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Objective · To observe the micro-structure changes in rat tooth movement process under different force values through Micro-CT dynamic observation. Methods · Fifteen SD adult male rats at the age of 8 weeks were divided into three groups randomly (n=5), with the left maxillary as the experimental side and the nickel titanium coil springs, fixed between the first molar and incisor where thrust augmentation was conducted respectively by 20, 50 and 100 gf (1gf=0.0098 N) for continuous 14 d to it. Rat scanning in vivo through Micro-CT was carried out at day 0, 3, 7, 10 and 14 after force values were loaded on. The root resorption crater volumes and structure parameters for bone trabecula at different time points were measured. Results · Three days after thrust augmentation was conducted, root resorption crater volume for each group had a slight increase and an obvious increase occurred from the 3rd day to the 10th day, and then a slow increase happened 10 d later; from the 7th day to the 14th day, root resorption crater volume for 100 gf stress group was obviously greater than those of the other groups with statistical differences (P<0.05). With time for thrust augmentation passing by, bone volume fraction at the pressure side of alveolar bone decreased gradually and bone trabecula morphology became tiny and exiguous; besides, bone trabecula gap became narrow first and broad afterwards, and trabeculae trended to change from clintheriform to rhabditiform. Furthermore, alveolar bone resorption occurred in each stress group with consistent tendency. Conclusion · Different orthodontic force values all can cause root resorption, which experiences lag phase, rapid phase and stationary phase. Over-loaded orthodontic force induces more root resorption. During the process of the tooth movement, the pressure side of alveolar bones appears reconstruction and absorption, whose variation is not related with force degree.
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<p><b>OBJECTIVE</b>This research explores the regulatory role of bone morphogenetic protein 2 (BMP2) in the expression of sclerostin in OCCM-30 cementoblast.</p><p><b>METHODS</b>OCCM-30 cementoblasts were treated with 50 and 100 ng · mL⁻¹ BMP2 for 3, 5, and 7 days. SOST mRNA was detected by real-time quantitative polymerase chain reaction (RT-PCR). Western blot analysis was employed to detect the sclerostin levels in the nucleus. Five groups were prepared for the experiments: control, BMP2, BMP2+dorsomorphin, BMP2+SB202190, and BMP2+PD98059. OCCM-30 was pretreated with BMP2 for 3 and 5 days, and then the sclerostin and SOST mRNA levels were measured.</p><p><b>RESULTS</b>RT-PCR and Western blot analyses showed that BMP2 upregulated the expression of SOST in a concentration-dependent manner. SOST expression increased with time (P < 0.05). Moreover, sclerostin levels of BMP2+dorsomorphin, BMP2+SB202190, and BMP2+PD98059 groups were lower than that of the BMP2 group, and the sclerostin level in BMP2+dorsomorphin group was lowest (P < 0.05).</p><p><b>CONCLUSION</b>The upregulation of SOST by BMP2 in OCCM-30 is mainly mediated by the BMP2/Smad signal pathway.</p>
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Blotting, Western , Bone Morphogenetic Protein 2 , Metabolism , Bone Morphogenetic Proteins , Metabolism , Dental Cementum , Metabolism , Genetic Markers , Signal Transduction , Up-RegulationABSTRACT
Objective To explore the relationship between cervical bone age and male juvenile mandibular second molar (Msm) root growth ,and to provide evidence for the development of bone and teeth in patients with orthodontic treatment . Methods The CBCT and lateral cephalometric radiographs of 114 cases of 9 .5 to 15 .5 years old children in Chongqing city and ad‐olescents cervical vertebral bone and MSM root length were measured ,using statistical analysis to explore the relationship between cervical vertebral bone ,tooth root length change of age and Msm .Results By Pearson correlation analysis ,Msm root length chan‐ges and cervical vertebral bone were positively correlated(r= 0 .737 ,P< 0 .01) .Msm root length changes showed a positive correla‐tion with age(r= 0 .681 ,P< 0 .01) .Msm root length changes was positively related with dental age(r = 0 .795 ,P< 0 .01) .Conclu‐sion The root growth of the mandibular second molar was highly correlated with cervical vertebral bone in male children .When the growth and development of patients were judged by orthodontic treatment ,we can adopt the mandibular second molar root length forecast growth level of male adolescents .
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<p><b>OBJECTIVE</b>Periodontal tissue remodeling includes remodeling of alveolar bone, periodontal ligament, and cementum. Cementoblast plays a main role in repairing root resorption. Canonical Wnt/β-catenin signaling can promote the odontogenic differentiation in osteoblast. However, the mechanism on how the orthodontic force influences the function of cementoblast and the relationship between the canonical Wnt/β-catenin signaling and Runx2 of cementoblast are not yet known. The aim of this study is focus on this relationship.</p><p><b>METHODS</b>OCCM30 cementoblasts were subjected to mechanical strain by four-point bending system with tension stress for 0, 3, 6, and 12 h. They were pretreated with different concentrations of Dikkopf-1 (DKK1) for 48 h. Western blot analysis was performed to detect the β-catenin levels in the nucleus. Runx2 mRNA was observed by real-time quantitative polymerase chain reaction (RT-PCR). OCCM30 cementoblasts were then pretreated with 150 ng · mL(-1) DKK1 for 48 h and subjected to mechanical strain by FX4000T system with tension stress for 12 h. Western blot analysis was conducted to detect the β-catenin levels in the nucleus, and Runx2 mRNA was observed by RT-PCR.</p><p><b>RESULTS</b>OCCM30 cementoblasts had significantly higher Runx2 mRNA and β-catenin levels after being loaded with mechanical stress. The amount of Runx2 mRNA in OCCM30 cementoblasts was significantly decreased by DKK1. When OCCM30 cemento-blasts were pretreated with DKK1 without stress, their β-catenin level was significantly decreased by DKK1 and Wnt signaling was blocked. When they were not pretreated with stress, the β-catenin level with DKK1 was lower than that without DKK1. Without DKK1, the β-catenin level in OCCM30 cemento- blasts increased afterbeing loaded with mechanical stress. With DKK1, the β-catenin level in OCCM30 cementoblasts, which were loaded with mechanical stress, was higher than that without mechanical stress.</p><p><b>CONCLUSION</b>Cementoblasts had higher Runx2 mRNA expression under mechanical stress because of the Wnt/β-catenin signaling pathway effect.</p>
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Humans , Cell Differentiation , Dental Cementum , In Vitro Techniques , Osteoblasts , Signal Transduction , Stress, Mechanical , Wnt Proteins , beta CateninABSTRACT
BACKGROUND:Estrogen has an effect on orthodontic tooth movement. Currently, only animal experiments show that the lower estrogen levels, the greater the amount of orthodontic tooth movement;the higher estrogen levels are, the smal er the amount of orthodontic tooth movement is. OBJECTIVE:To investigate effects of orthodontic force applied on orthodontic tooth movement at different stages of menstrual cycle among young female patients. METHODS:Twelve young female patients were included in this study, aged 14-18 years old. They already have regular menstrual cycle, and need to extract the first premolar in the maxil a. By using self-control method, these female patients with their maxil ary canine at both sides were randomly divided into two groups:orthodontic force at ovulatory period and orthodontic force at menstrual period. Micro-implant anchorage was implanted to the distal y moving canine. Orthodontic force was given to the group of ovulatory period 2 weeks after the force was given at menstrual period. Dentition models were taken at day 0 and 28 after force, to prepare a superhard plaster model using silastic impression materials. Between these two groups, the distances of the canine distal movement were measured and statistical analysis was performed with GraphPad Prism5 software. RESULTS AND CONCLUSIONS:The distances of the canine distal movement in the group of orthodontic force at menstrual period were greater than that in the other group (P<0.05). The orthodontic teeth with the application of orthodontic force at menstrual period move faster than that with the application of orthodontic force at ovulatory period, thus effectively shortening orthodontic treatment.
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<p><b>OBJECTIVE</b>To investigate the exerted force in different phases of the female menstrual cycle, as well as the changes in estrogen (E2), osteocalcin (OCN), receptor activator of nuclear factor-kappa B ligand (RANKL), and osteoprotegerin (OPG) levels in the gingival crevicular fluid (GCF) during orthodontic tooth movement, to provide a theoretical basis for the selection of the best opportunity for efficient tooth movement.</p><p><b>METHODS</b>Twelve women (aged 18 years to 28 years) with extracted first premolars had been selected. Six women in the group were randomly selected as the menstrual period group, whereas the remaining six were assigned to the ovulation period group. Right canines were retracted with 1.5 N NiTi close coil spring. GCF samples were collected prior to the force exertion experiments at 0 (T0), 15 (T1), 30 (T2), and 45 d (T3). The levels of E2, OCN, OPG and RANKL in GCF were measured by chemiluminescence and enzymelinked immunosorbent assay.</p><p><b>RESULTS</b>The E2 and OCN levels were significantly higher in the ovulation period group than in the menstrual period group (P < 0.05). No significant differences were found in RANKL and OPG levels between the two groups (P > 0.05). Finally, no significant difference was found in RANKL/OPG ratio between the two groups (P > 0.05).</p><p><b>CONCLUSION</b>Exerted force on teeth during the menstrual period may promote rapid tooth movement.</p>
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Female , Humans , Gingival Crevicular Fluid , Menstrual Cycle , Osteoprotegerin , RANK Ligand , Tooth Movement TechniquesABSTRACT
To train high-qualified dental practitioner, the students in Chongqing Medical U-niversity were guided and regulated through rigorous training programs. Special attention was paid to the management of each aspect of clinical practice, the educational philosophy of early clinical expo-sure, early scientific research exposure and early contact with society have been fully implemented during the teaching practice in our stomatology college.
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Objective To explore the effect of problem-based learning(PBL)in x-ray cephalometric teaching.Method Forty students were divided into two groups:the conventional teaching group(A)and the PBL group(B),each team twenty students.The teaching effectiveness was evaluated by subjective questionnaire and objective test.Resulte The evalution shows that group B was significantly superior to group A.Conclusions Problem-based learning can im-prove the students' understanding of the significance of cephalometric and deserve to be popu-larized in experiment teaching.
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0.05).The results showed that patients treated with Damon3TM brackets pay significantly lower treat- ment time(4.23 months),required significantly lower chairside time(137.15s)than those treated with conventionally-ligated brackets.Conclusions:In matched cases,Damon3TM brackets produced significant reductions in treatment time and the chair- side time,but gained the same treatment results comparing with conventionally-ligated brackets.