RESUMEN
Porous Ti-6Al-4V alloy was fabricated using the electron beam melting (EBM) process. The phases of the as-received powder and fabricated samples were characterized using X-ray diffraction (XRD) analysis. The XRD peaks of both diffraction patterns agree well, which indicated that the EBM process has not changed the composition of Ti-6Al-4V. The fabricated samples exhibited a Vickers microhardness value of around 428 HV. The compression and three-point bending tests were performed to evaluate the mechanical properties of the porous Ti-6Al-4V implant with a porosity of around 60 per cent. The compressive yield strength, Young's modulus, and ultimate compressive strength were 194.6 MPa, 4.25 GPa, and 222.6 MPa respectively. The bending stiffness and bending strength were 3.7 GPa and 126.3 MPa respectively. These results demonstrated that the porous Ti-6Al-4V implant with a low stiffness and high porosity could be a promising biomaterial for biomedical applications.
Asunto(s)
Materiales Biocompatibles/química , Ensayo de Materiales , Prótesis e Implantes , Titanio/química , Aleaciones , Módulo de Elasticidad , Porosidad , Estrés MecánicoRESUMEN
The solubilization of human gel-filtered platelets by octyl glucoside, Triton X-100, dodecylsulfate, and deoxycholate was compared from the analysis of (1) cell lysis, (2) marker leakiness, and (3) component solubility. These analyses all revealed that the effect of detergent concentration on the solubilization of platelets by these detergents was exerted in three stages, i.e., the prelytic, lytic, and complete platelet-lysis stages. These analyses also indicated several differences among platelets in these detergents. (i) The ratio of the platelet-saturation concentration (PSC) to critical micellar concentration (CMC) was about 1/2 for octyl glucoside. Triton X-100 and dodecylsulfate, while it was close to 1 for deoxycholate. (ii) Platelets in octyl glucoside. Triton X-100, and dodecylsulfate all showed parallel curves in cell lysis, protein solubilization and marker leakiness, while the platelet lysis in deoxycholate was identical to the phospholipid solubilization. (iii) The solubility curves of various components in Triton X-100 and deoxycholate were parallel. However, the solubility of cholesterol in octyl glucoside was lower than that of protein and phospholipid. In dodecylsulfate, the solubility of phospholipid and cholesterol was very low in comparison with that of protein. In addition, morphological studies using scanning electron microscopy (scanning EM) revealed that the solubilization by octyl glucoside or Triton X-100 might occur via membrane area expansion. On the other hand, the solubilization by dodecylsulfate or deoxycholate showed membrane vesiculation prior to cell lysis. Moreover, in the prelytic stage, the morphological change in platelets in octyl glucoside showed only concentration dependence by swelling to an ellipsoid and then to a sphere. However, the morphological change in platelets in the other three detergents was dependent not only on the detergent concentration but also on prolonged incubation. Specifically, in Triton X-100, the cells initially changed to spiculate discs and then reached their final shape as swollen discs with surface invagination. In dodecylsulfate and deoxycholate the morphological changes were almost the same. The cell initially deformed in shape to a spiculate disc and finally to a stretched-out flat form. The results are discussed according to the bilayer couple hypothesis. Also, in the prelytic stage, these detergents caused inhibition of the response of platelets to collagen and ADP-fibrinogen.
Asunto(s)
Plaquetas/citología , Detergentes/farmacología , Tensoactivos/farmacología , Plaquetas/efectos de los fármacos , Plaquetas/fisiología , Membrana Celular/efectos de los fármacos , Separación Celular , Cromatografía en Gel , Ácido Desoxicólico/farmacología , Glucósidos/farmacología , Humanos , Microscopía Electrónica de Rastreo , Octoxinol , Polietilenglicoles/farmacología , Dodecil Sulfato de Sodio/farmacología , SolubilidadRESUMEN
31P-NMR spectra were obtained from oriented multilayer preparations of normal sarcoplasmic reticulum and reconstituted sarcoplasmic reticulum with lipid to protein ratios varying between 41 : 1 and 110 : 1. The dependence of the 31P-NMr spectra on the alignment of the membranes with respect to the magnetic field was used to draw two conclusions about the motion of the phospholipid molecules that contribute to the observed spectra. First, the phosphate group and the two adjacent methylene groups are able to rapidly rotate (i.e., tau R much less than 10-5 S) around the normal to the plane of the membrane. Second, the restricted internal motion of the phosphate group and the glycerol CH2OP group is very similar to that found in liposomes formed from sarcoplasmic reticulum phospholipids. Calibration experiments showed that all (100 +/- 7%) of the phospholipid molecules in the membrane can be accounted for in the observed spectra. Thus, essentially all the phospholipid molecules in the sarcoplasmic reticulum and the reconstituted sarcoplasmic reticulum membranes have the same motion in the polar headgroup region as found in model bilayer membranes. Since a large fraction of the phospholipid molecules (between one-quarter and one-half, depending on ;the lipid to protein ratio) are immediately surrounding the calcium-pump protein, we conclude that the calcium-pump protein does not perturb the motion of these 'boundary-layer' lipids.
Asunto(s)
Liposomas , Lípidos de la Membrana/análisis , Fosfolípidos/análisis , Retículo Sarcoplasmático/ultraestructura , Animales , Espectroscopía de Resonancia Magnética , Microscopía Electrónica , Conformación Molecular , Músculos/análisis , ConejosRESUMEN
Gap arthroplasty, used in the treatment of temporomandibular joint (TMJ) ankylosis, is challenging, requiring resecting of massive abnormal bone formation at the skull base with complex and distorted anatomy. This study evaluated the application of image-guided navigation to gap arthroplasty. Four gap arthroplasties were performed on patients with unilateral TMJ ankylosis under computer-assisted navigation guidance. After preoperative planning and 3-dimensional simulation, the normal anatomic structures of the TMJ were created by superimposing and comparing the unaffected and affected sides. The amount and range of ankylotic bone to be resected was determined and displayed. Registration achieved an accurate match between the intra-operative anatomy and the CT virtual images. Anatomic structures and the position of surgical instruments were shown real time on the screen. In all cases the accuracy of the system measured by the computer did not exceed 1mm. No complications occurred and the mean minimal thickness of the skull base between middle cranial fossa and reconstructed glenoid fossa was 1.97 mm. Using image-guided navigation resulted in safe surgical excision of the bony ankylosis from the skull base. Navigation-guided resection of the ankylotic bone in the TMJ gap arthroplasty was a valuable and safe technique in this potentially complicated procedure.
Asunto(s)
Anquilosis/cirugía , Artroplastia/métodos , Cirugía Asistida por Computador , Trastornos de la Articulación Temporomandibular/cirugía , Adolescente , Anquilosis/diagnóstico por imagen , Niño , Femenino , Humanos , Masculino , Cóndilo Mandibular/cirugía , Sistemas de Información Radiológica , Rango del Movimiento Articular , Base del Cráneo/cirugía , Articulación Temporomandibular/cirugía , Trastornos de la Articulación Temporomandibular/diagnóstico por imagen , Tomografía Computarizada por Rayos X , Resultado del Tratamiento , Interfaz Usuario-ComputadorRESUMEN
OBJECTIVE:This study applied an SJ-1 bolt attachment partial denture to restorate distal extension edentulous areas.Finite element analysis (FEA) was used to monitor induced around abutment supporting tissues under the different number of splinted abutments.METHODS:Finite element analysis. RESULTS:The result demonstrate that the reduction of the number of splinted unit from three to two resulted in an insignificant increase of stress records,whereas reduction of the number from two to one resulted in a significant increase of stress nine times greater than the three unit splint values.CONCLUSION:Hence,at least two teeth on each side should be splinted when SJ 1 bolt(extracoronal) distal extension attachment prostheses are used.
RESUMEN
OBJECTIVE:This study applied finite element analysis (FEA) compared stress distribution characteristics of mandible,bilateral,SJ-1 bolt(extracoronal) distal extension attachment prostheses when the abutments were subject to eight different loss of periodontal support.METHODS:Finite element analysis.RESULTS:It was shown that periodontal support loss results in increased stress of the terminal abutment tooth without sudden changes.CONCLUSION:Compared favorable stress distribution result from splinted compromised abutment,and the first premolar periodontal support loss less than that of the second premolar and this loss below 30%.
RESUMEN
OBJECTIVE: A 3D geometric simulation of mandible with dental arch from CT has been obtained in this study. METHODS: This process uses automatic system assisted with interactive action to get 2D contour data from CT images,then 3D wireframe model and solid model were obtained by using CAD/CAM software Pro-E(USA) and DELCAM(UK). RESULTS: 3D solid model of mandible with dental arch were presented which can be fully edited. CONCLUSION: This model can be applied to further educational and clinical researches such as RP,biomechanics simulation in prosthetic dentistry.The processes of simulation has wide applications in clinical practice of dentistry and dental education.
RESUMEN
OBJECTIVE: Based on 3D reconstruction data from CT scanning, a solid model of mandible with dental arch is obtained via a rapid prototype machine using LOM method. METHODS: 3D reconstruction data is transferred to STL file using software of Delcam(UK),which will be fed to Magics RP software for detection and rebuilding. Reproduction of the papery model of mandible with dental arch is then performed with highly geometric similarity. RESULTS: The RP model of mandible with dental arch is obtained. CONCLUSION: Accuracy of the reproduction model meets the demands of students in prosthetic dentistry,which gives the possibility of computer aided design of prosthetic dentistry based on 3D solid model.