Yajun Hu1, Wentao Liu2, Zhijian Liu3, Wenying Kuang4, Hong He5. 1. a Student, The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China; and Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China. 2. b Lecturer, Department of Dermatology, Taihe Hospital, Hubei University of Medicine, Shiyan, China. 3. c Associate Professor, Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China. 4. d Student, Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China. 5. e Professor and Chair, Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China; and Professor, The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
Abstract
OBJECTIVE: To investigate the effects of growth hormone (GH) on local receptor activator of nuclear factor-kappa ligand (RANKL), OPG, and IGF-I expression during orthodontically induced inflammatory root resorption in rats. MATERIALS AND METHODS: Forty Wistar rats (gender: male; age: 7 weeks) were randomly divided into control and experimental groups. A force of 50 g was applied to move the right upper first molars mesially. The experimental and control groups received daily subcutaneous injections of recombinant human growth hormone (GH; 2 mg/kg) and equivalent volumes of saline, respectively. The rats were sacrificed on days 1, 3, 7, and 14. Micro-computed tomography-reconstructed images of the upper right first molars were used to survey root resorption and tooth movement. Horizontal sections of the maxillae were prepared for hematoxylin and eosin, tartrate-resistant acid phosphatase, and immunohistochemical staining. RESULTS: Resorption lacunae appeared on the compressed side of the distal buccal root of the right first molar on days 7 and 14. Compared with the control groups, GH-treated groups showed more RANKL-positive cells and osteoclasts on day 3 and more OPG- and IGF-I-positive cells and fewer odontoclasts on days 7 and 14. Indexes of root resorption were lower and tooth movement was faster in the GH-treated groups than in the control groups on days 7 and 14. CONCLUSIONS: The inhibitory effect of GH on root resorption by heavy force might be mediated by RANKL/OPG and IGF-I. Short-term GH administration may be a method with which to reduce root resorption and shorten treatment time, especially in patients who are susceptible to root resorption.
OBJECTIVE: To investigate the effects of growth hormone (GH) on local receptor activator of nuclear factor-kappa ligand (RANKL), OPG, and IGF-I expression during orthodontically induced inflammatory root resorption in rats. MATERIALS AND METHODS: Forty Wistar rats (gender: male; age: 7 weeks) were randomly divided into control and experimental groups. A force of 50 g was applied to move the right upper first molars mesially. The experimental and control groups received daily subcutaneous injections of recombinant humangrowth hormone (GH; 2 mg/kg) and equivalent volumes of saline, respectively. The rats were sacrificed on days 1, 3, 7, and 14. Micro-computed tomography-reconstructed images of the upper right first molars were used to survey root resorption and tooth movement. Horizontal sections of the maxillae were prepared for hematoxylin and eosin, tartrate-resistant acid phosphatase, and immunohistochemical staining. RESULTS: Resorption lacunae appeared on the compressed side of the distal buccal root of the right first molar on days 7 and 14. Compared with the control groups, GH-treated groups showed more RANKL-positive cells and osteoclasts on day 3 and more OPG- and IGF-I-positive cells and fewer odontoclasts on days 7 and 14. Indexes of root resorption were lower and tooth movement was faster in the GH-treated groups than in the control groups on days 7 and 14. CONCLUSIONS: The inhibitory effect of GH on root resorption by heavy force might be mediated by RANKL/OPG and IGF-I. Short-term GH administration may be a method with which to reduce root resorption and shorten treatment time, especially in patients who are susceptible to root resorption.