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The article describes the failure phenomenon, analysis and processing process of the high-voltage generator module, FRC unit, rack tilt circuit and slip ring system in the daily use of Philips Ingenuity CT, so as to sum up the experience, discuss with the medical staff, and further Deepen the understanding of Philips Ingenuity CT's structure and working principle, and jointly improve the maintenance skills of CT and other large equipments.
Subject(s)
Humans , Tomography, X-Ray ComputedABSTRACT
Abstract Objective This study evaluated the fracture resistance of endodontically treated teeth restored with fiber reinforced composite posts, using three resin composite core build-up materials, (Clearfil Photo Core (CPC), MultiCore Flow (MCF), and LuxaCore Z-Dual (LCZ)), and a nanohybrid composite, (Tetric N-Ceram (TNC)). Material and Methods Forty endodontically treated lower first premolars were restored with quartz fiber posts (D.T. Light-Post) cemented with resin cement (Panavia F2.0). Samples were randomly divided into four groups (n=10). Each group was built-up with one of the four core materials following its manufacturers’ instructions. The teeth were embedded in acrylic resin blocks. Nickel-Chromium crowns were fixed on the specimens with resin cement. The fracture resistance was determined using a universal testing machine with a crosshead speed of 1 mm/min at 1350 to the tooth axis until failure occurred. All core materials used in the study were subjected to test for the flexural modulus according to ISO 4049:2009. Results One-way ANOVA and Bonferroni multiple comparisons test indicated that the fracture resistance was higher in the groups with CPC and MCF, which presented no statistically significant difference (p>0.05), but was significantly higher than in those with LCZ and TNC (p<0.05). In terms of the flexural modulus, the ranking from the highest values of the materials was aligned with the same tendency of fracture loads. Conclusion Among the cores used in this study, the composite core with high filler content tended to enhance fracture thresholds of teeth restored with fiber posts more than others.
Subject(s)
Humans , Tooth Fractures , Post and Core Technique , Composite Resins/chemistry , Tooth, Nonvital/therapy , Surface Properties , Viscosity , Materials Testing , Random Allocation , Reproducibility of Results , Analysis of Variance , Statistics, Nonparametric , Pliability , Resin Cements/chemistry , Dental Restoration Failure , Methacrylates/chemistryABSTRACT
ABSTRACT This paper presents the experimental results of a reinforced concrete beams (RC) strengthened with internal steel fibers (SF) and external glass fiber reinforced polymer laminates (GFRP). The research work studied the load carrying capacity, deformation, crack width and ductility of the reinforced concrete beams strengthened with different steel fiber ratios and steel fiber reinforced concrete beams strengthened with three different glass fiber reinforced polymer laminates of two different thickness. The experimental results clearly shows that incorporating steel fibers in to the reinforced concrete beams reduced the crack width and distribute the crack evenly and also increases the bonding between tension face of the beam with glass fiber reinforced polymer laminates. The results also shows that glass fiber reinforced polymer laminates strengthened steel fiber reinforced concrete beams increases the flexural strength and ductility as compared with unstrengthened counterpart. In addition to this experimental work, theoretical calculations were done to find the ultimate load carrying capacity of the beam tested, and also compared with the experimental results.
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PURPOSE: Many studies have shown that airborne-particle abrasion of fiber post can improve the bonding strength to resin cement. But, airborne-particle abrasion may influence the property of fiber post. The purpose of this study is to evaluate the influence of airborne-particle abrasion on flexural strength of fiber post. MATERIALS AND METHODS: Two fiber-reinforced posts; DT Light Post Size 2 (1.8 mm diameter, Bisco Inc) and RelyX Fiber Post Size 3 (1.9 mm diameter, 3M ESPE); were used in this study. Each group was divided into 3 subgroups according to different surface treatments; without pretreatment: 50 µm aluminum oxide (Cobra®, Renfert): and 30 µm aluminum oxide modified with silica (Rocatec Soft®, 3M ESPE). After airborne-particle abrasion procedure, three-point bending test was done to determine the flexural strength and flexural modulus. The diameter of each posts was measured to an accuracy of 0.01 mm using a digital micrometer. There was no diameter change before and after airborneparticle abrasion. The mean flexural moduli and flexural strengths calculated using the appropriate equations. The results were statistically analyzed using One-way ANOVA and Scheffe's post-hoc test at 95% confidencial level. RESULTS: There was no significant difference on flexural strength between groups. CONCLUSION: In the limitation of this study, flexural strength and flexural modulus of fiber post are not affected by airborne-particle abrasion.
Subject(s)
Aluminum Oxide , Resin Cements , Silicon DioxideABSTRACT
PURPOSE: This study will evaluate the effectiveness of various pretreatments when fiber-reinforced composite (FRC) post is bonded to endodontically treated tooth with resin cement. MATERIALS AND METHODS: Canal shaping of FRC post (DT Light post, Size 3, Bisco Inc., Schaumburg, IL, USA) was performed on endodontically treated premolars at 1.5 cm from CEJ. Samples were divided into 6 groups of surface treatment after conventional washing and drying to the canal. Total of 24 FRC posts were randomly divided into 6 groups of surface treatment as follows: Group C: control - no surface treatment, Group A: airborne-particle abrasion (Cojet sand, 3M ESPE), Group S: silanization (Bis-silane, Bisco Inc.), Group M: universal primer (Monobond-plus primer, Ivoclar Vivadent Inc.), Group AS: silanization after airborne-particle abrasion, Group AM: universal primer treatment after airborne-particle abrasion. Pretreated fiber posts were cemented with resin-based luting material and photo-polymerized and cut to the thickness of 1 mm. Push-out test using a universal testing machine was performed. Bonding failure strength of post dislodgement was measured and the type of bonding failure was classified. Data were analyzed with Kruskal-Wallis test and multiple comparison groups were performed using Tukey HSD value of rank test (alpha=0.05). RESULTS: Group AS showed significantly highest bonding strength. Group S, group AM, group A, and group M showed lower bonding strength in order. The control group showed the lowest bonding strength. CONCLUSION: Surface treatment with silane showed to be the most effective of the surface pretreatment methods for cementation of FRC post. Surface treatment with universal primer showed no significant difference compared with no surface treatment group as for bonding strength.
Subject(s)
Bicuspid , Cementation , Resin Cements , Silicon Dioxide , Tooth , Tooth CervixABSTRACT
La incorporación de fibras de refuerzo a resinas compuestas se ha convertido en una alternativa de tratamiento protésico altamente conservador. De esta investigación fue evaluar la resistencia flexural (RF) de una resina compuesta indirecta reforzada con tres diferentes marcas comerciales de fibras de vidrio, variando su ubicación y sometidas a envejecido físico ó químico. Se fabricaron 98 especímenes de resina compuesta Gradia (GC-America Inc.) de 22 mm x 2 mm x 3 mm; a 14 muestras no se les colocó fibras (SF), se almacenaron en agua destilada por 60 días, luego se subdividieron en dos grupos de 7 muestras,G1 - SFA y G2 - SFT el cual se sometió a termociclado (3000 ciclos de 5°/55°C en intervalos de 1 min); las otras 84 muestras se reforzaron fibras unidireccionales: 42 muestras para ser almacenadas en agua por 60 días (CFA), divididas en dos sub-grupos de 21, en relación a la ubicación de la fibra en la zona de compresión (CFAC) ó tracción (CFAT); finalmente en tres grupos de 7, dependiendo de la marca; Fibrex-Lab® (Angelus) los grupos G3 - CFACFLab y G6 - CFATFLab, FibreKor® (Jeneric/Penton) los grupos G4 - CFACFKor y G7 - CFATFKor y Vectris® (Ivoclar/Vivadent) los grupos G5 - CFACVectris y G8 - CFATVectris. Las 42 restantes después del almacenamiento en agua se sometieron al termociclado , se dividieron en dos subgrupos de 21, en relación a la ubicación de la fibra en la zona de compresión (CFTC) ó de tracción (CFTT); finalmente se dividió en tres grupos de 7, entonces Fibrex-Lab® conformó los grupos G9 - CFTCFLab y G12 - CFTTFLab, FibreKor® los grupos G10 - CFTCFKor y G13 - CFTTFKor y Vectris® los grupos G11 - CFTCVectris y G14 - CFTTVectris. Las muestras fueron sometidas a la prueba de flexión de tres puntos hasta su fractura, en maquina de pruebas universales (Shimadzu AGS-J) a una velocidad de 1mm/min. Los datos fueron recolectados, tabulados en hoja de cálculo y luego analizados con un estadístico de t de student....
The incorporation of reinforce fibers to composite has turned into an alternative of high conservative prosthetic treatment. The aim of this study was to evaluate the flexure strength (RF) of a indirect reinforce composite using three fiber glass commercial brands, varying the location and submitted to physical o chemical aging. 98 specimen were made of 22 mm x 2 mm x 3 mm Gradia resin compound (GC-America Inc.); 14 samples were not reinforce with fiber glass (SF), They were store in distilled water for 60 days then divided in 2 groups of 7 samples, G1 - SFA and G2 - SFT was thermocycled (3000 cycles of 5 °/55°C in intervals of 1 min); the other 82 samples were reinforce with unidirectional fibers: 42 to be stored in distilled water for 60 days (CFA), divided in 2 subgroups of 21, in relation with the localization of the fiber on the compression zone (CFAC) or traction (CFAT); Finally divided in 3 groups of 7, depending on the brand; Fibrex-Lab® (Angelus) the groups G3 - CFACFLab and G6 - CFATFLab, FibreKor® (Jeneric/Penton) the groups G4 - CFACFKor and G7 - CFATFKor and Vectris® (Ivoclar/Vivadent) the groups G5 - CFACVectris and G8 - CFATVectris. The remaining 42 samples after storage in water were submitted to thermocycling, divided in 2 subgroups of 21, in relation with the localization of the fiber on the compression zone (CFTC) or traction (CFTT); Finally divided in 3 groups of 7 then G9 was conformed Fibrex-Lab® CFTCFLab and G12 - CFTTFLab, FibreKor® the groups G10 - CFTCFKor and G13 - CFTTFKor and Vectris® the groups G11 - CFTCVectris and G14 - CFTTVectris. The samples were submitted to the three points flexion test until fracture, in a universal testing machine (Shimadzu AGS-J) to a speed of 1mm/min. The information was gathered, tabulated in spreadsheet and then analyzed with a statistician t of student to determine differences between the groups without fibers and 3 factors ANOVA on the reinforced groups for the varying location...
Subject(s)
Dental Prosthesis , Cellular Senescence , Casts, Surgical/adverse effects , Composite Resins/therapeutic use , DentistryABSTRACT
The purpose of this study was to compare radiopacity and radiographic discriminability of various FRC-Posts. Six FRC-Posts were investigated ; 1) FRC Postec Plus (Ivoclar Vivadent AG, Schaan, Liechtenstein), 2) Snowlight (Carbotech, Lewis center, OH, USA), 3) Dentin Post (Komet Brasseler, Lamgo, Germany), 4) Rely-X Fiber Post (3M ESPE, St.paul, MN, USA), 5) D.T.-Light Post (BISCO, Schaumburg, IL,USA), 6) Luxapost (DMG, Hamburg, Germany) The radiographs of each post with a reference 1 mm / 2 mm aluminum step-wedge was taken using digital sensor. The optical density were calculated by gray value of 10 x 10 pixel and compared in mm Al equivalent at five points. Six maxillary incisors of similar radiopacity were used. Radiographs of posts in Mx. incisors of lingual side of dry mandible were taken. We showed radiographs and asked the questionnaire to 3 radiologists, 3 endodontists, 3 general practitioners. The questionnaire was comprised of choices of the highest, lowest radiopaque individual post and the choices of best discriminable post at apical, coronal area. The following results were obtained. 1. Each post system showed various radiopacity. 2. There was change of discriminability between each post and simulated specimens regardless of examiner. Although each post showed various radiopacity, the difference of radiopacity did not affect on discriminability.
Subject(s)
Humans , Acrylic Resins , Aluminum , Composite Resins , Dentin , General Practitioners , Incisor , Mandible , Polyurethanes , Resin Cements , Surveys and QuestionnairesABSTRACT
The cloning and identification of frc gene from Oxalobacter formigenes in the intestines of Chinese people were conducted. The genomic DNA of Oxalobacter formigenes was extracted. frc gene fragment was amplified by polymerase chain reaction (PCR) and linked with pEGFP-C1. The recombinant plasmid was designated pEGFP-frc and was identified by restriction-enzyme digestion and sequencing. Human embryo kidney 293 cells were transfected with pEGFP-frc, then RT-PCR and Western blotting were performed to detect the expression offrc gene. The length of frc gene was found to be 1287 bp, and the homology of nucleotides and amino-acid residue with the sequence in GenBank was 95.88% and 99.07%. Bright green fluorescent light could be observed in 293 cells transfected with the pEGFP-frc. frc mRNA and fusion protein FCoAT-EGFP were detected in the cells. It is concluded that frc gene cloned from the Oxalobacterformigenes in the intestines of Chinese people can be expressed in eucaryotic 293 cells and keep its enzyme activity.
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PURPOSE: Oxalobacter formigenes (O. formigenes) is an obligate anaerobe, which may be important in the prevention of stone formation. O. formigenes degrades oxalates using oxalyl-CoA decarboxylase and formyl- CoA transferase encoded by the oxc and frc genes, respectively. Attempts were made to develop recombinant Escherichia coli (E. coli) expressing both the oxc and frc genes of O. formigenenes. MATERIALS AND METHODS: After the extraction of total RNA from O. formigenes, a reverse transcriptase-polymerase chain reaction (RT-PCR) was carried out using primers synthesized according to the oxc and frc genes reported in GenBank. The cloned cDNA encoding oxalyl-CoA decarboxylase and formyl-CoA transferase was introduced into the pET-22b (+) plasmid vector. The constructs were verified by restriction analysis and DNA sequencing. The plasmid vector containing the cDNA fragment was transformed into competent E. coli BL21 (DE3). The recombinant E. coli was then analyzed using SD-SPAGE for the protein expressions of oxc and frc gene products, and visualized by staining with Coomassie Blue. RESULTS: Restriction enzyme and sequence analyses showed the gene cloned into the pET-22b (+) plasmid vector was identical to the reported oxc and frc genes. After the transformation into the competent E. coli, the SDS-PAGE analysis showed the recombinant E. coli expressed the proteins migrating at 66 and 50KD, which was identical to the reported weight of oxalyl-CoA decarboxylase and formyl-CoA transferase. CONCLISIONS: A recombinant E. coli, expressing oxc and frc genes, was successfully produced. Further studies may be necessary to investigate their enzymatic activities on the degradation of oxalate in the development of a new therapeutic strategy for the prevention of stone formation.
Subject(s)
Clone Cells , Databases, Nucleic Acid , DNA, Complementary , Electrophoresis, Polyacrylamide Gel , Escherichia coli , Escherichia , Oxalates , Oxalobacter formigenes , Plasmids , RNA , Sequence Analysis , Sequence Analysis, DNA , TransferasesABSTRACT
Fiber reinforced composite (FRC) is usually used as a connector joining a few teeth into one unit in orthodontics. However, fracture often occurs during the two to three years of the orthodontic treatment period due to repeated occlusal loading or water sorption in the oral environment. We simulated the repair by overlapping and attaching portions of two FRC strips in the middle and performed a three-point bending test to investigate the changes of the repair strength among the different FRC groups. The specimens were grouped according to the overlapping lengths of the two FRC strips, which were 1, 2, 3 and 4 mm (group E1, E2, E3 and E4, respectively) and the control group consisted of unrepaired, intact FRC strips. Each group consisted of 6 specimens and were cured with a light emitting diode curing unit. Group E4 showed the highest maximum loads of 2.67 N, then the control group (2.39 N), group E3 (2.35 N), E2 (2.10 N), and E1 (1.75 N) in decreasing order. Group E4 also showed the highest stiffness, which was 2.32 N/mm, however, the stiffness of group E3 (2.06 N/mm) was higher than that of the control group (1.88 N/mm). According to the visual examination, the specimens tended to be bent rather than being fractured into two pieces with an increased length of overlapping portions. The above results suggest that a minimum overlapping length of 3 mm was necessary to obtain an adequate repair of a 10 mm length of FRC connector. In addition, the critical section adjacent to the joint area, where the thickness decreased abruptly, should be reinforced with flowable resin to minimize the bending tendency.
Subject(s)
Joints , Orthodontics , Tooth , WaterABSTRACT
Fiber reinforced composite (FRC) has been widely used in operative and prosthetic fields of dentistry and its use is expanding into the orthodontic field. The purpose of this study was to examine the changes of flexural properties of FRC reinforced with silica glass fiber (FibreKor(R), Jeneric/Pentron Inc., Wallingford, U.S.A.) according to the duration of water absorption. Specimens were grouped according to their shape as round and rectangular cross sections, and were immersed in distilled water at room temperature (23 degrees C) for 0 hour, 1 hour, 1 week, 15 days, 1 month and 3 months. The number of specimens was 5 for each duration and bending test was done using a torque tester. The flexural stiffness after 24 hour water immersion was reduced to 59% for round specimens and 25% for rectangular specimens and after 3 months of water immersion it was reduced to 29% and 19% stiffness of the 0 hour-specimen respectively. Yield flexural moment after 24 hour water immersion was reduced to 45% for round specimens and 76% for rectangular specimens and after 3 months of water immersion it was reduced to 29% and 60% stiffness of the 0 hour-specimen respectively. Ultimate flexural moment after 24 hour water immersion was reduced to 36% for round specimens and 76% for rectangular specimens and after 3 months of water immersion it was reduced to 25% and 37% stiffness of 0 hour-specimen respectively. Those results suggested that the flexural stiffness of FibreKor(R) decreased greatly after initial water immersion. Consequently, further research for the maintenance of strength against water will be necessary.
Subject(s)
Absorption , Dentistry , Glass , Immersion , Silicon Dioxide , Torque , WaterABSTRACT
As Fiber-reinforced composite restorations cannot be made without leaving a marginal gap, luting cements play a pivotal role in sealing the margins as a prevention against margnal leakage. A recently introduced adhesive resin cement system is claimed to adhere chemically, as well as mechanically, to tooth substances, dental alloys and porcelain. But when considering the clinical variation, conventional cementation using Zinc Phosphate and Glass-Ionomer can be requested. A vitro study was undertaken to compare microleakage and marginal fitness of Fiberreinforced composite crowns(Targis/Vectris) depending upon luting cements. Fifty non-carious human premolar teeth were randomly divided into five experimental groups of 10 teeth each and luted with five luting cements.(Bistite II., Super-bond., Variolink II.), Zinc phosphate and Glass- Ionomer cement) After 24 hours of being luted, all specimens were thermocycled 300 times through water bath of 5degrees C and 55degrees C in each bath, then the quality of the marginal fitness was measured by the Digital Microscope and marginal leakage was characterized using Dye Penetration technique and the Digital Microscope The results were as follows : 1. The mean values of marginal fit were Bistite II(46.78micrometer), Variolink II(56.25micrometer), Super-Bond(56.78 micrometer), Glass-Ionomer(99.21micrometer), Zinc Phosphate(109.49micrometer) indicated a statistically significant difference at p<0.001. 2. The mean microleakage values of tooth-cement interface, restoration-cement interface were increased in the order of Variolink II, Bistite II, Super-Bond, Glass-Ionomer, Zinc Phosphate. 3. Crowns luted with resin cement (Bistite II, Super-Bond, Variolink II, etc) exhibited less marginal gap and marginal leakage than those luted with conventional Glass-Ionomer and Zinc Phosphate cement. 4. The results indicated that all five luting systems yielded comparable and acceptable marginal fit.