ABSTRACT
Objective:To evaluate skeletal,dentoalveolar and soft tissue profile changes by activator therapy in patients with different skeletal patterns of Class Ⅱ1 malocclusions.Methods:22 subjects(10 girls,12 boys,mean age 11.5 ±0.67 years) in the mixed or early permanent dentition,were included and divided into low angle(n =15) and average angle(n =7) groups on the basis of skeletal pattern.All patients were treated with a traditional activator.The skeletal,dentoalveolar and soft tissue profile changes were compared on lateral cephalograms before and after treatment.Statistical analysis was performed with t-test of SPSS 13.0 at a level of significance of P ＜ 0.05.Results:Activator treatment in these growing patients resulted in a correction of the skeletal Class Ⅱ relationship (decrease of ANB,Wits and NA-Pg),an advancement of the mandibular structures(increase of Co-Pg and L1-APg),and changes of the teeth(increase of L6-MP).The changes of Wits,NA-Pg and L1-APg value of low and average angle groups were 1.34° ± 1.82 ° and 3.50 ° ± 1.77°,(3.06 ± 2.00) mm and (5.80 ± 3.17) mm,(-1.16-± 1.74) mm and (-2.83 ± 1.48) mm respectively(P ＜0.05).No statistical significance was found in the soft tissue profile changes whether intra-class or inter-group comparison.Conclusion:The activator appliance is effective in treating growing patients with mandibular deficiency,and mandibular reconstruction,in patients with average angle it is more effective than in those with low angle.
ABSTRACT
<p><b>OBJECTIVE</b>To establish animal models for research of orthodontic tooth under rapid movement through distraction osteogenesis of the periodontal ligament, and to approach the rules of bone formation and the relationship between new bone formation and angiogenesis.</p><p><b>METHODS</b>48 rats of which the right maxillary first molars were removed were randomly divided into experimental and orthodontic control group. The orthodontic model was established according to traditional method, and the stretch device was installed in the experimental group after reducing the second molar's mesial bone resistance. Four animals in each group were randomly selected to be killed at 6 time points (at day 0, 3, 5, 10, 20, and 30). After specimens were obtained, immunohistochemical staining was done. The expression of vascular endothelial growth factor (VEGF) and osteocalcin (OC) were investigated.</p><p><b>RESULTS</b>In the experimental group, VEGF was mainly expressed in vascular endothelial cells, fibroblasts, osteoblasts, osteoclasts, and bone cells. The positive expression of VEGF gradually increased, the peak appeared at day 10 on the tension side, and the other side was at day 5. OC-positive signals were seen in the extracellular matrix of periodontal ligament and osteoblastic cells, and its peak appeared at day 10 on both tension and pressure side. The expression of VEGF and OC were similar in orthodontic control group, but the level was lower.</p><p><b>CONCLUSION</b>VEGF and OC involve in the remodeling of periodontal tissues and play an important role during periodontal ligament distraction osteogenesis. Angiogenesis is earlier than bone formation, or both appear simultaneously.</p>