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Objective To compare biomechanical effects of augmentative plating assisted by different types and numbers of intramedullary nails in the treatment of nonunion of femoral shaft fracture after intramedullary nailing.Methods Twenty-five specimens of synthetic femur were randomly divided into an experimental group (20 bones) and a control group (5 bones).All the bones were made into models of nonunion of femoral shaft fracture after intramedullary nailing.The control group was subjected to no augmentative plating.The experimental group was further divided into 4 subgroups (n =5) which were subjected to fixation respectively by:a 7-hole plate with 3 bicortical screws on each side,a 7-hole plate with 3 unicortical screws on each side,a 5-hole plate with 2 bicortical screws on each side,and a 5-hole plate with 2 unicortical screws on each side.The torque values of all the subgroups were measured and compared when the models were subjected to torsional angles of 5°,10°,15°,20° and 25°.Results The anti-torsional strengths at torsional angles of 5°,10°,15°,20° and 25° in the 4 experimental groups were all significantly greater than in the control group(P ＜ 0.05).At a torsion angle of 25°,the mean torque value in the 3-bicortical-screw group (46.51 ±6.66 nm) was significantly greater than in the 2-bicortical-screw group (39.03 ±8.52 nm) (P ＜0.05).At torsion angles of 5°,10°and 25°,the mean torque values in the 3-unicortical-screw group (13.48±1.68 nm,23.29±3.72 nm and 48.19±5.34 nm,respectively) were significantly greater than in the 3-unicortical-screw group (9.56 ± 3.62 nm,16.99 ± 5.49 nm and 38.69 ± 6.56 nm,respectively) (P ＜ 0.05).At torsion angles of 20° and 25°,the mean torque values in the 3-unicortical-screw group (39.15 ± 5.07 nm and 48.19 ± 5.34 nm) were significantly greater than in the 2-bicortical-screwgroup (32.50 ± 5.65 nm and 39.03 ± 8.52 nm) (P ＜0.05).Conclnsions The anti-torsional strength of fixation by 3 screws on each side is significantly greater than by 2 screws on each side.When the number of screws is the same,there is no significant difference between fixation by unicortical locking screws and that by bicortical conventional screws.Augmentative plating with 3 unicortical screws or 3 bicortical conventional screws on each side is recommended for treatment of nonunion of femoral shaft fracture after intramedullary nailing.
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Objective The Improved segmental arch technique can effectively intrude incisors and correct deep overbites. To research its biomechanical characteristics, we reconstruct 3D nonlinear finite element model of mandibular teeth with improved segmen-tal arch, study the biomechanical characteristics and the suitable loading force of intrusion arch. Methods Combined with the re-sults of previous research, we complete the reconstruction of 3D nonlinear finite element model of mandibular teeth with improved seg-mental arch.Then, we set loading force of intrusion arch five conditions from 0.2 N~0.6 N, calculate the movement trend and stress distribution of improved segmental arch. Results In the five conditions of improved segmental arch, lateral incisors and canines in-truded and tipped labially, first molars tipped distally and rotated. In addition, the moment the initial loading force of intrusive arch in-creased, the movement of these teeth increased. However, other teeth did not move clearly. When the initial loading force of improved segment arch was 0.5 N, it can achieve appropriate intrusion of anterior teeth. Conclusion Under an appropriate intrusive force, improved segment arch can effectively intrude incisors and control the extrusion of posterior teeth. It can be used to correct the deep overbites, especially with high mandibular planes, gummy smile or adult stage.
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Objective:To assess the guidance of 3D reconstruction in the surgical and orthodontic management of maxillary palatal impacted canines with cone-beam computed tomography (CBCT).Methods:22 adolescent patients with 26 impacted maxillary conines were examined by CBCT.CBCT 3D reconstruction was used to observe the impaction of the canines.Measurements were taken to evaluate spatial relationship between the canine and adjacent structures and resorption of neighboring incisor roots.Results:CBCT was effective to localize the impacted canines.All of the maxillary palatal impacted canines inclinated mesially,angles of impacted ca-nines to occlusal plane were 61.1°±18.1°,there were 8,5,3 and 10 impacted canines found in classⅠ,Ⅱ,Ⅲ and Ⅳ mesial mal-position respectively.3 adjacent lateral incisors and 2 central incisors were extracted because of severely root resorption.Normal occlu-sion was achieved for 26 impacted canines by the traction of the canines into dental arch and reaching the occlusal plane.Conclusion:CBCT can spatially show the palatal impaction of maxillary canines and the relationship to adjacent tooth,can guide the treatment plan and traction direction,therefore increase therapeutic effect.
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<p><b>OBJECTIVE</b>To reconstruct a three-dimensional nonlinear finite element model of mandibular teeth with three-pieces segment arch, and analyze the mechanical properties of intrusive arch and the biomechanical characteristics of three-pieces segment arch.</p><p><b>METHODS</b>Three-dimensional nonlinear finite element model of mandible with three-pieces segment arch was reconstructed by multi-slice spiral CT scanning, Mimics, CATIA and Anasys software. Then, the mechanical properties of intrusive arch, the movement trend and stress distribution of three-pieces segment arch were calculated by Anasys software.</p><p><b>RESULTS</b>In the range of 5 degrees-25 degrees, with the degree of intrusive arch increased, the force of intrusive arch also increased rapidly. The maximal force was 0.604 8 N in 30 degrees; the force was about 0.59 N in 30 degrees-65 degrees range. In condition of three-pieces segment arch mechanics, lateral incisor tipped labially and intruded; the first moral tipped distally and rotating; other teeth did not move clearly. The largest stress distribution in the whole arch was in the one-third labial cervical area of the lateral incisor root and the root bifurcations of first moral.</p><p><b>CONCLUSION</b>Under an appropriate intrusive force, three-pieces segment arch can intrude incisors and control the extrusion of posterior teeth. It can be used to correct the deep overbite, especially with high mandibular planes, gummy smile or adult patients.</p>
Subject(s)
Humans , Dental Arch , Finite Element Analysis , Incisor , Mandible , Tooth RootABSTRACT
<p><b>BACKGROUND</b>It has been showed that VEGF-C can induce the proliferation of lymphocytes. The aim of this study is to explore the expression of VEGF-C in human non-small cell lung can-cer (NSCLC) and its relationship with lymph node metastasis.</p><p><b>METHODS</b>The expression of VEGF-C was examined in 60 human NSCLC tissues by immunohistochemical technique..</p><p><b>RESULTS</b>The positive rate of VEGF-C expression was 65.00% (39/60) in NSCLC tissues. The expression of VEGF-C was significantly higher in cases with lymph node metastasis (83.33%, 20/24) than in those without lymph node metastasis (52.78%, 19/36) (P < 0.05).</p><p><b>CONCLUSIONS</b>There is an overexpression of VEGF-C protein in human NSCLC tissues, which may correlate with lymph node metastasis. The expression of VEGF-C protein might be used as a useful mar- ker of lymph node metastasis in NSCLC.</p>