Preliminary Study Of OPG As The Orthodontic Drug Anchorage

During orthodontic treatment,teeth is moved by orthodontic force. Theprocess of tooth movement is the process of jaw conversion. The dynamicbalance between osteoclast resorption and osteoblast bone formation andtheir coupling maintains the integrity of the bone. The previous studyconfirmed that a variety of drugs,hormones,growth factors and cytokinesinvolved in the regulation of jaw alterations. OPG/RANKL/RANKsystem is a physiological basis for the regulation of osteoclast formation,and thus the regulation of bone remodeling. Osteoprotegerin (OPG) is atumor necrosis factor receptor; RANKL is a tumor necrosis factor receptorligand, mainly secreted by osteoblasts.RANKL combines with osteoclastsurface specific receptor RANK to promote breaking differentiation andmaturation of precursor cells in the bone formation with bone resorptionfunction of osteoclasts. OPG competitively combines with RANK toprevent the combination of RANKL and RANK.The primary role of OPG is to inhibit osteoclastogenesis, activation, thusinhibiting the absorption of the jaw to maintain the integrity of the jaw. Thediphosphate is a synthetic analogue of pyrophosphate, a significantinhibition of hydroxyapatite crystallization of dissolved properties, and it is able to significantly inhibit osteolysis. In Orthodontic treatment, it isdifficult for orthodontic physicians to control the anchorage toothmovement. The traditional method to enhance the anchorage is to enhancethe mechanical force and its effect depends on the patients'cooperation.Application of a wide range of micro-implant anchorage in recent years hasthe advantage of steadily high strength anchorage, but the implants andremoval require surgery, and costs are high.To apply the pharmacologicalmechanisms and the mechanism of tooth movement in order to control thegeneration of osteoclasts and thus to control the absorption of alveolar bone,we would be able to achieve the purpose of tooth movement control,without patients' cooperation and without surgery.In this study, anchorage tooth movement during orthodontic treatment issimulated through the establishment of animal models.It covers:(1).Localinjection of different concentrations of OPG to compare the differentconcentrations of OPG distance of orthodontic tooth movement in rats, themorphological changes of the periodontal tissues and the number ofosteoclasts.(2). Local injection of alendronate to study the impact ondistance of orthodontic tooth movement in rats, the morphological changesof periodontal tissue and the number of osteoclasts.(3). Comparison theimpact of local injection of different concentrations of OPG andalendronate on the distance of orthodontic tooth movement, periodontaltissue morphology, the number of osteoclasts. The study chooses100 10-week-old male SD (Spargue-Dewley) rats, weight at250g-300g. Inaccordance with local injection and the concentration, rats are randomlydivided into0.5mg/kg OPG group,0.2mg/kg OPG group,0.05mg/kg OPGGroup,0.05mg/kg alendronate group,saline group. Placed between the rightmaxillary incisors and maxillary first molar nickel-titanium extensionspring, extension spring opened to produce40g force, and traction of themaxillary first molar mesial movement. In accordance with local injectiondose,OPG,alendronate and saline was injected into the right first molarperiosteum near the root of the bifurcation. After injection,1d,4d,7d,14d,5rats of each group were sacrificed, measuring the distance of the firstmolar movement, take with the first molars of the experimental side, themaxillary bone slices, HE staining and TRAP immunohistochemicalstaining to observe the changes in morphology, the osteoclastcount.Experiment obtained the following results:1.7d and14d, the amount of tooth movement:0.5mg/kg OPG group<0.2mg/kg OPG group<0.05mg/kg OPG group<0.05mg/kg alendronategroup <saline group,with a significant difference (p <0.05).2. HE staining observation, pressure side in0.05mg/kg saline group can beobserved significant alveolar bone absorption, alveolar bone resorptionof pressure side in0.5mg/kg OPG group,0.2mg/kg OPG group,0.05mg/kg OPG group and0.05mg/kg alendronate group is not obvious.3. Slice TRAP staining,4d and7d, number of osteoclasts in the first molar root pressure side:0.5mg/kg OPG group0.2mg/kg OPGgroup<0.05mg/kg OPG group<0.05mg/kg alendronate group <salinegroup (p <0.05).14d,0.5mg/kg OPG group <0.2mg/kg OPGgroup<0.05mg/kg OPG group <saline group(p<0.05),0.05mg/kg OPGgroup and0.05mg/kg alendronate group have no significant differences(p>0.05).