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Devido a constante necessidade de desenvolver materiais biocompatíveis com propriedades osteocondutores e osteoindutoras, a presente tese conta com o desenvolvimento de dois estudos in vitro com fibra de carbono obtida a partir de fibra PAN têxtil, incorporada com diferentes íons de metais, na osteogeÌnese com vistas à compreensão das necessidades da engenharia tecidual no desenvolvimento desse biomaterial com adequadas propriedades biológicas. As células foram obtidas dos fêmures de 09 ratos machos adultos (Wistar) pesando 300g, com 90 dias.Estudo 1: A partir da preparação da fibras foram obtidos corpos de prova de 4 mm de diâmetro e 2 mm de altura, dos seguintes grupos: fibra de carbono não ativada (FCNA), fibra carbono ativada (FCA) e fibra carbono ativada com prata (FCAAg). Após plaqueamento (n=5) em meio suplementado (MTS) e meio suplementado osteogênico (MTSO) foram analisados: viabilidade celular, conteúdo de proteína total (PT), atividade de fosfatase alcalina (ALP), interaçãocelular e formação de nódulos de mineralização. Foi avaliada a formação de biofilme nos corpos de prova, utilizando cepas de S. aureus, P. aeruginosa e E. coli. Na viabilidade celular, houve diferença estatística entre grupo controle celular (C) e FCA-MTS, FCAAg-MTS e FCAAg-MTSO. Em PT, não houvediferença, na ALP houve diferença entre C-MTS e as fibras, C-MTSO se mostrou semelhante. Em nódulos, houve diferença entre C-MTS e C-MTSO e as fibras do MTSO. Houve redução de formação de biofilme do S. aureus na FCAAg.Estudo 2: Foram obtidos corpos de prova da mesma dimensão do estudo 1 (n=5) dos seguintes grupos: fibra carbono ativada com prata (FCAAg), fibra carbono ativada com ouro (FCAAu), fibra carbono ativada com cobre (FCACu), fibra carbono ativada com paládio (FCAPd) e fibra carbono ativada com platina (FCAPt). Foram quantificadas a proliferação celular, viabilidade celular, formação de nódulos de mineralização, conteúdo de PT e ALP. Todas as amostras mostraram-se semelhantes quanto a proliferação celular, com exceção do grupo FCAAg comparado ao grupo controle (C). Sobre viabilidade celular, C obteve maior viabilidade que os outros grupos, e FCA obteve maior taxa que os grupos FCAAg, FCACu, FCAPt, sendo semelhante aos grupos FCAAu e FCAPd. Já os grupos FCAAu e FCAPd apresentaram diferença aos grupos FCAAg e FCACu. Na análise de expressão de PT apenas houve diferença entre FCA e FCAAu, sendo FCAAu com menor expressão de produção de PT. Na avaliação da ALP os grupos FCAAg e FACu mostraram diferença estatística e inferior com os grupos C, FCAAu, FCAPd e FCAPt, além disso, o grupo FCA mostrou menor taxa que C.Conclusões: As fibras utilizadas de base para a incorporação dos íons demonstraram grande potencial para uso como scaffold para reparação óssea, isso porque em ambos os estudos, na forma ativada e não ativada, as fibras apresentaram viabilidade celular e quantificação de cálcio satisfatórias. Sendo a versão não ativada mais econômica no que diz respeito ao tempo e custo de preparação. Mais estudos devem ser empregados a fim de assegurar sua segurança clínica em relação à citotoxicidade da incorporação de íons de ouro e paládio.(AU)
Due to the constant need to develop biocompatible materials with osteoconductive and osteoinductive properties, this thesis involves the development of two in vitro studies with carbon fiber obtained from textile PAN fiber, incorporated with different metal ions, in osteogenesis with a view to understanding the needs of tissue engineering in the development of this biomaterial with adequate biological properties. The cells were obtained from the femurs of 9 adult male rats (Wistar) weighing 300g, aged 90 days. Study 1: From the fiber preparation, specimens measuring 4 mm in diameter and 2 mm in height were obtained from the following groups: non-activated carbon fiber (FCNA), activated carbon fiber (FCA) and silver-activated carbon fiber (FCAAg). After plating (n=5) in supplemented medium (MTS) and supplemented osteogenic medium (MTSO), cell viability, total protein content (PT), alkaline phosphatase (ALP) activity, cell interaction and formation of mineralization nodules were analyzed. . Biofilm formation was evaluated in the specimens, using strains of S. aureus, P. aeruginosa and E. coli. In cell viability, there was a statistical difference between the cell control group (C) and FCAMTS, FCAAg-MTS and FCAAg-MTSO. In PT, there was no difference, in ALP there was a difference between C-MTS and fibers, C-MTSO was similar. In nodules, there was a difference between C-MTS and C-MTSO and MTSO fibers. There was a reduction in S. aureus biofilm formation on FCAAg. Study 2: Specimens of the same size as in study 1 (n=5) were obtained from the following groups: carbon fiber activated with silver (FCAAg), carbon fiber activated with gold (FCAAu), carbon fiber activated with copper (FCACu), palladium-activated carbon fiber (FCAPd) and platinum-activated carbon fiber (FCAPt). Cell proliferation, cell viability, formation of mineralization nodules, PT and ALP content were quantified. All samples were similar in terms of cell proliferation, with the exception of the FCAAg group compared to the control group (C). Regarding cell viability, C obtained higher viability than the other groups, and FCA obtained a higher rate than the FCAAg, FCACu, FCAPt groups, being similar to the FCAAu and FCAPd groups. The FCAAu and FCAPd groups showed differences to the FCAAg and FCACu groups. In the analysis of PT expression, there was only a difference between FCA and FCAAu, with FCAAu having lower expression of PT production. In the ALP assessment, the FCAAg and FACu groups showed a lower statistical difference compared to the C, FCAAu, FCAPd and FCAPt groups, in addition, the FCA group showed a lower rate than C. Conclusions: The fibers used as the basis for the incorporation of ions demonstrated great potential for use as a scaffold for bone repair, because in both studies, in activated and non-activated form, the fibers showed satisfactory cell viability and calcium quantification. The non-activated version is moreeconomical in terms of preparation time and cost. More studies must be carried out to ensure its clinical safety in relation to the cytotoxicity of the incorporation of gold and palladium ions. (AU)
Subject(s)
Animals , Rats , Osteogenesis , Cell Survival , Biofilms , Tissue Engineering , Carbon FiberABSTRACT
Introduction: The primary function of corono-radicular post is to provide retention for the core and to reinforce and to replace the remaining coronal tooth structure. There is considerable controversy regarding optimal choice of the material. An ideal post system should exhibit fracture resistance higher than the average masticatory forces. Finite elemental analysis (FEA) method facilitates precise analysis of the distribution and magnitude of stresses at any point of complex and irregular structures. Thus, this FEA study has been undertaken to evaluate the fracture stress distribution patterns in three fiber posts, viz., carbon, glass fiber, and everStick with an FEA. Materials and Methods: The FE stress analysis was performed with the FE software program (CATIA). Three two-dimensional FEA models of central incisor were simulated, and elastic moduli and Poisson's ratio of all the materials were fed to the software. For all the models, a 200 N vertical force was applied on the lingual surface of the tooth at an angle of 45°. Stress concentration and distribution were evaluated and noted down for all the models. To evaluate the stresses within the restored tooth, the modified von Mises failure criterion was used. The equivalent stresses found in the tested models were compared with the tensile strength of the respective materials. Contact stresses in the luting cement–dentin interface were calculated. Results: Finite element method revealed that maximum stress concentration was at the point of stress application. The stress value was highest in carbon fiber post followed by glass fiber post and least stresses found in everStick post. Maximum stress was observed at the labial surfaces of crown. However, the stress values and distribution were more homogenous in everStick post. Conclusion: The present findings suggest that everStick post has uniform stress distribution within tooth structure.
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A mini-infrared moxibustion instrument was developed on the base of carbon fiber heating film. This new type moxibustion instrument integrated the moxibusiton technique of TCM with modern technology. It is composed of a power module, an infrared generator module, a temperature sensor, a display screen and a main control panel. The carbon fiber is adopted as the material for infrared generator, which produces infrared rays in the range of the life light wave (from 8 to 15 μm), characterized as precise control of temperature, small gradient and wide range of temperature adjustment. The users can adjust the temperature and time of moxibustion by themselves. The instrument is small in size, light in weight, easy to carry and charge as well as comfortable and safe in application. It can be fixed directly at the required region without the posture restriction and be used whenever needed. Using PowerLab multichannel physiological recorder, the temperature carve is detected at different setting temperatures. The results show that the temperature is increased rapidly and stable.
Subject(s)
Acupuncture Points , Carbon Fiber , Moxibustion , TemperatureABSTRACT
BACKGROUND: Recently, carbon fibers have been utilized to develop a depth-type microelectrode array for chronic neural recording. Since the diameter of carbon fibers is smaller than the conventional electrodes made of metal wires or microfabricated silicon, the carbon fiber electrodes showed an improved capability for chronic neural recording with less tissue damages. However, the carbon fiber based microelectrodes have a limitation of short insertion depth due to a low stiffness. METHODS: We proposed a carbon fiber based microelectrode array embedded with a mechanical support structure to facilitate the penetration into the deeper brain. The support is made of biodegradable silk fibroin to reduce the reactive tissue responses. The 4-channel carbon fiber based microelectrode arrays were fabricated and accessed in terms of electrochemical impedance, recording capability for 1-month implantation in rat hippocampi. The electrodes with tungsten supports were fabricated and tested as a control group. Immunohistochemical analysis was performed to identify the reactive glial responses. RESULTS: The carbon fiber based electrode arrays with silk supports showed about 2-fold impedance increase 2 weeks after implantation while the number of active electrodes decreased simultaneously. However, after 1 month, the electrode impedance decreased back to its initial value and the percentage of active electrodes also increased above 70%. Immunohistochemical staining clearly showed that the electrodes with silk supports induced less reactive glial responses than that with tungsten supports. CONCLUSION: The proposed carbon fiber based microelectrode array is expected to be used for long-term in vivo neural recording from deep brain regions with the minimized reactive tissue response.
Subject(s)
Animals , Rats , Brain , Carbon , Electric Impedance , Electrodes , Fibroins , Microelectrodes , Silicon , Silk , TungstenABSTRACT
Objective:To analyze the attenuation of immobilization baseplate of carbon fiber for ray and the change of dose verification results for enhanced radiation field of MatriXX. And to primarily research the influence of this immobilization baseplate for the dose distribution of radiation field of radiotherapy.Methods: 20 patients with cervical cancer were enrolled in the research. The angle of gantry was 180°in the enhanced plan of immobilization field, and the corresponding verification plans were designed. When the verification plan was implemented on the Varian Clinac iX of accelerator, the two-dimensional ionization chamber array (MatriXX) was used to measure dose distributions of the plan. The immobilization baseplate of carbon fiber (ORFIT AIO) was used in the research. The situations of no baseplate (A group), one baseplate (B group), two baseplates (C group)and three baseplates (D group)between the handpiece of accelerator and Matri XX were researched, respectively. The data of the 4 groups were obtained by using software (OminiPro I'mRT), and the largest dose point and passing rate of Gamma in plane of radiation field were counted and analyzed.Results: Compared with A group, the average attenuation factors for ray on the largest dose point of B, C and D group in the plane of radiation field were (1.73±0.11)％, (3.44±0.36)％, and (5.48±0.44)％, respectively. The passing rates of Gamma in the 4 groups were (94.87±2.31)％, (99.18±0.61)％, (99.79±0.27)％ and (96.24±1.99)％, respectively. And the differences of passing rate between each group and A group were statistical significance (t=9.788,t=9.261,t=2.256,P<0.05).Conclusion:The immobilization baseplate of carbon fiber has influence for the attenuation of high-energy X-rays and it can affect the dose distribution of radiation field which has passed baseplate in some degrees. And when physicists calculates the dose, they should consider the effect of immobilization baseplate of carbon fiber for dose distribution of radiation field.
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Objective:To investigate the method of arthroplasty for reconstructing femporomandibular joint (TMJ) after the establishment of TMJ articular defect models in the rabbits,and to clarify the replacement and repair effects of carboh fiber reinforced polyetheretherketone (CFR-PEEK) material TMJ prostheses,and to provide an experimental basis for the clinical application of CFR-PEEK artificial joints to replace TMJ.Methods:Thirteen healthy adult Japanese rabbits were randomly divided into experimental group (n=6),positive control group (n=4) and negative control group (n =3).The right TMJ articular process of the rabbits in experimental group were resected to establish the joint defect models,and then the CFR-PEEK artificial joints were impanted.The right TMJ articular process of the rabbits in positive control group were resected,and the joint defect models were established without the CFR-PEEK artificial joint implantation.The rabbits in negative control group didn't receive any treatment.The body weights of the rabbits in each group were measured in 13 weeks.The effects of fixation and replacement after artificial joint implantation were assessed by CT imaging.Results:The TMJ articular process defect model was successfully implanted with the CFR-PEEK artificial joint.The CT imaging results after threedimensional reconstruction and CT images by contrast in vitro showed that the CFR-PEEK-implanted artificial joint was fixed well,it could be instead of the normal joint function.Compared with positive control group,the weights of rabbits in experimental group were significantly increased (P＜ 0.05) at 13 weeks;compared with positive control group,the weights of rabbits in experimental group and negative control group were both significantly increased (P＞0.05) at 13 weeks,but there was no significant difference between them (P＞0.05).The weights of rabbits in experimental group and negative control group kept normal growth;the weights of rabbits in positive control group was increased slowly,and even stopped growing or was negative.Conclusion:The CFR-PEEK artificial joint can be successfully implanted into the TMJ defect model and be used to repair the defect which help to restore chewing function.The CFR-PEEK is expected to be an ideal material for reconstructing TMJ.
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Objective:To investigate the method of arthroplasty for reconstructing femporomandibular joint (TMJ) after the establishment of TMJ articular defect models in the rabbits,and to clarify the replacement and repair effects of carboh fiber reinforced polyetheretherketone (CFR-PEEK) material TMJ prostheses,and to provide an experimental basis for the clinical application of CFR-PEEK artificial joints to replace TMJ.Methods:Thirteen healthy adult Japanese rabbits were randomly divided into experimental group (n=6),positive control group (n=4) and negative control group (n =3).The right TMJ articular process of the rabbits in experimental group were resected to establish the joint defect models,and then the CFR-PEEK artificial joints were impanted.The right TMJ articular process of the rabbits in positive control group were resected,and the joint defect models were established without the CFR-PEEK artificial joint implantation.The rabbits in negative control group didn't receive any treatment.The body weights of the rabbits in each group were measured in 13 weeks.The effects of fixation and replacement after artificial joint implantation were assessed by CT imaging.Results:The TMJ articular process defect model was successfully implanted with the CFR-PEEK artificial joint.The CT imaging results after threedimensional reconstruction and CT images by contrast in vitro showed that the CFR-PEEK-implanted artificial joint was fixed well,it could be instead of the normal joint function.Compared with positive control group,the weights of rabbits in experimental group were significantly increased (P＜ 0.05) at 13 weeks;compared with positive control group,the weights of rabbits in experimental group and negative control group were both significantly increased (P＞0.05) at 13 weeks,but there was no significant difference between them (P＞0.05).The weights of rabbits in experimental group and negative control group kept normal growth;the weights of rabbits in positive control group was increased slowly,and even stopped growing or was negative.Conclusion:The CFR-PEEK artificial joint can be successfully implanted into the TMJ defect model and be used to repair the defect which help to restore chewing function.The CFR-PEEK is expected to be an ideal material for reconstructing TMJ.
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Abstract The aim of this study was to evaluate the flexural strength and flexural modulus of different fiber-reinforcement composite (FRC) posts and determine the correlation between mechanical properties and structural characteristics. Eleven brands of fiber posts were analyzed (n=10): Exacto Cônico (Angelus), DT Light SL (VDW), RelyX Fiber Post (3M-Espe), Glassix Radiopaque (Nordim), Para Post Fiber White (Coltène), FRC Postec Plus (Ivoclar), Aestheti-Plus Post (Bisco), Superpost Cônico Estriado (Superdont), Superpost Ultrafine (Superdont), Reforpost (Angelus), and White Post DC (FGM). The posts were loaded in three-point bending test to calculate the flexural strength and flexural modulus using a mechanical testing machine (EMIC 2000 DL) at 0.5 mm/min. Data were submitted to one-way ANOVA and Scott-Knot test (p<0.05). The cross-sections of the posts were examined by scanning electron microscopy (SEM). Correlation between the mechanical properties and each of the structural variables was calculated by Pearson's correlation coefficients (p<0.05). The flexural strength values ranged from 493 to 835 MPa and were directly correlated with the fiber/matrix ratio (p=0.011). The flexural modulus ranged from 4500 to 8824 MPa and was inversely correlated with the number of fibers per mm2 of post (p<0.001). It was concluded that the structural characteristics significantly affected the properties of the FRC posts. The structural characteristic and mechanical properties of fiber glass posts are manufacture-dependent. A linear correlation between flexural strength and fiber/matrix ratio, as well as the flexural modulus and the amount of fiber was found.
Resumo O objetivo deste estudo foi avaliar a resistência à flexão e módulo de flexão de diferentes pinos reforçados com fibra (PRF) e determinar a correlação entre propriedades mecânicas e características estruturais. Foram analisadas onze marcas de pinos de fibra (n=10): Exacto Cónicos (Angelus), DT Luz SL (VDW), RelyX Fiber Post (3M ESPE), Glassix Radiopaque (Nordim), Pará Publicar Fiber White (Coltène), FRC Postec Plus (Ivoclar), Aestheti-Plus Post (Bisco), Superpost Cónicos Estriado (Superdont), Superpost Ultrafino (Superdont), Reforpost (Angelus), e White Post DC (FGM). Os pinos foram avaliados por meio de ensaio de flexão de três pontos para calcular a resistência à flexão e módulo de flexão utilizando uma máquina de ensaios mecânicos (EMIC 2000 DL) a 0,5 mm/min. Os dados foram submetidos a ANOVA one-way e teste de Scott-Knot (p<0,05). As secções transversais dos pinos foram examinadas usando microscopia eletrônica de varredura (MEV). A correlação entre as propriedades mecânicas e de cada uma das variáveis estruturais foi calculada por coeficientes de correlação de Pearson (p<0,05). Os valores da resistência à flexão variaram de 493-835 MPa e foram diretamente correlacionados com a proporção de fibra/matriz (p=0,011). O módulo de flexão variou de 4500 a 8824 MPa e foi inversamente correlacionado com o número de fibras por mm2 (p<0,001). Concluiu-se que as características estruturais afetam de forma significativa as propriedades dos pinos de fibra. As características estruturais e propriedades mecânicas dos pinos de fibra de vidro são dependentes do processo de fabricação. Existe uma correlação linear entre a resistência à flexão e proporção de fibra/matriz, bem como entre o módulo de flexão e a quantidade de fibras.
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Dental Materials , Post and Core Technique , Materials Testing , Microscopy, Electron, ScanningABSTRACT
Objective To construct the uniform electron density couch model (model A ED =0.25) and two components non uniform electron density couch model (model B FD =0.5and foam core=0.1) in the Monaco treatment planning system for the iBEAM(R) evo Extension 415,and to compare which model can better quantify the treatment couch influence on radiation dose.Methods Phantom was positioned in the center of the couch,the attenuation of the couch was evaluated with 6 MV for a field size of 10 cm× 10 cm.Dose measurements of couch attenuation were performed at gantry angles from 180.0° to 122.8°,using a 0.125cc semiflex ionization chamber (PTW),isocentrically placed in the center of a homogeneous cylindrical phantom.Each experimental setup was first measured on the linear accelerator and then reproduced in the TPS.By adjusting the relative-to water electron density (ED) values of the couch,the measured attenuation was replicated.The model accuracies of the model A and model B were evaluated by comparing the measured and calculated results at the minimum computational grid (2 mm) and maximum computing grid (5 mm),respectively.Results The maximum measured and calculated percentage deviation for the central phantom position was 4.01％.The couch model was included in the TPS with a uniform ED of 0.25 or a 2 component model with a fiber ED=0.5 and foam core ED=0.1.For model A and B under 2 and 5 mm voxel grid size,the mean absorbed dose with couch was reduced to 0.61％,0.84％,0.71％ and 0.92％from 2.8％ without couch.Conclusions Model A has a good agreement between measured and calculated dose distributions for all different voxel grid sizes and gantry angles.It can accurately describes the dose perturbations due to the presence of the couch and should therefore be used during treatment planning.
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Objective:To assess the clinical effects of carbon fiber reinforcement on the“All-on-Four”provisional prostheses.Methods:Provisional prostheses were divided into control group and carbon fiber reinforcing group according to whether carbon fiber reinforcement was used in the provisional prostheses base resin.In our study,a total of 60 patients (32 males and 28 females)with 71 provisional prostheses (28 maxilla and 43 mandible)were enrolled between April 2008 and December 201 2 for control group;a total of 23 patients (1 3 males and 1 0 females)with 28 provisional prostheses (9 maxillas and 1 9 mandi-bles)were enrolled between January 201 3 and March 201 4 for carbon fiber reinforcing group.The infor-mation of provisional prostheses in the patients was recorded according to preoperative examination.We used the date of definitive prosthesis restoration as the cut-off point,observing whether fracture occurred on the provisional prostheses in the two groups.Additionally we observed whether fiber exposure occurred on the tissue surface of the provisional prostheses and caused mucosal irritation.The interface between the denture base resin and the fibers was examined using scanning electron microscopy (SEM).Results:The age [(57.3 ±1 0.1 )years vs.(55.1 ±1 1 .4)years],gender (32 males and 28 females vs.1 3 males and 1 0 females),maxilla and mandible distributions (28 maxillas and 43 mandibles vs.9 maxillas and 1 9 mandibles),the number of extraction jaws (46 vs.23 ),the average using time [(7 .8 ±1 .3 ) months vs.(7 .5 ±1 .1 )months],and the opposing dentition distributions of provisional prostheses of the patients showed no significant differences between the control and reinforcing groups.There were 21 (29 .6%)fractures that occurred on the 71 provisional prostheses in the control group;there was no frac-ture that occurred on the 28 provisional prosthesesin the carbon fiber reinforcing group.The fracture rate of the carbon fiber reinforcing group was significantly lower than that of the control group (P=0.001 ). No carbon fiber exposure and mucosal irritation were observed from clinical examination.SEM revealed relatively continuous contact between the fiber and acrylic resin,and the resin particles adhered on the surface of the carbon fibers.Conclusion:The addition of carbon fibers between abutments placed on“All-on-Four”provisional fixed denture base resin may be clinically effective in preventing “All-on-Four”denture fracture and can provide several advantages for clinical use.
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Hydrogen evolution from water electrolysis is one of the effective ways to obtain clean hydrogen energy in the future. Pt-based materials are the efficient catalysts in hydrogen evolution reaction, but it is expensive, difficult to recycle, which impedes its application in the development of hydrogen energy and economy. Therefore, it is the key trend to develop efficient non-noble metal electrocatalysts with the aim of providing cost-competitive hydrogen energy. In this review, we highlighted the recent research efforts toward the synthesis of noble metal-free electrocatalysts for the hydrogen evolution reaction ( HER) , mainly focusing on nanomaterial catalysts supported on carbon fiber materials. We reviewed several important kinds of heterogeneous non-noble metal electrocatalysts, including sulfides, selenides, carbides, phosphides, and oxides. In the discussion, emphasis was given to the synthetic methods of these HER electrocatalysts, and the strategies for performance improvement. In addition, this paper also briefly summarized the application of carbon fiber material as substrate in the field of electroanalytical chemistry.
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This study was aimed to develop a simultaneous determination of zinc and cadmium with carbon fiber electrode by linear sweep stripping voltammetry. Effects of analytical base solution, accumulation potential, ac-cumulation time and scanning velocity were also investigated on the determination. The results showed that in 1 mol·L-1 H2SO4 medium solution, zinc and cadmium had good electrochemical response on the carbon fiber electrode and appeared sensitive anodic stripping peaks at-0.97 V and-0.77 V, respectively. The anodic stripping peak cur-rents and concentrations of zinc and cadmium showed good linear relationships, with correlation coefficients R2 of 0.996 5 and 0.995 4, respectively. The detection limits of zinc and cadmium (S/N=3) were 1.5×10-9 mol·L-1 and 1.0×10-10 mol·L-1, respectively. The average recoveries of zinc and cadmium were 98.9%and 98.1%with the rela-tive standard deviations (RSD) of 2.72%and 2.45%(n=6), respectively. It was concluded that the method of simul-taneous determination of zinc and cadmium with carbon fiber electrode was simple, sensitive and accurate.
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Objective To evaluate the effect of carbon fiber couch on dose distribution of radiotherapy planning and verification pass rate.Methods Establishing the carbon fiber treatment couch model in Pinnacle8.0m Treatment Planning system (TPS),and then this model was used to correct dose calculations of oblique fields in the treatment plans of 10 cases of nasopharyngeal carcinoma,10 cases of breast cancer and 10 cases of lung cancer and evaluate the effect of carbon fiber couch on the whole dose distribution of the plans.Then these plans were measured by three-dimensional dose verification equipment Delta4 to confirm the improvement extent of Gamma pass rate after considering the carbon fiber treatment couch.Results For the majority of plans,when the carbon fiber couch was taken into consideration,the target doses was significantly reduced (4772 cGy-7266 cGy vs.4859 cGy-7347 cGy,P=0.000-0.002) and the relative deviation of D95 was 1％ to 3％.Measurement results of Delta4 showed that Gamma pass rate (3 mm/3％ criteria) increased in all plans (96.4％-98.8％ vs.93.4％-97.3％,P =0.000),some of that were up to 5 percentage when the couch model was applied.Conclusions Target doses will be overestimated if the treatment couch is ignored in TPS measurement.,However it should arouse enough attention when the disease with smaller doses corresponding gradient.
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Objective To investigate the mechanical properties of carbon-fiber-reinforced polyether-ether-ketone (CF/PEEK)composite materials and to evaluate the biocompatibility and bioactivity of CF/PEEK after implanted into mandibula.Methods 27 adult Japanese white rabbits were randomly divided into experimental group (n=9) and control group (n=18),CF/PEEK was implanted into bilateral mandibula of the rabbits in experimental group, autologous bone was implanted into left mandibula of the rabbits in positive control group (n=9 )while the right sides were taken as blank control group (n=9 )without implants. The materials-bone interface of samples were collected to make the observation of gross,imaging and histology and to analyze the histological score after 8,12, and 16 weeks.Results All the animals and no infection had secondary fractures.Obviously callus formation was observed on the edge of the defect in both experimental group and positive control group in the imaging observation, while the rabbits in blank control group had no obvious change.Compared with 8 weeks after operation, the score evaluation of local cellular immune response showed significant decreasing in 12 weeks after operation(P 0.05).Trabecular bone and osteoblasts could be observed in the bone defect of both experimental group and positive control group after 16 weeks,and blank control group was filled with fibrous connective tissue.The osteogenesis rates in experimental group and positive control group were increased with the prolongation of time, and they were better than that in blank control group (P<0.01).Conclusion CF/PEEK material has good mechanical property,biocompatibility and bioactivity;and it has light immune response after implantation.
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OBJECTIVE: To evaluate the efficiency of carbon fiber composite frame and polyetheretherketone(PEEK) cages in the interbody fusion for surgical treatment of cervical disc diseases, we analyzed fusion time and subsidence rate. METHODS: From March 2004 to February 2007 fifty patients with cervical disc diseases underwent anterior discectomy and interbody fusion in 60 levels. The subjects were 26 men and 24 women with a mean age of 57.2 years ranging from 29 to 67. Among them 25 patients underwent operations using carbon fiber composite frame cages (Osta-Pek(R), Co-Ligne, Zurich, Switzerland) in 30 levels, and 25 patients using PEEK cages(Cornerstone(R), Medtronic, TN, USA) in 30 levels. The cages were packed with allograft bone or bone substitute(demineralised bone matrix). On lateral flexion-extension radiographs anterior disc height and posterior disc height were measured at preoperative time, postoperative 1, 3, 6 and 12 month respectively. Segmental stability(lordotic angle) was measured at postoperative 3, 6, and 12 months in all 60 levels for fusion time. RESULTS: The anterior disc height and posterior disc height were 4.87+/-1.36mm and 3.25+/-0.73mm at preoperative time, 7.32+/-1.41mm and 4.77+/-0.80mm at postoperative 1month, and 5.87+/-1.47mm and 3.22+/-0.93mm at posto- perative 12 months respectively in carbon fiber composite frame cage group(30 levels). The anterior disc height and posterior disc height were 4.88+/-1.18mm and 3.75+/-0.75mm at preoperative time, 7.26+/-1.17mm and 5.27+/-0.55mm at postoperative 1month, and 6.23+/-1.16mm and 3.96+/-0.69mm at postoperative 12months respectively in PEEK cage group(30 levels). The angular motion at the fused segment was measured in carbon fiber composite frame cage and PEEK group for segmental stability(two degrees or less flexion-extension range of motion at the fusion site). The carbon fiber composite frame cage group was stabilized between postoperative 3 months and 6 months, but PEEK cage group was stabilized between 6 months and 9 months. This result was statistically significant(p-value =0.003)(Fig. 2). Fusion rate of carbon composite frame cage group was 28%, 67% and 83% at 3, 6, 12 months after operation, and that of PEEK cage group was 24%, 48% and 86% at postoperative 3, 6 and 12 months respe- ctively. Complications included transient hoarseness, cage migration and subsidence. There was no persistent hoar- seness or Horner syndrome. We have observed severe subsidence(above 3mm) in two cases(6.7%) of carbon fiber composite frame cage group only. Anterior cage migration was shown in each one case(3.3%) of carbon fiber composite frame and PEEK cage group. CONCLUSION: The carbon fiber composite frame cage group showed a tendency of earlier fusion than PEEK cage group but both cages were same in the fusion rate at postoperative 1 year. But, restoration or maintenance of inter- vertebral height was much better in PEEK cage group than carbon fiber composite frame cage group. Subsidence rate was higher in carbon fiber cage group rather than PEEK cage group.
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Female , Humans , Male , Carbon , Diskectomy , Hoarseness , Horner Syndrome , Ketones , Polyethylene Glycols , Range of Motion, Articular , Transplantation, HomologousABSTRACT
Objective:To evaluate the protection of small bowel and bladder by Contoura carbon fiber belly board in patients with rectal cancer undergoing postoperative radiotherapy and the position deviation during radiotherapy. Methods: This study enrolled 45 consecutive patients with rectal cancer who had undergone prior surgery. Twenty patients who applied the belly board were defined as group A, and the other 25 patients were defined as group B. All the patients received threE-dimensional conformal radiation therapy(3D-CRT), and the prescriptive radiation dosage of 95% of planning target volume (PTV) was 50 Gy/25 times. Patients in group A underwent two sets of CT scans as follows: group A1, prone alone; group A2, prone with the use of the belly board. The radiation dosage and radiated volume in PTV, small bowel, and bladder were observed by dosE-volume histograms. Ten patients were selected randomly from group A and group B, respectively. Their position deviation during radiotherapy was measured by double exposure field verification system. The acute radiation reactions of all patients were observed and recorded during radiotherapy. Results: No significant difference was found in the total PTV and total volume of small bowel and bladder and mean irradiation dosage to PTV between groups A1 and A2. The mean irradiation dosage to the small bowel and bladder, the volume of small bowel irradiated at 10%-100% dose levels, and the volume of bladder irradiated at 30%-100% dose levels, were significantly decreased in group A2. The difference was significant. Compared with group B, the right-left and superior-inferior position deviations were significantly reduced in group A. The difference was significant (P<0.05). The anterior-posterior position deviation was also reduced, but the difference was not significant (P=0.705). The incidence of grade 3 or more adverse reactions were 15% (3/20) in group A and no patient broke off or stopped treatment; the incidence of grade 3 or more adverse reactions was 24% (6/25) in group B, and two patients broke off the treatment because of severe adverse reaction. One patient terminated the treatment. Conclusions: The Contoura carbon fiber belly board can reduce the irradiation dosage and volume of small bowel and bladder in patients with rectal cancer undergoing postoperative radiotherapy. The position deviation has better reproducibility and the acute radiation reactions are tolerable. It is worthy of application in clinic.
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Objective To evaluate the dosimetric effect of carbon fiber tabletop on the patient doses in radiotherapy. Methods The transmission factors of couch and inserts were measured in air and solid water phantom using 0.6 cm3 ion chamber and PTW 2D ion chamber array for 6 MV ,10 MV and 18 MV X-ray,respectively. Absorbed doses at depth of maximum dose ,5 cm and 10 cm in solid water were measured with the 2D ion chamber array. Absorbed doses fluctuations with different gantry angles and air gaps between phantom and couch were also measured. Results The posterior field measurement showed that the reductions of absorbed doses at the depth maximum dose,5 cm and 10 cm were within 5%. The ratios of the absorbed doses with to without couch increased with the oblique incident angles and varied slightly with the air gap at depth of 5 cm. The transmission factors of inserts were less than those of couch owing to its thinner thickness. Conclusion The carbon-fiber tabletop affects the absorbed doses and dose distributions of the target, and this effect changes with the gantry angle and air gap. Special considerations should be taken during treatment planning.
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OBJECTIVES: We report an outbreak of skin disorder in semiconductor packing workers. Through an evaluation of the degree of work-relatedness in this case, we aim to develop a method to overcome such health problems in the workplace. METHODS: A questionnaire investigating the job characteristics and skin symptoms was administered to 51 packing workers working in a semiconductor production factory and 49 questionnaires returned. The 16 subjects in the exposure group and 12 in the non-exposure group underwent doctor's examination and patch test. Two of 28 subjects were excluded in patch test. We investigated the work environment and carbon fiber level which was the potential causative agent. RESULTS: Forty-five (91.8%) of 49 packing workers complained of itching and stinging. Three of 14(21.4%) in the exposure group and 3 of 11 (27.3%) in the non-exposure group were positive at 48hr reading of patch test for carbon fiber and carbon fiber paper. None was positive at 96hr reading of patch test. Prominent carbon fibers were microscopically observed on the surface of the packing box and the fiber diameter, measured up to 6.0~7.5 micrometer, was likely to induce skin irritation to skin. To avoid worker's direct contact with to carbon fiber, carbon fiber paper box was substituted by a wax coated carbon fiber paper box was substituted for the original carbon fiber paper box, which caused and the workers' symptoms to of workers disappeared. CONCLUSION: The probably cause of this outbreak of skin disorder was mild irritant contact dermatitis for carbon fiber. To prevent outbreaks of such occupational skin disorder like this, workers should avoid direct contact with carbon fiber.
Subject(s)
Bites and Stings , Carbon , Dermatitis, Contact , Disease Outbreaks , Patch Tests , Pruritus , Surveys and Questionnaires , Semiconductors , SkinABSTRACT
Objective To explore the initial stability of a carbon fiber reinforced polyetheretherketone composite (CF/PEEK) stem in human femurs after total hip replacement. Methods 8 pairs of human cadaveric femurs were used to test the CF/PEEK prosthesis versus a conventional cementless stem of cobalt-chrome molybdemum alloy(CoCrMo). The bone-femoral prosthesis interface motion was measured in vitro using displacement transducers. Combined axial and torsional loads and simulated single-leg stance loading were applied. Subsidence, rotation and interface motion were measured with load cycles up to 1 000 N. Results The extent of the micro-motion in the proximal femoral region was larger than that in the distal femoral region. The CF/PEEK composite prosthesis showed less dynamic micro-motion in the proximal region compared with the CoCrMo alloy prosthesis stem, with the average difference being 42%. The extent of the distal micro-motion in the 2 groups was small but the difference was significant (P
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STATEMENT OF PROBLEM: Fiber-reinforced posts have lower modulus of elasticity than titanium post or cast post-core. With this similar elasticity to that of dentin, fiber-reinforced posts have been known to have a tendency to reduce the risk of root fracture. However, there were few studies on the teeth restored with fiber-reinforced posts under the condition of reduced periodontal support. PURPOSE: The purpose of this study was to evaluate the fracture strength and failure mode of endodontically treated teeth restored with fiber-reinforced posts and titanium posts under the condition of reduced periodontal support. MATERIAL AND METHOD: Extracted human maxillary incisor roots were divided into 3 groups (group 1 : carbon fiber post, group 2 : glass fiber post, and group 3 : titanium alloy post). After coronectomy and endodontic treatment, teeth were restored with each post systems and resin core according to the manufacturer's recommendation. Then, teeth with simulated periodontal ligament were embedded in the acrylic resin blocks at the level of 4 mm below the cemento-enamel junction. Each specimen was exposed to 105 load cycles with average 30 N force in 36.5 degrees C water using a computer-controlled chewing simulator. Loads were applied at 45.angle to the long axis of the teeth. After cyclic loading, teeth were subjected to a compressive load until failure at a crosshead speed of 0.5 mm/min. Fracture strength (N) and failure mode were examined. The fracture strength was analyzed with one-way ANOVA and the Sch ffe adjustment at the 95% significance level. RESULTS AND CONCLUSION: The results were as follows. 1. There was no statistically significant difference in the mean fracture strength among the groups ( P>0.05). 2. Carbon fiber post and glass fiber post group showed less root fracture tendency than control group. 3. All specimens with root fractures showed fracture lines above the level of acrylic resin block, except for only one specimen in group 3.