Lithium chloride attenuates root resorption during orthodontic tooth movement in rats

Abstract

Root resorption is a common side effect of orthodontic treatment. In the current study, lithium chloride (LiCl), a Wnt signaling activator, was examined to determine its effect on root resorption. In total, 10 Sprague Dawley rats were randomly allocated into the experimental group (EG) and control group (CG). Each group consisted of five subjects. By using closed nickel-titanium coil springs, a 50-g force was applied between the upper incisors and the maxillary right first molars in order to mimic orthodontic biomechanics in the EG and CG for 14 days. During the 14 days, the EG rats were gavage-fed 200 mg/kg LiCl every 48 h. Next, digital radiographs were captured using a micro-computational tomography scanner. The movement of the maxillary first molars and the root resorption area ratio were measured electronically on the digital radiographs. The outcomes were analyzed using ANOVA. Following 14 days of experimental force application, all rats had spaces of varying sizes between the first and second right maxillary molars. The average distance measured in the CG was slightly higher than in the EG, however, the difference was not found to be statistically significant (P=0.224). Root resorption craters were observed in the groups following the experiment. Rough cementum areas were observed on the mesial surface of the distobuccal and distopalatal roots. The mean root resorption area ratio of CG was significantly greater than EG (P<0.05). Results of the present study indicate that LiCl can attenuate orthodontically induce root resorption during orthodontic tooth movement. The effect of LiCl on tooth movement is insignificant. Introduction Orthodontic tooth movement is based on the response of biological tissue towards a mechanical force. The movement occurs as a result of alveolar bone remodeling through the prolonged application of a controlled force. The applied force induces bone resorption and bone formation on the pressure and tension zones, respectively. In order to move a tooth in the intended direction, bone resorption on the pressure side of the socket wall creates space for the advancing tooth, while bone deposition on the tension side maintains a progressively advancing socket wall behind the moving tooth (1,2). Bone remodeling involves the resorption of bone tissue with the simultaneous formation of new bone tissue; the two processes are in dynamic equilibrium in normal bone (3). During orthodontic tooth movement, alveolar bone resorption at the area of compression occurs through osteoclastic activities by osteoclasts, consequently creating lacunae which are later occupied by osteoblasts to cover the cavity. There are two processes in bone resorption, the solubilization of minerals and the degradation of the organ matrix, largely consisting of type I collagen. These processes are mediated by proteolytic enzymes, including matrix metalloproteinases and lysosomal cysteine proteinases (4). In the tension region, new bone is formed as a result of mechanical force during orthodontic treatment and osteoblasts differentiate from the local precursor cells. Then osteoid is formed by mature osteoblasts and is further mineralized with the secretion of calcium ion (5). Root resorption is a common feature during orthodontic tooth movement. Histological studies have reported that root resorption occurs in 90% of teeth that have been moved orthodontically (6,7). Root resorption, is an unavoidable pathological outcome of orthodontic tooth movement. It is considered to be the result of an inflammatory reaction; thus, certain researchers call this process ‘orthodontically-induced inflammatory root resorption’ (8). The fundamental component behind the root resorption process is local inflammation induced by mechanical forces which is essential for tooth movement during orthodontic treatment (9). Studies have confirmed that orthodontically‐induced root resorption is a part of the hyaline (sterile necrosis) zone elimination process. The first cells to be involved in the removal of necrotic tissue are macrophage-like cells, which may be activated by signals from sterile necrotic tissue, as a Lithium chloride attenuates root resorption during orthodontic tooth movement in rats YU WANG1, SHANG GAO1, HUAN JIANG1, PENG LIN1, XINGFU BAO1, ZHIMIN ZHANG2 and MIN HU1 Departments of 1Orthodontics and 2Endodontics, School of Stomatology, Jilin University, Changchun, Jilin 130021, P.R. China Received July 15, 2013; Accepted November 5, 2013 DOI: 10.3892/etm.2013.1410 Correspondence to: Professor Min Hu, Department of Orthodontics, School of Stomatology, Jilin University, 1500 Qinghua Road, Changchun, Jilin 130021, P.R. China E‐mail: humin@jlu.edu.cn Professor Zhimin Zhang, Department of Endodontics, School of Stomatology, Jilin University, 1500 Qinghua Road, Changchun, Jilin

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@inproceedings{Wang2014LithiumCA, title={Lithium chloride attenuates root resorption during orthodontic tooth movement in rats}, author={Yu Wang and Shang Gao and Huan Jiang and Peng Lin and Xingfu Bao and Zhimin Zhang and Min Hu}, year={2014} }