| Traditionally, the general rate of orthodontic tooth movement (OTM) is1mm per month. Therefore, the duration of orthodontic treatment is generally about two years or longer. Orthodontic treatment takes such a long time that some patients can not cooperate well with orthodontists, especially some adult patients. What is more, it may increase the risk of periodontal disease and cariers. How to move the teeth quickly and safely is of great concern for orthodontists all over the world since the1970’s. Many experimental approaches have been attempted to induce more efficient OTM by increasing the number of osteoclasts (Yamasaki et al.,1982). Recently, several researchers have shown that the application of thyrocalcitonin and vitamin D might lead to faster OTM. However, although these chemical medicines did improve the speed of OTM, most of them had clinical side effect or were still in experimental stage and cannot meet the needs of clinical application. Recently, attention has been turned from these medicines towards traditional Chinese medicine (TCM) which is known as lower price and little side effects. However, as the chemical constituents of TCM are complicated, the TCM may act on multi-targets to play a role in clinical treatment. A single or compound TCM preparation was used by most scholars in the past research, which was difficult to provide the mechanism of TCM action. With the fast development of biotechnology and modernization of TCM, many extract of major active constituent of TCM were isolated and identified. The single active ingredient of TCM is gradually applied to experimental studies. This study set up experimental animal models of OTM firstly. Wistar rats were selected as subjects in the study. In my experiment, we want to investigate effects of Asperosaponin D (ASD) of different concentration which was extracted from Chinese traditional medicine Dipsacaceae on OTM and to learn whether ASD can be an effective and safe way to facilitate OTM. The periodontal tissue and alveolar bone histological changes were inspected by light microscope to observe the difference among the four groups. Furthermore, tartrate resistant acid phosphatase(TRAP) was conducted to evaluate the number of osteoclast cells and osteoclast differentiation factor (ODF) immunohistochemisty strains were used to observe bone remodeling during OTM. Through this way we want to find if ASD can really increase the rate of tooth movement, so we can provide experimental basis for clinic OTM.Purpose:The study is to observe effects of local injection of ASD of different concentration and prostaglandin E2(PGE2) on the rate of tooth movement in combination with mechanical force in rats. Meanwhile, we detect the expression of ODF under the interference of ASD and PGE2and explore the possible mechanism. The study will provide new experimental basis on controlled tooth movement.Methods:Forty-eight8-week-old female wistar rats weighing180-200g (Shandong University experimental animal center) were selected. The48rats were randomly separated into four groups of12animals each:the ASD1group, the ASD2group, the PGE2group and the control group. The upper first molars of the rats were moved mesially by coil spring and the force of the coil spring after activation is approximately40g. ASD solution at the concentration of5mg/kg and10mg/kg were injected to the palatal submucosal area adjacent to the upper first molar in ASD1group and ASD2group respectively every2day during the OTM period. The rats of group PGE2were injected the PGE2solution at the concentration of25μg/kg. The same amount of0.9%normal saline was injected into the same area in control group. The rats were sacrificed in batch on the3rd,7th,14th,21st and28th days after orthodontic treatment. Slices from periodontium of the upper first molar were observed under optical microscope. HE strains were performed to show the change of periodontal tissue and new bone formation. TRAP was conducted to evaluate the number of osteoclast cells while the expression of ODF in the periodontal tissue was analyzed with immunohistochemical staining. All statistical analysis was performed by using SPSS software version13.0. Statistical significances were calculated by analysis of variance (ANOVA) for multiple comparisons, followed by individual comparisons between different groups at the same time point by paired t test. P<0.05was used to confirm the presence of a significant difference.Results:1. The distance between the first and second molar in wistar rats was successively increased from3to28days. On day3, there were significant difference between the PGE2group and the control group (P<0.05), but there were no significant difference among the ASD1group, ASD2group and the control group (P>0.05). Compared with the PGE2group, the tooth movement was decreased in the ASD1group and ASD2group. On day7, the distance between the first and second molar in the PGE2group and ASD2group were significantly increased compared with the control group (P<0.05), however, there were no significant difference between the ASD1group and the control group (P>0.05). The amount of tooth movement was significantly increased (P<0.05) in the ASD1group, ASD2group and PGE2group, when compared with the control group on the14th,21st and28th day. However, there were no significant difference (P>0.05) between the ASD2group and PGE2group.2. Histological changes in the periodontium of the upper first molar in the four groups:to observe osteoclasts histologically, we performed HE staining on the periodontium of the sections. The sections demonstrated differences among the four groups. We observed that on the tension side, the periodontal membrane telangiectasia appeared and space of periodontium increased, osteoblast appeared and new bone formed; on the pressure side, the space of periodontal membrane decreased, osteoclast and the alveolar bone resorption appeared. Bone resorption lacunae were apparent in the experimental group than in the control group at the surface of the alveolar bone on the7th,14th,21st and28th day on the pressure side.3. TRAP staining showed the obvious difference among the four groups. On day 3, we could find osteoclast in the section of the four groups, while there was no significant difference between control group and experiment group (P>0.05). On day7, the osteoclast number in the ASD2group and PGE2group was significantly increased (P<0.05) compared with the control group, but there were no significant difference between the ASD1group and the control group(P>0.05). Compared with the PGE2group, the osteoclast number was decreased in the ASD1group (P<0.05) and ASD2group (P>0.05). The amount of osteoclast was significantly increased (P <0.05) in the ASD1group, ASD2group and PGE2group, when compared with the control group on the14th,21st day. The osteoclast number was decreased in the ASD1group compared with the PGE2group (P<0.05). On day28, the osteoclast number was significantly increased (P<0.05) in the ASD1group, ASD2group and PGE2group, when compared with the control group. However, there was no significant difference (P>0.05) between the ASD2group and PGE2group.4. In the immunohistochemical anazysis of periodontium, the expression of ODF was higher as time goes by. On day21, the expression of ODF reached a peak, and then the expression became lower. The expression in the control group was lower when compared with the experimental groups, while the expression of ODF in the ASD2group and PGE2group almost has the same reaction. The results were consistent with the HE staining and TRAP staining.Conclusions:1. Local injection of ASD solution may accelerate orthodontic tooth movement.2. Local injection of ASD solution is beneficial to the alveolar bone remodeling by promoting osteoclast differentiation during OTM.3. ASD solution can make the expression of ODF higher and promote OTM.4. ASD solution at the proportion of10mg/kg can accelerate orthodontic tooth movement efficiently whose effect was similar to the PGE2solition, while ASD solution at the proportion of5mg/kg was not as effectual as the PGE2solition. |
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