Effect of simvastatin on bone morphogenetic protein-2 expression in the periodontal tissue after rat tooth movement / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of systematic administration of simvastatin on the bone morphogenetic protein-2 (BMP-2) expression in the periodontal tissue after rat tooth movement and on the relapse of tooth movement.</p><p><b>METHODS</b>Orthodontic tooth movement of upper first molar was performed in 32 rats with coil spring for 21 days. The 32 rats were randomly allocated into 4 groups: negative control group (isotonic saline) and three experimental groups (2.5 mg x kg(-1), 5.0 mg x kg(-1) and 10.0 mg x kg(-1)). The simvastatin started to be administered to the experimental groups 1 day before appliances were removed, and once a day there after for 4 weeks. The negative control group received the isotonic saline only. The interdental distance between the first and second maxillary molars were measured, when appliances were removed, and 1 week and 4 weeks after that. After the rats were sacrificed, sections of first maxillary molar and periodontal tissue were studied by immunohistochemistry.</p><p><b>RESULTS</b>The number and percentage of relapse was lower in the three experimental groups than in the negative control group (P < 0.05, P < 0.01). The lower dose was given, the less relapse there was, with the lowerest dose resulting in lowest percentage of relapse (26.81% and 53.38%). BMP-2 expression in experimental groups was higher than in the negative control group, with the lowerest dose group showing the highest expression (P < 0.001). The BMP-2 expression on the tension side was slightly stronger than that on the compression side (P > 0.05).</p><p><b>CONCLUSIONS</b>Systemic administration of simvastatin could decrease the extent of relapse of the orthodontic-moved tooth in rat, and the lower-dose of simvastatin seemed more effective. The possible mechanism for this may be that simvastatin functions by increasing the expression of BMP-2 in the periodontal tissue, accelerating the osteoblast activity and promoting bone formation.</p>

Research of cranio-occlusional change of skeletal class III malocclusion in permanent dentition treated by the multiloop edgewise arch wire technique / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the mechanics in correction of skeletal class III malocclusion with Multiloop Edgewise Arch Wire (MEAW).</p><p><b>METHODS</b>15 patients with skeletal class III malocclusion were treated with MEAW technique. Cephalometric analysis was performed with pre-treatment and post-treatment cephalograms. Paired t-test was conducted to assess the treatment effects.</p><p><b>RESULTS</b>L6-XI decreased by 2.87 mm, L6/MP increased by 8.60 degrees, L1-XI decreased by 2.60 mm, OP/MP increased by 2.33 degrees. Skeleton changed a little. There was no significant change in the soft tissue.</p><p><b>CONCLUSION</b>(1) Dento-alveolar compensation is the main change after the treatment by MEAW technique; (2) The improvement in molar relationship and overjet is achieved with upright and distal movement of the lower posterior teeth; (3) The lower anterior teeth moved lingually and protracted. Occlusal plane is flattened.</p>