Objective:To compare the therapeutic effects of debris spondylectomy,piecemeal spondylectomy,total en bloc spomdylectomy in treating lumbar metastatic tumors. Methods:The clinical data of 20 patients with lumbar metastatic tu-mors treated from January 2008 to October 2013 were retrospectively reviewed. There were 8 males and 12 females ,aged from 35 to 65 years old with an average of (49.50±9.97) years. All patients had single solitary metastases. Four cases were in L 1,5 cases in L2,4 cases in L3,4 cases in L4,and 3 cases in L5. According to the type of Tomita,typeⅡhad in 4 cases,typeⅢin 6 cases,typeⅣin 6 cases,type V in 4 cases. Tokuhashi score was 12.50±1.97. All patients complained with back or leg pain , VAS score was 8.13±0.85. Among patients,7 cases were treated with debris spondylectomy (group A),7 cases with piecemeal spondylectomy (group B),6 cases with total en bloc spondylectomy (group C). Statistical analysis was used to compare the three groups with respect to surgical trauma (including operative time,transoperative bleeding,and intraoperative blood trans-fusion),clinical symptoms (by VAS score at 1 week after operation),surgical procedures conditions (by AP and lateral X rays),and long term results (by recurrence and death information). Results:All patients were followed up from 6 to 36 months with an average of (16.50±7.88) months. Operative time for debris spondylectomy was (6.14±0.68) h,intraoperative bleeding was(3 457.14±399.40) ml,and intraoperative blood transfusion was(2 771.43±423.14)ml. Operative time for piece-meal spondylectomy was(4.93±0.61) h,intraoperative bleeding was(1 942.86±378.51) ml,and intraoperative blood transfu-sion was (1 500.00±336.65)ml. Operative time for total en bloc spondylectomy was(4.17±0.67) h,intraoperative bleeding was (1 341.67±361.13) ml,and intraoperative blood transfusion was (916.67±321.66) ml. There was significant differences in op-erative time,intraoperative blood loss,and intraoperative blood transfusion between three groups (P<0.05). In terms of these factors,total en bloc spondylectomy had the best outcome followed by piecemeal spondylectomy. All pains had released ,VAS score decreased obviously at 1 week after operation(P<0.05),and there was no significant differences between three groups(P>0.05). Surgical effects were well with these methods according to the evaluation of AP and lateral X rays . At final follow up, group A had 4 recurrences(2 with breast cancer,1 with prostate cancer,and 1 with thyroid cancer) and 3 deaths (2 with lung cancer and 1 with thyroid cancer);group B had 2 recurrences (1 with breast cancer and 1 with prostate cancer) and 3 deaths (1 with lung cancer,1 with breast cancer and 1 with kidney cancer);group C had no recurrences and 2 deaths for lung cancer. There was significant differences in recurrence and death between three groups(P<0.05). In terms of these factors,total en bloc spondylectomy had the best outcome in three methods. Conclusion:Three kinds of operation method can relieve pain ,improve nerve function,increase the spinal stability,control the local lesions,improve the patient's quality of life in treating lumbar metastatic tumors,but total en bloc spendylectomy,respect to operative time,transoperative bleeding,intraoperative blood transfusion,tumor recurrence and death is clearly superior to other two methods.

Objective: To construct a three-dimensional (3D) finite element model and analyze the biomechanical characteristics during mandibular second molar mesialization using customized lingual appliances and mini-implant. Methods: One adult student volunteer from The First Affiliated Hospital of Zhengzhou University with lower left first molar extraction was selected. After CT scanning, Mimics, Geomagic, ANSYS were employed to develop a 3D finite element model including customized lingual brackets, stainless steel lingual arch wire, buccal buckles, lower dentition, periodontal ligaments and alveolar bone. Four different loading methods (1. the force of 1.470 N loaded at the lingual side only; 2, 3, 4. the forces of 0.490, 0.735 and 0.980 N loaded at both buccal and lingual sides, respectively.) were included. The initial displacements of the lower second molar and stress distribution in the periodontal ligaments were analyzed. Results: More uniform stress distributions in the periodontal membrane of mandibular left second molar were found when the mesial force were loaded at both buccal and lingual sides than the force loaded at lingual side only. More inclination of the second molar was observed when force loaded at both sides than at lingual side only. With the values of the force increased, the mesial inclination potential of the second molar, the initial movement of the second molar and the stress distribution in the periodontal membrane increased. Under the force of 0.735 N at both buccal and lingual sides, mesially inclined initial displacements of the mandibuar second molar were observed and the stress values of von Mises was in the suitable area. Conclusions Less second molar rotation was found when the force loaded at both buccal and lingual sides than loaded at lingual side only. However, force loaded at both sides would increase the measial inclination potential of the second molar.