15IU/kg growth hormone intraperitoneally, and the rats in the control group were injected with the same amount of normal saline. At the end of the experiment, all of the rats were killed. The rat model of root resorption induced by orthodontic force was established. The root resorption was observed by HE staining, the movement distance of orthodontic teeth was measured by Vernier caliper, the positive expression of OPG and IGF-1 cells was observed by immunohistochemistry, and the positive expression of RANKL cells was observed by tartrate acid phosphatase staining (TRAP). 

Results: In the normal group, the surface of cementum was smooth and continuous, and no obvious root resorption lacunae were found. In the control group, obvious bone resorption lacunae were found on the booster side, osteoclasts were found in the lacunae, and root 1/3 and root bifurcation were more common in the control group. Bone resorption lacunae also appeared in the roots of the observation group, but the root resorption of the observation group was significantly lower than that of the control group. On the fifth day, there was no significant difference in orthodontic tooth movement distance in each group (P>0.05), but on the 10th and 15th day, the orthodontic tooth movement distance in the control group was significantly higher than that in the observation group (P<0.05). The results of TRAP staining showed that no obvious osteoclasts were found in the periodontal tissue of the normal group, a large number of positive cells were found in the bone resorption lacunae of the control group, and the number of positive cells in the bone resorption lacunae of the observation group was significantly lower than that of the control group. The expression of OPG in the control group and the observation group was positive in the periodontal tissue; the expression of OGF in the observation group was strongly positive, and the expression of OPG in the control group was weakly positive. There was significant difference between the two groups: the expression of IGF-1 in the control group and the observation group was strongly positive. Over time, the number of IGF-1 positive osteoclasts increased significantly, and the expression of IGF-1 positive osteoclasts in the observation group was higher than that in the control group. 

Conclusion: Growth hormone can inhibit the movement speed of orthodontic teeth, promote the expression of OPG and IGF-1, inhibit the expression of RANKL and inhibit root resorption. 

Keywords

Human growth hormone, orthodontic tooth movement, root resorption, RANKL, OPG, IGF-1.

DOI:

10.19193/0393-6384_2020_3_260