Sample records for biocompatible glass-ionomer cement

  1. Titanium and Glass-Ionomer Cement as Ossicular Replacement Materials: Biocompatibility Results after Implantation in the Rabbit

    Microsoft Academic Search

    Konrad Schwager; G. Geyer

    1998-01-01

    The middle ear poses unique challenges when finding suitable materials for ossicular reconstruction, primarily because of its link to the external environment via the eustachian tube, which leads to a greater potential for exposure to infectious agents. In this animal study, the biocompatibilities of titanium and glass-ionomer cement were assessed in the middle ear of the rabbit after being implanted

  2. Devitrification of ionomer glass and its effect on the in vitro biocompatibility of glass-ionomer cements.

    PubMed

    Hurrell-Gillingham, K; Reaney, I M; Miller, C A; Crawford, A; Hatton, P V

    2003-08-01

    The effects of devitrification of an ionomer glass with a molar composition 4.5SiO(2).3Al(2)O(3).1.5P(2)O(5).3CaO.2CaF(2) on cement formation and in vitro biocompatibility were investigated. Differential thermal analysis was used to study the phase evolution in the glass, and to determine the heat treatments for production of glass-ceramics. X-ray diffraction patterns from glass frit heat-treated at 750 degrees C for 2h contained peaks corresponding to apatite (JCPDS 15-876), whereas for samples heat-treated at 950 degrees C for 2h apatite and mullite (JCPDS 15-776) were the major phases detected. Transmission electron microscopy (TEM) confirmed that apatite and apatite-mullite phases were present after heat treatments at 750 degrees C and 950 degrees C respectively. Glass and glass-ceramics were ground to prepare <45microm powders and glass ionomer cements were produced using a ratio of 1g powder: 0.2g PAA: 0.3g 10% m/v tartaric acid solution in water. In vitro biocompatibility was evaluated using cultured rat osteosarcoma (ROS) cells. Scanning electron microscopy (SEM) showed that cells colonised the surfaces of cements prepared using untreated ionomer glass and glass crystallised to form apatite (750 degrees C/2h). However, quantitative evaluation using MTT and total protein assays indicated that more cell growth occurred in the presence of cements prepared using ionomer glasses crystallised to apatite than cements prepared using untreated glass. The least cell growth and respiratory activity was observed on cements made with crystallised glass containing both apatite and mullite. It was concluded that the controlled devitrification of ionomer glasses could be used to produce GIC bone cements with improved biocompatibility. PMID:12895588

  3. Thermal properties of glass ionomer cement.

    PubMed

    Inoue, T; Saitoh, M; Nishiyama, M

    1993-12-01

    Five currently available glass ionomer cements (BASE CEMENT, DENTIN CEMENT, HY-BOND GLAS IONOMER-F, KETAC CEM, TOKUSO IONOMER) were studied with regard to the relationship between thermal properties and powder-liquid ratio (P/L ratio). The experiments were performed using five different P/L ratio of 0.8, 0.9, 1.0, 1.1 and 1.2 (P/L = 1.0: manufacturer's instruction) and measured with a xenon flash thermal-constant measuring device. Thermal diffusivity of the glass ionomer cements ranged from 0.212 to 0.303 x 10(-2) cm2 s-1; it increased according to the increase in the P/L ratio. The specific thermal capacity of the glass ionomer cements ranged from 1.011 to 1.369 Jg-1 K-1; it decreased with the increase in the P/L ratio. Thermal conductivity of the glass ionomer cements ranged from 0.505 to 0.712 Wm-1 K-1; it increased according to the increase in the P/L ratio. PMID:8158286

  4. Glass-ionomer cements as adhesives

    Microsoft Academic Search

    A. O. Akinmade; J. W. Nicholson

    1993-01-01

    The literature on the clinical use of glass-ionomer cements is reviewed, and this shows that these materials are successful partly because of the good adhesion they exhibit towards a variety of substrates encountered in dentistry. The reasons for this good adhesion are identified as the good initial wetting of the surfaces met in clinical dentistry, the development of strong chemical

  5. How mobile are protons in the structure of dental glass ionomer cements?

    NASA Astrophysics Data System (ADS)

    Benetti, Ana R.; Jacobsen, Johan; Lehnhoff, Benedict; Momsen, Niels C. R.; Okhrimenko, Denis V.; Telling, Mark T. F.; Kardjilov, Nikolay; Strobl, Markus; Seydel, Tilo; Manke, Ingo; Bordallo, Heloisa N.

    2015-03-01

    The development of dental materials with improved properties and increased longevity can save costs and minimize discomfort for patients. Due to their good biocompatibility, glass ionomer cements are an interesting restorative option. However, these cements have limited mechanical strength to survive in the challenging oral environment. Therefore, a better understanding of the structure and hydration process of these cements can bring the necessary understanding to further developments. Neutrons and X-rays have been used to investigate the highly complex pore structure, as well as to assess the hydrogen mobility within these cements. Our findings suggest that the lower mechanical strength in glass ionomer cements results not only from the presence of pores, but also from the increased hydrogen mobility within the material. The relationship between microstructure, hydrogen mobility and strength brings insights into the material's durability, also demonstrating the need and opening the possibility for further research in these dental cements.

  6. How mobile are protons in the structure of dental glass ionomer cements?

    PubMed Central

    Benetti, Ana R.; Jacobsen, Johan; Lehnhoff, Benedict; Momsen, Niels C. R.; Okhrimenko, Denis V.; Telling, Mark T. F.; Kardjilov, Nikolay; Strobl, Markus; Seydel, Tilo; Manke, Ingo; Bordallo, Heloisa N.

    2015-01-01

    The development of dental materials with improved properties and increased longevity can save costs and minimize discomfort for patients. Due to their good biocompatibility, glass ionomer cements are an interesting restorative option. However, these cements have limited mechanical strength to survive in the challenging oral environment. Therefore, a better understanding of the structure and hydration process of these cements can bring the necessary understanding to further developments. Neutrons and X-rays have been used to investigate the highly complex pore structure, as well as to assess the hydrogen mobility within these cements. Our findings suggest that the lower mechanical strength in glass ionomer cements results not only from the presence of pores, but also from the increased hydrogen mobility within the material. The relationship between microstructure, hydrogen mobility and strength brings insights into the material's durability, also demonstrating the need and opening the possibility for further research in these dental cements. PMID:25754555

  7. Advanced antibacterial glass ionomer cements for improved dental restoratives

    Microsoft Academic Search

    Yiming Weng

    2011-01-01

    Secondary caries that often occurs at the interface between the restoration and the cavity preparation is mainly caused by demineralization of tooth structure due to invasion of plaque bacteria (acid-producing bacteria) such as Streptococcus mutans (S. mutans) in the presence of fermentable carbohydrates. Although glass-ionomer cements (GICs) are found to be the most cariostatic and somehow antibacterial due to release

  8. In vivo study of the pulp reaction to Fuji IX, a glass ionomer cement

    Microsoft Academic Search

    J.-J. Lasfargues; M. Goldberg

    2000-01-01

    Objective: Our aims were to investigate the pulp biocompatibility of Fuji IX, a glass ionomer cement (GIC) used as a restorative material in cavities prepared in rat's upper molars, and to assess the value of this in vivo model for testing dental biomaterials.Method: Half-moon class V-like cavities were drilled on the mesial aspect of 26 rat upper first molars. Half

  9. Response to thermal stimuli of glass ionomer cements

    Microsoft Academic Search

    Zhuoqun Yan; Sharanbir K. Sidhu; Thomas E. Carrick; John F. McCabe

    Objectives. This study was designed to determine the dimensional changes of glass ionomers caused by thermal stimuli under both dry and wet conditions. Methods. Eight cylindrical specimens (6 mm × 4 mm) were made (using a stainless steel mold) of each of the following materials: a conventional luting glass ionomer, two high viscosity restorative glass ionomers, a resin-modified glass ionomer

  10. Adhesive properties of modified glass-ionomer cements.

    PubMed

    Rusz, J E; Antonucci, J M; Eichmiller, F; Anderson, M H

    1992-01-01

    The incorporation of water-soluble polymers and/or vinyl monomers into glass-ionomer cements can yield toughened "hybrid cement-composites". This study compared a commercial water-hardening glass-ionomer cement and seven experimental hybrids in their bonding to both dentin and Silar composite. The cements were sanded and phosphoric-acid-etched or left with an unaltered matrix-formed surface when adhesion to composite was tested. The seven hybrids included: 15% 2-hydroxyethyl methacrylate (HEMA) with appropriate initiators/activators, 29% HEMA, 27% HEMA + 0.5% polyacrylic acid (PAA), 0.5% PAA, 1.5% PAA, 2.5% polyvinyl alcohol, and 2.5% gelatin. Acceptable bond strengths to applied composite and to dentin were observed for most of the modified hybrid cements. There were higher bond strengths with composite when the hybrids were left unetched. Bonding of some unetched, HEMA-containing cements achieved bond strengths (29% HEMA, 10.09 MPa) significantly higher than those of the unmodified cement (4.92 MPa). Resin-modified cements may promote better bonding by improved interaction and compatibility with the resin component of the composite. PMID:1387853

  11. Histological assessment of pulpal responses to resin modified glass ionomer cements in human teeth

    PubMed Central

    Eskandarizadeh, Ali; Parizi, Molook Torabi; Goroohi, Hossein; Badrian, Hamid; Asadi, Abbas; Khalighinejad, Navid

    2015-01-01

    Background: The biocompatibility of resin-modified glass ionomers (RMGIs) as a lining material is still under question. The present study evaluated the response of the pulp-dentin complex following application of resin-modified glass-ionomer cement, calcium hydroxide and conventional glass-ionomer in deep cavities prepared in human teeth. Materials and Methods: In this controlled clinical trial, 30 deep class V buccal cavities (3 mm × 2 mm × 2 mm) were prepared in human premolars treatment planned to be extracted for orthodontic reasons and divided into 3 groups. Groups were lined by a RMGI (Vivaglass), conventional glass Ionomer (Ionocid) and calcium hydroxide respectively. The cavities were subsequently filled with amalgam. Each group was then divided into two sub-groups according to time intervals 5 and 30 days. The patients were referred to Kerman Dental School and in accordance with orthodontic treatment plan; premolars were extracted and then prepared for histological assessment. The sections were stained with hematoxylin and eosin and periodic acid Schiff techniques. All of the samples were examined using a number of criteria including odontoblastic changes, inflammatory cells response, reactionary dentin formation and presence of microorganisms. The data were analyzed by Kruskal-Wallis and Mann-Whitney tests. P < 0.05 was considered as significant. Results: There was no significant difference among odontoblastic changes, reactionary dentin, presence of bacteria and inflammatory cells response of the groups (P > 0.05). Conclusion: Ionocid and Vivaglass resin-modified glass ionomers can be used as lining materials in human teeth. PMID:25878679

  12. Release of sodium fusidate from glass-ionomer dental cement.

    PubMed

    Mulla, Zoheb; Edwards, Mark; Nicholson, John W

    2010-06-01

    Restorative grade glass-ionomer cement has been studied for its potential as a controlled release material for the antimicrobial compound sodium fusidate. Sodium fusidate powder was incorporated into the cement at the mixing stage at levels of 1% and 5% by mass, and disc shaped specimens (6 mm diameter x 2 mm depth) prepared. After curing for 1 hour at 37 degrees C, specimens were placed in water and release of sodium fusidate at set time intervals determined using reverse-phase HPLC. Sets of five specimens were used in all experiments. Early release of sodium fusidate was shown to occur by diffusion for each level of addition, as shown by M(t)/M(infinity) being linear with respect to [square root]time in both cases. Diffusion coefficients were calculated as 4.4 x 10(-8) cm(2) s(-1) and 3.0 x 10(-8) cm(2) s(-1) for 1 and 5% respectively. These were an order of magnitude lower than had been found previously for water transport in glass-ionomer cements, a result that is attributed to the greater size of the sodium fusidate molecule compared with that of water. Cements released 20.4 and 22.8% respectively of the total sodium fusidate added after 2 weeks, values which were not significantly different from each other, and which exceeded total release previously reported for benzalkonium chloride and chlorhexidine. PMID:20376540

  13. A novel antibacterial dental glass-ionomer cement.

    PubMed

    Weng, Yiming; Guo, Xia; Gregory, Richard; Xie, Dong

    2010-10-01

    This study reports the synthesis and evaluation of a novel non-leachable poly(quaternary ammonium salt) (PQAS)-containing antibacterial glass-ionomer cement. Fuji II LC cement was used for comparison. Compressive strength (CS) and Streptococcus mutans viability were used to evaluate strength and antibacterial activity, respectively. All specimens were conditioned in distilled water at 37 degrees C before testing. After the addition of 1-30% PQAS, both cements showed a reduction in CS, of 25-95% for Fuji II LC and 13-78% for the experimental cement, and a reduction in S. mutans viability, of 40-79% for Fuji II LC and 40-91% for the experimental cement. The experimental cement showed less CS reduction and higher antibacterial activity compared with Fuji II LC. The result also indicates that the cements are permanently antibacterial, with no leaching of PQAS. It appears that the experimental cement is a clinically attractive dental restorative that can be potentially used for longlasting restorations as a result of its high mechanical strength and permanent antibacterial function. PMID:20853548

  14. Caries protection after orthodontic band cementation with glass ionomer.

    PubMed

    Marcushamer, M; Garcia-Godoy, F; Chan, D C

    1993-01-01

    This study evaluated the resistance of the enamel to an artificial caries challenge after removing orthodontic bands cemented with a glass ionomer cement (GIC). Ten extracted caries-free molars were cleaned with a slurry of pumice and randomly divided into 2 groups of 5 teeth each: Group 1: Cementation with GIC (Fuji) and Group 2: Cementation with a zinc phosphate cement (Mizzy). Both cements were handled according to manufacturer's instructions. Before cementing the bands, an area of S x S mm was masked with adhesive tape on the lingual surfaces of all teeth. The orthodontic bands were cemented over this adhesive tape. After band cementation, the occlusal and gingival margins of the band were delineated with a bur on the tooth surface. The teeth were thermocycled (200 cycles, 5-55 degrees C, 30-second dwell time) and stored in distilled water for 24 hours. Then, the bands and adhesive tape were removed and the teeth again stored in distilled water for a week, changing the water daily. The teeth were then varnished with the exception of a 5 x 5 mm window (including previously exposed and covered areas) on the buccal and lingual surfaces. All teeth were then placed in an acidified gel (pH 4.5) for 5 weeks to produce artificial caries. At least three sections from the exposed and covered areas were made from the buccal and lingual challenged areas. Sections were ground to approximately 100 microns. Polarized microscopy and image analysis were used to analyze the results.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8258573

  15. Push-out bond strength of fiber posts to root dentin using glass ionomer and resin modified glass ionomer cements

    PubMed Central

    PEREIRA, Jefferson Ricardo; da ROSA, Ricardo Abreu; SÓ, Marcus Vinícius Reis; AFONSO, Daniele; KUGA, Milton Carlos; HONÓRIO, Heitor Marques; do VALLE, Accácio Lins; VIDOTTI, Hugo Alberto

    2014-01-01

    Objective The purpose of this study was to assess the push-out bond strength of glass fiber posts to root dentin after cementation with glass ionomer (GICs) and resin-modified glass ionomer cements (RMGICs). Material and Methods Fifty human maxillary canines were transversally sectioned at 15 mm from the apex. Canals were prepared with a step back technique until the application of a #55 K-file and filled. Post spaces were prepared and specimens were divided into five groups according to the cement used for post cementation: Luting & Lining Cement; Fuji II LC Improved; RelyX Luting; Ketac Cem; and Ionoseal. After cementation of the glass fiber posts, all roots were stored at 100% humidity until testing. For push-out test, 1-mm thick slices were produced. The push-out test was performed in a universal testing machine at a crosshead speed of 0.5 mm/minute and the values (MPa) were analyzed by Kolmogorov-Smirnov and Levene's tests and by two-way ANOVA and Tukey's post hoc test at a significance level of 5%. Results Fiber posts cemented using Luting & Lining Cement, Fuji II LC Improved, and Ketac Cem presented the highest bond strength to root dentin, followed by RelyX Luting. Ionoseal presented the lowest bond strength values (P>0.05). The post level did not influence the bond strength of fiber posts to root dentin (P=0.148). The major cause of failure was cohesive at the cement for all GICs and RMGICs. Conclusions Except for Ionoseal, all cements provided satisfactory bond strength values. PMID:25004052

  16. Interaction of glass-ionomer cements with moist dentin.

    PubMed

    Yiu, C K Y; Tay, F R; King, N M; Pashley, D H; Sidhu, S K; Neo, J C L; Toledano, M; Wong, S L

    2004-04-01

    Glass-ionomer cements (GICs) are regarded as aqueous gels made up of polyalkenoic acid salts containing ion-leachable glass fillers. The consequence of water permeation across the GIC-dentin interface is unknown. This study used SEM, field-emission/environmental SEM (FE-ESEM), and TEM to examine the ultrastructure of GIC-bonded moist dentin. Dentin surfaces bonded with 6 auto-cured GICs were examined along the fractured GIC-dentin interfaces. Additional specimens fractured 3 mm away from the interfaces were used as controls. SEM revealed spherical bodies along GIC-dentin interfaces that resembled hollow eggshells. FE-SEM depicted similar bodies with additional solid cores. Energy-dispersive x-ray analysis and TEM showed that the spherical bodies consisted of a silicon-rich GIC phase that was absent from the air-voids in the controls. The GIC inclusions near dentin surfaces result from a continuation of the GI reaction, within air-voids of the original polyalkenoate matrix, that occurred upon water diffusion from moist dentin. PMID:15044500

  17. Influence of endodontic materials on the bonding of glass ionomer cement to dentin.

    PubMed

    Capurro, M A; Herrera, C L; Macchi, R L

    1993-04-01

    We assessed the bond strength of a glass ionomer cement to dentin that had been in contact with different materials. Flat dentin surfaces in freshly extracted human teeth were covered for 48 h with a 1 mm layer of a variety of materials that are used for temporary filling or root canal sealing. The products were mechanically removed and a glass ionomer cement cylindrical specimen bonded to the dentin surface. After 7-days immersion in 37 degrees C water the tensile bond strength was tested. The results were compared with those on dentin surfaces not in contact with any endodontic material. The statistical analysis showed that none of the materials used interfered with the bonding of the glass ionomer to dentin. PMID:8404700

  18. Initial Sliding Wear Kinetics of Two Types of Glass Ionomer Cement: A Tribological Study

    PubMed Central

    Ponthiaux, Pierre; Pradelle-Plasse, Nelly; Grosgogeat, Brigitte; Colon, Pierre

    2014-01-01

    The aim of this work was to characterize the initial wear kinetics of two different types of glass ionomer cement used in dentistry (the conventional glass ionomer cement and the resin-modified glass ionomer cement) under sliding friction after 28-day storing in distilled water or Ringer's solution. Sliding friction was applied through a pin-on-disk tribometer, in sphere-on-plane contact conditions, under 5 N normal load and 120 rotations per minute. The test lasted 7500 cycles and replicas were performed at 2500, 5000 and 7500 cycles. A profilometer was used to evaluate the wear volume. Data were analysed using Student's t-test at a significant level of 5%. There is no statistical significant difference between the results obtained for a given material with the maturation media (P > 0.05). However, for a given maturation medium, there are significant statistical differences between the data obtained for the two materials at each measurement (P < 0.0001). The wear rates of both materials decrease continuously during the running-in period between 0 and 2500 cycles. After 2500 cycles, the wear rate becomes constant and equal for both materials. The resin matrix contained in the resin-modified glass ionomer cement weakens the tribological behaviour of this material. PMID:25093185

  19. Effects of dentin surface treatments on shear bond strength of glass-ionomer cements

    PubMed Central

    Poggio, Claudio; Beltrami, Riccardo; Scribante, Andrea; Colombo, Marco; Lombardini, Marco

    2014-01-01

    Summary Aim The aim of this in vitro study was to evaluate the effect of different surface treatments on shear bond strength of a conventional glass-ionomer cement (GIC) and a resin-modified glass-ionomer cement (RMGIC) to dentin. Materials and methods 80 bovine permanent incisors were used. 40 cylindrical specimens of a GIC (Fuji IX GP Extra) and 40 cylindrical specimens of a RMGIC (Fuji II LC) were attached to the dentin. The teeth were then randomly assigned to 8 groups of equal size (n=10), 4 for every type of glass-ionomer cement, corresponding to type of dentin surface treatments. Group 1: GC Cavity Conditioner; Group 2: 37% phosphoric acid gel; Group 3: Clearfil SE Bond; Group 4: no dentin conditioning (control). The specimens were placed in a universal testing machine (Model 3343, Instron Corp., Canton, Mass., USA) and subsequently tested for shear bond strength (MPa). Results ANOVA showed the presence of significant differences among the various groups. Post hoc Tukey test showed different values of shear bond strength for Fuji IX GP Extra and for Fuji II LC. The different conditioners variably influence the adhesion of the glass-ionomer cements tested. Conclusions. RMGIC shear bond to dentin was higher than GIC. The use of a Self-etch adhesive system improved the shear bond strength values of RMGIC and lowered the shear bond strength values of GIC significantly. PMID:24753797

  20. Antimicrobial Effects of Dental Luting Glass Ionomer Cements on Streptococcus mutans

    PubMed Central

    Altenburger, Markus; Spitzmüller, Bettina; Anderson, Annette; Hellwig, Elmar

    2014-01-01

    Objective. To reduce secondary caries, glass ionomer luting cements are often used for cementing of indirect restorations. This is because of their well-known antimicrobial potential through the release of fluoride ions. The aim of this in vitro study was to investigate the antimicrobial effect of five dental luting cements which were based on glass ionomer cement technology. Methods. Five different glass ionomer based luting cements were tested for their antimicrobial effects on Streptococcus mutans in two different experimental setups: (i) determination of colony-forming units (CFUs) in a plate-counting assay; (ii) live/dead staining (LDS) and fluorescence microscopy. All experiments were conducted with or without prior treatment of the materials using sterilized human saliva. Antimicrobial effects were evaluated for adherent and planktonic bacteria. Bovine enamel slabs (BES) were used as negative control. BES covered with 0.2% chlorhexidine (CHX) served as positive control. Results. Each of the tested materials significantly reduced the number of initially adhered CFUs; this reduction was even more pronounced after prior incubation in saliva. Antimicrobial effects on adherent bacteria were confirmed by live-dead staining. Conclusion. All five luting cements showed an antimicrobial potential which was increased by prior incubation with human saliva, suggesting an enhanced effect in vivo. PMID:24795539

  1. Water-dependent Interfacial Transition Zone in Resin-modified Glass-ionomer Cement\\/Dentin Interfaces

    Microsoft Academic Search

    F. R. Tay; S. K. Sidhu; T. F. Watson; D. H. Pashley

    2004-01-01

    The function of the interfacial transition zone (absorption layer) in resin-modified glass-ionomer cements bonded to deep dentin remains obscure. This study tested the hypotheses that the absorption layer is formed only in the presence of water derived from hydrated dentin and allows for better bonding of resin-modified glass-ionomer cements to dentin. Ten percent polyacrylic acid-conditioned, hydrated, and dehydrated deep dentin

  2. Comparative Evaluation of Voids Present in Conventional and Capsulated Glass Ionomer Cements Using Two Different Conditioners: An In Vitro Study

    PubMed Central

    Sharma, Roshni; Reddy, Pallavi; Udameshi, Pooja; Vallakuruchi Jayabal, Narmatha

    2014-01-01

    This in vitro study evaluated the presence of voids in powder-liquid and capsulated glass ionomer cement. 40 cavities were prepared on root surfaces of maxillary incisors and divided into four groups. Cavities were conditioned with glass ionomer cement liquid (GC Corporation, Tokyo, Japan) in Groups 1 and 3 and with dentin conditioner (GC Corporation, Tokyo, Japan) in Groups 2 and 4. Conventional powder-liquid glass ionomer cement (GC Fuji II, GC Corporation, Tokyo, Japan) was used as a restorative material in Groups 1 and 2. Capsulated glass ionomer cement (GC Fuji II, GC Corporation, Tokyo, Japan) was used in Groups 3 and 4. Samples were sectioned and viewed under stereomicroscope to check for the presence of voids within the cement and at the cement-tooth junction. Data was analyzed using one-way ANOVA and Tukey's post hoc tests. Group 4 showed statistically significant results (P < 0.05) when compared to Groups 1 and 2 for voids within the cement. However, for voids at the margins, the results were statistically insignificant. PMID:25544842

  3. Calcium polyphosphate as an additive to zinc-silicate glass ionomer cements.

    PubMed

    Valliant, Esther Mae; Gagnier, David; Dickey, Brett Thomas; Boyd, Daniel; Joseph Filiaggi, Mark

    2015-07-01

    Aluminum-free glass ionomer cements (GICs) are under development for orthopedic applications, but are limited by their insufficient handling properties. Here, the addition of calcium polyphosphate (CPP) was investigated as an additive to an experimental zinc-silicate glass ionomer cement. A 50% maximum increase in working time was observed with CPP addition, though this was not clinically significant due to the short working times of the starting zinc-silicate GIC. Surprisingly, CPP also improved the mechanical properties, especially the tensile strength which increased by ?33% after 30 days in TRIS buffer solution upon CPP addition up to 37.5?wt%. This strengthening may have been due to the formation of ionic crosslinks between the polyphosphate chains and polyacrylic acid. Thus, CPP is a potential additive to future GIC compositions as it has been shown to improve handling and mechanical properties. In addition, CPP may stimulate new bone growth and provide the ability for drug delivery, which are desirable modifications for an orthopedic cement. PMID:25627650

  4. Effect of Self-etching Adhesives on the Bond Strength of Glass-Ionomer Cements

    PubMed Central

    Jaberi Ansari, Zahra; Panahandeh, Narges; Tabatabaei Shafiei, Zahra Sadat; Akbarzadeh Baghban, Alireza

    2014-01-01

    Objective: Statement of Problem: Adequate bond strength between glass ionomer cements and composite resin is necessary for the success of the sandwich technique. Purpose of Study: This study assessed the micro-shear bond strength of composite resin to glass-ionomer cements (GIC) using self-etch adhesives with different pH values. Materials and Methods: One hundred specimens (6×4×2 mm) were made using Fuji II and Fuji II LC GICs and treated with different adhesives as follows: Group 1:Fuji II+ Adper Prompt L-Pop, Group-2: Fuji II+SE bond, Group-3: Fuji II + AdheSE, Group-4:Fuji II+ Protect bond, Group-5: Fuji II + Single bond, Group-6:Fuji II LC+ Adper Prompt LPop, Group-7: Fuji II LC+SE bond, Group-8:Fuji II LC+ AdheSE, Group-9: Fuji II LC+ Protect bond, and Group-10: Fuji II LC+ Single bond. Each group consisted of 10 specimens. A cylinder of Z100 composite resin was placed on each sample and light cured. After 24 hours of water storage (37°C), the specimens were subjected to micro-shear bond strength tests (0.5 mm/min). Data were analyzed using two-way ANOVA and Tukey’s test. Results: The mean micro-shear bond strength of groups 1–10 was 11.66±1.79, 16.50±1.85, 18.47±1.77, 13.95±1.77, 15.27±1.49, 15.14±0.90, 20.03±1.19, 17.48±3.00, 16.24±1.98 and 16.03±1.49 MPa, respectively. There were significant differences between groups 1 and 7 (P<0.05). No significant difference was observed between other groups (P>0.05). Fuji II LC showed higher bond strength than Fuji II (P<0.05). Conclusion: Type of self-etch adhesive had no significant effect on micro-shear bond strength of glass-ionomer to composite resin. Resin modified glass ionomer cement (RMGIC) exhibited higher bond strength than the conventional GIC. PMID:25628698

  5. Translationally controlled tumor protein supplemented chitosan modified glass ionomer cement promotes osteoblast proliferation and function.

    PubMed

    Sangsuwan, Jiraporn; Wanichpakorn, Supreya; Kedjarune-Leggat, Ureporn

    2015-09-01

    The objective of this study was to evaluate the effect of translationally controlled tumor protein (TCTP) supplemented in a novel glass ionomer cement (BIO-GIC) on normal human osteoblasts (NHost cells). BIO-GIC was a glass ionomer cement (GIC) modified by adding chitosan and albumin to promote the release of TCTP. NHost cells were seeded on specimens of GIC, GIC+TCTP, BIO-GIC and BIO-GIC+TCTP. Cell proliferation was determined by BrdU assay. It was found that BIO-GIC+TCTP had significantly higher proliferation of cells than other specimens. Bone morphogenetic protein-2 (BMP-2) and osteopontin (OPN) gene expressions assessed by quantitative real time PCR and alkaline phosphatase (ALP) activity were used to determine cell differentiation. Bone cell function was investigated by calcium deposition using alizarin assay. Both BMP-2 and OPN gene expressions of cells cultured on specimens with added TCTP increased gradually up-regulation after day 1 and reached the highest on day 3 then down-regulation on day 7. The ALP activity of cells cultured on BIO-GIC+TCTP for 7days and calcium content after 14days were significantly higher than other groups. BIO-GIC+TCTP can promote osteoblast cells proliferation, differentiation and function. PMID:26046268

  6. The incorporation of nanoparticles into conventional glass-ionomer dental restorative cements.

    PubMed

    Gjorgievska, Elizabeta; Van Tendeloo, Gustaaf; Nicholson, John W; Coleman, Nichola J; Slipper, Ian J; Booth, Samantha

    2015-04-01

    Conventional glass-ionomer cements (GICs) are popular restorative materials, but their use is limited by their relatively low mechanical strength. This paper reports an attempt to improve these materials by incorporation of 10 wt% of three different types of nanoparticles, aluminum oxide, zirconium oxide, and titanium dioxide, into two commercial GICs (ChemFil® Rock and EQUIA™ Fil). The results indicate that the nanoparticles readily dispersed into the cement matrix by hand mixing and reduced the porosity of set cements by filling the empty spaces between the glass particles. Both cements showed no significant difference in compressive strength with added alumina, and ChemFil® Rock also showed no significant difference with zirconia. By contrast, ChemFil® Rock showed significantly higher compressive strength with added titania, and EQUIA™ Fil showed significantly higher compressive strength with both zirconia and titania. Fewer air voids were observed in all nanoparticle-containing cements and this, in turn, reduced the development of cracks within the matrix of the cements. These changes in microstructure provide a likely reason for the observed increases in compressive strength, and overall the addition of nanoparticles appears to be a promising strategy for improving the physical properties of GICs. PMID:25691120

  7. Effect of Nanoclay Dispersion on the Properties of a Commercial Glass Ionomer Cement

    PubMed Central

    Fareed, Muhammad A.; Stamboulis, Artemis

    2014-01-01

    Objective. The reinforcement effect of polymer-grade montmorillonite (PGV and PGN nanoclay) on Fuji-IX glass ionomer cement was investigated. Materials and Method. PGV and PGV nanoclays (2.0?wt%) were dispersed in the liquid portion of Fuji-IX. Fourier-transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC) were used to quantify acid-base reaction and the liquid portion of GIC. The mechanical properties (CS, DTS, FS, and Ef) of cements (n = 20) were measured at 1 hour, 1 day, and 1 month. The microstructure was examined by cryo-SEM and TEM. Results. FTIR shows that the setting reaction involves the neutralisation of PAA by the glass powder which was linked with the formation of calcium and aluminium salt-complexes. The experimental GICs (C-V and C-N) exhibited mechanical properties in compliance to ISO standard requirement have higher values than Fuji-IX cement. There was no significant correlation of mechanical properties was found between C-V and C-N. The average Mw of Fuji-IX was 15,700 and the refractive index chromatogram peak area was 33,800. TEM observation confirmed that nanoclays were mostly exfoliated and dispersed in the matrix of GIC. Conclusion. The reinforcement of nanoclays in GICs may potentially produce cements with better mechanical properties without compromising the nature of polyacid neutralisation. PMID:25210518

  8. Surface roughness of glass ionomer cements indicated for uncooperative patients according to surface protection treatment

    PubMed Central

    Pacifici, Edoardo; Bossù, Maurizio; Giovannetti, Agostino; La Torre, Giuseppe; Guerra, Fabrizio; Polimeni, Antonella

    2013-01-01

    Summary Background Even today, use of Glass Ionomer Cements (GIC) as restorative material is indicated for uncooperative patients. Aim The study aimed at estimating the surface roughness of different GICs using or not their proprietary surface coatings and at observing the interfaces between cement and coating through SEM. Materials and methods Forty specimens have been obtained and divided into 4 groups: Fuji IX (IX), Fuji IX/G-Coat Plus (IXC), Vitremer (V), Vitremer/Finishing Gloss (VFG). Samples were obtained using silicone moulds to simulate class I restorations. All specimens were processed for profilometric evaluation. The statistical differences of surface roughness between groups were assessed using One-Way Analysis of Variance (One-Way ANOVA) (p<0.05). The Two-Way Analysis of Variance (Two-Way ANOVA) was used to evaluate the influence of two factors: restoration material and presence of coating. Coated restoration specimens (IXC and VFG) were sectioned perpendicular to the restoration surface and processed for SEM evaluation. Results No statistical differences in roughness could be noticed between groups or factors. Following microscopic observation, interfaces between restoration material and coating were better for group IXC than for group VFG. Conclusions When specimens are obtained simulating normal clinical procedures, the presence of surface protection does not significantly improve the surface roughness of GICs. PMID:24611090

  9. A review of glass-ionomers: From conventional glass-ionomer to bioactive glass-ionomer.

    PubMed

    Khoroushi, Maryam; Keshani, Fateme

    2013-07-01

    Materials used in the body, especially the materials used in various oral cavity regions should be stable and passive without any interactions with the body tissues or fluids. Dental amalgam, composite resins and dental cements are the materials of choice with such properties. The first attempts to produce active materials, which could interact with the human body tissues and fluids were prompted by the concept that fluoride-releasing materials exert useful effects in the body. The concept of using the "smart" materials in dentistry has attracted a lot of attention in recent years. Conventional glass-ionomer (GI) cements have a large number of applications in dentistry. They are biocompatible with the dental pulp to some extent. GI is predominantly used as cements in dentistry; however, they have some disadvantages, the most important of which is lack of adequate strength and toughness. In an attempt to improve the mechanical properties of the conventional GI, resin-modified glass-ionomers have been marketed, with hydrophilic monomers, such as hydroxyethyl methacrylated (HEMA). Some recent studies have evaluated GI with bioactive glass in its structure to validate the claims that such a combination will improve tooth bioactivity, regeneration capacity and restoration. There is ever-increasing interest in the application of bioactive materials in the dental field in an attempt to remineralize affected dentin. The aim of this review article is to evaluate these materials and their characteristics and applications. PMID:24130573

  10. Evaluation on Shear Bond Strength of Different Glass Ionomer and Hydroxy Apatite Cements Used in Ossiculoplasty

    PubMed Central

    Kalc?o?lu, M. Tayyar; Uzun, ?smail Hakk?; Yalç?n, Muhammet; Malkoç, Meral Arslan; Ö?reten, Ay?e Tuba; Hanege, Fatih Mehmet

    2015-01-01

    Background: Glass ionomer cements (GIC) have been widely used in dentistry for many years. In recent years, GIC have also been used for ossiculoplasty. The bond strength of GIC used in ossiculoplasty and the way they may change over the years in the cementation area are being questioned. The bonding strength of the substance may be of importance for long-term outcomes. Aims: The aim of this study was to investigate the bond strength of different GIC on ossicles. Study Design: In vitro study. Methods: Twenty ossicles were obtained from patients who had undergone ear surgery. All specimens were randomly divided into four subgroups. All specimens were inserted into a specially designed apparatus for shear bond strength (SBS) testing. The tested materials [Aqua Meron (AM), Aqua Cem (AC), Ketac Cem (KC), and Otomimix CPB (OH)] were prepared and applied according to the manufacturer’s instructions. The SBS was tested using a universal testing machine at a crosshead speed of 0.5 mm/min. Results: The mean SBSs were found to be 13.28 MPa, 23.43 MPa, 8.51MPa, and 1.78 MPa for AM, AC, KC, and OH, respectively. AC had the highest SBS, which was statistically significantly different from that of KC and OH (p<0.05). Both AM and KC had higher SBS than OH (p<0.05). Conclusion: The results obtained in this study by investigating the bone-bonding strength of cements widely used in ossiculoplasty demonstrate that some of these substances have a greater ability to bond to ossicles compared to others. Further clinical investigations are needed to test different parameters. PMID:25759768

  11. Biaxial Flexural Strength of High-Viscosity Glass-Ionomer Cements Heat-Cured with an LED Lamp during Setting

    PubMed Central

    Fabián Molina, Gustavo; Cabral, Ricardo Juan; Mazzola, Ignacio; Brain Lascano, Laura; Frencken, Jo E.

    2013-01-01

    Adding heat to glass ionomers during setting might improve mechanical properties. The aim was to compare the biaxial flexural strength (BFS) between and within four glass ionomers, by time of exposure to a high-intensity LED light-curing unit. Materials and methods. Samples of Fuji 9 Gold Label, Ketac Molar Easymix, ChemFil Rock, and the EQUIA system were divided into three treatment groups (n = 30): without heating (Group 1), heated with LED lamp of 1400?mW/cm2 for 30?s while setting (Group 2), and heated with LED lamp of 1400?mW/cm2 for 60?s while setting (Group 3). Samples were stored for 48 hours in distilled water at 37°C until tested. BFS was tested, using a universal testing machine at a crosshead speed of 1?mm/min. Data were analyzed, using ANOVA test with the Bonferroni correction (? = 0.05). Heating the glass-ionomer cements with an LED curing light of 1400?mW/cm2 during setting for 30?s increased the BFS value of all GICs. No statistically significant difference in mean BFS scores was found between the EQUIA system and ChemFil Rock at 30?s and 60?s. The mean BFS value was statistically significantly higher for the EQUIA system and ChemFil Rock than for Fuji 9 Gold Label and Ketac Molar Easymix at all exposure times. PMID:23841095

  12. Development of a novel antimicrobial-releasing glass ionomer cement functionalized with chlorhexidine hexametaphosphate nanoparticles

    PubMed Central

    2014-01-01

    Background Glass ionomer cements (GICs) are a class of dental biomaterials. They have a wide range of uses including permanent restorations (fillings), cavity linings, fissure sealants and adhesives. One of the most common reasons for replacing a dental restoration is recurrent bacterial tooth decay around the margins of the biomaterial. Therefore, a dental biomaterial which creates a sustained antimicrobial environment around the restoration would be of considerable clinical benefit. In this manuscript, the formulation of a GIC containing novel antimicrobial nanoparticles composed of chlorhexidine hexametaphosphate at 1, 2, 5, 10 and 20% powder substitution by mass is reported. The aim is to create GICs which contain chlorhexidine-hexametaphosphate nanoparticles and characterize the nanoparticle size, morphology and charge and the release of chlorhexidine and fluoride, tensile strength and morphology of the GICs. Results The GICs released chlorhexidine, which is a broad spectrum antimicrobial agent effective against a wide range of oral bacteria, over the duration of the experiment in a dose-dependent manner. This was not at the expense of other properties; fluoride release was not significantly affected by the substitution of antimicrobial nanoparticles in most formulations and internal structure appeared unaffected up to and including 10% substitution. Diametral tensile strength decreased numerically with substitutions of 10 and 20% nanoparticles but this difference was not statistically significant. Conclusion A series of GICs functionalized with chlorhexidine-hexametaphosphate nanoparticles were created for the first time. These released chlorhexidine in a dose-dependent manner. These materials may find application in the development of a new generation of antimicrobial dental nanomaterials. PMID:24456793

  13. Research gaps identified during systematic reviews of clinical trials: glass-ionomer cements

    PubMed Central

    2012-01-01

    Background To report the results of an audit concerning research gaps in clinical trials that were accepted for appraisal in authored and published systematic reviews regarding the application of glass-ionomer cements (GIC) in dental practice Methods Information concerning research gaps in trial precision was extracted, following a framework that included classification of the research gap reasons: ‘imprecision of information (results)’, ‘biased information’, ‘inconsistency or unknown consistency’ and ‘not the right information’, as well as research gap characterization using PICOS elements: population (P), intervention (I), comparison (C), outcomes (O) and setting (S). Internal trial validity assessment was based on the understanding that successful control for systematic error cannot be assured on the basis of inclusion of adequate methods alone, but also requires empirical evidence about whether such attempt was successful. Results A comprehensive and interconnected coverage of GIC-related clinical topics was established. The most common reasons found for gaps in trial precision were lack of sufficient trials and lack of sufficient large sample size. Only a few research gaps were ascribed to ‘Lack of information’ caused by focus on mainly surrogate trial outcomes. According to the chosen assessment criteria, a lack of adequate randomisation, allocation concealment and blinding/masking in trials covering all reviewed GIC topics was noted (selection- and detection/performance bias risk). Trial results appear to be less affected by loss-to-follow-up (attrition bias risk). Conclusion This audit represents an adjunct of the systematic review articles it has covered. Its results do not change the systematic review’s conclusions but highlight existing research gaps concerning the precision and internal validity of reviewed trials in detail. These gaps should be addressed in future GIC-related clinical research. PMID:22747674

  14. Marginal gap, cement thickness, and microleakage of 2 zirconia crown systems luted with glass ionomer and MDP-based cements.

    PubMed

    Sener, Isil; Turker, Begum; Valandro, Luiz Felipe; Ozcan, Mutlu

    2014-01-01

    This in vitro study evaluated the marginal gap, cement thickness, and microleakage of glass-ionomer cement (GIC) and phosphate monomer-containing resin cement (MDP-RC) under 2 zirconia crown systems (Cercon and DC-Zirkon). Forty human premolars were prepared for all-ceramic zirconia crowns with a 1 mm circumferential finish line and a 1.5 mm occlusal reduction. The crowns (n = 10 per group) from each zirconia system were randomly divided into 2 groups and cemented either with GIC (Vivaglass CEM) or MDP-RC (Panavia F 2.0) cement. The cemented crowns were thermocycled 5000 times (5°-55°C). The crowns were immersed in 0.5% basic fuchsine dye solution for 24 hours and sectioned buccolingually and mesiodistally. Specimens were examined under optical microscope (100X). Data were analyzed using Student t-test and chi-square tests (? = 0.05). Mean marginal gap values for Cercon (85 ± 11.4 ?m) were significantly higher than for DC-Zircon (75.3 ± 13.2 ?m) (P = 0.018). The mean cement thickness values of GIC (81.7 ± 13.9 ?m) and MDP-RC (78.5 ± 12.5 ?m) were not significantly different (P = 0.447). Microleakage scores did not demonstrate significant difference between GIC (P = 0.385) and MDP-RC (P = 0.631) under Cercon or DC-Zircon. Considering the cement thickness values and microleakage scores obtained, both zirconia crown systems could be cemented in combination with either GIC or MDP-RC. PMID:24598500

  15. Evaluation of antibacterial and antifungal activity of new calcium-based cement (Biodentine) compared to MTA and glass ionomer cement

    PubMed Central

    Bhavana, Vankayala; Chaitanya, Krishna Popuri; Gandi, Padma; Patil, Jayaprakash; Dola, Binoy; Reddy, Rahul B.

    2015-01-01

    Objective: To evaluate the antibacterial and antifungal properties of calcium-based cement, Biodentine (Ca3SiO2), compared to commercial glass ionomer cements (GICs) and mineral trioxide aggregate (MTA). Materials and Methods: Pellets of GICs, ProRoot MTA, and Biodentine were prepared to test the influence of these cements on the growth of four oral microbial strains: Streptococcus mutans, Enterococcus faecalis, Escherichia coli, and Candida albicans; using agar diffusion method. Wells were formed by removing the agar and the manipulated materials were immediately placed in the wells. The pellets were lodged in seeded plates and the growth inhibition diameter around the material was measured after 24-72 h incubation at 37°C. The data were analyzed using analysis of variance (ANOVA) test to compare the differences among the three cements at different concentrations. Results: Test indicates that the antimicrobial activity of Biodentine, on all the microorganisms tested, was very strong, showing a mean inhibition zone of 3.2 mm, which extends over time towards all the strains. For Biodentine, GIC, and MTA, the diameters of the inhibition zones for S. mutans were significantly larger than for E. faecalis, Candida, and E. coli (P < 0.05). Conclusion: All materials showed antimicrobial activity against the tested strains except for GIC on Candida. Largest inhibition zone was observed for Streptococcus group. Biodentine created larger inhibition zones than MTA and GIC. PMID:25657526

  16. Antibacterial effect of chlorhexidine- containing glass ionomer cement in vivo: a pilot study.

    PubMed

    Frencken, J E; Imazato, S; Toi, C; Mulder, J; Mickenautsch, S; Takahashi, Y; Ebisu, S

    2007-01-01

    This in vivo pilot study was carried out to test the antibacterial effect of glass ionomer containing chlorhexidine (test group) in comparison to conventional glass ionomer (control group). Fifty 6- to 11-year-old children with one occlusal lesion in a molar were randomly allocated to test and control groups in a parallel-group design. The cavity walls and one half of the floor were cleaned and restored with one of the materials without dentine conditioning. The restorations were removed after 7 days. Dentine samples were taken from the cleaned (affected dentine) and noncleaned area (infected dentine) at baseline and at day 7. Samples were anaerobically and aerobically cultivated for mutans streptococci, lactobacilli and total viable bacterial count (TVC) following common laboratory procedures. ANCOVA was used to test for treatment effects. Seven days after treatment, a significant decrease in anaerobic and aerobic bacterial counts (p = 0.0001) was shown. Lower numbers of anaerobic lactobacilli (p = 0.02), TVC (p = 0.008) and aerobic lactobacilli and TVC (p = 0.03), but not of mutans streptococci, were indicated in the test group compared to the control group. A significant reduction in aerobic lactobacilli from infected dentine treated with the glass ionomer containing chlorhexidine (p = 0.05) was observed whereas in affected dentine, anaerobic mutans streptococci, lactobacilli and TVC and aerobic TVC and mutans streptococci were significantly lower in the test group 7 days after treatment (p = 0.01). We conclude that the present pilot study revealed lower microorganism counts in chlorhexidine-containing glass ionomers than in conventional glass ionomers for both affected and infected dentine over a 7-day period. PMID:17284910

  17. Effect of saliva contamination on the bond of dentin to resin-modified glass-ionomer cement.

    PubMed

    Safar, J A; Davis, R D; Overton, J D

    1999-01-01

    This in vitro study compared the shear bond strength of a resin-modified glass-ionomer restorative material (Fuji II LC) bonded to saliva-contaminated dentin versus non-contaminated dentin. Seventy-five extracted human molar teeth were randomly divided into five groups of 15 samples each. The dentin was treated with 10% polyacrylic acid for 20 seconds, rinsed, and dried. The acid-treated dentin surfaces in Groups 1-4 were contaminated with saliva. In Group 1, the saliva was air thinned. In Groups 2-4, saliva was dried completely with compressed air. The saliva-contaminated dentin in Group 3 was rinsed and dried. The saliva-contaminated dentin in Group 4 was rinsed, dried, treated with 10% polyacrylic acid, and dried. Specimens in Group 5 received no contamination. The resin-modified glass-ionomer cement restorative material was mixed and applied to the dentin surfaces. Following placement of the restorative material and 7 days of storage, the specimens were thermo-cycled 300 times. Using the Instron Universal Testing Machine, a shear force was applied to the restorative material. Shear bond strength values were compared among the groups using a one-way ANOVA and Student-Neuman-Keuls Multiple Range Test (alpha = 0.05). The non-contaminated specimens (Group 5) were significantly stronger than the contaminated specimens (Groups 1-4). There were no significant differences in bond strength among the groups containing contaminated specimens. Salivary contamination occurring after dentin etching significantly reduced the bond strength of the resin-modified glass-ionomer restorative material to dentin. Neither rinsing nor rinsing and re-etching resulted in bond strengths as great as to non-contaminated dentin. PMID:10823084

  18. An in-vitro study to compare the microhardness of glass ionomer cement set conventionally versus set under ultrasonic waves

    PubMed Central

    Baloch, FA; Mirza, AJ; Baloch, D.

    2010-01-01

    Objective: To assess the difference of surface hardness of glass ionomer cement (GIC) set by conventional setting method and under ultrasonically energized method. Method: 20 cylindrical samples measuring 2.5mm (diameter) and 5mm (length) were prepared with type IX GIC. Ten of these samples were allowed to set by conventional setting method and other ten were set under ultrasonic excitation energy. After finishing and polishing of the samples, three indentations were made on each sample using Vicker’s hardness machine with a load of 300 gm for 15 seconds. The surface microhardness of the indents was calculated by Vicker’s hardness formula. Results: Surface microhardness of samples set by ultrasound setting method was significantly higher than samples set by conventional method. Conclusion: This can be beneficial for the dental patients as when used as a restorative material, it will have a long lasting effect and can also be used in posterior load bearing areas. PMID:21475553

  19. Influence of powder/liquid ratio on the radiodensity and diametral tensile strength of glass ionomer cements

    PubMed Central

    FONSECA, Rodrigo Borges; BRANCO, Carolina Assaf; QUAGLIATTO, Paulo Sérgio; GONÇALVES, Luciano de Souza; SOARES, Carlos José; CARLO, Hugo Lemes; CORRER-SOBRINHO, Lourenço

    2010-01-01

    Objective To determine the influence of P/L ratio on the radiodensity and diametral tensile strength (DTS) of glass ionomer cements. Material and Methods There were 2 factors under study: P/L ratio (manufacturer's recommended P/L ratio and a 50% reduced P/L ratio), and materials (Vitro Molar, Vitro Fil, Vitro Cem conventional GICs and Vitro Fil LC, Ortho Glass LC RMGICs). Five 1-mm-thick samples of each material-P/L ratio were produced for radiodensity evaluation. Samples were x-ray exposed onto Digora phosphor plate and radiodensity was obtained using the software Digora for Windows 2.5 Rev 0. For DTS, five (4.0x8.0 mm) cylinder samples of each material were tested (0.5 mm/min). Data were subjected to one- and two-way ANOVA (5x2) followed by Tukey's HSD test, or Kruskal-Wallis and Dunn's method. For paired comparisons, t-test or Mann-Whitney test were used (a=0.05). Results There was a significant interaction (P=0.001) for the studied factors (materials vs. P/L ratio). Reduced P/L ratio resulted in significantly lower DTS for the RMGICs, but radiodensity was affected for all materials (P<0.05). Conclusions Reduced P/L ratio affected properties of the tested glass ionomer cements. RMGICs were more susceptible to lower values of DTS, but radiodensity decreased for all materials following P/L ratio reduction. PMID:21308288

  20. Enhancing glass ionomer cement features by using the HA/YSZ nanocomposite: a feed forward neural network modelling.

    PubMed

    Rajabzadeh, Ghadir; Salehi, Sahar; Nemati, Ali; Tavakoli, Razeih; Solati Hashjin, Mehran

    2014-01-01

    Despite brilliant properties of glass ionomer cement (GIC), its weak mechanical property poses an obstacle for its use in medical applications. The present research aims to formulate hydroxyapatite/yttria-stabilized zirconia (HA/YSZ) in the composition of GIC to enhance mechanical properties and to improve fluoride release of GIC. HA/YSZ was synthesized via a sol-gel method and characterized by applying X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photo-emission spectroscopy (XPS) and simultaneous thermal analysis (STA) along with transmission electron microscopy (TEM) methods. The synthesized nanocomposite was mixed with GIC at a fixed composition of 5wt%. The effect of different weight percentages of YSZ:HA on GIC was investigated by measuring the compressive strength, diametral tensile strength, microhardness and fluoride release. The results showed that, after 1 and 7 days of setting, the 20wt% nanohydroxyapatite/80wt% stabilized zirconia cement exhibited higher compressive strength (1857-245MPa), higher diametral tensile strength (11-14MPa) and greater microhardness (104-106MPa) as compared with the pure GIC (65-88MPa in compressive strength, 5-9.5MPa in diametral tensile strength and 70-89MPa in microhardness). The reinforced cement, also, exhibited higher fluoride release compared with pure GIC. The artificial neural network (ANN) was trained for modeling the system. Results obtained by ANN have proved to be completely in accordance with expectations. PMID:24140732

  1. Comparative evaluation of intracanal sealing ability of mineral trioxide aggregate and glass ionomer cement: An in vitro study

    PubMed Central

    Malik, Gauri; Bogra, Poonam; Singh, Simranjeet; Samra, Rupandeep K

    2013-01-01

    Aims: The purpose of this study was to compare the sealing ability of Mineral Trioxide Aggregate (MTA) and Glass Ionomer Cement (GIC) when used over gutta-percha as intracanal sealing materials. The study also evaluated the sealing ability of Zinc oxide eugenol (ZOE) cement and Acroseal sealer. Materials and Methods: Teeth were obturated with gutta-percha using sealer ZOE (group A, C, D) and Acroseal (group B). The groups were further divided into 2 subgroups (15 premolars each) on the basis of intracanal sealing material used: GIC subgroups (A1, B1) and MTA in subgroups (A2, B2). The clearing technique was used in this study for leakage evaluation. Seventy mandibular premolars were prepared using step-back technique and divided into experimental groups A and B (30 premolars each) and the positive and negative control groups C and D (5 premolars each). Statistical analysis used: Coronal microleakage was determined under stereomicroscope using 15X magnification. Data was statistically analyzed using one-way ANOVA followed by Post-Hoc Multiple comparison (Bonferroni). Results: MTA group leaked significantly less than GIC group (P < 0.05). Acroseal exhibited better sealing ability than ZOE sealer. Teeth with no intracanal barrier showed almost complete leakage. Conclusions: MTA may be preferred over GIC as an intracanal barrier. PMID:24347890

  2. Present and future of glass-ionomers and calcium-silicate cements as bioactive materials in dentistry: Biophotonics-based interfacial analyses in health and disease

    PubMed Central

    Watson, Timothy F.; Atmeh, Amre R.; Sajini, Shara; Cook, Richard J.; Festy, Frederic

    2014-01-01

    Objective Since their introduction, calcium silicate cements have primarily found use as endodontic sealers, due to long setting times. While similar in chemistry, recent variations such as constituent proportions, purities and manufacturing processes mandate a critical understanding of service behavior differences of the new coronal restorative material variants. Of particular relevance to minimally invasive philosophies is the potential for ion supply, from initial hydration to mature set in dental cements. They may be capable of supporting repair and remineralization of dentin left after decay and cavity preparation, following the concepts of ion exchange from glass ionomers. Methods This paper reviews the underlying chemistry and interactions of glass ionomer and calcium silicate cements, with dental tissues, concentrating on dentin–restoration interface reactions. We additionally demonstrate a new optical technique, based around high resolution deep tissue, two-photon fluorescence and lifetime imaging, which allows monitoring of undisturbed cement–dentin interface samples behavior over time. Results The local bioactivity of the calcium-silicate based materials has been shown to produce mineralization within the subjacent dentin substrate, extending deep within the tissues. This suggests that the local ion-rich alkaline environment may be more favorable to mineral repair and re-construction, compared with the acidic environs of comparable glass ionomer based materials. Significance The advantages of this potential re-mineralization phenomenon for minimally invasive management of carious dentin are self-evident. There is a clear need to improve the bioactivity of restorative dental materials and these calcium silicate cement systems offer exciting possibilities in realizing this goal. PMID:24113131

  3. In-vitro study of resin-modified glass ionomer cements for cementation of orthodontic bands. Isolation, surplus removal and humidity as factors influencing the bond strength between enamel, cement and metal.

    PubMed

    Liebmann, S M; Jost-Brinkmann, P G

    1999-01-01

    The aim of this in vitro study was to investigate different light-cured and chemically cured resin-modified glass ionomer cements used for the cementation of orthodontic bands and to analyze various factors influencing the adhesive strength between enamel, cement and stainless steel. Four resin-modified glass ionomers (Fuji Ortho LC/GC, Fuji Duet/GC, Unitek Multi-Cure Glass Ionomer Orthodontic Band Cement/3M Unitek, Vitremer/3M) and 1 compomer (Band-Lok/Reliance) were examined. Flattened and polished bovine teeth embedded in polyurethane resin were used as enamel specimens. Before cementation, 50% of the specimens were moistened with the aerosol of an inhalation device, while the rest were dried with compressed air. Stainless steel cylinders (CrNi 18 10) were perpendicularly bonded onto the polished enamel using a custom-made cementation device and immediately topped with a pressure of 0.25 MPa. The cement was isolated with either Ketac Glaze/ESPE, Fuji Coat/GC, Cacao Butter/GC, Dryfoil/Jalenko or Final Varnish/VOCO, or was left uncoated. Eight minutes after the beginning of mixing, either the surplus cement was removed with a scalpel or surplus removal was simulated with ultrasound. After 24 hours storage in a water bath at 37 degrees C and 1,000 thermocycles the shear bond strength was determined. Significant differences with respect to the shear bond strength were found among the following cements, ranking from highest to lowest: Fuji Duet, Unitek cement > Fuji Ortho LC > Vitremer > Band-Lok. The application of a barrier coating significantly increased the shear bond strength of all cements except Fuji Ortho LC. The light-cured resin Ketac Glaze proved to be the most effective barrier coating. A dry enamel surface increased the bond strength of all investigated cements except Unitek cement. The use of ultrasound led to no significant reduction in shear bond strength in comparison with surplus removal with a scalpel. PMID:10546417

  4. Bonding of contemporary glass ionomer cements to different tooth substrates; microshear bond strength and scanning electron microscope study

    PubMed Central

    El Wakeel, Aliaa Mohamed; Elkassas, Dina Wafik; Yousry, Mai Mahmoud

    2015-01-01

    Objective: This study was conducted to evaluate the microshear bond strength (?SBS) and ultramorphological characterization of glass ionomer (GI) cements; conventional GI cement (Fuji IX, CGI), resin modified GI (Fuji II LC, RMGI) and nano-ionomer (Ketac N100, NI) to enamel, dentin and cementum substrates. Materials and Methods: Forty-five lower molars were sectioned above the cemento-enamel junction. The occlusal surfaces were ground flat to obtain enamel and dentin substrates, meanwhile the cervical one-third of the root portion were utilized to evaluate the bonding efficacy to cementum substrate. Each substrate received microcylinders from the three tested materials; which were applied according to manufacturer instructions. ?SBS was assessed using a universal testing machine. The data were analyzed using two-way analysis of variance (ANOVA) and Tukey's post-hoc test. Modes of failure were examined using stereomicroscope at ×25 magnification. Interfacial analysis of the bonded specimens was carried out using environmental field emission scanning electron microscope. Results: Two-way ANOVA revealed that materials, substrates and their interaction had a statistically significant effect on the mean ?SBS values at P values; ?0.0001, 0.0108 and 0.0037 respectively. RMGI showed statistically significant the highest ?SBS values to all examined tooth substrates. CGI and RMGI show substrate independent bonding efficiency, meanwhile; NI showed higher ?SBS values to dentin and cementum compared to enamel. Conclusion: Despite technological development of GI materials, mainly the nano-particles use, better results have not been achieved for both investigations, when compared to RMGI, independent of tooth substrate.

  5. Glass ionomer as fissure sealant--a critical review.

    PubMed

    Simonsen, R J

    1996-01-01

    This paper presents a review of the literature on glass ionomer cements used as fissure sealants. An objective assessment of the presently available scientific literature on the use of glass ionomer materials as pit and fissure sealants is not encouraging in terms of retention, but appears somewhat more positive for caries prevention. At the time of this writing, the published literature indicates that retention for resin-based sealants is better than for glass ionomer sealants, but differences in caries prevention remain equivocal. Future research should concentrate on assessing the effects of fluoride-releasing, resin-modified, glass ionomer materials. PMID:8915960

  6. BOND STRENGTH OF RESIN MODIFIED GLASS IONOMER CEMENT TO PRIMARY DENTIN AFTER CUTTING WITH DIFFERENT BUR TYPES AND DENTIN CONDITIONING

    PubMed Central

    Nicoló, Rebeca Di; Shintome, Luciana Keiko; Myaki, Silvio Issáo; Nagayassu, Marcos Paulo

    2007-01-01

    The aim of this in vitro study was to evaluate the effect of different bur types and acid etching protocols on the shear bond strength (SBS) of a resin modified glass ionomer cement (RM-GIC) to primary dentin. Forty-eight clinically sound human primary molars were selected and randomly assigned to four groups (n=12). In G1, the lingual surface of the teeth was cut with a carbide bur until a 2.0-mm-diameter dentin area was exposed, followed by the application of RM-GIC (Vitremer – 3M/ESPE) prepared according to the manufacturer’s instructions. The specimens of G2, received the same treatment of G1, however the dentin was conditioned with phosphoric acid. In groups G3 and G4 the same procedures of G1 and G2 were conducted respectively, nevertheless dentin cutting was made with a diamond bur. The specimens were stored in distilled water at 37°C for 24h, and then tested in a universal testing machine. SBS. data were submitted to 2-way ANOVA (= 5%) and indicated that SBS values of RM-GIC bonded to primary dentin cut with different burs were not statistically different, but the specimens that were conditioned with phosphoric acid presented SBS values significantly higher that those without conditioning. To observe micromorphologic characteristics of the effects of dentin surface cut by diamond or carbide rotary instruments and conditioners treatment, some specimens were examined by scanning electron microscopy. Smear layer was present in all specimens regardless of the type of rotary instrument used for dentin cutting, and specimens etched with phosphoric acid presented more effective removal of smear layer. It was concluded that SBS of a RM-GIC to primary dentin was affected by the acid conditioning but the bur type had no influence. PMID:19089179

  7. Absence of carious lesions at margins of glass-ionomer cement and amalgam restorations: An update of systematic review evidence

    PubMed Central

    2011-01-01

    Background This article aims to update the existing systematic review evidence elicited by Mickenautsch et al. up to 18 January 2008 (published in the European Journal of Paediatric Dentistry in 2009) and addressing the review question of whether, in the same dentition and same cavity class, glass-ionomer cement (GIC) restored cavities show less recurrent carious lesions on cavity margins than cavities restored with amalgam. Methods The systematic literature search was extended beyond the original search date and a further hand-search and reference check was done. The quality of accepted trials was assessed, using updated quality criteria, and the risk of bias was investigated in more depth than previously reported. In addition, the focus of quantitative synthesis was shifted to single datasets extracted from the accepted trials. Results The database search (up to 10 August 2010) identified 1 new trial, in addition to the 9 included in the original systematic review, and 11 further trials were included after a hand-search and reference check. Of these 21 trials, 11 were excluded and 10 were accepted for data extraction and quality assessment. Thirteen dichotomous datasets of primary outcomes and 4 datasets with secondary outcomes were extracted. Meta-analysis and cumulative meta-analysis were used in combining clinically homogenous datasets. The overall results of the computed datasets suggest that GIC has a higher caries-preventive effect than amalgam for restorations in permanent teeth. No difference was found for restorations in the primary dentition. Conclusion This outcome is in agreement with the conclusions of the original systematic review. Although the findings of the trials identified in this update may be considered to be less affected by attrition- and publication bias, their risk of selection- and detection/performance bias is high. Thus, verification of the currently available results requires further high-quality randomised control trials. PMID:21396097

  8. Glass-ionomers: bioactive implant materials

    Microsoft Academic Search

    I. M. Brook; P. V. Hatton

    1998-01-01

    Glass-ionomer cements (GICs) originally designed for use as dental materials have a number of advantages over acrylic bone cements. These include lack of exotherm during setting, absence of monomer and improved release of incorporated therapeutic agents; this has resulted in the development of GICs for biomedical applications. Major landmarks in this history are the formulation of defined-composition ionomer glasses and

  9. An in vitro study on the maturation of conventional glass ionomer cements and their interface to dentin.

    PubMed

    Zoergiebel, Julius; Ilie, Nicoleta

    2013-12-01

    The objective of the study was to investigate the influence of long-term storage (up to 1 year) and coating on the variation of micro-mechanical properties of four conventional restorative glass ionomer cements (GICs) within 3.5 mm deep class I cavities. Four commercially available GICs (Riva Self Cure (SDI), ChemFil Rock (Dentsply), Fuji IX Fast and Fuji IX GP Extra/Equia (GC)) were applied to 100 teeth. In each tooth, two similar 3.5 mm deep class I cavities were prepared and filled with the GICs, with and without resin coating. The samples were stored in artificial saliva at 37 °C for 1 week, 1 month, 3 months, 6 months and 1 year. The variation in mechanical properties (indentation modulus (E) and Vickers hardness (HV)) were determined in 100 ?m steps starting from the filling surface, through the intermediate layer in between dentine and GIC, and ending 100 ?m in dentin. HV and E were strongly influenced by the material (P<0.05, partial eta-squared ?P(2) = 0.31 and 0.23) but less by aging duration (P<0.05, ?P(2) = 0.02 and 0.12) and resin coating (P<0.05, ?P(2) = 0.02 and 0.03). The depth of measurement (0-2 mm) has no influence on HV (P = 0.789). HV shows a gentle increase over the 1 year storage period (P = 0.002). A ?300 ?m GIC zone at the areas close to dentin with weaker properties as those measured in dentin or GIC was identified in all fillings, irrespective of the presence of coating, and at all storage periods. The thickness of this zone is more strongly influenced by storage (P<0.05, ?P(2) = 0.081) than by material type (P<0.05, ?P(2) = 0.056), while coating showed no influence (P = 0.869). Filler morphology and dimension were similar to upper parts of the GIC filling; however, the amount of low cations was higher. We concluded that the development of an intermediate layer in between dentine and GIC with lower mechanical properties might be responsible for the bond quality of GIC to dentine. Moreover, class I GIC restorations are unlikely to feature constant mechanical properties throughout the cavity, regardless of conditions such as aging and coating. PMID:23954325

  10. A preliminary clinical trial using flowable glass-ionomer cement as a liner in proximal-ART restorations: The operator effect

    PubMed Central

    Hesse, Daniela; Bönecker, Marcelo; Van Loveren, Cor; Van Amerongen, W E.; Raggio, Daniela P.

    2013-01-01

    Objectives: This in vivo study was carried out to assess the influence of the operator experience on the survival rate of proximal-ART restorations using a two-layer technique to insert the glass-ionomer cement (GIC). Study Design: Forty five proximal cavities in primary molars were restored in a school setting according to the ART technique. The cavities were restored by two operators with Ketac Molar Easymix, and received a flowable layer of GIC prior to a second GIC layer with a regular consistency. The operators had different clinical experiences with ART (no experience or two years of experience), but both completed a one-week training to perform the restorations and the GIC mixing in this study. Results: After a 12-month follow-up, 74% of the restorations survived; the main reason for failure was bulk fracture or total loss of the restoration.There was no operator influence (log-rank test p=0.2) Conclusion: The results encourage future well designed controlled clinical trials using the two-layer technique for insertion of GIC in proximal-ART restorations, after training the operators. Key words:Atraumatic Restorative Treatment (ART), Glass-ionomer, proximal restorations. PMID:23524424

  11. Fracture frequency and longevity of fractured resin composite, polyacid-modified resin composite, and resin-modified glass ionomer cement class IV restorations: an up to 14 years of follow-up

    Microsoft Academic Search

    Jan W. V. van Dijken; Ulla Pallesen

    2010-01-01

    The aim of this study was to evaluate the fracture frequency and longevity of fractured class IV resin composite (RC), polyacid-modified\\u000a resin composite (compomer; PMRC), and resin-modified glass ionomer cement (RMGIC) restorations in a longitudinal long-term\\u000a follow-up. Eighty-five class IV RC (43: Pekafil), PMRC (24: Dyract (D), Hytac (H)), and RMGIC (18: Fuji II LC (F), Photac\\u000a Fil (P)) restorations

  12. Influence of air-abrasion executed with polyacrylic acid-Bioglass 45S5 on the bonding performance of a resin-modified glass ionomer cement.

    PubMed

    Sauro, Salvatore; Watson, Timothy F; Thompson, Ian; Toledano, Manuel; Nucci, Cesare; Banerjee, Avijit

    2012-04-01

    The aim of this study was to test the microtensile bond strength (?TBS), after 6 months of storage in PBS, of a resin-modified glass ionomer cement (RMGIC) bonded to dentine pretreated with Bioglass 45S5 (BAG) using various etching and air-abrasion techniques. The RMGIC (GC Fuji II LC) was applied onto differently treated dentine surfaces followed by light curing for 30 s. The specimens were cut into matchsticks with cross-sectional areas of 0.9 mm(2). The ?TBS of the specimens was measured after 24 h or 6 months of storage in PBS and the results were statistically analysed using two-way anova and the Student-Newman-Keuls test (? = 0.05). Further RMCGIC-bonded dentine specimens were used for interfacial characterization, micropermeability, and nanoleakage analyses by confocal microscopy. The RMGIC-dentine interface layer showed no water absorption after 6 months of storage in PBS except for the interdiffusion layer of the silicon carbide (SiC)-abraded/polyacrylic acid (PAA)-etched bonded dentine. The RMGIC applied onto dentine air-abraded with BAG/H(2)O only or with BAG/PAA-fluid followed by etching procedures (10% PAA gel) showed no statistically significant reduction in ?TBS after 6 months of storage in PBS. The abrasion procedures performed using BAG in combination with PAA might be a suitable strategy to enhance the bonding durability and the healing ability of RMGIC bonded to dentine. PMID:22409224

  13. COMPARISON OF TWO MINIMALLY INVASIVE METHODS ON THE LONGEVITY OF GLASS IONOMER CEMENT RESTORATIONS: SHORT-TERM RESULTS OF A PILOT STUDY

    PubMed Central

    Barata, Terezinha Jesus Esteves; Bresciani, Eduardo; Mattos, Maria Cecília Ribeiro; Lauris, José Roberto Pereira; Ericson, Dan; Navarro, Maria Fidela de Lima

    2008-01-01

    The purpose of this study was to evaluate the clinical performance of glass ionomer cement (GIC) restorations comparing two minimally invasive methods in permanent teeth after 12 months. Fifty pregnant women (second trimester of pregnancy), mean age 22 ± 5.30 years, were treated by two previously trained operators. The treatment approaches tested were: chemomechanical method (CarisolvTM; MediTeam) and atraumatic restorative treatment (ART). A split-mouth study design was used in which the two treatments were randomly placed in 50 matched pairs of permanent teeth. The chemomechanical method (CM) was the test group and the ART was the control group. The treatments were performed in Public Health Centers. The tested restorative material was a high-strength GIC (Ketac Molar; 3M/ESPE). The restorations were placed according to the ART guidelines. Two calibrated independent examiners evaluated the restorations in accordance with ART criteria. The interexaminer kappa was 0.97. Data were analyzed using 95% confidence interval on the binomial distribution and Fisher's exact test at 5% significance level. In a 12-month follow-up, 86% of the restorations were evaluated. In the test group (CM), 100% (CI=93.3-100%) of the restorations were considered successful. In the control group (ART) 97.6% (CI=87.4-99.9%) of the restorations were considered successful and 2.4% unsuccessful (marginal defect >0.5 mm). There was no statistically significant difference between the 12-mounth success rate for both groups (Fisher's exact test: P=0.49) and between the two operators (Fisher's exact test: P=1.00). Both minimally invasive methods, chemomechanical method and ART, showed a similar clinical performance after 12 months of follow up. PMID:19089209

  14. Resin-modified glass ionomers for luting posterior ceramic restorations

    Microsoft Academic Search

    Birger Thonemann; Marianne Federlin; Gottfried Schmalz; Karl-Anton Hiller

    1995-01-01

    Objectives. Until recently, esthetic inlay restorations in posterior teeth have been limited to cavities surrounded by enamel. Dentin adhesive systems in combination with luting composites and light-cured resin-modified glass ionomer cements offer a possibility for bonding ceramic inlays to cavities when the cervical margin is in dentin. This study was designed to compare in vitro marginal integrity of ceramic inlays

  15. Creep behavior of glass-ionomer restorative materials.

    PubMed

    Papadogiannis, Y; Helvatjoglou-Antoniadi, M; Lakes, R C; Sapountjis, M

    1991-01-01

    The creep of microspecimens of five glass-ionomer filling materials and one glass-ionomer-cermet cement was studied by means of a torsional creep apparatus. The glass-ionomer specimens were aged one week and conditioned in 37 degrees C water. Shear stress of 2.47 x 10(-4) N.m was maintained for three h, and recovery was followed for 50 h. Creep curves were obtained at 21, 37, and 50 degrees C. The effect of temperature increase was studied. All the glass ionomers exhibited linear visco-elastic behavior at low deformations. Their shear moduli and resistance to creep were similar to those of some composites measured by the same method. The increase of temperature influenced the creep behavior and moduli of the materials (i.e., increased creep and residual strains and decreased shear modulus). Although the applied torque was very small, there was permanent deformation, the result of viscous flow in all experiments which was more pronounced at 50 degrees C. PMID:1901812

  16. Absence of carious lesions at margins of glass-ionomer cement (GIC) and resin-modified GIC restorations: a systematic review.

    PubMed

    Mickenautsch, Steffen; Tyas, Martin J; Yengopal, Veerasamy; Oliveira, Luciana B; Bönecker, Marcelo

    2010-09-01

    This systematic review sought to quantitatively answer the question as to whether, in tooth cavities of the same size, type of dentition and follow-up period, resin-modified glass-ionomer (GIC) restorations, when compared to conventional GIC restorations, offer a significant caries preventive effect, as measured by the absence of caries lesions at the margin of restorations. Six databases were searched for articles in English, Portuguese or Spanish until 07 May 2009. Four articles were accepted and 22 separate datasets extracted. The difference between both types of material were computed as relative risk (RR) with 95% confidence interval (CI). No meta-analysis was undertaken due to aspects of clinical/methodological heterogeneity. The results of the extracted datasets ranged between RR 0.90 (95% CI 0.81-1.01) and 1.08 (95% CI 0.71-1.63; p > 0.05) indicating no difference in the caries preventive effect between both types of materials. Further high-quality randomized control trials are needed in order to confirm these results. PMID:21077424

  17. Comparison of marginal adaptation of mineral trioxide aggregate, glass ionomer cement and intermediate restorative material as root-end filling materials, using scanning electron microscope: An in vitro study

    PubMed Central

    Gundam, Sirisha; Patil, Jayaprakash; Venigalla, Bhuvan Shome; Yadanaparti, Sravanthi; Maddu, Radhika; Gurram, Sindhura Reddy

    2014-01-01

    Aim: The present study compares the marginal adaption of Mineral Trioxide Aggregate (MTA), Glass Ionomer Cement (GIC) and Intermediate Restorative Material (IRM) as root-end filling materials in extracted human teeth using Scanning Electron Microscope (SEM). Materials and Methods: Thirty single rooted human teeth were obturated with Gutta-percha after cleaning and shaping. Apical 3 mm of roots were resected and retrofilled with MTA, GIC and IRM. One millimeter transverse section of the retrofilled area was used to study the marginal adaptation of the restorative material with the dentin. Mounted specimens were examined using SEM at approximately 15 Kv and 10-6 Torr under high vacuum condition. At 2000 X magnification, the gap size at the material-tooth interface was recorded at 2 points in microns. Statistical Analysis: One way ANOVA Analysis of the data from the experimental group was carried out with gap size as the dependent variable, and material as independent variable. Results: The lowest mean value of gap size was recorded in MTA group (0.722 ± 0.438 ?m) and the largest mean gap in GIC group (1.778 ± 0.697 ?m). Conclusion: MTA showed least gap size when compared to IRM and GIC suggesting a better marginal adaptation. PMID:25506146

  18. Comparative wear resistance of reinforced glass ionomer restorative materials.

    PubMed

    Yap, A U; Teo, J C; Teoh, S H

    2001-01-01

    This study investigated the wear resistance of three restorative reinforced glass ionomer cements (Fuji IX GP FAST [FJ], Miracle Mix [MM] and Ketac Silver [KS]). Microfilled (Silux [SX]) and mini-filled (Z100 [ZO]) composites were used for comparison. Six specimens were made for each material. The specimens were conditioned for one week in distilled water at 37 degrees C and subjected to wear testing at 20 MPa contact stress against SS304 counterbodies using a reciprocal compression-sliding wear instrumentation. Distilled water was used as lubricant. Wear depth (microm) was measured using profilometry every 2,000 cycles up to 10,000 cycles. Results were analyzed using ANOVA/Scheffe's test (p<0.05). After 10,000 cycles of wear testing, ranking was as follows: KS>ZO>MM>FJ>SX. Wear ranged from 26.1 microm for SX to 71.5 microm for KS. The wear resistance of KS was significantly lower than FJ, MM and SX at all wear intervals. Although KS had significantly more wear than ZO at 2,000 to 6,000 cycles, no significant difference in wear was observed between these two materials at 8,000 and 10,000 cycles. Sintering of silver particles to glass ionomer cement (KS) did not appear to improve wear resistance. The simple addition of amalgam alloy to glass ionomer may improve wear resistance but results in poor aesthetics (silver-black color). FJ, which relies on improved chemistry instead of metal fillers, showed comparable wear resistance to the composites evaluated and is tooth-colored. It may serve as a potential substitute for composites in low-stress situations where fluoride release is desirable and aesthetic requirements are not high. PMID:11504433

  19. Microleakage on Class V glass ionomer restorations after cavity preparation with aluminum oxide air abrasion.

    PubMed

    Corona, Silmara Aparecida Milori; Borsatto, Maria Cristina; Rocha, Renata Andréa Salvitti de Sá; Palma-Dibb, Regina Guenka

    2005-01-01

    This in vitro study assessed the marginal microleakage on class V cavities prepared with aluminum oxide air abrasion and restored with different glass ionomer cements. The cavities were prepared on the buccal and lingual surfaces of 15 sound third molars with an air- abrasion device (Kreativ Mach 4.1; New Image) using a 27.5-microm aluminum oxide particle stream, and were assigned to 3 groups of 10 cavities each. The restorative materials were: group I, a conventional glass ionomer cement (Ketac-Fil); groups II and III, resin-modified glass ionomer cements (Vitremer R and Fuji II LC, respectively). After placement of the restorations, the teeth were stored in distilled water at 37 degrees C for 24 h, polished and then submitted to a thermocycling regimen of 500 cycles, isolated, immersed in 0.2% Rhodamine B solution for 24 h, included and serially sectioned. Microleakage was assessed by viewing the specimens under an optical microscope connected to a color video camera and a computer. The images obtained were digitized and analyzed for microleakage using software that allows for a standard quantitative assessment of dye penetration in millimeters. Statistical analysis was done using the Kruskall-Wallis and Wilcoxon tests. Means of dye penetration (%) were: occlusal - I: 25.76 +/- 34.35, II: 20.00 +/- 42.16, III: 28.25 +/- 41.67; cervical - I: 23.72 +/- 41.84; II: 44.22 +/- 49.69, III: 39.27 +/- 50.74. No statistically significant differences (p>0.05) were observed among either the glass ionomer cements or the margins. In conclusion, class V cavities restored with either conventional or resin-modified glass ionomer cements after preparation with aluminum oxide air abrasion did not show complete sealing at the enamel and dentin/cementum margins. PMID:16113931

  20. Therapeutic effect of glass-ionomers: an overview of evidence.

    PubMed

    Mickenautsch, S; Mount, G; Yengopal, V

    2011-03-01

    The requirements for an ideal restorative material include adhesion to tooth structure (enamel and dentine) and an ability to withstand the traumas of occlusion. However, some level of an anticaries effect is also desirable. After a long history of glass-ionomer cement (GIC) development, an evidence base in support of the therapeutic effect of GIC, particularly with regard to its anticaries effect, is emerging. This evidence is increasingly presented through systematic reviews of clinical GIC application and, to a certain extent, relates to a caries-preventive effect of the material itself. However, the strength of evidence supporting other aspects of GIC, such as a higher remineralizing effect, fluoride uptake in hard tooth tissue and fluoride release of GIC, is limited. Nevertheless, the results of these in situ and laboratory trials provide valuable insights into factors that facilitate understanding of the clinical efficacy of GIC. PMID:21332735

  1. The influence of microstructure on thermal response of glass ionomers

    Microsoft Academic Search

    Zhuoqun Yan; Sharanbir K. Sidhu; John F. McCabe

    2007-01-01

    This study was designed to determine the dimensional changes caused by thermal stimuli of glass ionomers with different glass\\/matrix\\u000a ratios. Four cylindrical specimens were made for each of four powder\\/liquid ratios (3:1, 2.5:1, 2:1 and 1.5:1) for a conventional\\u000a luting glass ionomer, two high viscosity restorative glass ionomers and a restorative resin-modified glass ionomer. The thermal\\u000a characteristics were determined using

  2. Fluoride release and bioactivity evaluation of glass ionomer: Forsterite nanocomposite

    PubMed Central

    Sayyedan, Fatemeh Sadat; Fathi, Mohammadhossein; Edris, Hossein; Doostmohammadi, Ali; Mortazavi, Vajihesadat; Shirani, Farzaneh

    2013-01-01

    Background: The most important limitation of glass ionomer cements (GICs) is the weak mechanical properties. Our previous research showed that higher mechanical properties could be achieved by addition of forsterite (Mg2SiO4) nanoparticles to ceramic part of GIC. The objective of the present study was to fabricate a glass ionomer- Mg2SiO4 nanocomposite and to evaluate the effect of addition of Mg2SiO4 nanoparticles on bioactivity and fluoride release behavior of prepared nanocomposite. Materials and Methods: Forsterite nanoparticles were made by sol-gel process. X-ray diffraction (XRD) technique was used in order to phase structure characterization and determination of grain size of Mg2SiO4 nanopowder. Nanocomposite was fabricated via adding 3wt.% of Mg2SiO4 nanoparticles to ceramic part of commercial GIC (Fuji II GC). Fluoride ion release and bioactivity of nanocomposite were measured using the artificial saliva and simulated body fluid (SBF), respectively. Bioactivity of specimens was investigated by Fourier transitioned-infrared spectroscopy (FTIR), scanning electronmicroscopy (SEM), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and registration of the changes in pH of soaking solution at the soaking period. Statistical analysis was carried out by one Way analysis of variance and differences were considered significant if P < 0.05. Results: The results of XRD analysis confirmed that nanocrystalline and pure Mg2SiO4 powder was obtained. Fluoride ion release evaluation showed that the values of released fluoride ions from nanocomposite are somewhat less than Fuji II GC. SEM images, pH changes of the SBF and results of the ICP-OES and FTIR tests confirmed the bioactivity of the nanocomposite. Statistical analysis showed that the differences between the results of all groups were significant (P < 0.05). Conclusion: Glass ionomer- Mg2SiO4 nanocomposite could be a good candidate for dentistry and orthopedic applications, through of desirable fluoride ion release and bioactivity. PMID:24130579

  3. Thermal characterization of glass ionomer/vinyl IPN composites

    SciTech Connect

    Puckett, A.D.; Bennett, B.; Shelby, A. [Univ. of Mississippi Medical Center, Jackson, MS (United States)] Storey, R. [Univ. of Southern Mississippi, Hattiesburg, MS (United States)

    1993-12-31

    In and attempt to improve some of the disadvantages of the conventional glass ionomers such as Ketac-fil, two photocurable glass ionomer restoratives have been introduced to the dental profession. The initial objective of this study was to compare the thermal expansion coefficients on the new formulations, Vari-Glass and Fuji II ionomer to the conventional glass ionomer composites using thermal mechanical analysis and to determine the residual monomer contents after photopolymerization using differential scanning calorimetry. Results suggest that these materials exhibit multiphase morphologies. Conventional glass ionomers exhibit two distinct glass transition temperatures. While Fuji II exhibits many of the characteristics of a conventional glass ionomer, Vari-Glass behaves more as a glass-filled resin composite. Fuji II and Ketac-fil exhibit expansion coefficients which are compatible with tooth structure below body temperature, but may cause significant stress on the bond to tooth structure due to shrinkage of the materials at temperatures slightly above body temperature. In contrast, the Vari-Glass formulation exhibits an expansion coefficient which is over three times that of tooth structure and will result in significant stresses above or below body temperature.

  4. Microleakage of glass ionomer/composite laminate Class V restorations.

    PubMed

    McInnes, P; Perkins, E; Weinberg, R

    1990-02-01

    The aim of this investigation was to evaluate the effects on microleakage of pretreating dentin with polyacrylic acid (PAA), prior to placing a glass ionomer base/composite laminate restoration. Class V erosion-type lesions with the incisal margin on enamel and the cervical margin below the cemento-enamel junction (CEJ), were prepared in 50 sound extracted teeth. These teeth were divided into five dentin treatment groups: A) 10% PAA; B) 20% PAA; C) and D) 40% PAA; E) no dentin preconditioning. In groups A, B, C and E, a glass ionomer base was placed within 1 mm of the margins. In group D the glass ionomer base extended to the cervical margin. The glass ionomer base and the incisal enamel were etched with 37% phosphoric acid prior to placing a bonding agent and restoring with a composite. The restorations were finished and polished and the teeth were stored in distilled water at 37 degrees C for 7 days. They were thermocycled in 0.5% fuchsin dye for 500 cycles (5 degrees C to 60 degrees C), embedded in epoxy resin, and sectioned at 250 mu intervals through the restorations. The section of each tooth exhibiting the most severe dye penetration along the tooth/restoration interface was evaluated and scored both incisally and cervically: 0 = no leakage; 1 = leakage up to the glass ionomer base; 2 = leakage up to 1/2 the wall length; 3 = leakage exceeding 1/2 the wall length. Cervically, the median leakage for all groups was 3.0. Incisally, the median leakage for all the groups was 0.0.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2375848

  5. Retention of a resin-based sealant and a glass ionomer used as a fissure sealant in children with special needs

    PubMed Central

    Nualart-Grollmus, Zacy-Carola

    2014-01-01

    Objectives: The aim of this research is to evaluate the retention of sealants of resin and resin-modified ionomeric glass pits and fissures, on first permanent molars of special patients. Material and Methods: The sample was comprised by 32 children. The ages were between 7 and 18 years. The sealing procedure was made with the relative isolation of the molars to be sealed, through the use of cotton rolls. Two molars were sealed with Clinpro Sealant 3M Dental and the others with Vitremer. Checking of the sealants was made after 3 and 6 months of their placement, evaluating with 3 values: TR: Totally Restrained; PR: Partially Restrained; and CL: Completely Lost. Results: 67.18% of the resinous sealants, and 70.31% of the glass ionomer sealants were successful after three months. After six months, 57.81% of the resin-based sealants and 51.56% of the glass ionomer sealants were successful. When performing the Chi-square statistical analysis (P<0.05) no statistical significance was observed after 6 months. Conclusions: The retention of the resin sealant was similar to that of the glass ionomer cement at the end of six months and the retention of sealants on maxillary teeth was higher than on mandibular teeth. Key words:Sealant, glass ionomer, retention, caries, special needs. PMID:25674325

  6. Biocompatibility of a new pulp capping cement

    PubMed Central

    Poggio, Claudio; Ceci, Matteo; Beltrami, Riccardo; Dagna, Alberto; Colombo, Marco; Chiesa, Marco

    2014-01-01

    Summary Aim The aim of the present study was to evaluate the biocompatibility of a new pulp capping material (Biodentine, Septodont) compared with reference pulp capping materials: Dycal (Dentsply), ProRoot MTA (Dentsply) and MTA-Angelus (Angelus) by using murine odontoblast cell line and Alamar blue and MTT cytotoxicity tests. Methods The citocompatibility of murine odontoblasts cells (MDPC-23) were evaluated at different times using a 24 Transwell culture plate by Alamar blue test and MTT assay. Results The results were significantly different among the pulp capping materials tested. Biocompatibility was significant different among materials with different composition. Conclusions Biodentine and MTA-based products show lower cytotoxicity varying from calcium hydroxide-based material which present higher citotoxicity. PMID:25002921

  7. Enamel and Cementum Fluoride Uptake from a Glass Ionomer Cement

    Microsoft Academic Search

    D. H. Retief; E. L. Bradley; J. C. Denton; P. Switzer

    1984-01-01

    Class V cavities were prepared at the cemento-enamel junction on the facial surfaces of 45 extracted human central maxillary incisors. Enamel samples for analysis were obtained by means of perchloric acid etching from circular areas, 1 mm in diameter, positioned 1.5, 3.5, 5.5, and 7.5 mm from the incisal and apical margins of the restorations, respectively. The preparations were filled

  8. Comparative in vitro evaluation of internal adaptation of resin-modified glass ionomer, flowable composite and bonding agent applied as a liner under composite restoration: A scanning electron microscope study

    PubMed Central

    Soubhagya, M; Goud, K Mallikarjun; Deepak, B S; Thakur, Sophia; Nandini, T N; Arun, J

    2015-01-01

    Background: The use of resin-modified glass Ionomer cement in sandwich technique is widely practiced with the advent of various newer generation of composites the bond between resin-modified glass Ionomer and these resins should be validated. This study is done to evaluate the interfacial microgaps between different types of liners and dentin, liners and composite (Filtek p60 [FLp60]) using scanning electron microscope (SEM). Materials and Methods: Standardized Class V preparations were performed in buccal/lingual surfaces of 30 caries, crack and defect-free extracted human third molars. The prepared teeth were divided into three groups. Group I: Single bond (SB), Group II: SB + synergy flow, Group III: SB + vitrebond. They were restored with composite resin FLp60, according to the manufacturer instructions. The SB + vitrebond, cross-sectioned through the canter of the restoration. The specimens were fixed, dehydrated, polished, and processed for SEM. The internal adaptation of the materials to the axial wall was analyzed under SEM with ×1000 magnification. Results: The data obtained were analyzed with nonparametric tests (Kruskal–Wallis, P < 0.05). flowable composite or resin-modified glass ionomer applied in conjunction with adhesive resulted in statistically wider microgaps than occurred when the dentin was only hybridized prior to the restoration. Conclusion: Hybridization of dentin only provides superior sealing of the dentin-restoration interface than does flowable resin or resin-modified glass ionomer. PMID:25954067

  9. Measurement of hydrostatic pressures during simulated post cementation.

    PubMed

    Morando, G; Leupold, R J; Meiers, J C

    1995-12-01

    Tooth sensitivity and fracture after cementation of posts for endodontically treated teeth have been a problem. This investigation developed an in vitro method of measuring intraradicular hydrostatic pressures created during simulated post cementation. The testing apparatus consisted of a pressure transducer and brush recorder connected to precision milled post spaces in a Plexiglas block. Cast post and cores were fabricated and cemented with three different luting agents: resinous cement, glass ionomer cement, and zinc phosphate cement. Mean hydrostatic pressures (psi) recorded during post cementation were zinc phosphate cement, 22.67; resinous cement, 19.77; and glass ionomer cement, 17.66. Zinc phosphate cement created substantially greater hydrostatic pressures than either the resinous or glass ionomer cements. This in vitro system was capable of discriminating intraradicular hydrostatic pressures among different classes of luting agents. PMID:8778381

  10. Retentive strength of luting cements for stainless steel crowns: an in vitro study.

    PubMed

    Subramaniam, Priya; Kondae, Sapna; Gupta, Kamal Kishore

    2010-01-01

    The present study evaluated and compared the retentive strength of three luting cements. A total of forty five freshly extracted human primary molars were used in this study. The teeth were prepared to receive stainless steel crowns. They were then randomly divided into three groups, of fifteen teeth each, so as to receive the three different luting cements: conventional glass ionomer resin modified glass ionomer and adhesive resin. The teeth were then stored in artificial saliva for twenty four hours. The retentive strength of the crowns was determined by using a specially designed Instron Universal Testing Machine (Model 1011). The data was statistically analyzed using ANOVA to evaluate retentive strength for each cement and Tukey test for pair wise comparison. It was concluded that retentive strength of adhesive resin cement and resin modified glass ionomer cement was significantly higher than that of the conventional glass ionomer cement. PMID:20831131

  11. Comparison of shear bond strength of resin-modified glass ionomer to conditioned and unconditioned mineral trioxide aggregate surface: An in vitro study

    PubMed Central

    Gulati, Shikha; Shenoy, Vanitha Umesh; Margasahayam, Sumanthini Venkatasubramanyam

    2014-01-01

    Introduction: The aim of this study was to compare the shear bond strength of resin modified glass ionomer cement to conditioned and unconditioned mineral trioxide aggregate surface. Materials and Method: White Mineral Trioxide Aggregate (WMTA) and Resin Modified Glass Ionomer Cement (RMGIC) were used for the study. 60 WMTA specimens were prepared and stored in an incubator at 37° C and 100% humidity for 72 hrs. The specimens were then divided into two groups- half of the specimens were conditioned and remaining half were left unconditioned, subsequent to which RMGIC was placed over MTA. The specimens were then stored in an incubator for 24 hrs at 37° C and 100% humidity. The shear bond strength value of RMGIC to conditioned and unconditioned WMTA was measured and compared using unpaired 't ?’ test. Results: The mean shear bond strength of value of RMGIC to conditioned and unconditioned WMTA was 6.59 MPa and 7.587 MPa respectively. Statistical analysis using unpaired t-test revealed that the difference between values of two groups was not statistically significant (P > 0.05). Conclusions: During clinical procedures like pulp capping and furcal repair, if RMGIC is placed as a base over MTA, then conditioning should be done to increase the bond strength between RMGIC and dentin and any inadvertent contact of conditioner with MTA will not significantly affect the shear bond strength value of RMGIC to MTA. PMID:25298644

  12. The Biocompatibility of Porous vs Non-Porous Bone Cements: A New Methodological Approach

    PubMed Central

    Dall’Oca, C.; Maluta, T.; Cavani, F.; Morbioli, G.P.; Bernardi, P.; Sbarbati, A.; Degl’Innocenti, D.; Magnan, B.

    2014-01-01

    Composite cements have been shown to be biocompatible, bioactive, with good mechanical properties and capability to bind to the bone. Despite these interesting characteristic, in vivo studies on animal models are still incomplete and ultrastructural data are lacking. The acquisition of new ultrastructural data is hampered by uncertainties in the methods of preparation of histological samples due to the use of resins that melt methacrylate present in bone cement composition. A new porous acrylic cement composed of polymethyl-metacrylate (PMMA) and ?-tricalcium-phosphate (p-TCP) was developed and tested on an animal model. The cement was implanted in femurs of 8 New Zealand White rabbits, which were observed for 8 weeks before their sacrifice. Histological samples were prepared with an infiltration process of LR white resin and then the specimens were studied by X-rays, histology and scanning electron microscopy (SEM). As a control, an acrylic standard cement, commonly used in clinical procedures, was chosen. Radiographic ultrastructural and histological exams have allowed finding an excellent biocompatibility of the new porous cement. The high degree of osteointegration was demonstrated by growth of neo-created bone tissue inside the cement sample. Local or systemic toxicity signs were not detected. The present work shows that the proposed procedure for the evaluation of biocompatibility, based on the use of LR white resin allows to make a thorough and objective assessment of the biocompatibility of porous and non-porous bone cements. PMID:24998920

  13. Bioglass: A novel biocompatible innovation

    PubMed Central

    Krishnan, Vidya; Lakshmi, T.

    2013-01-01

    Advancement of materials technology has been immense, especially in the past 30 years. Ceramics has not been new to dentistry. Porcelain crowns, silica fillers in composite resins, and glass ionomer cements have already been proved to be successful. Materials used in the replacement of tissues have come a long way from being inert, to compatible, and now regenerative. When hydroxyapatite was believed to be the best biocompatible replacement material, Larry Hench developed a material using silica (glass) as the host material, incorporated with calcium and phosphorous to fuse broken bones. This material mimics bone material and stimulates the regrowth of new bone material. Thus, due to its biocompatibility and osteogenic capacity it came to be known as “bioactive glass-bioglass.” It is now encompassed, along with synthetic hydroxyapatite, in the field of biomaterials science known as “bioactive ceramics.” The aim of this article is to give a bird's-eye view, of the various uses in dentistry, of this novel, miracle material which can bond, induce osteogenesis, and also regenerate bone. PMID:23833747

  14. Mechanical and In Vitro Biocompatibility of Brushite Cement Modified by Polyethylene Glycol.

    PubMed

    Roy, Mangal; Devoe, Ken; Bandyopadhyay, Amit; Bose, Susmita

    2012-12-01

    Brushite (dicalcium phosphate dihydrate, DCPD) cement, owing to its high solubility in physiological condition and ability to guide new bone formation, is widely used to treat bone defects. In the present study, we have evaluated the effects of poly ethylene glycol (PEG) addition on the setting time, compressive strength and in vitro biocompatibility of brushite cement. The brushite cements were prepared by mixing ?-tricalcium phosphate [?-TCP, Ca(3)(PO(4))(2)] and monocalcium phosphate monohydrate [MCPM, Ca(H(2)PO(4))(2). H(2)O]. PEG was introduced at 2.0 and 5.0 wt% with the liquid. Introduction of PEG resulted in marginal increase in both initial and final setting time; however, significantly affected the compressive strength. Effects of PEG incorporation on in vitro biocompatibility of brushite cements were studied by using human fetal osteoblast cells (hFOB) cells. Field emission scanning electron microscope (FESEM) images and immunohistochemical analysis indicated that pure and PEG incorporated brushite cement facilitates cell adhesion, proliferation and differentiation. Fewer cells expressed vinculin protein with increased PEG content in the cement. Cell proliferation was found to decrease with increased PEG concentration while the cell differentiation increased with PEG content. Our results provide a better understanding of in vitro biocompatibility of PEG added brushite cements that can be used to customize the cement compositions based on application need. PMID:23139441

  15. Influence of citric acid on the surface texture of glass ionomer restorative materials

    PubMed Central

    Reddy, Dappili Swami Ranga; Kumar, Ramachandran Anil; Venkatesan, Sokkalingam Mothilal; Narayan, Gopal Shankar; Duraivel, Dasarathan; Indra, Rajamani

    2014-01-01

    Aim: This study determined the effectiveness of G-coat plus surface protective agent over petroleum jelly on the surface texture of conventional Glass ionomer restorative materials. Materials and Methods: Three chemically cured conventional glass ionomer restorative materials type II, type IX and ketac molar were evaluated in this study. Sixty specimens were made for each restorative material. They were divided into two groups of thirty specimens each. Of the sixty specimens, thirty were coated with G-coat plus (a nano-filler coating) and the rest with petroleum jelly. Thirty samples of both protective coating agents were randomly divided into six groups of five specimens and conditioned in citric acid solutions of differing pH (pH 2, 3, 4, 5, 6 & 7). Each specimen was kept in citric acid for three hours a day, and the rest of time stored in salivary substitute. This procedure was repeated for 8 days. After conditioning, the surface roughness (Ra, ?m) of each specimen was measured using a surface profilometer (Taylor & Habson, UK). Data was analyzed using one-way analysis of variance (ANOVA) and Tukey's HSD test at a significance level of 0.05. Results: The surface textures of all the tested glass ionomer restorative materials protected with G-coat plus were not significantly affected by acids at low pH. The surface textures of all the tested glass ionomer restorative materials protected with petroleum jelly coating were significantly affected by acids at low pH. Conclusion: The effects of pH on the surface texture of glass ionomer restoratives are material dependent. Among all the materials tested the surface texture of Type II GIC (Group I) revealed marked deterioration when conditioned in solutions of low pH and was statistically significant. Hence, a protective coating either with G-coat plus or with light polymerized low viscosity unfilled resin adhesives is mandatory for all the glass ionomer restorations to increase the wear resistance of the restorative materials. PMID:25298643

  16. Bonding ability of paste-paste glass ionomer systems to tooth structure: in vitro studies.

    PubMed

    Cook, N B; Feitosa, S A; Patel, A; Alfawaz, Y; Eckert, G J; Bottino, M C

    2015-01-01

    This study investigated the effect of nonrinse conditioners (ie, Ketac Nano Primer [KNP] and GC Self Conditioner [SC]) used as substrate pretreatment and their respective paste-paste resin-modified glass-ionomer cement (RMGIC) (ie, Ketac Nano [KN] and Fuji Filling LC [FF]) on microtensile bond strength to dentin and marginal sealing when compared with traditional RMGIC (ie, Photac Fil [PF] and Fuji II LC [FII]) used in association with polyacrylic acid (ie, Ketac Cavity Conditioner [KC] and GC Cavity Conditioner [CC]). A total of 192 extracted human molars were allocated into eight groups: KNP-KN, KC-KN, KNP-PF, KC-PF, SC-FF, CC-FF, SC-FII, and CC-FII. For microtensile bond strength, the teeth were sectioned to expose occlusal dentin and restored according to the group. After 24 hours the teeth were cut to yield nine beams per tooth (±0.8 mm(2)). Testing was done using a universal testing machine followed by failure mode classification. For microleakage testing, standardized cavity preparations were made on the buccal cementoenamel junction and restored according to the group. The teeth were thermocycled (500 cycles, 8°C to 48°C), sealed, immersed in methylene blue for 24 hours, and then assessed for microleakage using a stereomicroscope. Microtensile bond strengths in megapascals (mean±SE) were KNP-KN: 14.9 ± 1.6, KC-KN: 17.2 ± 1.5, KNP-PF: 31.2 ± 1.6, KC-PF: 26.2 ± 1.2, SC-FF: 23.6 ± 1.5, SC-FII: 31.2 ± 1.5, and CC-FII: 21.9 ± 1.5. Cervical margins showed more microleakage compared with occlusal margins. Overall, the use of nonrinse conditioners in association with traditional RMGICs demonstrated superior microtensile bond strengths to dentin when compared with the paste-paste RMGICs. Meanwhile, the association between polyacrylic acid (CC) and a traditional RMGIC (FII) led to the least microleakage for cervical locations when compared with all other groups. PMID:25535780

  17. Biocompatibility and resorption of a brushite calcium phosphate cement.

    PubMed

    Theiss, Felix; Apelt, Detlef; Brand, Bastian; Kutter, Annette; Zlinszky, Katalin; Bohner, Marc; Matter, Sandro; Frei, Christian; Auer, Joerg A; von Rechenberg, Brigitte

    2005-07-01

    A hydraulic calcium phosphate cement with beta-tricalcium phosphate (TCP) granules embedded in a matrix of dicalcium phosphate dihydrate (DCPD) was implanted in experimentally created defects in sheep. One type of defect consisted of a drill hole in the medial femoral condyle. The other, partial metaphyseal defect was located in the proximal aspect of the tibia plateau and was stabilized using a 3.5 mm T-plate. The bone samples of 2 animals each per group were harvested after 2, 4, 6 and 8 weeks. Samples were evaluated for cement resorption and signs of immediate reaction, such as inflammation, caused by the cement setting in situ. Differences regarding these aspects were assessed for both types of defects using macroscopical, radiological, histological and histomorphometrical evaluations. In both defects the brushite matrix was resorbed faster than the beta-TCP granules. The resorption front was followed directly by a front of new bone formation, in which residual beta-TCP granules were embedded. Cement resorption occurred through (i) extracellular liquid dissolution with cement disintegration and particle formation, and (ii) phagocytosis of the cement particles through macrophages. Signs of inflammation or immunologic response leading to delayed new bone formation were not noticed at any time. Cement degradation and new bone formation occurred slightly faster in the femur defects. PMID:15701367

  18. Caries-preventive effect of glass ionomer and resin-based fissure sealants on permanent teeth: a meta analysis.

    PubMed

    Yengopal, Veerasamy; Mickenautsch, Steffen; Bezerra, Ana C; Leal, Soraya C

    2009-09-01

    The purpose of this quantitative systematic review was to appraise the evidence on the caries-preventive effect of glass ionomer cement (GIC) in relation to resin-based fissure sealants. Nine English and two Portuguese databases were searched (15 January 2008). Randomized clinical trials and systematic reviews were considered for inclusion. Trial exclusion criteria were: drop-out rates > 33%; no randomization; baseline differences in groups not statistically adjusted; and no clinically important outcomes were presented. Two authors reviewed the articles independently. The outcome measure for the caries preventive effect was caries absence on sealed teeth. Of the 112 identified articles, 25 were selected for review. Of these, 14 were excluded and 11 accepted (8 trials; 3 systematic reviews). The accepted reviews provided no evidence of superiority of either sealant material. Six trials were included for meta-analysis. The pooled odds ratio was 0.96, 95% CI 0.62-1.49, indicating no difference in the caries-preventive effect of GIC and resin-based fissure sealant material. This systematic review with meta-analysis found no evidence that either material was superior to the other in the prevention of dental caries. Thus, both materials appear equally suitable for clinical application as a fissure sealant material. PMID:19776504

  19. Ultrastructural study of a glass ionomer-based, all-in-one adhesive

    Microsoft Academic Search

    Franklin R. Tay; Hidehiko Sano; Junji Tagami; Masanori Hashimoto; Keith M. Moulding; Cynthia Yiu; David H. Pashley

    2001-01-01

    Objective: Reactmer Bond (Shofu Inc., Kyoto, Japan) is a glass ionomer (GI) based, tri-curable, all-in-one, filled adhesive. Both fluoroaluminosilicate glass (FASG) and fully pre-reacted glass (F-PRG) are used as fillers. This study examined the ultrastructure and elemental composition of resin–dentine interfaces that were treated with this adhesive.Methods: Dentine disks prepared from human third molars were abraded with either 600- or

  20. The bactericidal and biocompatible characteristics of reinforced calcium phosphate cements

    Microsoft Academic Search

    Tianyi Wu; Xiaolin Hua; Zhiwei He; Xinfu Wang; Xiaowei Yu; Weiping Ren

    2012-01-01

    Infection remains a serious medical problem in orthopaedic surgery. Antibiotic administration can be available either systemically via the blood stream or locally, directly into the infected bone. One of the main limitations of antibiotic administration is the development of multi-antibiotic-resistant bacterial strains. In this study, we developed bactericidal calcium phosphate cements (CPC) by incorporation of different molecular weight chitosan and

  1. Biocompatibility and resorption of a brushite calcium phosphate cement

    Microsoft Academic Search

    Felix Theiss; Detlef Apelt; Bastian Brand; Annette Kutter; Katalin Zlinszky; Marc Bohner; Sandro Matter; Christian Frei; Joerg A. Auer; Brigitte von Rechenberg

    2005-01-01

    A hydraulic calcium phosphate cement with ?-tricalcium phosphate (TCP) granules embedded in a matrix of dicalcium phosphate dihydrate (DCPD) was implanted in experimentally created defects in sheep. One type of defect consisted of a drill hole in the medial femoral condyle. The other, partial metaphyseal defect was located in the proximal aspect of the tibia plateau and was stabilized using

  2. The bactericidal and biocompatible characteristics of reinforced calcium phosphate cements.

    PubMed

    Wu, Tianyi; Hua, Xiaolin; He, Zhiwei; Wang, Xinfu; Yu, Xiaowei; Ren, Weiping

    2012-08-01

    Infection remains a serious medical problem in orthopaedic surgery. Antibiotic administration can be available either systemically via the blood stream or locally, directly into the infected bone. One of the main limitations of antibiotic administration is the development of multi-antibiotic-resistant bacterial strains. In this study, we developed bactericidal calcium phosphate cements (CPC) by incorporation of different molecular weight chitosan and hydroxypropyltrimethyl ammonium chloride chitosan (HACC). Two standard strains, S. epidermidis (ATCC35984) and S. aureus (ATCC25923), and one clinical isolate, methicillin-resistant S. epidermidis (MRSE), were selected to evaluate the antibacterial activity of these bone cements. Our data showed that the CPC loaded with low molecular weight chitosan and HACC significantly inhibited the bacterial adhesion and biofilm formation. In addition, HACC-containing CPC has no cytotoxic effects on both mouse pluripotent C3H10T1/2cell line and a murine L929 fibroblast cell line. We propose that HACC-containing CPC represents a promising polymer-based bactericidal bone scaffold in controlling orthopaedic surgery-related infection. PMID:22556166

  3. Dental polyelectrolyte cements: II: effect of powder/liquid ratio on their rheology.

    PubMed

    Cook, W D

    1983-01-01

    The rheological behaviour during the setting of a range of zinc polycarboxylate and glass ionomer dental cements has been studied. The influence of the powder/liquid ratio was found to alter the rate of reaction without altering the basic form of the kinetics. Two models were advanced to explain the rheological and chemical differences between the two types of polyelectrolyte cement. The setting of the glass ionomer cements was consistent with the development of a homogeneous polymer network whereas the zinc polycarboxylate cements were viewed as setting by an inhomogeneous core-growth reaction. PMID:6838954

  4. Evaluation of the Effect of Different Food Media on the Marginal Integrity of Class V Compomer, Conventional and Resin-Modified Glass-Ionomer Restorations: An In Vitro Study

    PubMed Central

    Dinakaran, Shiji

    2015-01-01

    Background: Cervical lesions of anterior and posterior teeth are a common finding in routine dental practice. They are of much concern to the patient, if present in esthetically sensitive regions. Adhesive tooth-colored restorative materials are generally recommended for treating such lesions. The aim of the present study was to evaluate and compare the effect of various food media (lime juice, tea, coffee, and Coca-Cola) on the marginal integrity of Class V compomer (Dyract®), conventional glass-ionomer (Fuji II) and resin-modified glass-ionomer (Fuji II LC improved) restorations along their cemental and enamel margins with saline as control media. Materials and Methods: After restoration of prepared Class V cavities in human premolars with the three different materials (n = 8), they were immersed in the test media for 7 days and then stained with methylene blue dye. Buccolingual sections were prepared and examined under stereomicroscope and scores (0-2) were given. Results: Data were analyzed statistically using one-way analysis of variance in SPSS version 16.0. P < 0.05 were considered statistically significant. Conclusions: Among the three tested materials Compomer (Dyract®) showed more marginal integrity than the other two. Micro leakage values of Fuji II and Fuji II LC improved were statistically significant in acidic media (lime juice and Coca-Cola) compared to saline. Enamel margins showed more marginal adaptation than cemental margins. PMID:25878480

  5. Comparative evaluation of microleakage of nano-filled resin-modified glass ionomer: An in vitro study

    PubMed Central

    Eronat, Nesrin; Yilmaz, Emir; Kara, Nazan; Topaloglu, Ak Asli

    2014-01-01

    Objective: This in vitro study evaluated the microleakage of a nano-filled resin-modified glass ionomer and a high viscosity glass-ionomer restorations in class V cavities. Materials and Methods: Thirty-two class V cavities prepared on the buccal and lingual surfaces of 16 sound, third molar teeth were randomly assigned into two groups and restored by one of the glass ionomer material; Group A: A high viscosity (Ketac Molar, 3M ESPE) Group B: A nano-filled resin-modified (Ketac N100, 3M ESPE) glass ionomer. One clinician prepared all the cavities. The materials were used according to the manufacturers’ recommendations. The restored teeth were then stored in distilled water at 37°C for 24 h, thermocycled at 5-55°C for 1000 cycles. The specimens were immersed in aqueous solution of Indian ink dye for 48 h at room temperature. They were embedded in resin polyester and sectioned longitudinally in a buccolingual direction. Microleakage was assessed according to the depth of dye penetration along the restoration. The extent of dye penetration at the occlusal and gingival margins was assessed using a stereo microscope. Randomly selected samples from each group were prepared for scanning electron microscope evaluation. The data were statistically analyzed with Friedman and Wilcoxon signed ranks tests. Results: There were statistically significant differences between the microleakage scores of the two groups for both occlusal and gingival scores (P = 0.001). Occlusal and gingival scores for high viscosity glass ionomer (P = 0.024) and nanoionomer (P = 0.021) using Wilcoxon signed ranks tests showed statistically significant differences. High viscosity glass ionomer showed significantly less microleakage compared to the nano-filled resin-modified glass-ionomer (RMGIs) at occlusal margin (P = 0.001). No significant differences were found between the groups at gingival margin (P = 0.0317). Conclusion: Within the limitations of this in vitro study, nano-filled RMGIs restorations did not perform better than high viscosity glass ionomer in class V cavities in terms of microleakage assessment. PMID:25512723

  6. In vivo microleakage of luting cements for cast crowns.

    PubMed

    White, S N; Yu, Z; Tom, J F; Sangsurasak, S

    1994-04-01

    Standardized tooth preparations were completed on previously intact human molars in vivo, and castings were made with a precious metal ceramic alloy by conventional techniques. The castings were randomly assigned to the following luting agents: zinc phosphate, composite resin-glass ionomer hybrid, and a composite resin-glass ionomer hybrid with a dentinal bonding agent and were cemented in a standardized manner to periodontally compromised molars. After 6 months the teeth were carefully extracted, stained, embedded, and sectioned, and the in vivo microleakage was measured. ANOVA disclosed significant differences between groups, and a multiple comparisons test revealed that the zinc phosphate group leaked significantly more than other cement groups. PMID:8195995

  7. Comparison of effect of desensitizing agents on the retention of crowns cemented with luting agents: an in vitro study

    PubMed Central

    Pandharinath, Dange Shankar; Arun, Khalikar; Smita, Vaidya

    2012-01-01

    PURPOSE Many dentists use desensitizing agents to prevent hypersensitivity. This study compared and evaluated the effect of two desensitizing agents on the retention of cast crowns when cemented with various luting agents. MATERIALS AND METHODS Ninety freshly extracted human molars were prepared with flat occlusal surface, 6 degree taper and approximately 4 mm axial length. The prepared specimens were divided into 3 groups and each group is further divided into 3 subgroups. Desensitizing agents used were GC Tooth Mousse and GLUMA® desensitizer. Cementing agents used were zinc phosphate, glass ionomer and resin modified glass ionomer cement. Individual crowns with loop were made from base metal alloy. Desensitizing agents were applied before cementation of crowns except for control group. Under tensional force the crowns were removed using an automated universal testing machine. Statistical analysis included one-way ANOVA followed by Turkey-Kramer post hoc test at a preset alpha of 0.05. RESULTS Resin modified glass ionomer cement exhibited the highest retentive strength and all dentin treatments resulted in significantly different retentive values (In Kg.): GLUMA (49.02 ± 3.32) > Control (48.61 ± 3.54) > Tooth mousse (48.34 ± 2.94). Retentive strength for glass ionomer cement were GLUMA (41.14 ± 2.42) > Tooth mousse (40.32 ± 3.89) > Control (39.09 ± 2.80). For zinc phosphate cement the retentive strength were lowest GLUMA (27.92 ± 3.20) > Control (27.69 ± 3.39) > Tooth mousse (25.27 ± 4.60). CONCLUSION The use of GLUMA® desensitizer has no effect on crown retention. GC Tooth Mousse does not affect the retentive ability of glass ionomer and resin modified glass ionomer cement, but it decreases the retentive ability of zinc phosphate cement. PMID:22977719

  8. Effect of Tricalcium Aluminate on the Physicochemical Properties, Bioactivity, and Biocompatibility of Partially Stabilized Cements

    PubMed Central

    Chang, Kai-Chun; Chang, Chia-Chieh; Huang, Ying-Chieh; Chen, Min-Hua; Lin, Feng-Huei; Lin, Chun-Pin

    2014-01-01

    Background/Purpose Mineral Trioxide Aggregate (MTA) was widely used as a root-end filling material and for vital pulp therapy. A significant disadvantage to MTA is the prolonged setting time has limited the application in endodontic treatments. This study examined the physicochemical properties and biological performance of novel partially stabilized cements (PSCs) prepared to address some of the drawbacks of MTA, without causing any change in biological properties. PSC has a great potential as the vital pulp therapy material in dentistry. Methods This study examined three experimental groups consisting of samples that were fabricated using sol-gel processes in C3S/C3A molar ratios of 9/1, 7/3, and 5/5 (denoted as PSC-91, PSC-73, and PSC-55, respectively). The comparison group consisted of MTA samples. The setting times, pH variation, compressive strength, morphology, and phase composition of hydration products and ex vivo bioactivity were evaluated. Moreover, biocompatibility was assessed by using lactate dehydrogenase to determine the cytotoxicity and a cell proliferation (WST-1) assay kit to determine cell viability. Mineralization was evaluated using Alizarin Red S staining. Results Crystalline phases, which were determined using X-ray diffraction analysis, confirmed that the C3A contents of the material powder differed. The initial setting times of PSC-73 and PSC-55 ranged between 15 and 25 min; these values are significantly (p<0.05, ANOVA and post-hoc test) lower than those obtained for MTA (165 min) and PSC-91 (80.5 min). All of the PSCs exhibited ex vivo bioactivity when immersed in simulated body fluid. The biocompatibility results for all of the tested cements were as favorable as those of the negative control, except for PSC-55, which exhibited mild cytotoxicity. Conclusion PSC-91 is a favorable material for vital pulp therapy because it exhibits optimal compressive strength, a short setting time, and high biocompatibility and bioactivity. PMID:25247808

  9. Evaluation of the in vitro biocompatibility of PMMA/high-load HA/carbon nanostructures bone cement formulations.

    PubMed

    Gonçalves, Gil; Portolés, María-Teresa; Ramírez-Santillán, Cecilia; Vallet-Regí, María; Serro, Ana Paula; Grácio, José; Marques, Paula A A P

    2013-12-01

    Although commercially-available poly(methyl methacrylate) bone cement is widely used in total joint replacements, it has many shortcomings, a major one being that it does not osseointegrate with the contiguous structures. We report on the in vitro evaluation of the biocompatibility of modified formulations of the cement in which a high loading of hydroxyapatite (67 wt/wt%), an extra amount of benzoyl peroxide, and either 0.1 wt/wt% functionalized carbon nanotubes or 0.5 wt/wt% graphene oxide was added to the cement powder and an extra amount of dimethyl-p-toluidiene was added to the cement's liquid monomer. This evaluation was done using mouse L929 fibroblasts and human Saos-2 osteoblasts. For each combination of cement formulation and cell type, there was high cell viability, low apoptosis, and extensive spread on disc surfaces. Thus, these two cement formulations may have potential for use in the clinical setting. PMID:23963685

  10. The impact of zirconium oxide nanoparticles on the hydration chemistry and biocompatibility of white Portland cement.

    PubMed

    Li, Qiu; Deacon, Andrew D; Coleman, Nichola J

    2013-01-01

    Zirconium oxide (ZrO2) has been nominated as a radiopacifying agent for use in MTA-like Portland cement-based root-filling materials. This research examines the impact of 20 wt% ZrO2 nanoparticles in the size range 50 to 75 nm on the early hydration chemistry of white Portland cement. Nano-ZrO2 was found to accelerate the degree of hydration by 26% within the first 24 h by presenting efficient nucleation sites for the precipitation and growth of the early C-S-H gel products. The presence of nano-ZrO2 was also found to divert the fate of the aluminium-bearing reaction products by lowering the ettringite to monosulphate ratio, reducing the size of the ettringite crystals and by increasing the Al:Si ratio of the C-S-H gel phase. The chemical and microstructural changes conferred upon the cement matrix by the nano-ZrO2 particles had a positive impact on in vitro biocompatibility with respect to MG63 osteosarcoma cells (via MTT assay). PMID:24088838

  11. Influence of 2-hydroxyethyl methacrylate content on the optical properties of experimental 2-hydroxyethyl methacrylate-added dental glass ionomer

    Microsoft Academic Search

    Ho-Nam Lim; Bin Yu; Jin Ik Lim; Jin-Soo Ahn; Yong-Keun Lee

    2009-01-01

    The influence of 2-hydroxyethyl methacrylate (HEMA) on the properties of HEMA-added dental glass ionomer (HAGI) should be determined systematically to develop a smart restorative material. The purposes of this study were to determine the influence of incrementally added HEMA in experimental HAGIs on the color, translucency, opalescence, fluorescence and compressive strength, and to compare with those of commercial resin-modified glass

  12. In vitro bioactivity and biocompatibility of calcium phosphate cements using Hydroxy-propyl-methyl-Cellulose (HPMC)

    NASA Astrophysics Data System (ADS)

    Jyoti, M. Anirban; Thai, Van Viet; Min, Young Ki; Lee, Byong-Taek; Song, Ho-Yeon

    2010-12-01

    In this study, the bioactivity and biocompatibility of new calcium phosphate bone cements (CPC) using Hydroxy-propyl-methyl-Cellulose (HPMC) was evaluated to understand the effect of HPMC on bone-bonding apatite formation and biocompatibility. In vitro bioactivity was investigated by incubating the CPC samples containing different ratios of HPMC (0%, 2% and 4% HPMC) in simulated body fluid (SBF) for 2, 7, 14 and 28 days. The formation of bone like apatite was confirmed on CPC surfaces by SEM and XRD analysis. Higher HPMC content of CPC showed faster apatite deposition in SBF. A high Ca ion dissolution profile was also reported with an increase of pH in all samples in SBF. The apatite formation ability of these CPC samples was found to be dependent on both surface chemistry and immersion time in SBF. The In vitro cytotoxicity test showed that the CPC samples with 4% HPMC were fairly cytocompatible for fibroblast L-929 cells. SEM images showed that MG-63 cells were successfully attached to the CPC samples and well proliferated.

  13. Do Laboratory Results Concerning High-Viscosity Glass-Ionomers versus Amalgam for Tooth Restorations Indicate Similar Effect Direction and Magnitude than that of Controlled Clinical Trials? - A Meta-Epidemiological Study

    PubMed Central

    Mickenautsch, Steffen; Yengopal, Veerasamy

    2015-01-01

    Background A large percentage of evidence concerning dental interventions is based on laboratory research. The apparent wealth of laboratory evidence is sometimes used as basis for clinical inference and recommendations for daily dental practice. In this study two null-hypotheses are tested: whether trial results from laboratory and controlled clinical trials concerning the comparison of high-viscosity glass-ionomer cements (HVGIC) to amalgam for restorations placed in permanent posterior teeth have: (i) similar effect direction and (ii) similar effect magnitude. Methods 7 electronic databases were searched, as well as reference lists. Odds ratios (OR) and Standardised Mean Differences (SMD) with 95% Confidence intervals were computed for extracted dichotomous and continuous data, respectively. Pooled effect estimates for laboratory and clinical data were computed to test for effect direction. Odds ratios were converted into SMDs. SMDs from laboratory and clinical data were statistically compared to test for differences in effect magnitude. The analysed results were further investigated within the context of potential influencing or confounding factors using a Directed acyclic graph. Results Of the accepted eight laboratory and nine clinical trials, 13 and 21 datasets could be extracted, respectively. The pooled results of the laboratory datasets were highly statistically significant in favor of amalgam. No statistically significant differences, between HVGICs and amalgam, were identified for clinical data. For effect magnitude, statistically significant differences between clinical and laboratory trial results were found. Both null-hypotheses were rejected. Conclusion Laboratory results concerning high-viscosity glass-ionomers versus amalgam for tooth restorations do not indicate similar effect direction and magnitude than that of controlled clinical trials. PMID:26168274

  14. Efficiency of Amorphous Calcium Phosphate–Containing Orthodontic Composite and Resin Modified Glass Ionomer on Demineralization Evaluated By a New Laser Fluorescence Device

    PubMed Central

    Uysal, Tancan; Amasyali, Mihri; Koyuturk, Alp Erdin; Sagdic, Deniz

    2009-01-01

    Objectives: The aim of this in vitro study was to compare the efficacy of Amorphous Calcium Phosphate (ACP)-containing orthodontic composite and resin-modified glass ionomer cement (RMGIC) on enamel demineralization adjacent to orthodontic brackets evaluated by a new laser fluorescence device. Methods: Sixty extracted maxillary premolars were used in the present study. Twenty orthodontic brackets were bonded with ACP-containing orthodontic adhesive (Aegis-Ortho), 20 were bonded with RMGIC (Fuji Ortho LC) and 20 were bonded with Transbond XT composite as the control. All samples were then cycled for 21 days through a daily procedure of demineralization for 6 hours and remineralization for 17 hours. After this procedure, demineralization evaluations were undertaken by a pen-type laser fluorescence device (DIAGNO-dent Pen). Analysis of variance (ANOVA) and Tukey test was used for statistical evaluation, at P<.05 level. Results: According to ANOVA, significant demineralization variations (?D) were determined among groups (F=6.650; P<.01). The ACP-containing composite showed the lowest (mean: 8.98±2.38) and the control composite showed the highest (mean:12.15±3.83) ?D, during 21 days demineralization process (P<.01). Significant difference was also observed between the ?D scores of the RMGIC (mean: 9.24±2.73) and control (P<.05). No significant differences was found in preventive effects of ACP-containing composite and RMGIC (P<.05) against demineralization. Conclusions: The use of both ACP-containing orthodontic composite and RMGIC should be recommended for any at-risk orthodontic patient to provide preventive actions and potentially remineralize subclinical enamel demineralization. PMID:19421393

  15. Methods and preliminary findings of a cost-effectiveness study of glass-ionomer-based and composite resin sealant materials after 2 yr.

    PubMed

    Goldman, Ann S; Chen, Xi; Fan, Mingwen; Frencken, Jo E

    2014-06-01

    The cost-effectiveness of glass-carbomer, conventional high-viscosity glass-ionomer cement (HVGIC) [without or with heat (light-emitting diode (LED) thermocuring) application], and composite resin sealants were compared after 2 yr in function. Estimated net costs per sealant were obtained from data on personnel time (measured with activity sampling), transportation, materials, instruments and equipment, and restoration costs for replacing failed sealants from a community trial involving 7- to 9-yr-old Chinese children. Cost data were standardized to reflect the placement of 1,000 sealants per group. Outcomes were the differences in the number of dentine caries lesions that developed between groups. The average sealant application time ranged from 5.40 min (for composite resin) to 8.09 min (for LED thermocured HVGIC), and the average cost per sealant for 1,000 performed per group (simulation sample) ranged from $US3.73 (for composite resin) to $US7.50 (for glass-carbomer). The incremental cost-effectiveness of LED thermocured HVGIC to prevent one additional caries lesion per 1,000 sealants performed was $US1,106 compared with composite resin. Sensitivity analyses showed that differences in the cost of materials across groups had minimal impact on the overall cost. Cost and effectiveness data enhance policymakers' ability to address issues of availability, access, and compliance associated with poor oral-health outcomes, particularly when large numbers of children are excluded from care, in economies where oral health services are still developing. PMID:24799118

  16. Fatigue and biocompatibility properties of a poly(methyl methacrylate) bone cement with multi-walled carbon nanotubes.

    PubMed

    Ormsby, Ross; McNally, Tony; O'Hare, Peter; Burke, George; Mitchell, Christina; Dunne, Nicholas

    2012-03-01

    Composites of multi-walled carbon nanotubes (MWCNT) of varied functionality (unfunctionalised and carboxyl and amine functionalised) with polymethyl methacrylate (PMMA) were prepared for use as a bone cement. The MWCNT loadings ranged from 0.1 to 1.0 wt.%. The fatigue properties of these MWCNT-PMMA bone cements were characterised at MWCNT loading levels of 0.1 and 0.25 wt.% with the type and wt.% loading of MWCNT used having a strong influence on the number of cycles to failure. The morphology and degree of dispersion of the MWCNT in the PMMA matrix at different length scales were examined using field emission scanning electron microscopy. Improvements in the fatigue properties were attributed to the MWCNT arresting/retarding crack propagation through the cement through a bridging effect and hindering crack propagation. MWCNT agglomerates were evident within the cement microstructure and the degree of agglomeration was dependent on the level of loading and functionality of the MWCNT. The biocompatibility of the MWCNT-PMMA cements at MWCNT loading levels upto 1.0 wt.% was determined by means of established biological cell culture assays using MG-63 cells. Cell attachment after 4h was determined using the crystal violet staining assay. Cell viability was determined over 7 days in vitro using the standard colorimetric MTT assay. Confocal scanning laser microscopy and SEM analysis was also used to assess cell morphology on the various substrates. PMID:22023747

  17. In Vitro Comparison of Coronal Microleakage between Resilon Alone and Gutta-Percha with a Glass-ionomer Intraorifice Barrier Using a Fluid Filtration Model

    Microsoft Academic Search

    Ryan M. Jack; Gary G. Goodell

    2008-01-01

    The prevention and control of coronal microleakage is critical for successful endodontic outcomes. The purpose of this study was to compare coronal microleakage between Resilon alone and gutta-percha with a glass ionomer intraorifice barrier using a fluid filtration model. Thirty-four extracted human teeth were decoronated, prepared to a standardized length of 16 mm, and instrumented to a .06 taper ISO

  18. Comparative Assessment of ActiV GP\\/Glass Ionomer Sealer, Resilon\\/Epiphany, and Gutta-Percha\\/AH Plus Obturation: A Bacterial Leakage Study

    Microsoft Academic Search

    Joel N. Fransen; Jianing He; Gerald N. Glickman; Alejandro Rios; Jay D. Shulman; Allen Honeyman

    2008-01-01

    The objective of this study was to compare the sealing ability of ActiV GP\\/glass ionomer (GI) sealer (Brasseler USA, Savannah, GA), Resilon\\/Epiphany (Pentron Clinical Technologies, Wallingford, CT), and gutta-percha (GP)\\/AH Plus (Dentsply Maillefer, Tulsa, OK). Seventy-three human single-rooted teeth were randomly divided into three test groups (20 canals each) and two control groups (5 positive and 8 negative). Using Enterococcus

  19. Long-term monitoring of microleakage of dental cements by radiochemical diffusion.

    PubMed

    Powis, D R; Prosser, H J; Wilson, A D

    1988-06-01

    Radioactive 14C sucrose was found to be an ideal marker for microleakage because it did not penetrate tooth tissue, dental cement, or mounting resin. The main finding is that the adhesive cements--the glass-ionomer and polycarboxylate--are significantly more effective at preventing microleakage than are the traditional phosphate cements--silicate and zinc phosphate. The differences can be as high as two orders of magnitude. The adhesive cements provide almost perfect and reliable seals. By contrast, the nonadhesive cements are erratic sealants with most of the restorations leaking. PMID:3042960

  20. Practical clinical considerations of luting cements: A review

    PubMed Central

    Lad, Pritam P; Kamath, Maya; Tarale, Kavita; Kusugal, Preethi B

    2014-01-01

    The longevity of fixed partial denture depends on the type of luting cement used with tooth preparation. The clinician’s understating of various cements, their advantages and disadvantages is of utmost importance. In recent years, many luting agents cements have been introduced claiming clinically better performance than existing materials due to improved characteristics. Both conventional and contemporary dental luting cements are discussed here. The various agents discussed are: Zinc phosphate, Zinc polycarboxylate, Zinc oxide-eugenol, Glass-ionomer, Resin modified GIC, Compomers and Resin cement. The purpose of this article is to provide a discussion that provides a clinical perspective of luting cements currently available to help the general practitioner make smarter and appropriate choices. How to cite the article: Lad PP, Kamath M, Tarale K, Kusugal PB. Practical clinical considerations of luting cements: A review. J Int Oral Health 2014;6(1):116-20. PMID:24653615

  1. Acrylic formulations containing bioactive and biodegradable fillers to be used as bone cements: properties and biocompatibility assessment.

    PubMed

    Lopes, P P; Garcia, M P; Fernandes, M H; Fernandes, M H V

    2013-04-01

    The solid phase of bioactive self-curing acrylic cements was modified by different biodegradable fillers such as poly(3-hydroxybutyrate) (PHB) and its copolymer with hydroxyvalerate (PHBV). The addition of the biodegradable fillers made the cement partially degradable, which is important to allow new bone replacement and ingrowth. The thermal analysis, crystallinity, curing parameters, mechanical properties, degradation and cellular tests were studied in order to characterize the cement performance. Within this context it was verified that the incorporation of the PHBV polymer made the cement more resistant, reaching values within the range reported for typical PMMA bone cements. The results also showed that the cement filled with PHBV took up more water than the cement with PHB after 60 days, for all studied formulations. Regarding the osteoblastic cytocompatibility assessment, the inclusion of the PHBV greatly improved the biological response in both cements filled with the silicate or the borate glass, compared to the inclusion of the PHB. The importance of this novel approach resides on the combination of the properties of the cements components and the possibility of allowing bone regeneration, improving the interfaces with both the prosthesis and the bone, and leading to a new material with suitable performance for application as bone cement. PMID:23827574

  2. Effects of curing mode of resin cements on the bond strength of a titanium post: An intraradicular study

    PubMed Central

    Reza, Fazal; Lim, Siau Peng

    2012-01-01

    Aim: To compare push-out bond strength between self-cured and dual-cured resin cement using a titanium post. Background: Dual-cured resin cements have been found to be less polymerized in the absence of light; thus the bond strength of cements would be compromised due to the absence of light with a metallic post. Materials and Methods: Ten extracted teeth were prepared for cement titanium PARAPOST, of five specimens each, with Panavia F [dual-cured (PF)] and Rely×Luting 2 [self-cured resin-modified glass ionomer luting cement (RL)]; the push-out bond strength (PBS) at three different levels of the sectioned roots was measured. The failure modes were observed and the significance of the differences in bond strength of the two types of cement at each level and at different levels of the same type was analyzed with non-parametric tests. Results: The push-out bond strength of the RL group was greater at all the three levels; with significant differences at the coronal and middle levels (P<0.05). No significant differences in PBS at different levels of the same group were observed. Cement material around the post was obvious in the PF group. The failure mode was mostly adhesive between the post and resin cement in the RL group. Conclusion: Bond strength was greater with self-cured, resin-modified glass ionomer luting cement, using titanium post. PMID:22557808

  3. [Biocompatibility of a new ionomer bone cement in endoprosthetics. In vitro testing using a mixed bone cell culture].

    PubMed

    Meyer, U; Szulczewski, D H; Möller, K; Jones, D B; Wuisman, P

    1996-01-01

    Periosteal derived bovine osteoblasts and osteoclasts migrated in culture onto an ionomeric cement, currently evaluated as a cement for orthopaedic implants. Cell cultures were maintained for 4 weeks and used to study the in-vitro behaviour of cells on the material surface. Osteoblasts and osteoclasts colonized the substrate in monolayers and exhibited their phenotypic morphology. Differentiation into both cell lines were demonstrated by immunostaining. Staining for aluminium in cells growing on the bone cement showed an uptake and storage of aluminium in the cells. EDAX-microanalysis revealed high concentrations of Al and Si in the periosteal tissue. Despite uptake of Al in the cells, signs of toxicity were not apparent in the cell culture system. PMID:8779254

  4. Effect of the CO2 laser on the microleakage of conventional and laser apicetomized teeth retrofilled with glass ionomer: in vitro study

    NASA Astrophysics Data System (ADS)

    Pinheiro, Antonio L. B.; Martorelli, Sergio B. F.

    2000-03-01

    There is a need for further improvement on the level of apical sealing. The use of lasers on apical surgery is still not fully understood, however some good results have been reported. The aim of this study was to assess the effect of the use of the CO2 laser following conventional apicoectomy and retrofilling with glass ionomer using different combinations of power and types of emission 'In Vitro.' Seventy extracted human upper anterior teeth were used on this study. The teeth after conventional apicoectomy were retrofilled with VitremerTM. The samples were randomized into seven groups of 10, Group I acted as negative control. Groups II, III and IV were lased on defocused mode with superpulsed CO2 laser on CW with power output of 0,5; 3 and 7 Watts during 5 seconds respectively. Groups V, VI e VII were lased on defocused mode with continuous emission on CW mode with power output of 1, 10 and 20 Watts during 5 seconds respectively. All specimens were immersed on 2% Methylene Blue solution during 48 h, washed in running tap water and longitudinally sectioned. Three calibrated examiners regarding apical infiltration graded the samples. The results showed difference between groups, where Group II showed smaller level of apical infiltration. It is concluded that improving on apical sealing is better achieved by using 0.5 W on superpulsed on CW.

  5. Comparison of Marginal Microleakage of Glass Ionomer Restorations in Primary Molars Prepared by Chemo-mechanical Caries Removal (CMCR), Erbium: Yttrium Aluminum-Garnet (Er:YAG) Laser and Atraumatic Restorative Technique (ART)

    PubMed Central

    Juntavee, Niwut; Peerapattana, Jomjai; Nualkaew, Nartsajee; Sutthisawat, Sitikorn

    2013-01-01

    ABSTRACT Background: It is important to emphasize that the aspects of pretreatment techniques, as well as the composition and mechanism of adhesion, may decisively influence the effectiveness of the restorative materials in sealing cavity margins and preventing marginal leakage. Aims: This study assessed the in vitro influence of surface preparation techniques on the microleakage of glass ionomer restorations in primary teeth. Materials and methods: The study groups were divided into three different techniques: (1) The chemomechanical caries removal (CMCR) method using the Apacaries gel, (2) the erbium:yttrium aluminum-garnet (Er:YAG) laser method and (3) the atraumatic restorative technique (ART). The teeth restored with a glass ionomer restorative material (Fuji IX GP capsule, GC Corporation, Tokyo, Japan). The dye penetration was measured in micrometers using a polarized light microscope and specific computer software. Results: The results showed that the mean microleakage level after was lowest with the CMCR method using Apacaries gel and highest with the Er:YAG laser. There was a statistically significant difference regarding the mean microleakage level between the group with the CMCR method using Apacaries gel and the Er:YAG laser. Conclusion: Marginal leakage was significantly higher with preparations made using the Er:YAG laser than with the CMCR method using Apacaries gel and spoon excavator (p < 0.05). How to cite this article: Juntavee A, Juntavee N, Peerapattana J, Nualkaew N, Sutthisawat S. Comparison of Marginal Microleakage of Glass Ionomer Restorations in Primary Molars Prepared by Chemomechanical Caries Removal (CMCR), Erbium: Yttrium Aluminum-Garnet (Er:YAG) Laser and Atraumatic Restorative Technique (ART). Int J Clin Pediatr Dent 2013;6(2):75-79. PMID:25206196

  6. Diagnosis and management of cemental tear: a case report.

    PubMed

    Gupta, Hitesh; Puri, Abhinhay; Kumar, Saru

    2014-01-01

    A 32-year-old man complained of swelling after an extraction in the vicinity of the left maxillary premolars. The occlusal surface of the first premolar showed no caries while the second premolar was covered with a crown. Radiographic examination revealed a thin radiolucent defect subgingivally below the cementodentinal junction on the distal aspect. During a review of medical history, the patient presented an extracted fragment that was sent for histopathological examination. A root canal was performed and the defect was closed with mineral trioxide aggregate followed by glass ionomer cement. Histopathology revealed the fragment to be a cemental tear, a condition associated typically with old age, trauma, and traumatic occlusion. Dentists should be aware of this rare entity as a differential diagnosis in cases involving noncarious odontogenic pain. PMID:24784522

  7. Cytotoxicity of commonly used luting cements -An in vitro study.

    PubMed

    Trumpaite-Vanagiene, Rita; Bukelskiene, Virginija; Aleksejuniene, Jolanta; Puriene, Alina; Baltriukiene, Daiva; Rutkunas, Vygandas

    2015-06-01

    The study aimed to 1) evaluate the cytotoxicity of luting cements: Hoffmann's Zinc Phosphate (Hoffmann's ZP), GC Fuji Plus Resin Modified Glass Ionomer (Fuji Plus RMGI) and 3M ESPE RelyX Unicem Resin Cement (RelyX Unicem RC) and 2) test if pre-washing reduces the cements' cytotoxicity. In vitro human gingival fibroblast (HGF) culture model was chosen. The cytotoxicity was evaluated by MTT test, the cell viability -by staining the cells with AO/EB dye mixture. The means±SD of Cell Survival Ratio (CSR%) were compared among different cement types under two testing conditions, with or without cement pre-washing. The CSR%s were compared by ANOVA and linear multiple regression (LMR). Hoffmann's ZPC was less cytotoxic, while Fuji Plus RMGIC and RelyX Unicem RC were more cytotoxic (ANOVA, p<0.001). The type of cement and cement pre-washing jointly explained 90% of cell survival (LMR, p<0.001, adjusted squared R=0.889). The commonly used luting cements such as Hoffmann's ZP, Fuji Plus RMGI and RelyX Unicem RC may have a cytotoxic potential. PMID:25904168

  8. Effect of a calcium-silicate-based restorative cement on pulp repair.

    PubMed

    Tran, X V; Gorin, C; Willig, C; Baroukh, B; Pellat, B; Decup, F; Opsahl Vital, S; Chaussain, C; Boukpessi, T

    2012-12-01

    In cases of pulp injury, capping materials are used to enhance tertiary dentin formation; Ca(OH)(2) and MTA are the current gold standards. The aim of this study was to evaluate the capacity of a new calcium-silicate-based restorative cement to induce pulp healing in a rat pulp injury model. For that purpose, cavities with mechanical pulp exposure were prepared on maxillary first molars of 27 six-week-old male rats, and damaged pulps were capped with either the new calcium-silicate-based restorative cement (Biodentine), MTA, or Ca(OH)(2). Cavities were sealed with glass-ionomer cement, and the repair process was assessed at several time-points. At day 7, our results showed that both the evaluated cement and MTA induced cell proliferation and formation of mineralization foci, which were strongly positive for osteopontin. At longer time-points, we observed the formation of a homogeneous dentin bridge at the injury site, secreted by cells displaying an odontoblastic phenotype. In contrast, the reparative tissue induced by Ca(OH)(2) showed porous organization, suggesting a reparative process different from those induced by calcium silicate cements. Analysis of these data suggests that the evaluated cement can be used for direct pulp-capping. PMID:22983409

  9. A more reliable method for incudostapedial rebridging ossiculoplasty: bone cement and wire.

    PubMed

    Hafiz, Gunter

    2005-01-01

    Polymaleinate glass ionomer cement is a commercially available bone cement (Ketac Cem Radiopaque, ESPE, Germany) that can be used to reconstruct a discontinuity between the incus and the stapes. The popularity of bone cement in otologic surgery is increasing. If the missing part of the incus is too long, the results in the long term could be unsatisfying. Under such circumstances, a new method of incudostapediopexy that uses wire and involves remodeling of the long process of the incus with bone cement is introduced. A retrospective analysis of the outcomes of incudostapedial rebridging ossiculoplasty (ISRO) procedures carried out in 21 patients between June 1999 and September 2003 was performed. A total of 17 patients were treated with bone cement only; in 4 of these patients, hearing loss reoccurred within 6 months. The procedure was repeated in 2 of these patients using both bone cement and wire with satisfactory hearing results (air-bone gaps, 7.5 and 8.8 decibels hearing level [dB HL]) after 1 year. Four patients underwent ISRO wire and bone cement initially. The long-term results of these 6 "wire-and-cement" cases, which were followed for a mean of 21 months, were satisfactory (air-bone gap, 9.8 dB HL). The postoperative air-bone gap in the 15 patients who were treated by ISRO with bone cement only excluding the 2 reoperation cases was 12.1 dB HL. ISRO with bone cement is a cost-effective and safe procedure that yields good hearing results in selected cases. If the distance between eroded incus and stapes is too long to be reconstructed with bone cement alone, the surgeon should consider using wire with bone cement. PMID:15943223

  10. Orthodontic Cements and Demineralization: An In Vitro Comparative Scanning Electron Microscope Study

    PubMed Central

    Prabhavathi, V; Jacob, Josy; Kiran, M Shashi; Ramakrishnan, Murugesan; Sethi, Esha; Krishnan, C S

    2015-01-01

    Background: Comparison of the demineralization potential of four luting cements, i.e. zinc phosphate, conventional glass ionomer cement (GIC), resin-modified GIC and acid modified composite resin. Materials and Methods: This study was conducted on 75 extracted premolar teeth, which were grouped into five, each group containing 15 teeth. Groups were non-banded control, teeth cemented with the above-mentioned cements. These were incubated at 37°C for 30 days in sealable plastic containers, after which the teeth were debanded, cleaned and placed in acid gelatin solution at 37°C for 4 weeks to simulate the cariogenic solution. Then, the teeth were sectioned and examined under scanning electron microscope. The depth of the carious lesions was measured using image analysis with Digimizer software. Results: The depth of the carious lesions was maximum with non-banded group, followed by zinc phosphate, acid modified composite resin, resin-modified GIC and conventional GIC. Conclusions: Among the four orthodontic banding cements compared, the enamel demineralization potential is least with conventional GIC, followed by resin-modified GIC, acid modified composite resin and zinc phosphate. PMID:25859103

  11. In vivo behavior of three different injectable hydraulic calcium phosphate cements

    Microsoft Academic Search

    D. Apelt; F. Theiss; A. O. El-Warrak; K. Zlinszky; R. Bettschart-Wolfisberger; M. Bohner; S. Matter; J. A. Auer; B. von Rechenberg

    2004-01-01

    Two dicalcium phosphate dihydrate (DCPD) hydraulic cements and one apatite hydraulic cement were implanted in epiphyseal and metaphyseal, cylindrical bone defects of sheep. The in vivo study was performed to assess the biocompatibility of the DCPD cements, using the apatite cement as control. After time periods of 2, 4 and 6 months the cement samples were clinically and histologically evaluated.

  12. Conservative approach of a symptomatic carious immature permanent tooth using a tricalcium silicate cement (Biodentine): a case report

    PubMed Central

    Grosgogeat, Brigitte; Seux, Dominique; Farge, Pierre

    2013-01-01

    The restorative management of deep carious lesions and the preservation of pulp vitality of immature teeth present real challenges for dental practitioners. New tricalcium silicate cements are of interest in the treatment of such cases. This case describes the immediate management and the follow-up of an extensive carious lesion on an immature second right mandibular premolar. Following anesthesia and rubber dam isolation, the carious lesion was removed and a partial pulpotomy was performed. After obtaining hemostasis, the exposed pulp was covered with a tricalcium silicate cement (Biodentine, Septodont) and a glass ionomer cement (Fuji IX extra, GC Corp.) restoration was placed over the tricalcium silicate cement. A review appointment was arranged after seven days, where the tooth was asymptomatic with the patient reporting no pain during the intervening period. At both 3 and 6 mon follow up, it was noted that the tooth was vital, with normal responses to thermal tests. Radiographic examination of the tooth indicated dentin-bridge formation in the pulp chamber and the continuous root formation. This case report demonstrates a fast tissue response both at the pulpal and root dentin level. The use of tricalcium silicate cement should be considered as a conservative intervention in the treatment of symptomatic immature teeth. PMID:24303363

  13. Novel experimental cements for use on the dentin-pulp complex.

    PubMed

    Dantas, Raquel Venâncio Fernandes; Conde, Marcus Cristian Muniz; Sarmento, Hugo Ramalho; Zanchi, Cesar Henrique; Tarquinio, Sandra Beatriz Chaves; Ogliari, Fabrício Aulo; Demarco, Flávio Fernando

    2012-01-01

    This aim of this study was to evaluate the physicochemical and biological properties of novel experimental cements (Hybrid, Paste and Resin) based on synergistic combinations of existing materials, including pH, diametral tensile strength (DTS) and cytotoxicity comparing them with mineral trioxide aggregate (MTA - Angelus®) and a glass ionomer cement (GIC) developed at our laboratory. For the physicochemical and biological tests, specimens with standard dimensions were produced. pH measurements were performed with digital pH meter at the following time intervals: 3, 24, 48 and 72 h. For the DTS test, cylindrical specimens were subjected to compressive load until fracture. The MTT assay was performed for cytotoxicity evaluation. Data were analyzed by ANOVA and Tukey's test (?=0.05). Paste group showed pH values similar to MTA, and Hybrid group presented pH values similar to GIC (p>0.05). The tested materials showed pH values ranging from alkaline to near neutrality at the evaluated times. MTA and GIC showed similar DTS values. The lowest and highest DTS values were seen in the Paste and Resin groups, respectively (p<0.05). Cell viability for MTA and experimental Hybrid, Paste and Resin groups was 49%, 93%, 90% and 86%, respectively, when compared with the control group. The photo-cured experimental resin cement showed similar or superior performance compared with the current commercial or other tested experimental materials. PMID:23207847

  14. Film Thickness and Flow Properties of Resin-Based Cements at Different Temperatures

    PubMed Central

    Bagheri, R

    2013-01-01

    Statement of Problem: For a luting agent to allow complete seating of prosthetic restorations, it must obtain an appropriate flow rate maintaining a minimum film thickness. The performance of recently introduced luting agents in this regard has not been evaluated. Purpose: To measure and compare the film thickness and flow properties of seven resin-containing luting cements at different temperatures (37°C, 25°C and10°C). Material and Methods: Specimens were prepared from five resin luting cements; seT (SDI), Panavia F (Kuraray), Varioloink II (Ivoclar), Maxcem (Kerr), Nexus2 (Kerr) and two resin-modified glass-ionomer luting cements (RM-GICs); GC Fuji Plus (GC Corporation), and RelyX Luting 2 (3 M/ESPE). The film thickness and flow rate of each cement (n=15) was determined using the test described in ISO at three different temperatures. Results: There was a linear correlation between film thickness and flow rate for most of the materials. Cooling increased fluidity of almost all materials while the effect of temperature on film thickness was material dependent. At 37°C, all products revealed a film thickness of less than 25µm except for GC Fuji Plus. At 25°C, all cements produced a film thickness of less than 27 µm except for seT. At 10°C, apart from seT and Rely X Luting 2, the remaining cements showed a film thickness smaller than 20 µm. Conclusion: Cooling increased fluidity of almost all materials, however. the film thickness did not exceed 35 µm in either condition, in spite of the lowest film thickness being demonstrated at the lowest temperature. PMID:24724120

  15. Effects of surface treatments and storage times on the tensile bond strength of adhesive cements to noble and base metal alloys.

    PubMed

    Burmann, Paulo Afonso; Santos, Jose Fortunato Ferreira; May, Liliana Gressler; Pereira, Joao Eduardo da Silva; Cardoso, Paulo Eduardo Capel

    2008-01-01

    This work evaluated two resin cements and a glass-ionomer cement and their bond strength to gold-palladium (Au-Pd), silver-palladium (Ag-Pd), and nickel-chromium-beryllium (Ni-Cr-Be) alloys, utilizing three surface treatments over a period of six months. Eight hundred ten pieces were cast (in a button shape flat surfaces) in one of three alloys. Each alloy group was assigned to three other groups, based on the surface treatment utilized. Specimens were fabricated by bonding similar buttons in using one of three adhesive cements. The 405 pairs were thermocycled and stored in saline solution (0.9% NaCl) at 37 degrees C. The tensile bond strengths were measured in a universal testing machine after storage times of 2, 90, or 180 days. The highest mean bond strength value was obtained with the base metal alloy (10.9 +/- 8.6 MPa). In terms of surface treatment, oxidation resulted in the highest mean bond strength (13.7 +/- 7.3 MPa), followed by sandblasting (10.3 +/- 5.5 MPa) and polishing (3.0 +/- 6.4 MPa). Panavia Ex (13.2 +/- 9.3 MPa) showed significantly higher bond strengths than the other two cements, although the storage time reduced all bond strengths significantly. PMID:18348374

  16. Mineral Trioxide Aggregate and Portland Cement for Direct Pulp Capping in Dog: A Histopathological Evaluation

    PubMed Central

    Bidar, Maryam; Naghavi, Neda; Mohtasham, Nooshin; Sheik-Nezami, Mahshid; Fallahrastegar, Amir; Afkhami, Farzaneh; Attaran Mashhadi, Negin; Nargesi, Iman

    2014-01-01

    Background and aims. Mineral trioxide aggregate and calcium hydroxide are considered the gold standard pulp-capping materials. Recently, Portland cement has been introduced with properties similar to those of mineral trioxide aggregate. Histopathological effects of direct pulp capping using mineral trioxide aggregate and Portland cements on dog dental pulp tissue were evaluated in the present study. Materials and methods. This histopatological study was carried out on 64 dog premolars. First, the pulp was exposed with a sterile bur. Then, the exposed pulp was capped with white or gray mineral trioxide aggregates and white or gray Portland cements in each quadrant and sealed with glass-ionomer. The specimens were evaluated under a light microscope after 6 months. Statistical analysis was carried out using Kruskal-Wallis test. Statistical significance was defined at ?=5%. Results. There was no acute inflammation in any of the specimens. Chronic inflammation in white and gray mineral trioxide aggregates and white and gray Portland cements was reported to be 45.5%, 27.3%, 57.1% and 34.1%, respectively. Although the differences were not statistically significant, severe inflammation was observed mostly adjacent to white mineral trioxide aggregate. The largest extent of increased vascularization (45%) and the least increase in fibrous tissue were observed adjacent to white mineral trioxide aggregate, with no significant differences. In addition, the least calcified tissue formed adjacent to white mineral trioxide aggregate, although the difference was not significant. Conclusion. The materials used in this study were equally effective as pulp protection materials following direct pulp capping in dog teeth. PMID:25346831

  17. Microdrilling of Biocompatible Materials

    E-print Network

    Mohanty, Sankalp

    2012-02-14

    This research studies microdrilling of biocompatible materials including commercially pure titanium, 316L stainless steel, polyether ether ketone (PEEK) and aluminum 6061-T6. A microdrilling technique that uses progressive pecking and micromist...

  18. Injectable PLGA microsphere\\/calcium phosphate cements: physical properties and degradation characteristics

    Microsoft Academic Search

    W. J. E. M. Habraken; J. G. C. Wolke; A. G. Mikos; J. A. Jansen

    2006-01-01

    Calcium phosphate (CaP) cements show an excellent biocompatibility and often have a high mechanical strength, but in general degrade relatively slow. To increase degradation rates, macropores can be introduced into the cement, e.g., by the inclusion of biodegradable microspheres into the cement. The aim of this research is to develop an injectable PLGA microsphere\\/CaP cement with sufficient setting\\/cohesive properties and

  19. Biocompatible interfaces for biosensors

    Microsoft Academic Search

    Andrew Gill; Geoffrey Lillie; Giosi Farace; Pankaj Vadgama

    2005-01-01

    Electrochemical biosensors need to interface reliably with complex biological samples. The latter are characterized by high surface activity and the presence of numerous interferent molecules. Polymeric membranes through their ability to act as surface modifiers of biosensors and as selective barriers help to minimize selectivity and biocompatibility problems for biosensors. Membranes studied include those based on PVC, polyether sulphone and

  20. Biocompatible implant surface treatments.

    PubMed

    Pattanaik, Bikash; Pawar, Sudhir; Pattanaik, Seema

    2012-01-01

    Surface plays a crucial role in biological interactions. Surface treatments have been applied to metallic biomaterials in order to improve their wear properties, corrosion resistance, and biocompatibility. A systematic review was performed on studies investigating the effects of implant surface treatments on biocompatibility. We searched the literature using PubMed, electronic databases from 1990 to 2009. Key words such as implant surface topography, surface roughness, surface treatment, surface characteristics, and surface coatings were used. The search was restricted to English language articles published from 1990 to December 2009. Additionally, a manual search in the major dental implant journals was performed. When considering studies, clinical studies were preferred followed by histological human studies, animal studies, and in vitro studies. A total of 115 articles were selected after elimination: clinical studies, 24; human histomorphometric studies, 11; animal histomorphometric studies, 46; in vitro studies, 34. The following observations were made in this review: · The focus has shifted from surface roughness to surface chemistry and a combination of chemical manipulations on the porous structure. More investigations are done regarding surface coatings. · Bone response to almost all the surface treatments was favorable. · Future trend is focused on the development of osteogenic implant surfaces. Limitation of this study is that we tried to give a broader overview related to implant surface treatments. It does not give any conclusion regarding the best biocompatible implant surface treatment investigated till date. Unfortunately, the eventually selected studies were too heterogeneous for inference of data. PMID:23059581

  1. Physical properties and cytotoxicity comparison of experimental gypsum-based biomaterials with two current dental cement materials on L929 fibroblast cells

    PubMed Central

    Mahshim, Nafsiyah; Reza, Fazal; Omar, Nor Shamsuria

    2013-01-01

    Aim: To evaluate physical properties and cytotoxicity of pure gypsum-based (pure-GYP) and experimental gypsum-based biomaterials mixed with polyacrylic acid (Gyp-PA). The results were compared with calcium hydroxide (CH) and glass ionomer cement (GIC) for application as base/liner materials. Materials and Methods: Vicat's needle was used to measure the setting time and solubility (%) was determined by percentage of weight loss of the materials following immersion in distilled water. For cytotoxicity test, eluates of different concentrations of materials were obtained and pipetted onto L-929 mouse fibroblast cultures and incubated for 3 days. Cellular viability was assessed using Dimethylthiazol diphenyltetrazolium bromide test to determine the cytotoxicity level. Statistical significance was determined by one-way analysis of variance followed by post hoc test (P < 0.05). Results: Setting time was significantly higher for pure-GYP and Gyp-PA; solubility test showed a similar tendency (pure-Gyp > Gyp-PA > CH = GIC). The pure-Gyp was found as the least cytotoxic materials at different concentrations. At 100 mg/mL dilutions of materials in growth medium highest cytotoxicity was observed with CH group. Conclusion: Cytotoxic effect was not observed with pure-Gyp; application of this novel biomaterial on deeper dentin/an exposed pulp and possibility of gradual replacement of this biodegradable material by dentin like structure would be highly promising. PMID:23956536

  2. Biocompatibility of composite resins

    PubMed Central

    Mousavinasab, Sayed Mostafa

    2011-01-01

    Dental materials that are used in dentistry should be harmless to oral tissues, so they should not contain any leachable toxic and diffusible substances that can cause some side effects. Reports about probable biologic hazards, in relation to dental resins, have increased interest to this topic in dentists. The present paper reviews the articles published about biocompatibility of resin-restorative materials specially resin composites and monomers which are mainly based on Bis-GMA and concerns about their degradation and substances which may be segregated into oral cavity. PMID:23372592

  3. Effect of fluoride varnish on demineralization adjacent to brackets bonded with RMGI cement.

    PubMed

    Schmit, Jason L; Staley, Robert N; Wefel, James S; Kanellis, Michael; Jakobsen, Jane R; Keenan, Peter J

    2002-08-01

    Far too often a less-than-optimal esthetic result occurs after orthodontic treatment due to demineralization of enamel adjacent to fixed orthodontic appliances in patients with inadequate oral hygiene. In vitro studies have shown that a resin-modified glass ionomer (RMGI) cement and a fluoride varnish might help clinicians combat this problem. The purpose of this study was to evaluate, in vitro, the effect of a fluoride-releasing cavity varnish on inhibition of enamel demineralization adjacent to orthodontic brackets bonded with RMGI and composite resin cements. Brackets were bonded to 48 extracted human third molars. Half were bonded with a composite resin (Transbond, 3M Unitek, Monrovia, Calif) and half with an RMGI (Fuji Ortho LC, GC America, Alsip, Ill). Each group was further divided into 2, with half receiving an application of fluoride-releasing varnish (Duraflor, Pharmascience, Montreal, Québec, Canada). The samples were cycled in an artificial caries solution for an hour twice daily for 31 days. After each caries challenge, the teeth were brushed with a soft toothbrush to simulate normal mechanical wear of the varnish. The loss of fluoride varnish was timed. Teeth were sectioned longitudinally and photographed under polarized light microscopy. Mean lesion depth was measured, and analysis of variance (ANOVA) (P cement showed no significant differences in lesion depth between varnish and nonvarnish groups. Both RMGI groups had 50% smaller mean lesion depths when compared with the composite resin group without fluoride varnish. Samples bonded with RMGI cement illustrated a wedge effect, with lesion depth shallower near the bracket. A chi-square test showed that the fluoride varnish was lost significantly faster in samples bonded with Fuji Ortho LC (P =.013). Although the fluoride varnish could not prevent demineralization, it appears to be beneficial in reducing lesion formation. Clinicians should consider applying fluoride varnish on areas of enamel that exhibit demineralization or are at risk of demineralization in patients with poor oral hygiene. PMID:12165766

  4. Surface studies on acrylic bone cement.

    PubMed

    Bettencourt, A; Calado, A; Amaral, J; Alfaia, A; Vale, F M; Monteiro, J; Montemor, M F; Ferreira, M G S; Castro, M

    2004-06-18

    Poly(methyl methacrylate) (PMMA) is used to fill the gap between the prosthesis and the surrounding bone in cemented arthroplasties. Biocompatibility problems related to bone cement application limit the clinical success of these cemented arthroplasties. Being the cement surface in close connection with the living bone, it is reasonable to assume that surface properties such as, surface composition and surface energy, will play a role in the biomaterial performance. X-ray photoelectron spectroscopy (XPS) analysis and surface energy studies were carried out during 4 months, in order to assess a possible correlation between aging time and surface changes. The aging of PMMA, in a biological model fluid, strongly influences the composition and wettability of the cement surface. These changes may be explained through the hydrolysis of PMMA ester groups and the subsequent hydrogen bonding. Although our study does not exactly reproduce the in vivo environment surrounding a prosthesis, it suggests that the changes in the composition and wettability of the surface may modulate the host response towards the implant, thus contributing to its loosening. PMID:15158960

  5. Cement kiln NOx control

    Microsoft Academic Search

    A. T. McQueen; S. J. Bortz; M. S. Hatch; H. J. Buening; D. E. Shore; R. L. Leonard; E. F. Bouse

    1993-01-01

    Cement kilns represent an important source of NOx emissions. The results of a critical analysis of the state-of-the-art in cement kiln NOx control are presented. A survey of current and anticipated cement kiln NOx regulations, NOx formation mechanisms and common NOx control technologies (as applied to boilers) is presented. Cement kiln features relating to NO x control, such as combustion

  6. A Novel Composite PMMA-based Bone Cement with Reduced Potential for Thermal Necrosis.

    PubMed

    Lv, Yang; Li, Ailing; Zhou, Fang; Pan, Xiaoyu; Liang, Fuxin; Qu, Xiaozhong; Qiu, Dong; Yang, Zhenzhong

    2015-06-01

    Percutaneous vertebroplasty (VP) and balloon kyphoplasty (BKP) are now widely used to treat patients who suffer painful vertebral compression fractures. In each of these treatments, a bone cement paste is injected into the fractured vertebral body/bodies, and the cement of choice is a poly(methyl methacrylate) (PMMA) bone cement. One drawback of this cement is the very high exothermic temperature, which, it has been suggested, causes thermal necrosis of surrounding tissue. In the present work, we prepared novel composite PMMA bone cement where microcapsules containing a phase change material (paraffin) (PCMc) were mixed with the powder of the cement. A PCM absorbs generated heat and, as such, its presence in the cement may lead to reduction in thermal necrosis. We determined a number of properties of the composite cement. Compared to the values for a control cement (a commercially available PMMA cement used in VP and BKP), each composite cement was found to have significantly lower maximum exothermic temperature, increased setting time, significantly lower compressive strength, significantly lower compressive modulus, comparable biocompatibility, and significantly smaller thermal necrosis zone. Composite cement containing 20% PCMc may be suitable for use in VP and BKP and thus deserves further evaluation. PMID:25966790

  7. Biocompatibility of Artificial Organs: An Overview

    Microsoft Academic Search

    Lee W. Henderson; Dennis Chenoweth

    1987-01-01

    Papers that are presented in this symposium on biocompatibility of foreign surfaces used in artificial organs are commented upon and set in an overall context of the biocompatibility of foreign surfaces to blood. A working formulation of the events comprising lack of biocompatibility of hemodialysis membranes to the complement system is given as a possible model to which other foreign

  8. THE BIOCOMPATIBILITY OF MESOPOROUS SILICATES

    PubMed Central

    Hudson, Sarah; Padera, Robert F.; Langer, Robert; Kohane, Daniel S.

    2008-01-01

    Micro- and nano- mesoporous silicate particles are considered potential drug delivery systems because of their ordered pore structures, large surface areas and the ease with which they can be chemically modified. However, few cytotoxicity or biocompatibility studies have been reported, especially when silicates are administered in the quantities necessary to deliver low-potency drugs. The biocompatibility of mesoporous silicates of particle sizes ~ 150 nm, ~ 800 nm and ~ 4 µm and pore sizes of 3 nm, 7 nm and 16 nm respectively are examined here. In vitro, mesoporous silicates showed a significant degree of toxicity at high concentrations with mesothelial cells. Following subcutaneous injection of silicates in rats, the amount of residual material decreased progressively over three months, with good biocompatibility on histology at all time points. In contrast, intra peritoneal and intra venous injections in mice resulted in death or euthanasia. No toxicity was seen with subcutaneous injection of the same particles in mice. Microscopic analysis of the lung tissue of the mice indicates that death may be due to thrombosis. Although local tissue reaction to mesoporous silicates was benign, they caused severe systemic toxicity. This toxicity could be mitigated by modification of the materials. PMID:18675454

  9. CHH Cement Composite

    NASA Astrophysics Data System (ADS)

    Cwirzen, A.; Habermehl-Cwirzen, K.; Nasibulina, L. I.; Shandakov, S. D.; Nasibulin, A. G.; Kauppinen, E. I.; Mudimela, P. R.; Penttala, V.

    The compressive strength and electrical resistivity for hardened pastes produced from nanomodified Portland SR cement (CHH- Carbon Hedge Hog cement) were studied. The nanomodification included growing of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) on the cement particles. Pastes having water to binder ratio of 0.5 were produced. The obtained hardened material was characterized by increased compressive strength in comparison with the reference specimens made from pristine SR cement, which was attributed to reinforcing action of the CNTs and CNFs. The electrical resistivity of CHH composite was lower by one order of magnitude in comparison with reference Portland cement paste.

  10. ULTRA-LIGHTWEIGHT CEMENT

    SciTech Connect

    Fred Sabins

    2002-04-29

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). This report includes results from laboratory testing of ULHS systems along with other lightweight cement systems, including foamed and sodium silicate slurries. During this project quarter, comparison studies of the three cement systems examined several properties: tensile strength, Young's modulus, and shear bond. Testing to determine the effect of temperature cycling on the shear bond properties of the cement systems was also conducted. In addition, the stress-strain behavior of the cement types was studied. This report discusses a software program that is being developed to help design ULHS cements and foamed cements.

  11. Acrylic bone cements: the role of nanotechnology in improving osteointegration and tunable mechanical properties.

    PubMed

    Lissarrague, María H; Fascio, Mirta L; Goyanes, Silvia; D'Accorso, Norma B

    2014-12-01

    Nanotechnology is an extremely powerful emerging technology, which is expected to have a substantial impact on biomedical technology, especially in tissue engineering and drug delivery. The use of nanocompounds and nanoparticles in the synthesis of improved bone cements to be applied in vertebroplasty/kyphoplasty and arthroplasty, is of great interest due to the increasing incidence of osteoporosis and osteoarthritis. This review reports new advances in the development of acrylic bone cements, using different radio-opalescent nanomaterials taking into consideration their influence on the mechanical behavior and biocompatibility of the resulting acrylic bone cement. Furthermore, other non-radiopaque nanoparticles capable of mechanically reinforcing the bone cement as well as induce osteointegration, are also reviewed. Additionally, nanoparticles used to improve the controlled release of antibiotics contained in acrylic bone cements are briefly described. PMID:26000369

  12. ULTRA-LIGHTWEIGHT CEMENT

    SciTech Connect

    Fred Sabins

    2001-01-15

    The objective of this project is to develop an improved ultra-lightweigh cement using ultralight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Problems, Task 2: Review Russian Ultra-Lightweight Cement Literature, and Task 3: Test Ultra-Lightweight Cements. Results reported this quarter include a review and summary surface pipe and intermediate casing cementing conditions historically encountered in the US and establishment of average design conditions for ULHS cements. Russian literature concerning development and use of ultra-lightweight cements employing either nitrogen or ULHS was reviewed, and a summary is presented. Quality control testing of materials used to formulate ULHS cements in the laboratory was conducted to establish baseline material performance standards. A testing protocol was developed employing standard procedures as well as procedures tailored to evaluate ULHS. This protocol is presented and discussed. finally, results of initial testing of ULHS cements is presented along with analysis to establish cement performance design criteria to be used during the remainder of the project.

  13. Biocompatibility of plasma nanostructured biopolymers

    NASA Astrophysics Data System (ADS)

    Slepi?ková Kasálková, N.; Slepi?ka, P.; Ba?áková, L.; Sajdl, P.; Švor?ík, V.

    2013-07-01

    Many areas of medicine such as tissue engineering requires not only mastery of modification techniques but also thorough knowledge of the interaction of cells with solid state substrates. Plasma treatment can be used to effective modification, nanostructuring and therefore can significantly change properties of materials. In this work the biocompatibility of the plasma nanostructured biopolymers substrates was studied. Changes in surface chemical structure were studied by X-ray photoelectron spectroscopy (XPS). The morphology pristine and modified samples were determined using atomic force microscopy (AFM). The surface wettability was determined by goniometry from contact angle. Biocompatibility was determined by in vitro tests, the rat vascular smooth muscle cells (VSMCs) were cultivated on the pristine and plasma modified biopolymer substrates. Their adhesion, proliferation, spreading and homogeneous distribution on polymers was monitored. It was found that the plasma treatment leads to rapid decrease of contact angle for all samples. Contact angle decreased with increasing time of modification. XPS measurements showed that plasma treatment leads to changes in ratio of polar and non-polar groups. Plasma modification was accompanied by a change of surface morphology. Biological tests found that plasma treatment have positive effect on cells adhesion and proliferation cells and affects the size of cell's adhesion area. Changes in plasma power or in exposure time influences the number of adhered and proliferated cells and their distribution on biopolymer surface.

  14. Evaluation of four biodegradable, injectable bone cements in an experimental drill hole model in sheep.

    PubMed

    von Rechenberg, Brigitte; Génot, Oliver R; Nuss, Katja; Galuppo, Larry; Fulmer, Mark; Jacobson, Evan; Kronen, Peter; Zlinszky, Kati; Auer, Jörg A

    2013-09-01

    Four cement applications were tested in this investigation. Two dicalcium phosphate dihydrate (DCPD-brushite) hydraulic cements, an apatite hydraulic fiber loaded cement, and a calcium sulfate cement (Plaster of Paris) were implanted in epiphyseal and metaphyseal cylindrical bone defects in sheep. The in vivo study was performed to assess the biocompatibility and bone remodeling of four cement formulations. After time periods of 2, 4, and 6 months, the cement samples were clinically and histologically evaluated. Histomorphometrically, the amount of new bone formation, fibrous tissue, and bone marrow and the area of remaining cement were measured. In all specimens, no signs of inflammation were detectable either macroscopically or microscopically. Cements differed mainly in their resorption time. Calcium sulfate was already completely resorbed at 2 months and showed a variable amount of new bone formation and/or fibrous tissue in the original drill hole over all time periods. The two DCPD cements in contrast were degraded to a large amount at 6 months, whereas the apatite was almost unchanged over all time periods. PMID:23680585

  15. CHH Cement Composite

    Microsoft Academic Search

    A. Cwirzen; K. Habermehl-Cwirzen; L. I. Nasibulina; S. D. Shandakov; A. G. Nasibulin; E. I. Kauppinen; P. R. Mudimela; V. Penttala

    2009-01-01

    The compressive strength and electrical resistivity for hardened pastes produced from nanomodified Portland SR cement (CHH-\\u000a Carbon Hedge Hog cement) were studied. The nanomodification included growing of carbon nanotubes (CNTs) and carbon nanofibers\\u000a (CNFs) on the cement particles. Pastes having water to binder ratio of 0.5 were produced. The obtained hardened material was\\u000a characterized by increased compressive strength in comparison

  16. ULTRA-LIGHTWEIGHT CEMENT

    SciTech Connect

    Fred Sabins

    2003-01-31

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). This report discusses testing that was performed for analyzing the alkali-silica reactivity of ULHS in cement slurries. DOE joined the Materials Management Service (MMS)-sponsored joint industry project ''Long-Term Integrity of Deepwater Cement under Stress/Compaction Conditions.'' Results of the project contained in two progress reports are also presented in this report.

  17. Polycrystalline Silicon: a Biocompatibility Assay

    SciTech Connect

    Pecheva, E.; Fingarova, D.; Pramatarova, L.; Hikov, T. [Institute of Solid State Physics, Bulgarian Academy of Sciences, Sofia (Bulgaria); Laquerriere, P.; Bouthors, Sylvie [NSERM, ERM 0203 (labo des biomateriaux), IFR53, Reims (France); Dimova-Malinovska, D. [Central Laboratory of Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, Sofia (Bulgaria); Montgomery, P. [1 Institut d'Electronique du Solide et des Systemes (InESS), UDS-CNRS, UMR 7163, 23 rue du Loess, 67037 Strasbourg (France)

    2010-01-21

    Polycrystalline silicon (poly-Si) layers were functionalized through the growth of biomimetic hydroxyapatite (HA) on their surface. HA is the mineral component of bones and teeth and thus possesses excellent bioactivity and biocompatibility. MG-63 osteoblast-like cells were cultured on both HA-coated and un-coated poly-Si surfaces for 1, 3, 5 and 7 days and toxicity, proliferation and cell morphology were investigated. The results revealed that the poly-Si layers were bioactive and compatible with the osteoblast-like cells. Nevertheless, the HA coating improved the cell interactions with the poly-Si surfaces based on the cell affinity to the specific chemical composition of the bone-like HA and/or to the higher HA roughness.

  18. Enhanced Biocompatibility of Porous Nitinol

    PubMed Central

    Munroe, Norman; Pulletikurthi, Chandan; Haider, Waseem

    2009-01-01

    Porous Nitinol (PNT) has found vast applications in the medical industry as interbody fusion devices, synthetic bone grafts, etc. However, the tendency of the PNT to corrode is anticipated to be greater as compared to solid nitinol since there is a larger surface area in contact with body fluids. In such cases, surface preparation is known to play a major role in a material’s biocompatibility. In an effort to check the effect of surface treatments on the in vitro corrosion properties of PNT, in this investigation, they were subjected to different surface treatments such as boiling in water, dry heating, and passivation. The localized corrosion resistance of alloys before and after each treatment was evaluated in phosphate buffer saline solution (PBS) using cyclic polarization tests in accordance with ASTM F 2129-08. PMID:19956797

  19. Cement kiln NOX control

    Microsoft Academic Search

    A. T. McQueen; S. J. Bortz; M. S. Hatch; R. L. Leonard

    1995-01-01

    Control of NOX emissions from combustion sources has become an important issue in recent years, particularly in the ozone nonattainment areas of California. Cement kilns represent an important source of NOX emissions, and they either have already been regulated or are being considered for future regulations. This paper presents the results of a critical analysis of the state-of-the-art in cement

  20. How polysulfone dialysis membranes containing polyvinylpyrrolidone achieve excellent biocompatibility?

    Microsoft Academic Search

    Masayo Hayama; Ken-ichiro Yamamoto; Fukashi Kohori; Kiyotaka Sakai

    2004-01-01

    Polysulfone (PS) dialysis membranes hydrophilized by blending polyvinylpyrrolidone (PVP) are well known to have excellent biocompatibility in clinical use. The objective of the present study is thus to clarify how PVP improves biocompatibility of PS membranes and furthermore to develop a patient-friendly PS dialysis membrane with higher biocompatibility. Biocompatibility based on both lactate dehydrogenase (LDH) activity and amount of protein

  1. Setting reaction and hardening of an apatitic calcium phosphate cement.

    PubMed

    Ginebra, M P; Fernández, E; De Maeyer, E A; Verbeeck, R M; Boltong, M G; Ginebra, J; Driessens, F C; Planell, J A

    1997-04-01

    The combination of self-setting and biocompatibility makes calcium phosphate cements potentially useful materials for a variety of dental applications. The objective of this study was to investigate the setting and hardening mechanisms of a cement-type reaction leading to the formation of calcium-deficient hydroxyapatite at low temperature. Reactants used were alpha-tricalcium phosphate containing 17 wt% beta-tricalcium phosphate, and 2 wt% of precipitated hydroxyapatite as solid phase and an aqueous solution 2.5 wt% of disodium hydrogen phosphate as liquid phase. The transformation of the mixture was stopped at selected times by a freeze-drying techniques, so that the cement properties at various stages could be studied by means of x-ray diffraction, infrared spectroscopy, and scanning electron microscopy. Also, the compressive strength of the cement was measured as a function of time. The results showed that: (1) the cement setting was the result of the alpha-tricalcium phosphate hydrolysis, giving as a product calcium-deficient hydroxyapatite, while beta-tricalcium phosphate did not participate in the reaction; (2) the extent of conversion of alpha-TCP was nearly 80% after 24 hr; (3) both the extent of conversion and the compressive strength increased initially linearly with time, subsequently reaching a saturation level, with a strong correlation observed between them, indicating that the microstructural changes taking place as the setting reaction proceeded were responsible for the mechanical behavior of the cement; and (4) the microstructure of the set cement consisted of clusters of big plates with radial or parallel orientations in a matrix of small plate-like crystals. PMID:9126187

  2. Ossiculoplasty with hydroxyapatite bone cement: our reconstruction philosophy.

    PubMed

    Gérard, Jean-Marc; De Bie, Gersende; Franceschi, Daniel; Deggouj, Naima; Gersdorff, Michel

    2015-07-01

    The main objective of this study is to analyze results obtained with hydroxyapatite bone cement (HABC) ossiculoplasties. This is a retrospective study of a case series. This study was conducted in an academic hospital and tertiary referral center. A total of 127 ossiculoplasties using HABC were evaluated. Ears were divided into three groups according to procedure: group 1 involved reinforcement of the incudostapedial joint with cement and reconstruction of an incus long process defect with cement. Group 2 involved partial ossicular reconstruction between the stapes and malleus handle with HABC. Group 3 was divided into two subgroups. Group 3B entailed reconstruction of the stapes with a mobile footplate (Austin-Kartush type B = group 3B) and group 3F with a fixed footplate (Austin-Kartush type F = group 3F) using a K-Helix piston (Grace Medical, Memphis, TN, USA) or a classical titanium piston (Kurz, Fuerth, Germany) glued to the incus remnant or malleus handle with cement. Anatomical and pre- and postoperative audiological results were assessed. The mean follow-up was 26 ± 14 months. Percentages of average postoperative air-bone gap ?20 dB were 95, 82.5, 50 and 83.3 %, and for air-bone gap ?10 dB, 80, 50.9, 16.6 and 50 % for groups 1, 2, 3B and 3F, respectively. No complications related to the cement or extrusion occurred. Hearing outcomes also remained stable over time. In our experience, ossiculoplasty with cement provides good and stable functional results, is safe, cost effective, and easy to use. HABC with or without biocompatible ossicular prostheses allows repair of different types of ossicular defects with preservation of the anatomical and physiological ossicular chain, as well as improved stability. Reconstruction of the incus long process or incudostapedial joint defect with cement is preferred over partial ossicular reconstruction. PMID:24615652

  3. Liquid-solid phase transition alloy as reversible and rapid molding bone cement.

    PubMed

    Yi, Liting; Jin, Chao; Wang, Lei; Liu, Jing

    2014-12-01

    Acrylic bone cement has been an essential non-metallic implant used as fixing agent in the cemented total joint arthroplasty (THA). However, the currently available materials based mainly on polymethylmethacrylate (PMMA) still encounter certain limitations, such as time-consuming polymerization, thermal and chemical necrosis and troublesome revision procedure. Here from an alternative way, we proposed for the first time to adopt the injectable alloy cement to address such tough issues through introducing its unique liquid-solid phase transition mechanism. A typical cement along this way is thus made of an alloy Bi/In/Sn/Zn with a specifically designed low melting point 57.5 °C, which enables its rapid molding into various desired shapes with high plasticity and ultimate metallic behaviors. The fundamental characteristics including the mechanical strength, biocompatibility and phase transition-induced thermal effects have been clarified to demonstrate the importance of such alloy as unconventional cement with favorable merits. In addition, we also disclosed its advantage as an excellent contrast agent for radiation imaging on the bone interior structure which is highly beneficial for guiding the surgery and monitoring the therapeutic effects. Particularly, the proposed alloy cement with reversible phase transition feature significantly simplifies the revision of the cement and prosthesis. This study opens the way for employing the injectable alloy materials as reversible bone cement to fulfill diverse clinical needs in the coming time. PMID:25239039

  4. Sealing ability of materials used as retrograde root fillings in endodontic surgery.

    PubMed

    Thirawat, J; Edmunds, D H

    1989-11-01

    The sealing ability of retrograde root fillings of amalgam plus cavity varnish, EBA cement, glass ionomer cement, light-cured composite resin, dentine bonding agent, and light-cured composite resin plus dentine bonding agent were compared with laterally condensed conventional root fillings. A dye penetration technique was used to assess microleakage and it was concluded that none of the materials produced a perfect seal but that glass ionomer cement, light-cured composite resin, light-cured composite resin plus dentine bonding agent and dentine bonding agent alone produced better seals than conventional laterally condensed gutta-percha, amalgam plus cavity varnish and EBA cement. PMID:2639873

  5. Timing of syntaxial cement

    SciTech Connect

    Perkins, R.D.

    1985-02-01

    Echinodermal fragments are commonly overgrown in ancient limestones, with large single crystals growing in optical continuity over their skeletal hosts (i.e., syntaxial overgrowths). Such syntaxial cements are usually considered to have precipitated from meteoric pore waters associated with a later stage of subaerial exposure. Although several examples have been reported from ancient carbonates where petrographic relationships may indicate an early submarine formation of syntaxial cement, no occurrences have been noted in Holocene submarine-cemented rocks. Syntaxial cements of submarine origin have been found in Bermuda beachrock where isopachous high-magnesian calcite cements merge with large optically continuous crystals growing on echinodermal debris. Examination of other Holocene sediments cemented by magnesian calcite indicates that echinodermal fragments are not always overgrown syntaxially, but may be rimmed by microcrystalline calcite. The reason for this difference is not clear, although it may be a function of the spacing of nucleation sites and rates of crystal growth. A review of syntaxial cements from several localities in ancient carbonate sequences reveals that many are best interpreted as having formed in the submarine setting, whereas it is more clear that others formed from meteoric precipitation. These occurrences suggest that care should be exercised in inferring meteoric diagenesis from syntaxial overgrowths and that the possibility of submarine formation should be considered.

  6. Preparation, Physical-Chemical Characterization, and Cytocompatibility of Polymeric Calcium Phosphate Cements

    PubMed Central

    Khashaba, Rania M.; Moussa, Mervet; Koch, Christopher; Jurgensen, Arthur R.; Missimer, David M.; Rutherford, Ronny L.; Chutkan, Norman B.; Borke, James L.

    2011-01-01

    Aim. Physicochemical mechanical and in vitro biological properties of novel formulations of polymeric calcium phosphate cements (CPCs) were investigated. Methods. Monocalcium phosphate, calcium oxide, and synthetic hydroxyapatite were combined with either modified polyacrylic acid, light activated polyalkenoic acid, or polymethyl vinyl ether maleic acid to obtain Types I, II, and III CPCs. Setting time, compressive and diametral strength of CPCs was compared with zinc polycarboxylate cement (control). Specimens were characterized using X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. In vitro cytotoxicity of CPCs and control was assessed. Results. X-ray diffraction analysis showed hydroxyapatite, monetite, and brushite. Acid-base reaction was confirmed by the appearance of stretching peaks in IR spectra of set cements. SEM revealed rod-like crystals and platy crystals. Setting time of cements was 5–12?min. Type III showed significantly higher strength values compared to control. Type III yielded high biocompatibility. Conclusions. Type III CPCs show promise for dental applications. PMID:21941551

  7. Bone cement implantation syndrome.

    PubMed

    Razuin, R; Effat, O; Shahidan, M N; Shama, D V; Miswan, M F M

    2013-06-01

    Bone cement implantation syndrome (BCIS) is characterized by hypoxia, hypotension, cardiac arrhythmias, increased pulmonary vascular resistance and cardiac arrest. It is a known cause of morbidity and mortality in patients undergoing cemented orthopaedic surgeries. The rarity of the condition as well as absence of a proper definition has contributed to under-reporting of cases. We report a 59-year-old woman who sustained fracture of the neck of her left femur and underwent an elective hybrid total hip replacement surgery. She collapsed during surgery and was revived only to succumb to death twelve hours later. Post mortem findings showed multiorgan disseminated microembolization of bone marrow and amorphous cement material. PMID:23817399

  8. Environmentally compatible spray cement

    SciTech Connect

    Loeschnig, P. [Heidelberger Baustofftechnik GmbH, Leimen (Germany)

    1995-12-31

    Within the framework of a European research project, Heidelberger Zement developed a quickly setting and hardening binder for shotcrete, called Chronolith S, which avoids the application of setting accelerators. Density and strength of the shotcrete produced with this spray cement correspond to those of an unaccelerated shotcrete. An increased hazard for the heading team and for the environment, which may occur when applying setting accelerators, can be excluded here. Owing to the special setting properties of a spray cement, the process engineering for its manufacturing is of great importance. The treatment of a spray cement as a dry concrete with kiln-dried aggregates is possible without any problems. The use of a naturally damp pre-batched mixture is possible with Chronolith S but requires special process engineering; spray cement and damp aggregate are mixed with one another immediately before entering the spraying machinery.

  9. Preliminary evaluation of a novel strong/osteoinductive calcium phosphate cement.

    PubMed

    Qu, Yili; Yang, Yang; Li, Juan; Chen, Zhiqing; Li, Jidong; Tang, Kuangyun; Man, Yi

    2011-09-01

    We developed a novel calcium phosphate cement (CPC) by combining the silk fibroin and osteogenic supplements (?-glycerophosphate, ascorbic acid, and dexamethasone) with ?-tricalcium phosphate cement. Mesenchymal stem cells (MSCs) were cultured on the novel CPC scaffold. Results showed that the novel CPC scaffold was biocompatible and favorable for the adhesion, spreading, and proliferation of MSCs. Osteogenic differentiation of MSCs was confirmed by high osteocalcin content and elevated gene expressions of bone markers, such as alkaline phosphatase, collagen type I, and osteocalcin. Therefore, the novel CPC scaffold may be potentially useful for implant fixation and more rapid new bone formation in moderate load-bearing applications. PMID:20566653

  10. Biocompatibility of a calcium hydroxide-propolis experimental paste in rat subcutaneous tissue.

    PubMed

    Mori, Graziela Garrido; Rodrigues, Sindineia da Silva; Shibayama, Sheila Tieko; Pomini, Marcelo; do Amaral, Cristhiane Olivia Ferreira

    2014-01-01

    Intracanal medications are fundamental for disinfection of the root canal system and participate in periapical repair, so their biocompatibility is of utmost importance to avoid tissue damage. This study evaluated the biocompatibility of a experimental paste of calcium hydroxide and propolis in the subcutaneous tissue of rats. The study was conducted on 15 male Wistar rats. Two incisions were made on the dorsal region of each animal for introduction of 4 tubes: one tube was empty; one contained zinc oxide-eugenol cement, and the two other tubes were filled with experimental paste. After 7, 14 and 30 days, the animals were euthanized and the specimens were subjected to histotechnical preparation. The hematoxylin and eosin-stained histological sections were analyzed by light microscopy. Scores were established according to the inflammatory process and statistically compared by the Tukey test (? = 5%). The analysis of histological sections showed non-significant or mild inflammatory reaction in the connective tissue in contact with the empty tubes in all study periods while the contact of subcutaneous tissue with zinc oxide-eugenol elicited moderate or severe inflammation similarly without significant difference among the study periods. The connective tissue was moderately inflamed at 7 days when contacting the experimental paste, but the inflammatory process was non-significant or mild at 14 and 30 days. The experimental paste was biocompatible with the tissues after 14 days of subcutaneous implantation. PMID:25140713

  11. Polymeric-Calcium Phosphate Cement Composites-Material Properties: In Vitro and In Vivo Investigations

    PubMed Central

    Khashaba, Rania M.; Moussa, Mervet M.; Mettenburg, Donald J.; Rueggeberg, Frederick A.; Chutkan, Norman B.; Borke, James L.

    2010-01-01

    New polymeric calcium phosphate cement composites (CPCs) were developed. Cement powder consisting of 60?wt% tetracalcium phosphate, 30?wt% dicalcium phosphate dihydrate, and 10?wt% tricalcium phosphate was combined with either 35%?w/w poly methyl vinyl ether maleic acid or polyacrylic acid to obtain CPC-1 and CPC-2. The setting time and compressive and diametral tensile strength of the CPCs were evaluated and compared with that of a commercial hydroxyapatite cement. In vitro cytotoxicity and in vivo biocompatibility of the two CPCs and hydroxyapatite cement were assessed. The setting time of the cements was 5–15?min. CPC-1 and CPC-2 showed significantly higher compressive and diametral strength values compared to hydroxyapatite cement. CPC-1 and CPC-2 were equivalent to Teflon controls after 1 week. CPC-1, CPC-2, and hydroxyapatite cement elicited a moderate to intense inflammatory reaction at 7 days which decreased over time. CPC-1 and CPC-2 show promise for orthopedic applications. PMID:20811498

  12. MARGINAL ADAPTATION AND PERFORMANCE OF BIOACTIVE DENTAL RESTORATIVE MATERIALS IN DECIDUOUS AND YOUNG PERMANENT TEETH

    PubMed Central

    Gjorgievska, Elizabeta; Nicholson, John W.; Iljovska, Snezana; Slipper, Ian J.

    2008-01-01

    Objective: The aim of this study was to investigate the adaptation of different types of restorations towards deciduous and young permanent teeth. Materials and Methods: Class V cavities were prepared in deciduous and young permanent teeth and filled with different materials (a conventional glass-ionomer, a resin-modified glass-ionomer, a poly-acid-modified composite resin and a conventional composite resin). Specimens were aged in artificial saliva for 1, 6, 12 and 18 months, then examined by SEM. Results: The composite resin and the polyacid-modified composite had better marginal adaptation than the glass-ionomers, though microcracks developed in the enamel of the tooth. The glass-ionomers showed inferior marginal quality and durability, but no microcracking of the enamel. The margins of the resin-modified glass-ionomer were slightly superior to the conventional glass-ionomer. Conditioning improved the adaptation of the composite resin, but the type of tooth made little or no difference to the performance of the restorative material. All materials were associated with the formation of crystals in the gaps between the filling and the tooth; the quantity and shape of these crystals varied with the material. Conclusions: Resin-based materials are generally better at forming sound, durable margins in deciduous and young permanent teeth than cements, but are associated with microcracks in the enamel. All fluoride-releasing materials give rise to crystalline deposits. PMID:19089281

  13. Retention of crowns cemented on implant abutments with temporary cements.

    PubMed

    Nagasawa, Yuko; Hibino, Yasushi; Nakajima, Hiroshi

    2014-01-01

    This study was to examine the retentive force of crowns to implant abutments with commercial temporary cements. Six different temporary cements were investigated. Cast crowns were cemented to the abutments using each cement and their retentive forces to abutments were determined 7 or 28 days after cementing (n=10). The retentive force of the cements to abutments varied widely among the products [27-109 N (7-day), 18-80 N (28-days)]. The retentive force of all the cements was not reduced as the time elapsed, except for two products tested. The polycarboxylate cements and paste-mixing type eugenol-free cements revealed comparable retentive force after 28 days of storage. The powder-liquid type cements showed a positive correlation (p<0.05) between the retentive force and the shear strength, while a negative correlation (p<0.05) was obtained for paste-mixing type cement between the retentive force and compressive strength. Mechanical strength of temporary cements could not be a prominent predicting factor for retention of the crowns on the abutments. PMID:25483383

  14. Set retarded cement compositions and methods for well cementing

    SciTech Connect

    Brothers, L.E.; Lindsey, D.W.; Terry, D.T.

    1990-07-17

    This patent describes a method of cementing a zone in a subterranean formation penetrated by a wellbore; It comprises: forming a pumpable set retarded cement slurry comprising hydraulic cement, fresh water, particulate silica having a particle size in the range of from about 0.02 to about 0.5 micron and a set retarder comprising a copolymer consisting essentially of 2-acrylamido, 2-methylpropane sulfonic acid (AMPS) and acrylic acid having an average molecular weight below about 5000 and comprising from about 40 to about 60 mole percent AMPS; pumping the cement slurry into the zone by way of the wellbore, and allowing the cement slurry to set therein.

  15. Bacterial Cellulose: Long-Term Biocompatibility Studies

    Microsoft Academic Search

    Renata A. N. Pértile; Susana Moreira; Rui M. Gil da Costa; Alexandra Correia; Luisa Guãrdao; Fátima Gartner; Manuel Vilanova; Miguel Gama

    2012-01-01

    The bacterial cellulose (BC) secreted by Gluconacetobacter xylinus is a network of pure cellulose nanofibres which has high crystallinity, wettability and mechanical strength. These characteristics make BC an excellent material for tissue-engineering constructs, noteworthy for artificial vascular grafts. In this work, the in vivo biocompatibility of BC membranes produced by two G. xylinus strains was analyzed through histological analysis of

  16. Preparation of small bio-compatible microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Dreyer, William J. (Inventor)

    1979-01-01

    Small, round, bio-compatible microspheres capable of covalently bonding proteins and having a uniform diameter below about 3500 A are prepared by substantially instantaneously initiating polymerization of an aqueous emulsion containing no more than 35% total monomer including an acrylic monomer substituted with a covalently bondable group such a hydroxyl, amino or carboxyl and a minor amount of a cross-linking agent.

  17. Biocompatibility of nickel and cobalt dental alloys.

    PubMed

    Grimaudo, N J

    2001-01-01

    Allergies related to dentistry generally constitute delayed hypersensitivity reactions to specific dental materials. Although true allergic hypersensitivity to dental materials is rare, certain products have definite allergenic properties. This review presents a comparative evaluation of the biocompatibility of nickel-chromium, nickel-chromium-beryllium, and cobalt-chromium alloys. PMID:12017794

  18. A biocompatible Parylene thermal flow sensing array

    Microsoft Academic Search

    Ellis Meng; Po-Ying Li; Yu-Chong Tai

    2008-01-01

    A microelectromechanical systems (MEMS) thermal flow sensing array constructed of biocompatible materials has been designed, fabricated, and tested. In addition to the construction, the electronic biasing conditions were selected such that sensor operation was compatible with biological fluids. The device comprises several thin film platinum sensing elements sandwiched in a Parylene C membrane. The membrane is suspended over a bulk-micromachined

  19. Gentamicin in bone cement

    PubMed Central

    Chang, Y.; Tai, C-L.; Hsieh, P-H.; Ueng, S. W. N.

    2013-01-01

    Objectives The objective of this study is to determine an optimal antibiotic-loaded bone cement (ALBC) for infection prophylaxis in total joint arthroplasty (TJA). Methods We evaluated the antibacterial effects of polymethylmethacrylate (PMMA) bone cements loaded with vancomycin, teicoplanin, ceftazidime, imipenem, piperacillin, gentamicin, and tobramycin against methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staph. aureus (MRSA), coagulase-negative staphylococci (CoNS), Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Standardised cement specimens made from 40 g PMMA loaded with 1 g antibiotics were tested for elution characteristics, antibacterial activities, and compressive strength in vitro. Results The ALBC containing gentamicin provided a much longer duration of antibiotic release than those containing other antibiotic. Imipenem-loading on the cement had a significant adverse effect on the compressive strength of the ALBC, which made it insufficient for use in prosthesis fixation. All of the tested antibiotics maintained their antibacterial properties after being mixed with PMMA. The gentamicin-loaded ALBC provided a broad antibacterial spectrum against all the test organisms and had the greatest duration of antibacterial activity against MSSA, CoNS, P. aeruginosa and E. coli. Conclusion When considering the use of ALBC as infection prophylaxis in TJA, gentamicin-loaded ALBC may be a very effective choice. Cite this article: Bone Joint Res 2013;2:220–6. PMID:24128666

  20. [Radioactivity of bone cement].

    PubMed

    Scherer, M A; Winkler, R; Ascherl, R; Lenz, E

    1993-01-01

    A total of 14 samples of different types of bone cement from five different manufacturers were examined for their radioactivity. Each of the investigated bone cements showed a low radioactivity level, i.e. between < 1 and 100 Bq/kg. The content of U-238 and K-40 always was below the limit of detection (< 1-< 10 Bq/kg). Significant differences were detected in the amount of Ra-226, Pb-210, and Ra-228 detected between different samples of the same product from the same manufacturer, as well as between various types of cements. The highest radioactivity level was measured for Ra-226. Although stochastic radiation effects can not totally be excluded, it is extremely unlikely that the small amount of radioactive substances additionally transferred into the body by the bone cement has negative effects on the recipient's organism or on the fate of the alloplastic implant: "The risk factor and extrapolation in a low dosage range ... do not lead to an underestimation but more likely to an overestimation of the radiation hazard" [18]. PMID:8441806

  1. Biocompatibility of fixation materials in the brain.

    PubMed

    Mofid, M M; Thompson, R C; Pardo, C A; Manson, P N; Vander Kolk, C A

    1997-07-01

    Recent clinical reports documenting passive intracranial translocation of microplates and microscrews have prompted concerns regarding brain biocompatibility and neurotoxicity of fixation hardware used in craniofacial surgery. Although the effects of commercially pure titanium. Vitallium (cobalt-chromium-molybdenum), stainless steel, and various alloys have been well assessed in bone and soft tissues, there are no comprehensive studies of these materials in the brain. To investigate this, the biocompatibility of titanium, vitallium, and 316L stainless steel was evaluated in the rabbit brain and compared with silicone elastomer shunt tubing, a material that is used commonly as a neurosurgical implant material with well-established brain biocompatibility. Forty-eight juvenile New Zealand White rabbits were randomly assigned to one of three groups and underwent placement of either commercially pure titanium microscrews, vitallium microscrews, or 316L monofilament stainless steel wire into the parietal region. Silicone elastomer strips of similar size were implanted in the contralateral hemisphere of each rabbit. Animals were assessed daily for signs of neurotoxicity. Rabbits in each group were sacrificed at 2, 4, 8, and 26 weeks following implantation. Brains were sectioned at the implantation site and were examined by means of standard hematoxylin and eosin stains and with immunohistochemical markers sensitive to inflammatory changes in the brain. None of the animals showed any behavioral changes or neurologic deficits suggestive of either systemic or localized toxicity from the implant materials. Silicone clastomer was found to cause the least amount of inflammation relative to other materials tested at all sacrifice points, suggesting that as a standard neurosurgical implant material, it is an appropriate control for studies of brain biocompatibility. At 2 weeks, titanium was found to cause the largest inflammatory response in surrounding brain parenchyma based on analysis of markers for microglial proliferation, gliosis, and leukocyte infiltration. At the 26-week endpoint of our study, the biocompatibility of titanium was nearly equal to the biocompatibility of vitallium based on all studied markers of inflammation. A progressive increase in the inflammatory response surrounding stainless steel implants was noted at 8 and 26 weeks. Relative to all materials studied, at 26 weeks the greatest leukocyte response was found with stainless steel implants. Our results indicate that at the 26-week end-point of our study, titanium and vitallium incited a similar inflammatory response in the rabbit brain that was greater than the response found with silicone elastomer, a standard neurosurgical implant material, but less than that found with stainless steel wire, which is commonly recommended as an alternative fixation material. PMID:9207654

  2. Thermal Shock-resistant Cement

    SciTech Connect

    Sugama T.; Pyatina, T.; Gill, S.

    2012-02-01

    We studied the effectiveness of sodium silicate-activated Class F fly ash in improving the thermal shock resistance and in extending the onset of hydration of Secar #80 refractory cement. When the dry mix cement, consisting of Secar #80, Class F fly ash, and sodium silicate, came in contact with water, NaOH derived from the dissolution of sodium silicate preferentially reacted with Class F fly ash, rather than the #80, to dissociate silicate anions from Class F fly ash. Then, these dissociated silicate ions delayed significantly the hydration of #80 possessing a rapid setting behavior. We undertook a multiple heating -water cooling quenching-cycle test to evaluate the cement’s resistance to thermal shock. In one cycle, we heated the 200 and #61616;C-autoclaved cement at 500 and #61616;C for 24 hours, and then the heated cement was rapidly immersed in water at 25 and #61616;C. This cycle was repeated five times. The phase composition of the autoclaved #80/Class F fly ash blend cements comprised four crystalline hydration products, boehmite, katoite, hydrogrossular, and hydroxysodalite, responsible for strengthening cement. After a test of 5-cycle heat-water quenching, we observed three crystalline phase-transformations in this autoclaved cement: boehmite and #61614; and #61543;-Al2O3, katoite and #61614; calcite, and hydroxysodalite and #61614; carbonated sodalite. Among those, the hydroxysodalite and #61614; carbonated sodalite transformation not only played a pivotal role in densifying the cementitious structure and in sustaining the original compressive strength developed after autoclaving, but also offered an improved resistance of the #80 cement to thermal shock. In contrast, autoclaved Class G well cement with and without Class F fly ash and quartz flour failed this cycle test, generating multiple cracks in the cement. The major reason for such impairment was the hydration of lime derived from the dehydroxylation of portlandite formed in the autoclaved cement, causing its volume to expand.

  3. Electroactive biocompatible materials for nerve cell stimulation

    NASA Astrophysics Data System (ADS)

    Yang, Mei; Liang, Youlong; Gui, Qingyuan; Chen, Jun; Liu, Yong

    2015-04-01

    In the past decades, great efforts have been developed for neurobiologists and neurologists to restore nervous system functions. Recently much attention has been paid to electrical stimulation (ES) of the nervous system as a potential way to repair it. Various conductive biocompatible materials with good electrical conductivity, biocompatibility, and long-term ES or electrical stability have been developed as the substrates for ES. In this review, we summarized different types of materials developed in the purpose for ES of nervous system, including conducting polymers, carbon nanomaterials and composites from conducting polymer/carbon nanomaterials. The present review will give our perspective on the future research directions for further investigation on development of ES particularly on the nerve system.

  4. Interleukin 8 and Biocompatibility of Dialysis Membranes

    Microsoft Academic Search

    Toshimitsu Niwa; Takashi Miyazaki; Motoyoshi Sato; Fukushi Kambe; Tetsuya Tsuzuki; Kanji Uema; Kenji Maeda; Hisao Seo

    1995-01-01

    To determine whether interleukin 8 (IL-8) can be used as an index of biocompatibility of dialysis membranes, the effects of hemodialysis (HD) on plasma IL-8 levels and the expression of IL-8 mRNA in peripheral blood mononuclear cell (PBMC) were compared among regenerated cellulose (RC), polyacrylonitrile (PAN) and polymethylmethacrylate (PMMA) dialyzers. HD using RC dialyzers significantly increased plasma IL-8 levels and

  5. Biocompatibility of prosthetic meshes in abdominal surgery

    Microsoft Academic Search

    Marcel Binnebösel; Klaus T. von Trotha; Petra Lynen Jansen; Joachim Conze; Ulf P. Neumann; Karsten Junge

    2011-01-01

    Surgical meshes today represent a group of implants mainly used for hernia repair. Modern hernia surgery is no longer imaginable\\u000a without the application of these special biomaterials leading to millions of implantations each year worldwide. Because clinical\\u000a trials are insufficient to evaluate the distinct effects of modified mesh materials in regard to tissue biocompatibility and\\u000a functionality, a basic understanding of

  6. Abrasive wear of cemented carbides

    SciTech Connect

    Hawk, Jeffrey A.; Wilson, Rick D.

    2003-10-01

    Cemented carbides are used for a wide variety of applications where wear is a problem. Usually the wear of the cemented carbides is a combination of metal-to-metal and abrasion. Wear can occur at room or elevated temperatures. This research summarizes initial research to understand the abrasive wear of various cemented carbides (various grain sizes, carbide types, carbide grain sizes and binder compositions) in terms of absolute material removal rates and material removal mechanisms.

  7. Cementing techniques in hip resurfacing.

    PubMed

    Chandler, M; Kowalski, R S Z; Watkins, N D; Briscoe, A; New, A M R

    2006-02-01

    The subject of the cementing technique in hip resurfacing has been poorly studied to date. The hip resurfacing prosthesis is unique in the family of cemented prostheses because the cement mantle is blind (hidden underneath the implant) and is radiographically obscured. This presents an immediate challenge to the surgeon at the time of surgery, but also has a longer-term implication in terms of lack of post-operative clinical observation. This should be compared with total hip replacement or total knee replacement where the cement mantle can at least be partially observed both intra- and post-operatively. With this in mind, the objective of this review is, firstly, to understand the cement mantles typically achieved in current clinical practice and, secondly, to identify those factors affecting the cement mantle and to consolidate them into an improved and reproducible cementing technique. The outcome of this work shows that the low-viscosity technique can commonly lead to excessive cement penetration in the proximal femoral head and an incompletely seated component, whereas a more consistent controlled cement mantle can be achieved with a high-viscosity cementing technique. Consequently, it is recommended that a high-viscosity technique should be used to minimize the build-up of excessive cement, to reduce the temperature created by the exothermic polymerization, and to help to ensure correct seating of the prosthesis. A combination of these factors is potentially critical to the clinical success of some articular surface replacement (ASR) procedures. It is important to note that we specifically studied the DePuy ASR system; therefore only the general principles (and not the specifics) of the cementing technique may apply to other resurfacing prostheses, because of differences in internal geometry, clearance, and surgical technique. PMID:16669398

  8. Development of a 3D polymer reinforced calcium phosphate cement scaffold for cranial bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Alge, Daniel L.

    The repair of critical-sized cranial bone defects represents an important clinical challenge. The limitations of autografts and alloplastic materials make a bone tissue engineering strategy desirable, but success depends on the development of an appropriate scaffold. Key scaffold properties include biocompatibility, osteoconductivity, sufficient strength to maintain its structure, and resorbability. Furthermore, amenability to rapid prototyping fabrication methods is desirable, as these approaches offer precise control over scaffold architecture and have the potential for customization. While calcium phosphate cements meet many of these criteria due to their composition and their injectability, which can be leveraged for scaffold fabrication via indirect casting, their mechanical properties are a major limitation. Thus, the overall goal of this work was to develop a 3D polymer reinforced calcium phosphate cement scaffold for use in cranial bone tissue engineering. Dicalcium phosphate dihydrate (DCPD) setting cements are of particular interest because of their excellent resorbability. We demonstrated for the first time that DCPD cement can be prepared from monocalcium phosphate monohydrate (MCPM)/hydroxyapatite (HA) mixtures. However, subsequent characterization revealed that MCPM/HA cements rapidly convert to HA during degradation, which is undesirable and led us to choose a more conventional formulation for scaffold fabrication. In addition, we developed a novel method for calcium phosphate cement reinforcement that is based on infiltrating a pre-set cement structure with a polymer, and then crosslinking the polymer in situ. Unlike prior methods of cement reinforcement, this method can be applied to the reinforcement of 3D scaffolds fabricated by indirect casting. Using our novel method, composites of poly(propylene fumarate) (PPF) reinforced DCPD were prepared and demonstrated as excellent candidate scaffold materials, as they had increased strength and ductility and were biocompatible in vitro. Furthermore, 3D PPF reinforced DCPD scaffolds had strengths comparable to trabecular bone. Based on these results, 3D PPF reinforced DCPD scaffolds were evaluated in vivo using a rabbit calvarial defect model. Although bone formation was not enhanced by the addition of mesenchymal stem cells, significant bone ingrowth from the surrounding tissue was observed. The results of this work provide a foundation for future research on 3D polymer reinforced calcium phosphate cement scaffolds.

  9. Characterization of bone repair in rat femur after treatment with calcium phosphate cement and autogenous bone graft

    Microsoft Academic Search

    Edela Puricelli; Adriana Corsetti; Deise Ponzoni; Gustavo L Martins; Mauro G Leite; Luis A Santos

    2010-01-01

    BACKGROUND: In this study, the biocompatibility, stability and osteotransductivity of a new cement based on alpha-tricalcium phosphate (alpha-TCP) were investigated in a bone repair model using a rat model. METHODS: The potential of alpha-TCP on bone repair was compared to autogenous bone grafting, and unfilled cavities were used as negative control. Surgical cavities were prepared and designated as test (T),

  10. Biocompatibility of septal defect closure devices

    PubMed Central

    Sigler, Matthias

    2007-01-01

    Objective Despite their clinical introduction 10?years ago, no human series on the healing response to Amplatzer and Starflex devices in humans have been reported yet. We sought to investigate the biocompatibility of Amplatzer and Cardioseal/Starflex septal occluder devices in humans and compare the findings to results in experimental animals. Methods The healing response of Amplatzer and Cardioseal/Starflex septal occluder devices in humans (n?=?12, follow?up periods from 5?days to 4?years) and in experimental animals (n?=?32, follow?up periods from 4?days to 1?year) was studied using a uniform work up protocol. Histological sections of paraffin?wax?embedded or methacrylate?embedded specimen and scanning electron microscopy were used for biocompatibility screening. Results Neoendothelialisation of all examined devices was complete after 3?months in vivo. Protruding metal frame parts, like screw threads and spring arms, were covered last. The initial deposition of fibrin and blood cells on the polyester fabric was subsequently organised by ingrown fibroblastic cells. Loosely arranged and poorly vascularised young granulation tissue was transformed time?dependently into quiescent fibre?rich connective repair tissue poor of cellular and capillary vessel components. Consistently, a mild chronic inflammatory response directed against textile fibres of both types of implants characterised by lymphocytic infiltration and multinucleated foreign body giant cells was observed equally in human and animal explants. Conclusions Systematic biocompatibility screening in a series of explanted human septal occluder devices showed results corresponding to findings in animal studies with regard to neoendothelialisation, cellular organisation of initial thrombus and persisting immune response. PMID:17035510

  11. Biphasic products of dicalcium phosphate-rich cement with injectability and nondispersibility.

    PubMed

    Ko, Chia-Ling; Chen, Jian-Chih; Hung, Chun-Cheng; Wang, Jen-Chyan; Tien, Yin-Chun; Chen, Wen-Cheng

    2014-06-01

    In this study, a calcium phosphate cement was developed using tetracalcium phosphate and surface-modified dicalcium phosphate anhydrous (DCPA). This developed injectable bone graft substitute can be molded to the shape of the bone cavity and set in situ through the piping system that has an adequate mechanical strength, non-dispersibility, and biocompatibility. The materials were based on the modified DCPA compositions of calcium phosphate cement (CPC), where the phase ratio of the surface-modified DCPA is higher than that of the conventional CPC for forming dicalcium phosphate (DCP)-rich cement. The composition and morphology of several calcium phosphate cement specimens during setting were analyzed via X-ray diffractometry and transmission electron microscopy coupled with an energy dispersive spectroscopy system. The compressive strength of DCP-rich CPCs was greater than 30MPa after 24h of immersion in vitro. The reaction of the CPCs produced steady final biphasic products of DCPs with apatite. The composites of calcium phosphate cements derived from tetracalcium phosphate mixed with surface-modified DCPA exhibited excellent mechanical properties, injectability, and interlocking forces between particles, and they also featured nondispersive behavior when immersed in a physiological solution. PMID:24863195

  12. Adhesion enhancement of steel fibers to acrylic bone cement through a silane coupling agent.

    PubMed

    Kotha, S P; Lieberman, M; Vickers, A; Schmid, S R; Mason, J J

    2006-01-01

    The use of a silane coupling agent (methacryloxypropyl-trichlorosilane) to improve the mechanical properties of steel fiber-reinforced acrylic bone cements was assessed. Changes to the tensile and fracture properties of bone cements reinforced with silane-coated or uncoated 316L stainless steel fibers of different aspect ratios were studied. Contact-angle measurements indicated that the coupling agent coats the metal surface through room temperature treatments in a short time (within 2 h). Push-out tests indicated that the interfacial shear strength of silane-coated 316L stainless steel rods is 141% higher than the uncoated rods. The elastic moduli, ultimate stresses, and fracture toughness of the silane-coated, steel fiber-reinforced bone cements are significantly higher than the bone cements reinforced with uncoated steel fibers. There were no differences in the tensile mechanical properties of the silane-coated or uncoated, steel fiber-reinforced cements after aging in a physiological saline solution, indicating that the bonding effectiveness is decreased by the intrusion of water at the metal-polymer interface. Because of possible biocompatibility issues with leaching of the silane coupling agent and no long-term mechanical benefit in simulated aging experiments, the use of these agents is not recommended for in vivo use. PMID:16224777

  13. Polymeric additives to enhance the functional properties of calcium phosphate cements

    PubMed Central

    Perez, Roman A; Kim, Hae-Won

    2012-01-01

    The vast majority of materials used in bone tissue engineering and regenerative medicine are based on calcium phosphates due to their similarity with the mineral phase of natural bone. Among them, calcium phosphate cements, which are composed of a powder and a liquid that are mixed to obtain a moldable paste, are widely used. These calcium phosphate cement pastes can be injected using minimally invasive surgery and adapt to the shape of the defect, resulting in an entangled network of calcium phosphate crystals. Adding an organic phase to the calcium phosphate cement formulation is a very powerful strategy to enhance some of the properties of these materials. Adding some water-soluble biocompatible polymers in the calcium phosphate cement liquid or powder phase improves physicochemical and mechanical properties, such as injectability, cohesion, and toughness. Moreover, adding specific polymers can enhance the biological response and the resorption rate of the material. The goal of this study is to overview the most relevant advances in this field, focusing on the different types of polymers that have been used to enhance specific calcium phosphate cement properties. PMID:22511991

  14. Sulphate Resistance of Slag Cements

    Microsoft Academic Search

    Charles A. Low

    1980-01-01

    The vulnerability of concrete to sulphate attack has been recognized and studied for at least two centuries. The basic needs that prompted that study were: (a) there are no available Canadian Standards on the sulphate resistance of slag cements; and (b) slag cements in general are not well known in Canada. There were three main phases in the study: Phase

  15. Dispersion strengthened cemented carbides

    SciTech Connect

    Cutler, R.A.; Alexander, G.B.; Plichta, M.R.

    1983-09-01

    The research studied the feasibility of strengthening WC-CO cermets by adding refractory oxides to the binder phase. Cemented carbides containing 0.06 to 1.5 vol. % finely dispersed oxide particles in cobalt powder, prior to liquid phase sintering, were densified and compared to undoped control powders. Three different processes for dispersing refractory oxides in cobalt metal were investigated. Results suggest that the oxide particles coalesced and/or segregated to WC-CO interfaces during the liquid-phase sintering process.

  16. Cement brand and preparation effects cement-in-cement mantle shear strength.

    PubMed

    Holsgrove, Timothy P; Pentlow, Alanna; Spencer, Robert F; Miles, Anthony W

    2015-01-01

    Creating bi-laminar cement mantles as part of revision hip arthroplasty is well-documented but there is a lack of data concerning the effect of cement brand on the procedure. The aim of this study was to compare the shear strength of bi-laminar cement mantles using various combinations of two leading bone cement brands.Bi-laminar cement mantles were created using Simplex P with Tobramycin, and Palacos R+G: Simplex-Simplex (SS); Simplex-Palacos (SP); Palacos-Simplex (PS); and Palacos-Palacos (PP). Additionally, specimens were produced by rasping (R) the surface of the original mantle, or leaving it unrasped (U), leading to a total of eight groups (n = 10). Specimens were loaded in shear, at 0.1 mm/min, until failure, and the maximum shear strength calculated.The highest mean shear strength was found in the PSU and PSR groups (23.69 and 23.89 MPa respectively), and the lowest in the PPU group (14.70 MPa), which was significantly lower than all but two groups. Unrasped groups generally demonstrated greater standard error than rasped groups.In a further comparison to assess the effect of the new cement mantle brand, irrespective of the brand of the original mantle, Simplex significantly increased the shear strength compared to Palacos with equivalent preparation.It is recommended that the original mantle is rasped prior to injection of new cement, and that Simplex P with Tobramycin be used in preference to Palacos R+G irrespective of the existing cement type. Further research is needed to investigate more cement brands, and understand the underlying mechanisms relating to cement-in-cement procedures. PMID:25044271

  17. Dual setting ?-tricalcium phosphate cements.

    PubMed

    Christel, T; Kuhlmann, M; Vorndran, E; Groll, J; Gbureck, U

    2013-03-01

    An extension of the application of calcium phosphate cements (CPC) to load-bearing defects, e.g. in vertebroplasty, would require less brittle cements with an increased fracture toughness. Here we report the modification of CPC made of alpha-tricalcium phosphate (?-TCP) with 2-hydroxyethylmethacrylate (HEMA), which is polymerised during setting to obtain a mechanically stable polymer-ceramic composite with interpenetrating organic and inorganic networks. The cement liquid was modified by the addition of 30-70 % HEMA and ammoniumpersulfate/tetramethylethylendiamine as initiator. Modification of ?-TCP cement paste with HEMA decreased the setting time from 14 min to 3-8 min depending on the initiator concentration. The 4-point bending strength was increased from 9 MPa to more than 14 MPa when using 50 % HEMA, while the bending modulus decreased from 18 GPa to approx. 4 GPa. The addition of ?50 % HEMA reduced the brittle fracture behaviour of the cements and resulted in an increase of the work of fracture by more than an order of magnitude. X-ray diffraction analyses revealed that the degree of transformation of ?-TCP to calcium deficient hydroxyapatite was lower for polymer modified cements (82 % for polymer free cement and 55 % for 70 % HEMA) after 24 h setting, while the polymerisation of HEMA in the cement liquid was quantitative according to FT-IR spectroscopy. This work demonstrated the feasibility of producing fracture resistant dual-setting calcium phosphate cements by adding water soluble polymerisable monomers to the liquid cement phase, which may be suitable for an application in load-bearing bone defects. PMID:23239262

  18. Biocompatibility and osteogenic properties of porous tantalum

    PubMed Central

    WANG, QIAN; ZHANG, HUI; LI, QIJIA; YE, LEI; GAN, HONGQUAN; LIU, YINGJIE; WANG, HUI; WANG, ZHIQIANG

    2015-01-01

    Porous tantalum has been reported to be a promising material for use in bone tissue engineering. In the present study, the biocompatibility and osteogenic properties of porous tantalum were studied in vitro and in vivo. The morphology of porous tantalum was observed using scanning electron microscopy (SEM). Osteoblasts were cultured with porous tantalum, and cell morphology, adhesion and proliferation were investigated using optical microscopy and SEM. In addition, porous tantalum rods were implanted in rabbits, and osteogenesis was observed using laser scanning confocal microscopy and hard tissue slice examination. The osteoblasts were observed to proliferate over time and adhere to the tantalum surface and pore walls, exhibiting a variety of shapes and intercellular connections. The porous tantalum rod connected tightly with the host bone. At weeks 2 and 4 following implantation, new bone and small blood vessels were observed at the tantalum-host bone interface and pores. At week 10 after the porous tantalum implantation, new bone tissue was observed at the tantalum-host bone interface and pores. By week 12, the tantalum-host bone interface and pores were covered with new bone tissue and the bone trabeculae had matured and connected directly with the materials. Therefore, the results of the present study indicate that porous tantalum is non-toxic, biocompatible and a promising material for use in bone tissue engineering applications. PMID:25667628

  19. Mechanical biocompatibility of highly deformable biomedical materials.

    PubMed

    Mazza, Edoardo; Ehret, Alexander E

    2015-08-01

    Mismatch of mechanical properties between highly deformable biomedical materials and adjacent native tissue might lead to short and long term health impairment. The capability of implants to deform at the right level, i.e. similar to the macroscopic mechanical response of the surrounding biological materials, is often associated with dissimilar microstructural deformation mechanisms. This mismatch on smaller length scales might lead to micro-injuries, cell damage, inflammation, fibrosis or necrosis. Hence, the mechanical biocompatibility of soft implants depends not only on the properties and composition of the implant material, but also on its organization, distribution and motion at one or several length scales. The challenges related to the analysis and attainment of mechanical biocompatibility are illustrated with two examples: prosthetic meshes for hernia and pelvic repair and electrospun scaffolds for tissue engineering. For these material systems we describe existing methods for characterization and analysis of the non-linear response to uniaxial and multiaxial stress states, its time and history dependence, and the changes in deformation behavior associated with tissue in-growth and material resorption. We discuss the multi-scale deformation behavior of biomaterials and adjacent tissue, and indicate major interdisciplinary questions to be addressed in future research. PMID:25916818

  20. Corrosion resistant cemented carbide

    SciTech Connect

    Hong, J.

    1990-10-16

    This paper describes a corrosion resistant cemented carbide composite. It comprises: a granular tungsten carbide phase, a semi-continuous solid solution carbide phase extending closely adjacent at least a portion of the grains of tungsten carbide for enhancing corrosion resistance, and a substantially continuous metal binder phase. The cemented carbide composite consisting essentially of an effective amount of an anti-corrosion additive, from about 4 to about 16 percent by weight metal binder phase, and with the remaining portion being from about 84 to about 96 percent by weight metal carbide wherein the metal carbide consists essentially of from about 4 to about 30 percent by weight of a transition metal carbide or mixtures thereof selected from Group IVB and of the Periodic Table of Elements and from about 70 to about 96 percent tungsten carbide. The metal binder phase consists essentially of nickel and from about 10 to about 25 percent by weight chromium, the effective amount of an anti-corrosion additive being selected from the group consisting essentially of copper, silver, tine and combinations thereof.

  1. Development of an injectable bioactive bone filler cement with hydrogen orthophosphate incorporated calcium sulfate.

    PubMed

    Sony, Sandhya; Suresh Babu, S; Nishad, K V; Varma, Harikrishna; Komath, Manoj

    2015-01-01

    Calcium sulfate cement (CSC) has emerged as a potential bone filler material mainly because of the possibility of incorporating therapeutic agents. Delivery of the cement through a needle or cannula will make it more useful in clinical applications. However, it was not possible to make CSC injectable because of the inherent lack of viscosity. The present work demonstrates the design development of a viscous and fully-injectable CSC by incorporating hydrogen orthophosphate ions, which does not hamper the biocompatibility of the material. The effect of addition of hydrogen orthophosphate on the rheological properties of the CSC paste was studied using a custom made capillary rheometer. The physicochemical changes associated with cement setting process were examined using X-ray diffraction and Fourier transform infrared spectroscopy and the thermal changes were measured through isothermal differential scanning calorimetry. Micromorphological features of different compositions were observed in environmental scanning electron microscopy and the presence of phosphate ions was identified with energy dispersive X-ray spectroscopic analysis and inductively coupled plasma-optical emission spectroscopy. The results indicated that HPO4 (2-) ions have profound effects on the rheological properties and setting of the CSC paste. Significant finding is that the HPO4 (2-) ions are getting substituted in the calcium sulfate dihydrate crystals during setting. The variations of setting time and compressive strength of the cement with the additive concentration were investigated. An optimum concentration of 2.5 % w/w gave a fully-injectable cement with clinically relevant setting time (below 20 min) and compressive strength (12 MPa). It was possible to inject the optimised cement paste from a syringe through an 18-gauge needle with thumb pressure. This cement will be useful both as bone filler and as a local drug delivery medium and it allows minimally invasive bone defect management. PMID:25578708

  2. Evaluation of injectable strontium-containing borate bioactive glass cement with enhanced osteogenic capacity in a critical-sized rabbit femoral condyle defect model.

    PubMed

    Zhang, Yadong; Cui, Xu; Zhao, Shichang; Wang, Hui; Rahaman, Mohamed N; Liu, Zhongtang; Huang, Wenhai; Zhang, Changqing

    2015-02-01

    The development of a new generation of injectable bone cements that are bioactive and have enhanced osteogenic capacity for rapid osseointegration is receiving considerable interest. In this study, a novel injectable cement (designated Sr-BBG) composed of strontium-doped borate bioactive glass particles and a chitosan-based bonding phase was prepared and evaluated in vitro and in vivo. The bioactive glass provided the benefits of bioactivity, conversion to hydroxyapatite, and the ability to stimulate osteogenesis, while the chitosan provided a cohesive biocompatible and biodegradable bonding phase. The Sr-BBG cement showed the ability to set in situ (initial setting time = 11.6 ± 1.2 min) and a compressive strength of 19 ± 1 MPa. The Sr-BBG cement enhanced the proliferation and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells in vitro when compared to a similar cement (BBG) composed of chitosan-bonded borate bioactive glass particles without Sr. Microcomputed tomography and histology of critical-sized rabbit femoral condyle defects implanted with the cements showed the osteogenic capacity of the Sr-BBG cement. New bone was observed at different distances from the Sr-BBG implants within eight weeks. The bone-implant contact index was significantly higher for the Sr-BBG implant than it was for the BBG implant. Together, the results indicate that this Sr-BBG cement is a promising implant for healing irregularly shaped bone defects using minimally invasive surgery. PMID:25591177

  3. Current perspectives of bio-ceramic technology in endodontics: calcium enriched mixture cement - review of its composition, properties and applications

    PubMed Central

    Nawal, Ruchika Roongta; Talwar, Sangeeta; Verma, Mahesh

    2015-01-01

    Advancements in bio-ceramic technology has revolutionised endodontic material science by enhancing the treatment outcome for patients. This class of dental materials conciliates excellent biocompatibility with high osseoconductivity that render them ideal for endodontic care. Few recently introduced bio-ceramic materials have shown considerable clinical success over their early generations in terms of good handling characteristics. Calcium enriched mixture (CEM) cement, Endosequence sealer, and root repair materials, Biodentine and BioAggregate are the new classes of bio-ceramic materials. The aim of this literature review is to present investigations regarding properties and applications of CEM cement in endodontics. A review of the existing literature was performed by using electronic and hand searching methods for CEM cement from January 2006 to December 2013. CEM cement has a different chemical composition from that of mineral trioxide aggregate (MTA) but has similar clinical applications. It combines the biocompatibility of MTA with more efficient characteristics, such as significantly shorter setting time, good handling characteristics, no staining of tooth and effective seal against bacterial leakage. PMID:25671207

  4. Multiblock copolyesters as biomaterials: in vitro biocompatibility testing

    Microsoft Academic Search

    B. SAAD; O. M KEISER; M WELTI; G. K UHLSCHMID; P NEUENSCHWANDER; U. W SUTER

    1997-01-01

    Cell adhesion, cell growth and cell activities of macrophages and fibroblasts, cultured on newly developed degradable multiblock-copolyesters were studied to examine the biocompatibility and the possible use of these polymers for medical applications. The biocompatibility and the biodegradability of the polymers were confirmed by subcutaneous implantation of polymer foils in rats.

  5. Biodegradation and biocompatibility of PLA and PLGA microspheres

    Microsoft Academic Search

    James M Anderson; Matthew S Shive

    1997-01-01

    A fundamental understanding of the in vivo biodegradation phenomenon as well as an appreciation of cellular and tissue responses which determine the biocompatibility of biodegradable PLA and PLGA microspheres are important components in the design and development of biodegradable microspheres containing bioactive agents for therapeutic application. This chapter is a critical review of biodegradation, biocompatibility and tissue\\/material interactions, and selected

  6. The quantification of biocompatibility: toward a new definition

    Microsoft Academic Search

    Buddy Ratner

    2008-01-01

    Implantable medical devices, and the biomaterials that comprise them, form a 100B business worldwide. Medical devices save lives and\\/or improve the quality of life for millions. Tissue engineering also makes extensive use of biomaterials -- biomaterials are an enabling technology for tissue engineering. A central word to understanding the effectiveness of such materials and devices is biocompatibility. The word ``biocompatible''

  7. Calcium phosphate cement - gelatin powder composite testing in canine models: Clinical implications for treatment of bone defects.

    PubMed

    Yomoda, Mitsuhiro; Sobajima, Satoshi; Kasuya, Akihiro; Neo, Masashi

    2015-05-01

    Previous studies have reported the excellent biocompatibility of calcium phosphate cement. However, calcium phosphate cement needs further improvement in order for it to promote bone replacement and eventual bone substitution, as it exhibits slow biodegradability and thus remains in the body over an extended period of time. In this study, we mixed calcium phosphate cement with gelatin powder in order to create a composite containing macropores with interconnectivity, and we then implanted it into canine femurs from the diaphysis to the distal metaphysis. Eight dogs were divided into the sham group, the control (C0) group with 100 wt% calcium phosphate cement, the C10 group with 90 wt% calcium phosphate cement and 10 wt% gelatin powder, and the C15 group with 85 wt% calcium phosphate cement and 15 wt% gelatin powder. Bone replaceability in C10 and C15 at 3 and 6 months was evaluated by radiography, micro-CT, histomorphometry, and mineral apposition rate. New bone formation was seen in C10 and C15 although that was not seen in C0 at six months. The mineral apposition rate was significantly higher in C15 than in C10 in both the diaphysis and metaphysis, and the composite was found to have excellent biodegradability and bone replaceability in canine subjects. As the composite is easily and rapidly prepared, it is likely to become a new bone substitute for use in clinical settings. PMID:25550332

  8. Holocene cemented beach deposits in Belize

    Microsoft Academic Search

    Eberhard Gischler; Anthony J. Lomando

    1997-01-01

    Two types of cemented beach deposits occur on reef islands off the coast of Belize. These are (1) intertidal beachrock that is dominantly cemented by marine aragonite and high-magnesium-calcite cements, and (2) supratidal cayrock that is cemented mainly by vadose low-magnesium-calcite cements. Besides differences in position relative to present sea level and resulting early diagenesic features, beachrock and cayrock can

  9. Biostability and biocompatibility of modified polyurethane elastomers

    NASA Astrophysics Data System (ADS)

    Christenson, Elizabeth Marie

    Several strategies have been employed to increase the biostability of medical grade polyurethanes while maintaining the desirable properties of current poly(ether urethanes). It was hypothesized that polyurethane surface chemistry controls biodegradation/biostability that can lead to ultimate failure/success of these materials in clinical applications. Chemical modification or replacement of the susceptible soft segment was evaluated as a design strategy to increase the biostability of medical grade polyurethanes. The effect of soft segment chemistry on the phase morphology, mechanical properties and in vivo response of commercial polyurethanes were compared. Poly(ether urethane) (PEU), silicone-modified poly(ether urethane) (PEU-S), poly(carbonate urethane) (PCU) and silicone-modified poly(carbonate urethane) (PCU-S) elastomers were investigated. AFM phase imaging indicated that the overall two-phase morphology of poly(ether urethanes), necessary for its thermoplastic elastomeric properties, was not disrupted by changing the soft segment chemistry. All of the polyurethanes exhibited thermoplastic elastomeric behavior similar to that of the poly(ether urethane). Following material characterization, the biocompatibility of the polyurethane elastomers was evaluated using a subcutaneous cage implant protocol. All of the polyurethanes tested retained the excellent biocompatibility typical of poly(ether urethane) elastomers. Overall, the candidate polyurethanes were concluded to be suitable replacements of current poly(ether urethane) elastomers in medical applications. The results from the cage implant study and cell culture experiments indicated that monocytes adhere, differentiate and fuse to form foreign body giant cells (FBGCs) on all of the polyurethane specimens. It is now generally accepted that the reactive oxygen species released by these adherent macrophages and FBGCs initiate PEU biodegradation. ATR-FTIR analysis of explanted samples provided evidence of chain scission and crosslinking in all of the polyurethane specimens. Therefore, it was concluded that the chosen soft segment modifications were insufficient to fully inhibit biodegradation. (Abstract shortened by UMI.)

  10. Molecular mechanisms of crystallization impacting calcium phosphate cements

    PubMed Central

    Giocondi, Jennifer L.; El-Dasher, Bassem S.; Nancollas, George H.; Orme, Christine A.

    2010-01-01

    The biomineral calcium hydrogen phosphate dihydrate (CaHPO4·2H2O), known as brushite, is a malleable material that both grows and dissolves faster than most other calcium minerals, including other calcium phosphate phases, calcium carbonates and calcium oxalates. Within the body, this ready formation and dissolution can play a role in certain diseases, such as kidney stone and plaque formation. However, these same properties, along with brushite’s excellent biocompatibility, can be used to great benefit in making resorbable biomedical cements. To optimize cements, additives are commonly used to control crystallization kinetics and phase transformation. This paper describes the use of in situ scanning probe microscopy to investigate the role of several solution parameters and additives in brushite atomic step motion. Surprisingly, this work demonstrates that the activation barrier for phosphate (rather than calcium) incorporation limits growth kinetics and that additives such as magnesium, citrate and bisphosphonates each influence step motion in distinctly different ways. Our findings provide details of how, and where, molecules inhibit or accelerate kinetics. These insights have the potential to aid in designing molecules to target specific steps and to guide synergistic combinations of additives. PMID:20308110

  11. Performance Cements Focus on Sustainability

    E-print Network

    - Composite Cement CEM IV - Pozzolanic CEM III - Blast furnace slag CEM II - Portland-composite CEM II - Portland-limestone CEM II - Portland-fly ash CEM II - Portland-pozzolana CEM II - Portland-slag CEM I

  12. VersaBond bone cement

    Microsoft Academic Search

    Tore Dalén; Kjell G. Nilsson

    2005-01-01

    VersaBond is a newly developed bone cement. To investigate its clinical performance, VersaBond was compared to Palacos R in a prospective randomized study in total knee replacement. Fifty-nine patients (61 knees) undergoing total knee replacement were randomized to either VersaBond or Palacos R bone cement and followed for 24 months using radiostereometric analysis (RSA).Up to 2 years there were no

  13. Portland cement-blast furnace slag blends in oilwell cementing applications

    SciTech Connect

    Mueller, D.T.; DiLullo, G.; Hibbeler, J. [and others

    1995-12-31

    Recent investigations of blast furnace slag cementing technologies. have been expanded to include Portland cement/blast furnace slag blends. Mixtures of Portland cement and blast furnace slag, while having a long history of use in the construction industry, have not been used extensively in oilwell cementing applications. Test results indicate that blending blast furnace slag with Portland cement produces a high quality well cementing material. Presented are the design guidelines and laboratory test data relative to mixtures of blast furnace slag and Portland cements. Case histories delineating the use of blast furnace slag - Portland cement blends infield applications are also included.

  14. Cement pulmonary embolism after vertebroplasty.

    PubMed

    Sifuentes Giraldo, Walter Alberto; Lamúa Riazuelo, José Ramón; Gallego Rivera, José Ignacio; Vázquez Díaz, Mónica

    2013-01-01

    In recent years, the use of vertebral cementing techniques for vertebroplasty and kyphoplasty has spread for the treatment of pain associated with osteoporotic vertebral compression fractures. This is also associated with the increased incidence of complications related with these procedures, the most frequent being originated by leakage of cementation material. Cement can escape into the vertebral venous system and reach the pulmonary circulation through the azygous system and cava vein, producing a cement embolism. This is a frequent complication, occurring in up to 26% of patients undergoing vertebroplasty but, since most patients have no clinical or hemodynamical repercussion, this event usually goes unnoticed. However, some serious, and even fatal cases, have been reported. We report the case of a 74-year-old male patient who underwent vertebroplasty for persistent pain associated with osteoporotic L3 vertebral fracture and who developed a cement leak into the cava vein and right pulmonary artery during the procedure. Although he developed a pulmonary cement embolism, the patient remained asymptomatic and did not present complications during follow-up. PMID:23481509

  15. Intramedullary cement osteosynthesis (IMCO): a pilot study in sheep.

    PubMed

    Mirzasadeghi, Alireza; Narayanan, Sri Subanesh; Ng, Min Hwei; Sanaei, Reza; Cheng, Chen Hui; Bajuri, Mohd Yazid; Shukur, Mohammad Hassan

    2014-01-01

    The application of bone substitutes and cements has a long standing history in augmenting fractures as a complement to routine fracture fixation techniques. Nevertheless, such use is almost always in conjunction with definite means of fracture fixation such as intramedullary pins or bone plates. The idea of using biomaterials as the primary fixation bears the possibility of simultaneous fixation and bone enhancement. Intramedullary recruitment of bone cements is suggested in this study to achieve this goal. However, as the method needs primary testings in animal models before human implementation, and since the degree of ambulation is not predictable in animals, this pilot study only evaluates the outcomes regarding the feasibility and safety of this method in the presence of primary bone fixators. A number of two sheep were used in this study. Tibial transverse osteotomies were performed in both animals followed by external skeletal fixation. The medullary canals, which have already been prepared by removing the marrow through proximal and distal drill holes, were then injected with calcium phosphate cement (CPC). The outcomes were evaluated postoperatively by standard survey radiographs, morphology, histology and biomechanical testings. Healing processes appeared uncomplicated until week four where one bone fracture recurred due to external fixator failure. The results showed 56% and 48% cortical thickening, compared to the opposite site, in the fracture site and proximal and distal diaphyses respectively. This bone augmentative effect resulted in 264% increase in bending strength of the fracture site and 148% increase of the same value in the adjacent areas of diaphyses. In conclusion, IMCO, using CPC in tibia of sheep, is safe and biocompatible with bone physiology and healing. It possibly can carry the osteopromotive effect of the CPCs to provide a sustained source of bone augmentation throughout the diaphysis. Although the results must be considered preliminary, this method has possible advantages over conventional methods of bone fixation at least in bones with compromised quality (i.e. osteoporosis and bone cysts), where rigid metal implants may jeopardize eggshell cortices. PMID:25226916

  16. Manufacture and properties of fluoride cement

    NASA Astrophysics Data System (ADS)

    Malata-Chirwa, Charles David

    This research work aimed at characterising composition, hydration and physical properties of fluoride cement, by studying samples of the cement obtained from Malawi, and comparing them to ordinary Portland cement. By confirming the suitable characteristics of fluoride cement through this work, the results of the research work provide a good basis for the wider adoption of fluoride cement as an alternative to ordinary Portland cement, especially in developing economies. Numerous accounts have been cited regarding the production and use of fluoride cement. Since there have not been conclusive agreement as to its properties, this study was limited to the theories of successful incorporation of fluoride compounds in the manufacture of fluoride cement. Hence, the properties and characteristics reported in this study relate to the cement currently manufactured in Malawi, and, on a comparative basis only, to that manufactured in other parts of the world. Samples of the fluoride cement used in the study were obtained by synthetic manufacture of the cement using common raw materials for the manufacture of fluoride cement that is limestone, silica sand, and fluorspar. These samples were subjected to several comparative tests used to characterise cements including examination under x-ray diffractometer, scanning electron microscopy and tests for setting time and compressive strength. Under similar laboratory conditions, it was possible to prove that fluoride cement hardens more rapidly than ordinary Portland cement. Also observed during the experimental work is that fluoride cement develops higher compressive strengths than ordinary Portland cement. The hardening and setting times are significantly different between the two cements. Also the nature of the hydration products, that is the microstructural development is significantly different in the two cements. The differences brought about between the two cements are because of the presence of fluorine during the clinkering process. It was observed in the laboratory simulated production of fluoride cement, that the clinkering temperature is much lower (around 1 170 °C) compared to that for the production of ordinary Portland cement. The other observed differences were attributed to the different mineralogical composition as a result of fluoride incorporation into the cement. While fluorine content is very minimal in fluoride cement, not more than 2 %, the resulting cementitious products are altered significantly as was observed from the study. Part of the experimental results has been used as reference material in the preparation of a draft Malawi Standard on fluoride cement. This draft standard will be submitted to the Malawi Bureau of Standards for further processing before it can be officially endorsed as a Malawi Standard.

  17. Effect of Different Intraorifice Barriers on the Fracture Resistance of Roots Obturated with Resilon or Gutta-Percha

    Microsoft Academic Search

    Emre Nagas; Ozgur Uyanik; Emre Altundasar; Veli Durmaz; Zafer C. Cehreli; Pekka K. Vallittu; Lippo V. J. Lassila

    2010-01-01

    IntroductionThis study investigated and compared the root reinforcement potential of 3 different intraorifice barriers (mineral trioxide aggregate [MTA], resin-modified glass ionomer cement [Vitremer], and fiber-reinforced composite [FRC]) placed over root canals obturated with gutta-percha or Resilon.

  18. Providing an environment for reparative dentine induction in amputated rat molar pulp by high molecular-weight hyaluronic acid

    Microsoft Academic Search

    Takahisa Sasaki; Hidemi Kawamata-Kido

    1995-01-01

    To study provision of this environment, wound healing was examined by light and electron microscopy following pulp amputation and direct capping with hyaluronic acid. Molar pulps of female Sprague-Dawley rats were mechanically exposed and directly capped; the cavities were then restored with glass-ionomer cement. As an experimental control, Calvital (a commercial preparation of calcium hydroxide paste) was used as the

  19. Collages en odontologie

    Microsoft Academic Search

    O. Guastalla; S. Viennot; Y. Allard

    2005-01-01

    In odontology, bonding has become an efficient means, useful in consolidating restorations while remaining conservative and aesthetic. However, due to the complexity of the bonding process, available materials need to keep evolving. New glues have been developed, with specific utilization protocols, aimed at bonding materials that also progress perpetually. Methacryl resins, glass ionomer cements and other glues have different properties.

  20. Overview of Stabilizing Ligands for Biocompatible Quantum Dot Nanocrystals

    PubMed Central

    Zhang, Yanjie; Clapp, Aaron

    2011-01-01

    Luminescent colloidal quantum dots (QDs) possess numerous advantages as fluorophores in biological applications. However, a principal challenge is how to retain the desirable optical properties of quantum dots in aqueous media while maintaining biocompatibility. Because QD photophysical properties are directly related to surface states, it is critical to control the surface chemistry that renders QDs biocompatible while maintaining electronic passivation. For more than a decade, investigators have used diverse strategies for altering the QD surface. This review summarizes the most successful approaches for preparing biocompatible QDs using various chemical ligands. PMID:22247651

  1. Microleakage of temporary endodontic restorations in teeth restored with amalgam.

    PubMed

    Turner, J E; Anderson, R W; Pashley, D H; Pantera, E A

    1990-01-01

    Microleakage of seven temporary restorative materials was evaluated in endodontic access preparations made in teeth restored with amalgam. Ten teeth were used for each of the seven materials: Cavit, Cavit-G, TERM, zinc phosphate cement, polycarboxylate cement, glass ionomer cement, and IRM. A class I amalgam was placed in the occlusal surface of each experimental tooth and an endodontic access preparation was made entirely within the amalgam. Then the access preparation was restored with one of the temporary restorative materials, and microleakage was evaluated using a fluid filtration technique. The amount of microleakage was quantitated by measuring the fluid flow at 15 min, 1 h, 24 h, 1 wk, and 2 wk after insertion of the temporary restoration. Cavit, Cavit-G, TERM, IRM, and glass ionomer cement all provided excellent seals while zinc phosphate cement and polycarboxylate cement provided less effective seals. PMID:2388011

  2. Mesoporous silica nanoparticle nanocarriers: biofunctionality and biocompatibility.

    PubMed

    Tarn, Derrick; Ashley, Carlee E; Xue, Min; Carnes, Eric C; Zink, Jeffrey I; Brinker, C Jeffrey

    2013-03-19

    The study of ordered mesoporous silica materials has exploded since their discovery by Mobil researchers 20 years ago. The ability to make uniformly sized, porous, and dispersible nanoparticles using colloidal chemistry and evaporation-induced self-assembly has led to many applications of mesoporous silica nanoparticles (MSNPs) as "nanocarriers" for delivery of drugs and other cargos to cells. The exceptionally high surface area of MSNPs, often exceeding 1000 m²/g, and the ability to independently modify pore size and surface chemistry, enables the loading of diverse cargos and cargo combinations at levels exceeding those of other common drug delivery carriers such as liposomes or polymer conjugates. This is because noncovalent electrostatic, hydrogen-bonding, and van der Waals interactions of the cargo with the MSNP internal surface cause preferential adsorption of cargo to the MSNP, allowing loading capacities to surpass the solubility limit of a solution or that achievable by osmotic gradient loading. The ability to independently modify the MSNP surface and interior makes possible engineered biofunctionality and biocompatibility. In this Account, we detail our recent efforts to develop MSNPs as biocompatible nanocarriers (Figure 1 ) that simultaneously display multiple functions including (1) high visibility/contrast in multiple imaging modalities, (2) dispersibility, (3) binding specificity to a particular target tissue or cell type, (4) ability to load and deliver large concentrations of diverse cargos, and (5) triggered or controlled release of cargo. Toward function 1, we chemically conjugated fluorescent dyes or incorporated magnetic nanoparticles to enable in vivo optical or magnetic resonance imaging. For function 2, we have made MSNPs with polymer coatings, charged groups, or supported lipid bilayers, which decrease aggregation and improve stability in saline solutions. For functions 3 and 4, we have enhanced passive bioaccumulation via the enhanced permeability and retention effect by modifying the MSNP surfaces with positively charged polymers. We have also chemically attached ligands to MSNPs that selectively bind to receptors overexpressed in cancer cells. We have used encapsulation of MSNPs within reconfigurable supported lipid bilayers to develop new classes of responsive nanocarriers that actively interact with the target cell. Toward function 4, we exploit the high surface area and tailorable surface chemistry of MSNPs to retain hydrophobic drugs. Finally, for function 5, we have engineered dynamic behaviors by incorporating molecular machines within or at the entrances of MSNP pores and by using ligands, polymers, or lipid bilayers. These provide a means to seal-in and retain cargo and to direct MSNP interactions with and internalization by target cells. Application of MSNPs as nanocarriers requires biocompatibility and low toxicity. Here the intrinsic porosity of the MSNP surface reduces the extent of hydrogen bonding or electrostatic interactions with cell membranes as does surface coating with polymers or lipid bilayers. Furthermore, the high surface area and low extent of condensation of the MSNP siloxane framework promote a high rate of dissolution into soluble silicic acid species, which are found to be nontoxic. Potential toxicity is further mitigated by the high drug capacity of MSNPs, which greatly reduces needed dosages compared with other nanocarriers. We anticipate that future generations of MSNPs incorporating molecular machines and encapsulated by membrane-like lipid bilayers will achieve a new level of controlled cellular interactions. PMID:23387478

  3. Stage cementing valve

    SciTech Connect

    Lindsey, H.E.; Adams, R.W.

    1989-11-14

    This patent describes a method for stage cementing a string of pipe in a well bore. The string of pipe includes a stage valve having a tubular valve collar intermediate of its length and has a tubular sleeve valve member slidably received in the stage collar for movement between first and second longitudinal positions relative to the stage collar and where the sleeve valve member has a flange in engagement with an engagement surface on the valve collar in the first longitudinal position. The sleeve valve member has a piston portion located in an annular chamber between the sleeve valve member and the valve collar and where the sleeve valve member has a sleeve valve port with access to one surface of the piston portion in the annular chamber for placing the one surface in fluid communication with the bore of the sleeve valve member. The valve collar has a valve collar port with access to the other surface of the of the piston portion in the annular chamber for placing the other surface in fluid communication with the exterior of the valve collar. The piston portion separates the sleeve valve port from the valve collar in a the first longitudinal position and permits the ports to be in fluid communication with one another in an the second longitudinal position.

  4. Performance and biocompatibility of extremely tough alginate/polyacrylamide hydrogels

    E-print Network

    Suo, Zhigang

    National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20982 26 July 2013 Keywords: Biocompatibility Hydrogel Mechanical properties Tendon prosthesis a b s t r

  5. Biocompatible polymer microarrays for cellular high-content screening 

    E-print Network

    Pernagallo, Salvatore

    2010-11-25

    The global aim of this thesis was to study the use of microarray technology for the screening and identification of biocompatible polymers, to understand physiological phenomena, and the design of biomaterials, implant ...

  6. Set retarded cement compositions and methods for well cementing

    SciTech Connect

    Brothers, L.E.; Lindsey, D.W.; Terry, D.T.

    1991-09-17

    This patent describes a retarded cement composition consisting essentially of hydraulic cement, water, a set retarder and a borate compound. It comprises the set retarder, a copolymer consisting of acrylic acid and 2-acrylamido, 2-methylpropane sulfonic acid (AMPS) present in the copolymer in the range of from about 40 to about 60 mole percent, the copolymer having an average molecular weight below about 5,000 such that a 10 percent aqueous solution of the copolymer has a Brookfield viscosity reading at 20 rpm of the UL Adapter Spindle in the range of from about 2 to less than 5 centipoises, the amount in the range of from about 0.3 percent to about 5.0 percent by weight of the hydraulic cement; and further wherein the borate compound is capable of providing a borate ion species in the composition.

  7. Bacterial Cellulose: Long-Term Biocompatibility Studies.

    PubMed

    Pértile, Renata A N; Moreira, Susana; Costa, Rui M Gil da; Correia, Alexandra; Guardão, Luisa; Gartner, Fátima; Vilanova, Manuel; Gama, Miguel

    2011-06-28

    The bacterial cellulose (BC) secreted by Gluconacetobacter xylinus is a network of pure cellulose nanofibres which has high crystallinity, wettability and mechanical strength. These characteristics make BC an excellent material for tissue-engineering constructs, noteworthy for artificial vascular grafts. In this work, the in vivo biocompatibility of BC membranes produced by two G. xylinus strains was analyzed through histological analysis of long-term subcutaneous implants in the mice. The BC implants caused a mild and benign inflammatory reaction that decreased along time and did not elicit a foreign body reaction. A tendency to calcify over time, which may be related to the porosity of the BC implants, was observed, especially among the less porous BC-1 implants. In addition, the potential toxicity of BC nanofibres - obtained by chemical-mechanical treatment of BC membranes - subcutaneously implanted in mice was analysed through bone marrow flow cytometryand histological analyses. At 2 and 4 months post-implantation, the nanofibres implants were found to accumulate intracellularly, in subcutaneous foamy macrophages aggregates. Moreover, no differences were observed between the controls and implanted animals in thymocyte populations and in B lymphocyte precursors and myeloid cells in the bone marrow. PMID:21722421

  8. Ocular Biocompatibility of Nitinol Intraocular Clips

    PubMed Central

    Velez-Montoya, Raul; Erlanger, Michael

    2012-01-01

    Purpose. To evaluate the tolerance and biocompatibility of a preformed nitinol intraocular clip in an animal model after anterior segment surgery. Methods. Yucatan mini-pigs were used. A 30-gauge prototype injector was used to attach a shape memory nitinol clip to the iris of five pigs. Another five eyes received conventional polypropylene suture with a modified Seipser slip knot. The authors compared the surgical time of each technique. All eyes underwent standard full-field electroretinogram at baseline and 8 weeks after surgery. The animals were euthanized and eyes collected for histologic analysis after 70 days (10 weeks) postsurgery. The corneal thickness, corneal endothelial cell counts, specular microscopy parameters, retina cell counts, and electroretinogram parameters were compared between the groups. A two sample t-test for means and a P value of 0.05 were use for assessing statistical differences between measurements. Results. The injection of the nitinol clip was 15 times faster than conventional suturing. There were no statistical differences between the groups for corneal thickness, endothelial cell counts, specular microscopy parameters, retina cell counts, and electroretinogram measurements. Conclusions. The nitinol clip prototype is well tolerated and showed no evidence of toxicity in the short-term. The injectable delivery system was faster and technically less challenging than conventional suture techniques. PMID:22064995

  9. Nanoscale contact mechanics of biocompatible polyzwitterionic brushes.

    PubMed

    Zhang, Zhenyu; Morse, Andrew J; Armes, Steven P; Lewis, Andrew L; Geoghegan, Mark; Leggett, Graham J

    2013-08-27

    Friction force microscopy has been used to demonstrate that biocompatible, lubricious poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC) brushes exhibit different frictional properties depending on the medium (methanol, ethanol, 2-propanol, and water; the latter also with different quantities of added salt). The chemical functionalization of the probe (amine-, carboxylic acid-, and methyl-terminated probes were used) is not as important as the medium in determining the contact mechanics. For solvents such as methanol, where the adhesion between AFM probe and PMPC brushes is negligible, a linear friction-load relationship is observed. In contrast, the friction-load plot is nonlinear in ethanol or water, media in which stronger adhesion is measured. For ethanol, the data indicate Johnson-Kendall-Roberts (JKR) mechanics, whereas the Derjaguin-Muller-Toporov (DMT) model provided a good fit for the data acquired in water. Contact mechanics on zwitterionic PMPC brushes immersed in aqueous solutions of varying ionic strength followed the same trend, with high adhesion energies being correlated with a nonlinear friction-load relationship. These results can be rationalized by treating the friction force as the sum of a load-dependent term, attributed to molecular plowing, and an area-dependent shear term. In a good solvent for PMPC such as methanol, the shear term is negligible and the sliding interaction is dominated by molecular plowing. However, the adhesion energy is significantly larger in water and ethanol and the shear term is no longer negligible. PMID:23855771

  10. Tribological study of lubricious DLC biocompatible coatings.

    PubMed

    Brizuela, M; Garcia-Luis, A; Viviente, J L; Braceras, I; Oñate, J I

    2002-12-01

    DLC (diamond-like carbon) coatings have remarkable tribological properties due mainly to their good frictional behavior. These coatings can be applied in many industrial and biomedical applications, where sliding can generate wear and frictional forces on the components, such as orthopaedic metal implants. This work reports on the development and tribological characterization of functionally gradient titanium alloyed DLC coatings. A PVD-magnetron sputtering technique has been used as the deposition method. The aim of this work was to study the tribological performance of the DLC coating when metal to metal contact (cobalt chromium or titanium alloys) takes place under dry and lubricated test conditions. Prior work by the authors demonstrates that the DLC coating reduced considerably the wear of the ultra-high-molecular-weight polyethylene (UHMWPE). The DLC coating during mechanical testing exhibited a high elastic recovery (65%) compared to the values obtained from Co-Cr-Mo (15%) and Ti-6Al-4V (23%). The coating exhibited an excellent tribo-performance against the Ti-6Al-4V and Co-Cr-Mo alloys, especially under dry conditions presenting a friction value of 0.12 and almost negligible wear. This coating has passed biocompatibility tests for implant devices on tissue/bone contact according to international standards (ISO 10993). PMID:15348654

  11. Degradable borate glass polyalkenoate cements.

    PubMed

    Shen, L; Coughlan, A; Towler, M; Hall, M

    2014-04-01

    Glass polyalkenoate cements (GPCs) containing aluminum-free borate glasses having the general composition Ag2O-Na2O-CaO-SrO-ZnO-TiO2-B2O3 were evaluated in this work. An initial screening study of sixteen compositions was used to identify regions of glass formation and cement compositions with promising rheological properties. The results of the screening study were used to develop four model borate glass compositions for further study. A second round of rheological experiments was used to identify a preferred GPC formulation for each model glass composition. The model borate glasses containing higher levels of TiO2 (7.5 mol %) tended to have longer working times and shorter setting times. Dissolution behavior of the four model GPC formulations was evaluated by measuring ion release profiles as a function of time. All four GPC formulations showed evidence of incongruent dissolution behavior when considering the relative release profiles of sodium and boron, although the exact dissolution profile of the glass was presumably obscured by the polymeric cement matrix. Compression testing was undertaken to evaluate cement strength over time during immersion in water. The cements containing the borate glass with 7.5 mol % TiO2 had the highest initial compressive strength, ranging between 20 and 30 MPa. No beneficial aging effect was observed-instead, the strength of all four model GPC formulations was found to degrade with time. PMID:24435528

  12. Cement plant CKD recovery system

    SciTech Connect

    Cohen, S.M.; Prokesch, M.E. [Fuller Co., Bethlehem, PA (United States)

    1996-12-31

    A fluid bed system has been developed to produce a low alkali cement clinker from cement plant kiln ducts (CKD). The system is comprised of three main components: feed preparation system, fluid bed reactor and process gas handling system. Cement kiln dust is first pelletized and dried, then processed at 1,300--1,320 C in the fluid bed reactor. The combination of excellent thermal transfer and extended retention time at reaction temperatures provides typical volatilization rates on the order of 90% K{sub 2}O, 70% Na{sub 2}O, 90% SO{sub 3}, and 95% Cl. High concentrations of volatilized alkali compounds in the process off gas stream are cooled and condensed in a specially designed heat exchange system while providing preheated process air for the fluid bed reactor. Condensed alkali compounds are collected at the dust collector in the form of a fine, white powder. This co-product may offer marketable value due to its high concentration of potassium sulfates. The system offers the potential for a 100% recovery of cement kiln dusts to produce cement clinker and an alkali co-product.

  13. Influence of cement and admixture on autogenous shrinkage of cement paste

    Microsoft Academic Search

    Ei-ichi Tazawa; Shingo Miyazawa

    1995-01-01

    It has recently been proved that autogenous shrinkage is considerably large for highstrength concrete. In this study influences of cement, chemical admixture, mineral admixture and water-cement ratio on autogenous shrinkage of cement paste were experimentally studied. It was proved that autogenous shrinkage could be estimated form mineral composition of cement. Some admixtures which were able to reduce autogenous shrinkage were

  14. Cusp Fracture Resistance of Maxillary Premolars Restored with the Bonded Amalgam Technique Using Various Luting Agents

    PubMed Central

    Marchan, Shivaughn M.; Coldero, Larry; White, Daniel; Smith, William A. J.; Rafeek, Reisha N.

    2009-01-01

    Objective. This in vitro study uses measurements of fracture resistance to compare maxillary premolars restored with the bonded amalgam technique using a new resin luting cement, glass ionomer, and resin-modified glass ionomer as the bonding agents. Materials. Eighty-five sound maxillary premolars were selected and randomly assigned to one of five test groups of 17 teeth each. One group of intact teeth served as the control. The remaining groups were prepared to a standard cavity form relative to the dimensions of the overall tooth and restored with amalgam alone or a bonded amalgam using one of three luting agents: RelyX Arc (a new resin luting cement), RelyX luting (a resin-modified glass ionomer), or Ketac-Cem ? (a glass ionomer) as the bonding agents. Each tooth was then subjected to compressive testing until catastrophic failure occurred. The mean loads at failure of each group were statistically compared using ANOVA with a post hoc Bonferroni test. Results. It was found that regardless of the luting cement used for the amalgam bonding technique, there was little effect on the fracture resistance of teeth. Conclusion. Cusp fracture resistance of premolars prepared with conservative MOD cavity preparations is not improved by using an amalgam-bonding technique compared to similar cavities restored with amalgam alone. PMID:20339450

  15. Neutron Scattering Studies of Cement

    NASA Astrophysics Data System (ADS)

    Allen, Andrew

    2010-03-01

    Despite more than a century of research, basic questions remain regarding both the internal structure and the role of water in Ordinary Portland cement (OPC) concrete, the world's most widely used manufactured material. Most such questions concern the primary hydration product and strength-building phase of OPC paste, the calcium silicate hydrate (C-S-H) gel. When cement and water are mixed, this phase precipitates as clusters of nanoscale (nearly amorphous) colloidal particles with an associated water-filled inter-particle pore system. Most attempts to characterize the C-S-H gel and the behavior of the associated water involve drying or other processes that, themselves, change the bound water content within and around the gel. Neutron scattering methods do not suffer from this disadvantage. Furthermore, the neutron isotope effect and the neutron's sensitivity to molecular motion have enabled considerable progress to be made in recent years by: (i) determining the C-S-H composition, density and gel structure in small-angle neutron scattering (SANS) H/D contrast variation studies; (ii) elucidating the changing state of water within cement as hydration progresses using quasielastic neutron scattering (QENS); and (iii) measuring the production and consumption of nanoscale calcium hydroxide (CH), a by-product of cement hydration that co-exists with the C-S-H gel, using inelastic neutron scattering (INS). These experiments have provided new insights into the physics and chemistry of cement hydration, and have implications for the design of new concretes with pozzolanic cement additions that are intended to address environmental concerns and sustainability issues.

  16. Autonomic healing of acrylic bone cement.

    PubMed

    Gladman, A Sydney; Celestine, Asha-Dee N; Sottos, Nancy R; White, Scott R

    2015-01-28

    Self-healing in orthopedic bone cement is demonstrated with a novel thermoplastic solvent-bonding approach. Low toxicity solvent-filled microcapsules, embedded in a commercial acrylic bone cement matrix, enable recovery of up to 80% of the virgin fracture toughness of the cement at room and body temperature conditions without external stimuli or human intervention. PMID:25116439

  17. MICROCALORIMETRIC STUDY ON CALCIUM ALUMINATE CEMENT HYDRATION

    Microsoft Academic Search

    Neven Ukrainczyk; Pero Dabi?

    Calcium aluminate cement (CAC) is very versatile special cement used for specific applications. During the hydration of CAC a large quantity of heat is liberated within one day that causes a considerable increase of temperature in material. This paper examines the hydration of three samples (A, B and aged B) of commercial CAC ISTRA 40 (producer: Istra Cement, Pula, Croatia).

  18. CO 2 Capture in the Cement Industry

    Microsoft Academic Search

    D. J. Barker; S. A. Turner; P. A. Napier-Moore; M. Clark; J. E. Davison

    2009-01-01

    Modern cement plants have high energy efficiencies and the scope to reduce CO2 emissions by further efficiency improvements is small. One of the few ways of greatly reducing CO2 production from cement production is CO2 capture and storage (CCS). This paper summarises a study which assessed the technologies that could be used for CO2 capture in cement plants, their costs,

  19. Blended cement using volcanic ash and pumice

    Microsoft Academic Search

    Khandaker M. Anwar Hossain

    2003-01-01

    This paper reports the results of investigation to assess the suitability of volcanic ash (VA) and pumice powder (VPP) for blended cement production. Tests were conducted on cement where Portland cement (PC) was replaced by VA and VPP within the range of 0 to 50%. The physical and chemical properties of VA and VPP were critically reviewed to evaluate the

  20. The relationship between biocompatibility and interleukin-1.

    PubMed

    Shaldon, S; Dinarello, C A

    1987-01-01

    Biocompatibility is redefined as the quality of being mutually tolerant with life. In so far as this represents a quality which is as likely to be achieved as is the alchemist's dream of turning lead into gold, a compromise approach is recommended. It is suggested that all extracorporeal or body invasive procedures stimulate the inflammatory defence mechanism of the body by stimulating the monocyte to produce a family of polypeptides currently known collectively as Interleukin-1 (IL-1). So far two dissimilar gene products have been cloned and there are probably more. The IL-1 group of polypeptides possess hormonal functions which orchestrate nearly every instrument of the body's defence system. Inducers of IL-1 are present in dialysate and induce bacterial pyrogen and acetate. In addition bacterial cell wall glycoprotein may be cleaved into muramyl peptides by the release of granulocyte lysozyme at the membrane interface. Muramyl dipeptides have been found in CAPD drain fluid and are more potent inducers of IL-1 than endotoxin. Membrane activation of the fifth component of the complement with the release of C5a will also induce monocytes to produce IL-1. The consequences of repeated stimulation of the acute phase response are undesirable and may include muscle wasting, osteopenia and bone cysts (Shrinking man syndrome), fibrosis of scapulo-humeral joints and the carpal-tunnel syndrome. These latter lesions are often associated with deposition of amyloid fibrils related to beta 2-microglobulin. Efforts to reduce these complications are urgently required.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3501505

  1. Biocompatibility of materials for total joint replacement.

    PubMed

    Escalas, F; Galante, J; Rostoker, W

    1976-03-01

    The clinical use of total joint prostheses demands absolute biocompatibility of the materials employed. The purpose of this experiment was the bioassay of some materials considered as possible candidates for use in total joint prostheses as load-bearing members or as wear-resistant surfaces. Some materials already in use were also tested. 316L stainless steel was used as a control. The materials were implanted as a standardized rod and in particulate form. An average of 12 samples per material were implanted in soft tissue for six months and a total of 145 rabbits were used in this study. Twenty-five materials including metals, polymers, and ceramics were tested in solid and powdered form. A semiquantitative evaluation of local tissue reaction and a study of organs was performed. Polymers and metallic materials showed in general a mild tissue reaction. Ceramics, which some authors describe as the best tolerated materials, elicited variable tissue responses. Some of these (glass-ceramics) presented very poor tissue tolerance. The least reactive, titanium oxide, titanium aluminate, and aluminum oxide, presented a degree of tissue reaction comparable to that of corrosion resistant metals, but not superior to them. Moderate reactivity was the general rule for particulate materials except for the Pyroceram glass-ceramics, polymides, and Teflon. Ultrahigh molecular weight polyethylene in particulate form elicited a rather cellular tissue response, a fact to be considered when projecting long-term results in total joint arthroplasty. No pathological changes compatible with systemic toxicity by materials tested were observed in the study of the organs. PMID:1254613

  2. Effect of surface condition of dental zirconia ceramic (Denzir) on bonding.

    PubMed

    Uo, Motohiro; Sjögren, Göran; Sundh, Anders; Goto, Mitsunari; Watari, Fumio; Bergman, Maud

    2006-09-01

    Yttria partially stabilized zirconia (YPSZ) ceramics are suitable for dental and medical use because of their high fracture toughness and chemical durability. The purpose of this study was to examine the bonding behavior of a dental YPSZ ceramic, Denzir. After being subjected to various surface treatments, Denzir specimens were bonded to each other using an adhesive resin composite, glass ionomer, or zinc phosphate cement. Bonding strength was then determined by the shearing test. No significant differences (p>0.05) were observed between SiC- and Al2O3-blasted specimens. In all surface treatments, the shear bond strength significantly (p<0.05) increased in the order of adhesive resin composite cement > glass ionomer cement > zinc phosphate cement. Moreover, silanization with methacryloxy propyl trimethoxysilane slightly increased the bonding strength of the adhesive resin composite cement. PMID:17076338

  3. Retentiveness of various luting agents used with implant-supported prosthesis: an in vitro study.

    PubMed

    Garg, Pooja; Pujari, Malesh; Prithviraj, D R; Khare, Sumit

    2014-12-01

    Desired retrievability of cemented implant-supported fixed prosthesis makes the retentive strength of cementing agents an important consideration. The aim of the study was to evaluate the retentiveness of purposely designed implant cement and compare its retentiveness with dental cements that are commonly used with implant systems. Ten implant analogs were embedded in auto-polymerizing acrylic resin blocks and titanium abutments were attached to them. Fifty standardized copings were waxed directly on the abutment and casted. The cements used were: (1) resin-bonded zinc oxide eugenol cement, (2) purposely designed implant cement, (3) zinc phosphate cement, (4) zinc polycarboxylate cement, and (5) glass ionomer cement. After cementation, each sample was subjected to a pull-out test using universal testing machine and loads required to remove the crowns were recorded. The mean values and standard deviations of cement failure loads were analyzed using ANOVA and Bonferroni test. The mean values (± SD) of loads at failure (n = 10) for various cements were as follows (N): resin-bonded zinc oxide eugenol cement 394.62 (± 9.76), Premier implant cement 333.86 (± 18.91), zinc phosphate cement 629.30 (± 20.65), zinc polycarboxylate cement 810.08 (± 11.52), and glass ionomer cement 750.17 (± 13.78). The results do not suggest that one cement type is better than another, but they do provide a ranking order of the cements regarding their ability to retain the prosthesis and facilitate easy retrievability. PMID:25506659

  4. Cement-Lock for Decontaminating

    E-print Network

    Brookhaven National Laboratory

    of these tests was to characterize the concrete and establish a mix design for the beneficial use project that an appropriate concrete mix design could be developed for a specific application. Table ES-1. Results for Portland cement in concrete. CTLGroup also prepared a batch of concrete made with Ecomelt (40% replacement

  5. Integrated system for preparation of bone cement and effects on cement quality and environment.

    PubMed

    Müller-Wille, P; Wang, J S; Lidgren, L

    1997-01-01

    We developed a prepacked mixing system for the preparation of bone cement. The system is based on mixing and collection of bone cement under a vacuum and serves as both the storage and mixing device for the cement components, thereby minimizing the exposure of the operating staff to the monomer and the risk for contamination of the cement during preparation. We evaluated the system using Palacos R and Simplex P. The cement produced was compared with cement obtained from a commercially available mixing system. Temperature evolution during curing, handling characteristics, density, and porosity of the cement obtained were analyzed. The results showed that the experimental system produces cement with physical properties (i.e., setting times and temperature, porosity, and density) equal to or better than those obtained with commercially available systems. Reducing the amount of monomer in the experimental system led to a reduction of the curing temperature without compromising the physical properties of the cements. PMID:9178741

  6. Preparation of a biocompatible magnetic film from an aqueous ferrofluid

    NASA Astrophysics Data System (ADS)

    Albornoz, Cecilia; Jacobo, Silvia E.

    2006-10-01

    Very promising nanoparticles for biomedical applications or in medical drug targeting are superparamagnetic nanoparticles based on a core consisting of iron oxides (SPION) that can be targeted through external magnets. Polyvinyl alcohol (PVA) is a unique synthetic biocompatible polymer that can be chemically cross-linked to form a gel. Biotechnology applications of magnetic gels include biosensors, targeted drug delivery, artificial muscles and magnetic buckles. These gels are produced by incorporating magnetic materials in the polymer composites. In this paper we report the synthesis of an aqueous ferrofluid and the preparation of a biocompatible magnetic gel with polyvinyl alcohol and glutharaldehyde (GTA). HClO 4 was used to induce the peptization since this kind of ferrofluid does not have surfactant. The magnetic gel was dried to generate a biocompatible film.

  7. Cell culture approach to biocompatibility evaluation of unconventionally prepared hydroxyapatite.

    PubMed

    Kundu, P K; Waghode, T S; Bahadur, D; Datta, D

    1998-09-01

    Hydroxyapatite (HA), Ca10(PO4)6(OH)2 was produced by microwave irradiation of calcium nitrate (CaNO3.4H2O) and di-ammonium phosphate in aqueous solution. The HA formation was confirmed by X-ray diffraction analysis. HA prepared by this unconventional route was subjected to biocompatibility assay by a cell-culture method using the hybridoma cell line AE9D6 in both conventional Dulbecco's modification of Eagle's medium (DMEM) and simulated body fluid (SBF), both supplemented with 5% fetal calf serum. HA synthesised through this unconventional method showed the presence of tricalcium phosphate which can be reduced only after heat treatment at 1150 degrees C. The HA conformed to the X-ray data index file for hydroxyapatite. Biocompatibility assays showed reproducible growth and secretion patterns of cells both in DMEM as well as in SBF, thereby indicating the effectiveness of this method for the production of biocompatible HA. PMID:10367453

  8. Biocompatibility correlation of polymeric materials using human osteosarcoma cells

    NASA Astrophysics Data System (ADS)

    Geckeler, K. E.; Wacker, Roland; Aicher, Wilhelm K.

    Metal implants are the preferred materials to generate articular prostheses, plates, or bone pegs in orthopedic surgery. Although titanium and titanium alloys show a relatively good biocompatibility, clinical experience revealed that coating of the metallic implant surface may increase the biocompatibility. In a search for optimum bone implant surfaces, we determined polarity and contact angle parameters of a variety of polymers and substances and correlated the findings in a biocompatibility assay using an in vitro bone cell model. We report that an optimum adherence of SAOS-2 cells to such surfaces and a good vitality for polymers are characterized by water-based contact angles of 80° and 20° for advancing and receding probes, respectively.

  9. The quantification of biocompatibility: toward a new definition

    NASA Astrophysics Data System (ADS)

    Ratner, Buddy

    2008-03-01

    Implantable medical devices, and the biomaterials that comprise them, form a 100B business worldwide. Medical devices save lives and/or improve the quality of life for millions. Tissue engineering also makes extensive use of biomaterials -- biomaterials are an enabling technology for tissue engineering. A central word to understanding the effectiveness of such materials and devices is biocompatibility. The word ``biocompatible'' is widely used in reference to biomaterials and medical devices and most everyone has some value understanding of its meaning. Many formal definitions have been proposed for this word, but it is still largely used in an imprecise manner. Four descriptions or definitions of biocompatibility will be reviewed: a widely adopted definition from a consensus conference, a surgeon's perspective on this word, the regulatory agency view and the factors that clearly influence biocompatibility. In this talk, the classical definition of biocompatibility will be contrasted to a newer definition embracing molecular concepts and the understanding of normal wound healing. The biological data on the in vivo healing responses of mammals to implants will be described. A strategy to improve the healing of biomaterials will be presented. It is based upon surface molecular engineering. First, non-specific protein adsorption must be inhibited. Strategies to achieve this design parameter will be presented. Then methods to deliver the specific protein signals will be addressed. Matricellular proteins such as osteopontin, thrombospondin 2 and SPARC will be introduced with an emphasis on exploiting the special reactivity of such proteins. A discussion of the influence of surface textures and porosities will also be presented. Finally a new scheme based upon macrophage phenotypic pathways will be proposed that may allow a quantitative measure of extent of biocompatibility.

  10. Biocompatibility of diamond-like nanocomposite thin films.

    PubMed

    Das, T; Ghosh, D; Bhattacharyya, T K; Maiti, T K

    2007-03-01

    Diamond-like nanocomposite (DLN) films consist of network structure of amorphous carbon and quartz like silicon. In the present work, DLN films have been synthesized on pyrex glass and subsequently, their biocompatibility have been investigated through primary and secondary cell adhesion, cytotoxicity, protein adsorption and murine peritoneal macrophage activation experiments. Variable degree of cell and protein response have been found based on variable film synthesis parameters but in overall, required biocompatibility has been established for all types of film-coating. PMID:17334700

  11. [Study on biocompatibility of MIM 316L stainless steel].

    PubMed

    Wang, Guohui; Zhu, Shaihong; Li, Yiming; Zhao, Yanzhong; Zhou, Kechao; Huang, Boyun

    2007-04-01

    This study was aimed to evaluate the biocompatibility of metal powder injection molding (MIM) 316L stainless steel. The percentage of S-period cells was detected by flow cytometry after L929 cells being incubated with extraction of MIM 316L stainless steel, and titanium implant materials for clinical application were used as control. In addition, both materials were implanted in animals and the histopathological evaluations were carried out. The statistical analyses show that there are no significant differences between the two groups (P > 0.05), which demonstrate that MIM 316L stainless steel has good biocompatibility. PMID:17591253

  12. Bone cement based on vancomycin loaded mesoporous silica nanoparticle and calcium sulfate composites.

    PubMed

    Li, Hanwen; Gu, Jisheng; Shah, Luqman Ali; Siddiq, Mohammad; Hu, Jianhua; Cai, Xiaobing; Yang, Dong

    2015-04-01

    A novel bone cement pellet, with sustained release of vancomycin (VAN), was prepared by mixing VAN loaded mesoporous silica nanoparticle (MSN) and calcium sulfate ?-hemihydrate (CS) together. To improve the VAN loading ability, MSN was functionalized with aminopropyltriethoxysilane (APS) to give APS-MSN. The VAN loading content and entrapment efficiency of APS-MSN could reach up to 45.91±0.81% and 84.88±1.52%, respectively, much higher than those of MSN, which were only 3.91% and 4.07%, respectively. The nitrogen adsorption-desorption measurement results demonstrated that most of the VAN were in the pores of APS-MSN. The CS/VAN@APS-MSN composite pellet showed a strongly drug sustained release effect in comparison with CS control pellet. The in vitro cell assays demonstrated that CS/APS-MSN composite was highly biocompatible and suitable to use as bone cement. Furthermore, CS/VAN@APS-MSN pellet showed no pyrogenic effect and meet the clinical requirements on hemolytic reaction. These results imply that CS/VAN@APS-MSN was an ideal candidate to replace CS bone cement in the treatment of open fractures. PMID:25686941

  13. Properties of injectable ready-to-use calcium phosphate cement based on water-immiscible liquid.

    PubMed

    Heinemann, S; Rössler, S; Lemm, M; Ruhnow, M; Nies, B

    2013-04-01

    Calcium phosphate cements (CPCs) are highly valuable materials for filling bone defects and bone augmentation by minimal invasive application via percutaneous injection. In the present study some key features were significantly improved by developing a novel injectable ready-to-use calcium phosphate cement based on water-immiscible carrier liquids. A combination of two surfactants was identified to facilitate the targeted discontinuous exchange of the liquid for water after contact with aqueous solutions, enabling the setting reaction to take place at distinct ratios of cement components to water. This prolonged the shelf life of the pre-mixed paste and enhanced reproducibility during application and setting reactions. The developed paste technology is applicable for different CPC formulations. Evaluations were performed for the formulation of an ?-TCP-based CPC as a representative example for the preparation of injectable pastes with a powder-to-carrier liquid ratio of up to 85:15. We demonstrate that the resulting material retains the desirable properties of conventional CPC counterparts for fast setting, mechanical strength and biocompatibility, shows improved cohesion and will most probably show a similar degree of resorbability due to identical mineral structure of the set products. PMID:23261920

  14. Research of magnesium phosphosilicate cement

    NASA Astrophysics Data System (ADS)

    Ding, Zhu

    Magnesium phosphosilicate cement (MPSC) is a novel phosphate bonded cement, which consists mainly of magnesia, phosphate and silicate minerals. The traditional magnesium phosphate cements (MPCs) usually composed by ammonium phosphate, and gaseous ammonia will emit during mixing and in service. There is no noxious ammonia released from MPSC, furthermore, it can recycle a large volume of the non-hazardous waste. The goal of this research is to investigate the composition, reaction products, reaction mechanism, microstructure, properties, durability and applications of the MPSC. MPSC sets rapidly and has high early strength. It reacts better with solid industrial waste when compared to Portland cement. Many solid industrial wastes, such as fly ash, steel slag, coal gangue, red coal gangue, red mud, barium-bearing slag, copper slag, silica fume, and ground granulated blast furnace slag, have been used as the main component (40% by weight) in MPSC. The research has found that these aluminosilicate (or ironsilicate, or calciumsilicate) minerals with an amorphous or glass structure can enhance the performance of MPSC. The disorganized internal structure of amorphous materials may make it possess higher reactivity compared to the crystalline phases. Chemical reaction between phosphate and these minerals may form an amorphous gel, which is favorable to the cementing. Borax, boric acid and sodium tripolyphosphate have been used as retardants in the MPSC system. It is found that boric acid has a higher retarding effect on the setting of cement, than borax does. However, sodium polyphosphate accelerates the reaction of MPSC. The hydration of MPSC is exothermic reaction. The heat evolution may prompt hydrates formation, and shorten the setting process. Modern materials characterization techniques, XRD, DSC, TG-DTA FTIR, XPS, MAS-NMR, SEM, TEM, MIP, etc. were used to analyze the phase composition, micro morphology, and microstructure of hardened MPSC. The main hydration product in MPSC is MgKPO4·6H2O (MKP), which has both crystalline and amorphous phases. There are many unreacted magnesia grains in the hardened MPSC paste. They act as nucleus of the hardened framework. The hydrates grow around the magnesia grains rims, fill in the voids among the magnesia grains and bond unreacted magnesia part into a solid continuum. (Abstract shortened by UMI.)

  15. Surface pretreatment for prolonged survival of cemented tibial prosthesis components: full- vs. surface-cementation technique

    PubMed Central

    Marx, Rudolf; Qunaibi, Mutaz; Wirtz, Dieter Christian; Niethard, Fritz Uwe; Mumme, Thorsten

    2005-01-01

    Background One of few persisting problems of cemented total knee arthroplasty (TKA) is aseptic loosening of tibial component due to degradation of the interface between bone cement and metallic tibial shaft component, particularly for surface cemented tibial components. Surface cementation technique has important clinical meaning in case of revision and for avoidance of stress shielding. Degradation of the interface between bone cement and bone may be a secondary effect due to excessive crack formation in bone cement starting at the opposite metallic surface. Methods This study was done to prove crack formation in the bone cement near the metallic surface when this is not coated. We propose a newly developed coating process by PVD layering with SiOx to avoid that crack formation in the bone cement. A biomechanical model for vibration fatigue test was done to simulate the physiological and biomechanical conditions of the human knee joint and to prove excessive crack formation. Results It was found that coated tibial components showed a highly significant reduction of cement cracking near the interface metal/bone cement (p < 0.01) and a significant reduction of gap formation in the interface metal-to-bone cement (p < 0.05). Conclusion Coating dramatically reduces hydrolytic- and stress-related crack formation at the prosthesis interface metal/bone cement. This leads to a more homogenous load transfer into the cement mantle which should reduce the frequency of loosening in the interfaces metal/bone cement/bone. With surface coating of the tibial component it should become possible that surface cemented TKAs reveal similar loosening rates as TKAs both surface and stem cemented. This would be an important clinical advantage since it is believed that surface cementing reduces metaphyseal bone loss in case of revision and stress shielding for better bone health. PMID:16262888

  16. Retention of gold alloy crowns cemented with traditional and resin cements.

    PubMed

    Pinzón, Lilliam M; Frey, Gary N; Winkler, Mark M; Tate, William H; Burgess, John O; Powers, John M

    2009-01-01

    The aim of this study was to measure in vitro retention of cast gold crowns cemented with traditional and resin cements. Forty-eight human molars were prepared on a lathe to produce complete crown preparations with a consistent taper and split into six groups, eight crowns in each group. Crowns were cast in a high-gold alloy and then cemented. After 24 hours, the retention force (N) was recorded and mean values were analyzed by one-way analysis of variance and the Fisher post-hoc least significant difference (PLSD) multiple comparisons test (a = .05). Failure sites were examined under 3100 magnification and recorded. Mean values (SD) for each group in increasing order of retention force were: Harvard Cement: 43 N (27), TempoCem: 59 N (16), PermaCem Dual: 130 N (42), RelyX Luting Cement: 279 N (26), Contax and PermaCem Dual: 286 N (38), and TempoCem with Contax and PermaCem Dual: 340 N (14). The Fisher PLSD interval (P = .05) for comparing cements was 29 N. Zinc-phosphate cement and provisional resin cements had the lowest retention forces. Resin cement with a bonding agent and the hybrid-ionomer cement had similar retention forces. Resin cement with a bonding agent applied after use of a provisional resin cement had a significantly higher retention force than the other cements tested. PMID:19639070

  17. Microfluidic Fabrication of Monodisperse Biocompatible and Biodegradable Polymersomes with Controlled Permeability

    E-print Network

    Microfluidic Fabrication of Monodisperse Biocompatible and Biodegradable Polymersomes monodisperse polymersomes with biocompatible and biodegradable diblock copolymers for efficient encapsulation into vesicle structures. These polymersomes can be used to encapsulate small hydrophilic solutes. When

  18. In vitro cytotoxicity of four calcium silicate-based endodontic cements on human monocytes, a colorimetric MTT assay

    PubMed Central

    Khedmat, Sedigheh; Dehghan, Somayyeh; Hadjati, Jamshid; Masoumi, Farimah; Dummer, Paul Michael Howell

    2014-01-01

    Objectives This study was performed to evaluate the cytotoxicity of four calcium silicate-based endodontic cements at different storage times after mixing. Materials and Methods Capillary tubes were filled with Biodentine (Septodont), Calcium Enriched Mixture (CEM cement, BioniqueDent), Tech Biosealer Endo (Tech Biosealer) and ProRoot MTA (Dentsply Tulsa Dental). Empty tubes and tubes containing Dycal were used as negative and positive control groups respectively. Filled capillary tubes were kept in 0.2 mL microtubes and incubated at 37?. Each material was divided into 3 groups for testing at intervals of 24 hr, 7 day and 28 day after mixing. Human monocytes were isolated from peripheral blood mononuclear cells and cocultered with 24 hr, 7 day and 28 day samples of different materials for 24 and 48 hr. Cell viability was evaluated using an MTT assay. Results In all groups, the viability of monocytes significantly improved with increasing storage time regardless of the incubation time (p < 0.001). After 24 hr of incubation, there was no significant difference between the materials regarding monocyte viability. However, at 48 hr of incubation, ProRoot MTA and Biodentine were less cytotoxic than CEM cement and Biosealer (p < 0.01). Conclusions Biodentine and ProRoot MTA had similar biocompatibility. Mixing ProRoot MTA with PBS in place of distilled water had no effect on its biocompatibility. Biosealer and CEM cement after 48 hr of incubation were significantly more cytotoxic to on monocyte cells compared to ProRoot MTA and Biodentine. PMID:25110637

  19. The density of cement phases

    SciTech Connect

    Balonis, M. [Department of Chemistry, Meston Building, University of Aberdeen, Aberdeen, AB24 3UE, Scotland (United Kingdom)], E-mail: m.balonis@abdn.ac.uk; Glasser, F.P. [Department of Chemistry, Meston Building, University of Aberdeen, Aberdeen, AB24 3UE, Scotland (United Kingdom)

    2009-09-15

    The densities of principal crystalline phases occurring in Portland cement are critically assessed and tabulated, in some cases with addition of new data. A reliable and self-consistent density set for crystalline phases was obtained by calculating densities from crystallographic data and unit cell contents. Independent laboratory work was undertaken to synthesize major AFm and AFt cement phases, determine their unit cell parameters and compare the results with those recorded in the literature. Parameters were refined from powder diffraction patterns using CELREF 2 software. A density value is presented for each phase, showing literature sources, in some cases describing limitations on the data, and the weighting attached to numerical values where an averaging process was used for accepted data. A brief discussion is made of the consequences of the packing of water to density changes in AFm and AFt structures.

  20. Fracture measurements on cement paste

    Microsoft Academic Search

    D. D. Higgins; J. E. Bailey

    1976-01-01

    This paper describes an investigation into the fracture behaviour of hardened cement paste. Notched specimens of the material\\u000a were tested to failure in flexure and tension. In the initial flexural tests on beams of fixed overall depth, the stress intensity\\u000a factor at failure as calculated from linear-elastic fracture mechanics appeared to be a material constant. However, further\\u000a investigation showed that

  1. Microbiological or chemical models of enamel secondary caries compared by polarized-light microscopy and energy dispersive X-ray spectroscopy.

    PubMed

    Paradella, Thaís Cachuté; de Sousa, Fernando Augusto Cervantes Garcia; Koga-Ito, Cristiane Yumi; Jorge, Antonio Olavo Cardoso

    2009-08-01

    Different secondary caries models may present different results. The purpose of this study was to compare different in vitro secondary caries models, evaluating the obtained results by polarized-light microscopy (PLM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Standardized human enamel specimens (n = 12) restored with different materials (Z250 conventional composite resin-CRZ, Freedom polyacid-modified composite resin-CRF, Vitremer resin-modified glass-ionomer-GIV, and Fuji IX conventional glass-ionomer cement-GIF) were submitted to microbiological (MM) or chemical caries models (CM). The control group was not submitted to any caries model. For MM, specimens were immersed firstly in sucrose broth inoculated with Streptococcus mutans ATCC 35688, incubated at 37 degrees C/5% CO(2) for 14 days and then in remineralizing solution for 14 days. For CM, specimens were submitted to chemical pH-cycling. Specimens were ground, submitted to PLM and then were dehydrated, gold-sputtered and submitted to SEM and EDS. Results were statistically analyzed by Kruskall-Wallis and Student-Newman-Keuls tests (alpha = 0.05). No differences between in vitro caries models were found. Morphological differences in enamel demineralization were found between composite resin and polyacid-modified composite resin (CRZ and CRF) and between the resin-modified glass-ionomer and the glass-ionomer cement (GIF and GIV). GIF showed higher calcium concentration and less demineralization, differing from the other materials. In conclusion, the glass-ionomer cement showed less caries formation under both in vitro caries models evaluated. PMID:19204918

  2. Influence of Nano-HA Coated Bone Collagen to Acrylic (Polymethylmethacrylate) Bone Cement on Mechanical Properties and Bioactivity

    PubMed Central

    Li, Tao; Weng, Xisheng; Bian, Yanyan; Zhou, Lei; Cui, Fuzhai; Qiu, Zhiye

    2015-01-01

    Objective This research investigated the mechanical properties and bioactivity of polymethylmethacrylate (PMMA) bone cement after addition of the nano-hydroxyapatite(HA) coated bone collagen (mineralized collagen, MC). Materials & Methods The MC in different proportions were added to the PMMA bone cement to detect the compressive strength, compression modulus, coagulation properties and biosafety. The MC-PMMA was embedded into rabbits and co-cultured with MG 63 cells to exam bone tissue compatibility and gene expression of osteogenesis. Results 15.0%(wt) impregnated MC-PMMA significantly lowered compressive modulus while little affected compressive strength and solidification. MC-PMMA bone cement was biologically safe and indicated excellent bone tissue compatibility. The bone-cement interface crosslinking was significantly higher in MC-PMMA than control after 6 months implantation in the femur of rabbits. The genes of osteogenesis exhibited significantly higher expression level in MC-PMMA. Conclusions MC-PMMA presented perfect mechanical properties, good biosafety and excellent biocompatibility with bone tissues, which has profoundly clinical values. PMID:26039750

  3. Activated fly ash\\/slag blended cement

    Microsoft Academic Search

    Feng-Qing Zhao; Wen Ni; Hui-Jun Wang; Hong-Jie Liu

    2007-01-01

    This paper presents the results of the preparation of an ecological cementing material from granulated blast-furnace slag (GBFS) and Class C fly ash (CCFA). The desulphurization gypsum, calcined at 600–800°C for 0.5–1.5h, works as the main ingredient of the activator in the cementing material. The optimized formulation of the cementing material was obtained with the aid of factorial design method:

  4. Heat evolution in hydrating expansive cement systems

    Microsoft Academic Search

    W. Nocu?-Wczelik; A. Stok; Z. Konik

    2010-01-01

    Calorimetry was applied to follow the hydration of special cement mixtures exhibiting expansion or shrinkage compensation.\\u000a The standard, common cements show generally less or more visible shrinkage on setting and hardening but mixed with and expansive\\u000a agent, usually of aluminate and sulfate nature, they can exhibit the increase of volume. The calcium aluminate cement CAC\\u000a 40 was ground together with

  5. Three-dimensional laser micromachining and imaging of biocompatible polymers

    E-print Network

    Oldenburg, Amy

    lamination [3], and 3D printing [4]. All of these methods, with the exception of melt molding, require of America OCIS codes: (220.4000) Microstructure fabrication; (180.6900) 3D microscopy; (140.3440) Laser by producing the appropriate topography within a scaffolding material that is biocompatible as well as pliable

  6. Biocompatibility of Textile Titanium Nickel Implants with Fibroblast Culture.

    PubMed

    Kokorev, O V; Khodorenko, V N; Anikeev, S G; Gunther, V E

    2015-05-01

    The parameters of biocompatibility of titanium nickel implants of different design with fibroblast culture are studied. Colonization of textile and mesh implants with fibroblasts and tissue development depend on the size of mesh cells and thread diameter. Titanium nickel implants of different constructions do not inhibit the growth of fibroblast culture. PMID:26028231

  7. Biocompatibility of dialysis membranes: Effects of chronic complement activation

    Microsoft Academic Search

    Raymond M Hakim; Douglas T Fearon; J Michael Lazarus; Cynthia S Perzanowski

    1984-01-01

    Biocompatibility of dialysis membranes: Effects of chronic complement activation. The ability of three dialysis membranes (cuprophane, cellulose acetate, and polymethylmethacrylate) to activate complement was studied prospectively in ten chronic dialysis patients using new and reused membranes. Patients were dialyzed for 1 month with each type of membrane. New cuprophane membranes caused the most intense activation, while polymethylmethacrylate (PMMA) surfaces caused

  8. Dynamic In Vivo Biocompatibility of Angiogenic Peptide Amphiphile Nanofibers

    PubMed Central

    Ghanaati, Shahram; Webber, Matthew J.; Unger, Ronald E.; Orth, Carina; Hulvat, James F.; Kiehna, Sarah E.; Barbeek, Mike; Rasic, Angela; Stupp, Samuel I.; Kirkpatrick, C. James

    2009-01-01

    Biomaterials that promote angiogenesis have great potential in regenerative medicine for rapid revascularization of damaged tissue, survival of transplanted cells, and healing of chronic wounds. Supramolecular nanofibers formed by self-assembly of a heparin-binding peptide amphiphile and heparan sulfate-like glycosaminoglycans were evaluated here using a dorsal skinfold chamber model to dynamically monitor the interaction between the nanofiber gel and the microcirculation, representing a novel application of this model. We paired this model with a conventional subcutaneous implantation model for static histological assessment of the interactions between the gel and host tissue. In the static analysis, the heparan sulfate-containing nanofiber gels were found to persist in the tissue for up to 30 days and revealed excellent biocompatibility. Strikingly, as the nanofiber gel biodegraded, we observed the formation of a de novo vascularized connective tissue. In the dynamic experiments using the dorsal skinfold chamber, the material again demonstrated good biocompatibility, with minimal dilation of the microcirculation and only a few adherent leukocytes, monitored through intravital fluorescence microscopy. The new application of the dorsal skinfold model corroborated our findings from the traditional static histology, demonstrating the potential use of this technique to dynamically evaluate the biocompatibility of materials. The observed biocompatibility and development of new vascularized tissue using both techniques demonstrates the potential of these angiogenesis-promoting materials for a host of regenerative strategies. PMID:19683342

  9. Biocompatibility of atomic layer-deposited alumina thin films.

    PubMed

    Finch, Dudley S; Oreskovic, Tammy; Ramadurai, Krishna; Herrmann, Cari F; George, Steven M; Mahajan, Roop L

    2008-10-01

    Presented in this paper is a study of the biocompatibility of an atomic layer-deposited (ALD) alumina (Al2O3) thin film and an ALD hydrophobic coating on standard glass cover slips. The pure ALD alumina coating exhibited a water contact angle of 55 degrees +/- 5 degrees attributed, in part, to a high concentration of -OH groups on the surface. In contrast, the hydrophobic coating (tridecafluoro-1,1,2,2-tetrahydro-octyl-methyl-bis(dimethylamino)silane) had a water contact angle of 108 degrees +/- 2 degrees. Observations using differential interference contrast microscopy on human coronary artery smooth muscle cells showed normal cell proliferation on both the ALD alumina and hydrophobic coatings when compared to cells grown on control substrates. These observations suggested good biocompatibility over a period of 7 days in vitro. Using a colorimetric assay technique to assess cell viability, the cellular response between the three substrates can be differentiated to show that the ALD alumina coating is more biocompatible and that the hydrophobic coating is less biocompatible when compared to the control. These results suggest that patterning a substrate with hydrophilic and hydrophobic groups can control cell growth. This patterning can further enhance the known advantages of ALD alumina, such as conformality and excellent dielectric properties for bio-micro electro mechanical systems (Bio-MEMS) in sensors, actuators, and microfluidics devices. PMID:18085647

  10. The biocompatibility of crosslinkable copolymer coatings containing sulfobetaines and phosphobetaines

    Microsoft Academic Search

    Sofie L. West; Jonathan P. Salvage; Emma J. Lobb; Steven P. Armes; Norman C. Billingham; Andrew L. Lewis; Geoffrey W. Hanlon; Andrew W. Lloyd

    2004-01-01

    The comparison of copolymers containing sulfobetaine or phosphobetaine moieties for use as potential biocompatible coatings has been investigated. Two statistical copolymers were produced by a free radical polymerisation technique, one based on a sulfobetaine and the other on a phosphobetaine, both with a silyl group component to allow thermal crosslinking after coating. PMMA and glass discs were dip-coated with the

  11. Biocompatibility and biofouling of MEMS drug delivery devices

    Microsoft Academic Search

    Gabriela Voskerician; Matthew S. Shive; Rebecca S. Shawgo; Horst von Recum; James M. Anderson; Michael J. Cima; Robert Langer

    2003-01-01

    The biocompatibility and biofouling of the microfabrication materials for a MEMS drug delivery device have been evaluated. The in vivo inflammatory and wound healing response of MEMS drug delivery component materials, metallic gold, silicon nitride, silicon dioxide, silicon, and SU-8TM photoresist, were evaluated using the cage implant system. Materials, placed into stainless-steel cages, were implanted subcutaneously in a rodent model.

  12. General hydration model for portland cement and blast furnace slag cement

    Microsoft Academic Search

    L. Taerwe

    1995-01-01

    This paper focusses on the evolution of the heat of hydration of hardening concrete or cement based materials. Based on isothermal and adiabatic hydration tests a new general hydration model is developed, valid both for portland cement and blast furnace slag cement. This hydration model enables the calculation of the heat production rate as a function of the actual temperature

  13. Use of diatomite as partial replacement for Portland cement in cement mortars

    Microsoft Academic Search

    Nurhayat Degirmenci; Arin Yilmaz

    2009-01-01

    The aim of the present study is to investigate the use of diatomite as a partial replacement for cement in the production of cement mortar. Diatomite was used at 0%, 5%, 10% and 15% replacement by weight for cement while sand and water quantities were kept constant. Compressive and flexural strength, freeze–thaw resistance, sulfate resistance, water absorption and dry unit

  14. Method of producing light weight cement for use of cementation of oil and gas wells

    Microsoft Academic Search

    Skjeldal

    1983-01-01

    A cement slurry of low specific density for cementation of oil and gas wells is produced by mixing oil-well cement with finely divided emission products comprising amorphous silica dust which has been obtained during the electrothermal preparation of ferrosilicon and\\/or silicon metal, water, and any desirable dispersion components, the emission products being added in an amount in the range of

  15. Early-Age Properties of Cement-Based Materials. I: Influence of Cement Fineness

    Microsoft Academic Search

    Dale P. Bentz; Gaurav Sant; Jason Weiss

    2008-01-01

    The influence of cement fineness on early-age properties of cement-based materials is investigated using a variety of experimental techniques. Properties that are critical to the early- age performance of these materials are tested, including heat release, temperature rise, chemical shrinkage and autogenous deformation. Measurements of these properties for two cements of widely different fineness are supplemented with other performance measures,

  16. Communication Defect dynamics of cement paste under repeated compression

    E-print Network

    Chung, Deborah D.L.

    Communication Defect dynamics of cement paste under repeated compression studied by electrical resistivity measurement during repeated compression of cement paste in the elastic regime, are characterized effect; Cement paste 1. Introduction Defects greatly affect the properties of a material, so

  17. Control of gas flow through cement column

    SciTech Connect

    Ganguli, K.K.

    1992-03-31

    This patent describes a method of inhibiting gas channeling during the cementing of a casing in a borehole penetrating a high temperature subterranean formation. It comprises: introducing a cementing composition into the annulus between the conduit and the formation, the cementing composition comprising a gas channeling inhibiting additive comprised of a copolymer of 5 to 95 weight percent of 2-acrylamido-2-methylpropane-3-sulphonic acid; 5 to 95 weight percent of a vinylacylamide; and 0 to 80 weight percent of acrylamide; and allowing the cementing composition to set within the space.

  18. About radioactivity in some PMMA bone cements.

    PubMed

    Hopf, W; Hopf, C G; Glöbel, B

    1990-01-01

    Various bone cements containing zirconium oxide (ZrO2) as X-ray contrast medium were tested for radioactivity by means of a gamma spectrometer. All measured bone cements (PALACOS, IMPLAST, SULFIX-6) showed a certain degree of radioactivity. The radiation source in the bone cement is the added zirconium oxide, which is polluted by radioactive elements. As these X-ray contrast media remain in the body for decades as components of the bone cement, the radioactive zirconium oxides should be substituted by high purity radiation-free zirconium oxide or barium sulfate. PMID:2239190

  19. The compressive modulus and strength of saturated calcium sulphate dihydrate cements: implications for testing standards.

    PubMed

    Koh, Ilsoo; López, Alejandro; Helgason, Benedikt; Ferguson, Stephen J

    2014-06-01

    Calcium sulphate-based bone cement is a bone filler with proven biological advantages including biodegradability, biocompatibility and osteoconductivity. Mechanical properties of such brittle ceramic cements are frequently determined using the testing standard designed for ductile acrylic cements. The aims of the study were (1) to validate the suitability of this common testing protocol using saturated calcium sulphate dihydrate (CSD), and (2) to compare the strength and effective modulus of non-saturated and saturated CSD, in order to determine the changes in the mechanical behavior of CSD upon saturation. Unconfined compression tests to failure were performed on 190 cylindrical CSD samples. The samples were divided into four groups having different saturation levels (saturated, non-saturated) and end conditions (capped and non-capped). Two effective moduli were calculated per sample, based on the deformations measured using the machine platens and a sample-mounted extensometer. The effective moduli of non-saturated groups were found to be independent of the end conditions. The saturated and capped group showed no difference in the effective moduli derived from different measurement methods, while the saturated and non-capped group showed a significant difference between the machine platen- and extensometer-derived moduli. Strength and modulus values were significantly lower for saturated samples. It was assumed that the existence of water in saturated CSD alters the mechanical response of the material due to the changes in chemical and physical behaviors. These factors are considered to play important roles to decrease the shear strength of CSD. It was proposed that the reduction in CSD shear strength evokes local deformation at the platen-sample boundary, affecting the strength and effective moduli derived from the experiments. The results of this study highlighted the importance of appropriate and consistent testing methods when determining the mechanical properties of saturated ceramic cements. PMID:24603215

  20. Liquid antibiotics in bone cement

    PubMed Central

    Chang, Y. H.; Tai, C. L.; Hsu, H. Y.; Hsieh, P. H.; Lee, M. S.; Ueng, S. W. N.

    2014-01-01

    Objectives The objective of this study was to compare the elution characteristics, antimicrobial activity and mechanical properties of antibiotic-loaded bone cement (ALBC) loaded with powdered antibiotic, powdered antibiotic with inert filler (xylitol), or liquid antibiotic, particularly focusing on vancomycin and amphotericin B. Methods Cement specimens loaded with 2 g of vancomycin or amphotericin B powder (powder group), 2 g of antibiotic powder and 2 g of xylitol (xylitol group) or 12 ml of antibiotic solution containing 2 g of antibiotic (liquid group) were tested. Results Vancomycin elution was enhanced by 234% in the liquid group and by 12% in the xylitol group compared with the powder group. Amphotericin B elution was enhanced by 265% in the liquid group and by 65% in the xylitol group compared with the powder group. Based on the disk-diffusion assay, the eluate samples of vancomycin-loaded ALBC of the liquid group exhibited a significantly larger inhibitory zone than samples of the powder or the xylitol group. Regarding the ALBCs loaded with amphotericin B, only the eluate samples of the liquid group exhibited a clear inhibitory zone, which was not observed in either the xylitol or the powder groups. The ultimate compressive strength was significantly reduced in specimens containing liquid antibiotics. Conclusions Adding vancomycin or amphotericin B antibiotic powder in distilled water before mixing with bone cement can significantly improve the efficiency of antibiotic release than can loading ALBC with the same dose of antibiotic powder. This simple and effective method for preparation of ALBCs can significantly improve the efficiency of antibiotic release in ALBCs. Cite this article: Bone Joint Res 2014;3:246–51. PMID:25104836

  1. Characterization of bone repair in rat femur after treatment with calcium phosphate cement and autogenous bone graft

    PubMed Central

    2010-01-01

    Background In this study, the biocompatibility, stability and osteotransductivity of a new cement based on alpha-tricalcium phosphate (alpha-TCP) were investigated in a bone repair model using a rat model. Methods The potential of alpha-TCP on bone repair was compared to autogenous bone grafting, and unfilled cavities were used as negative control. Surgical cavities were prepared and designated as test (T), implanted with alpha-TCP blocks; negative control (C - ), unfilled; and positive control (C + ), implanted with autogenous bone graft. Results were analyzed on postoperative days three, seven, 14, 21 and 60. Results The histological analyses showed the following results. Postoperative day three: presence of inflammatory infiltrate, erythrocytes and proliferating fibroblasts in T, C - and C + samples. Day seven: extensive bone neoformation in groups T and C + , and beginning of alpha-TCP resorption by phagocytic cells. Days 14 and 21: osteoblastic activity in the three types of cavities. Day 60: In all samples, neoformed bone similar to surrounding bone. Moderate interruption on the ostectomized cortical bone. Conclusions Bone neoformation is seen seven days after implantation of alpha-TCP and autogenous bone. Comparison of C - with T and C + samples showed that repair is faster in implanted cavities; on day 60, control groups presented almost complete bone repair. Alpha-TCP cement presents biocompatibility and osteotransductivity, besides stability, but 60 days after surgery the cavities were not closed. PMID:20579394

  2. Fatigue Behavior of Geopolymer Cemente Concrete

    Microsoft Academic Search

    A. C. R. Silva; C. Thaumaturgo

    In this work, a Geopolymeric Cement Concrete (GCC) was developed through adequate portions of geopolymer components. Its characteristics were compared with Portland Cement Concrete (PCC), through of the establishment of some parameters of design, as consumption of binders, water\\/aggregates ratio and mortar content. The concrete mechanical performance was evaluated with emphasis to the fatigue behavior. Were tested the effects of

  3. HPMC and HEMC influence on cement hydration

    Microsoft Academic Search

    J. Pourchez; A. Peschard; P. Grosseau; R. Guyonnet; B. Guilhot; F. Vallée

    2006-01-01

    Cellulose ethers such as hydroxyethylmethyl cellulose (HEMC) and hydroxypropylmethyl cellulose (HPMC) are common admixtures in factory made mortars. Nevertheless, their use principally remains empirical, and no cement–admixture interaction mechanism has ever been rigorously demonstrated. The main issue of this publication deals with the control of secondary effects generated by these admixtures such as the retardation of cement hydration. In this

  4. Acrylic bone cement: current concept review.

    PubMed

    Magnan, B; Bondi, M; Maluta, T; Samaila, E; Schirru, L; Dall'Oca, C

    2013-08-01

    Acrylic bone cement has had for years an important role in orthopedic surgery. Polymethylmethacrylate (PMMA) has been extended from the ophthalmological and dental fields to orthopedics, as acrylic cement used for fixation of prosthetic implants, for remodeling osteoporotic, neoplastic and vertebral fractures repair. The PMMA bone cement is a good carrier for sustained antibiotic release in the site of infection. Joint prostheses chronic infection requires surgical removal of the implant, in order to eradicate the infection process. This can be performed in the same surgical time (one-stage procedure) or in two separate steps (two-stage procedure, which involves the use of an antibiotic-loaded cement spacer). The mechanical and functional characteristics of the spacers allow a good joint range of motion, weight-bearing in selected cases and a sustained release of antibiotic at the site of infection. The improvement of fixation devices in recent years was not accompanied by the improvement of elderly bone quality. Some studies have tested the use of PMMA bone cement or calcium phosphate as augmentation support of internal fixation of these fractures. Over the past 20 years, experimental study of acrylic biomaterials (bone cement, bioglass ceramic, cement additives, absorbable cement, antibiotic spacers) has been of particular importance, offering numerous models and projects. PMID:23893506

  5. Engineering properties of cement with coal gangue

    Microsoft Academic Search

    Yan Zhang; Jun Zhang

    2011-01-01

    Engineering properties of cement with coal gangue was studied to determine the compressive strength, freeze-thaw and shrinkage characteristics of the material. The composition of coal gangue was determined using the screening test; the liquid limit, plastic limit and water ratio of the cement with coal gangue were measured using the Liquid and Plastic Limit Joint Detector. The optimal water ratio

  6. Topics in cement and concrete research

    Microsoft Academic Search

    H. J. H. Brouwers

    2007-01-01

    The present paper addresses several topics in regard to the sustainable design and use of concrete. First, major features concerning the sustainable aspects of the material concrete are summarised. Then the major constituent, from an environmental point of view, cement is discussed in detail, particularly the hydration and application of slag cement. The intelligent combining of mineral oxides, which are

  7. Cement analysis using d + D neutrons

    NASA Astrophysics Data System (ADS)

    Womble, Phillip C.; Paschal, Jon; Moore, Ryan

    2005-12-01

    In the cement industry, the primary concern is quality control. The earlier the cement industry can institute quality control upon their product, the more significant their savings in labor, energy and material. We are developing a prototype cement analyzer using pulsed neutrons from a d-D electronic neutron generator with the goal of ensuring quality control of cement in an on-line manner. By utilizing a low intensity d-D neutron source and a specially-designed moderator assembly, we are able to produce one of the safest neutron-based systems in the market. Also, this design includes some exciting new methods of data acquisition which may substantially reduce the final installation costs. In our proof-of-principle measurements, we were able to measure the primary components of cement (Al, Si, Ca and Fe) to limits required for the raw materials, the derived mixes and the clinkers utilizing this neutron generator.

  8. Surgical repair of invasive cervical root resorption with calcium-enriched mixture cement: a case report.

    PubMed

    Asgary, Saeed; Fazlyab, Mahta

    2015-01-01

    Invasive cervical resorption (ICR) occurs in the cervical area of the teeth due to the formation of a soft tissue that progressively resorbs dentin. The disease is asymptomatic unless the pulp is exposed. This article presents a case involving a mandibular canine that was treated with a calcium-enriched mixture (CEM) cement. After a full mucoperiosteal flap was performed, the soft tissue was curetted away and the cavity filled with CEM biomaterial. One week later, the supragingival surface of the CEM was polished and covered with composite resin. At a 1-year follow-up visit, the pulp was healthy and the gingival probing depth decreased from >3 mm to 1 mm, showing attachment gain. As a biocompatible material, CEM has proven its ability in dentinogenesis, cementogenesis, and osteogenesis; it may prove to be a suitable biomaterial for treating ICR cases. PMID:25574717

  9. Biodegradation and biocompatibility of mechanically active magnetoelastic materials

    NASA Astrophysics Data System (ADS)

    Holmes, Hal R.; DeRouin, Andrew; Wright, Samantha; Riedemann, Travor M.; Lograsso, Thomas A.; Rajachar, Rupak M.; Ghee Ong, Keat

    2014-09-01

    Magnetoelastic (ME) materials have many advantages for use as sensors and actuators due to their wireless, passive nature. This paper describes the application of ME materials as biodegradable implants with controllable degradation rates. Experiments have been conducted to show that degradation rates of ME materials are dependent on the material compositions. In addition, it was shown that the degradation rates of the ME materials can be controlled remotely by applying a magnetic field, which causes the ME materials to generate low-magnitude vibrations that hasten their degradation rates. Another concern of ME materials for medical applications is biocompatibility. Indirect cytotoxicity analyses were performed on two types of ME materials: Metglas™ 2826 MB (FeNiMoB) and iron-gallium alloy. While results indicate Metglas is not biocompatible, the degradation products of iron-gallium materials have shown no adverse effects on cell viability. Overall, these results present the possibility of using ME materials as biodegradable, magnetically-controlled active implants.

  10. Magnesium-based composites with improved in vitro surface biocompatibility

    PubMed Central

    Huan, Zhiguang; Duszczyk, Jurek

    2010-01-01

    In this study, bioactive glass (BG, 45S5) particles were added to a biodegradable magnesium alloy (ZK30) through a semi-solid high-pressure casting process in order to improve the surface biocompatibility of the biomaterial and potentially its bioactivity. The observation of the as-cast microstructures of ZK30-BG composites indicated homogeneous dispersion of BG particles in the matrix. SEM, EDX and EPMA showed the retention of the morphological characteristics and composition of BG particles in the as-cast composite materials. In vitro tests in a cell culture medium confirmed that the composites indeed possessed an enhanced ability to induce the deposition of a bone-like apatite layer on the surface, indicating an improved surface biocompatibility as compared with the matrix alloy. PMID:20922559

  11. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    SciTech Connect

    Farquar, G; Leif, R

    2009-07-15

    Biocompatible polymers with hydrolyzable chemical bonds have been used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres were produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  12. Improving biocompatibility of zirconia surface by incorporating Ca ions.

    PubMed

    Sasaki, Keisuke; Hayashi, Tatsuhide; Asakura, Masaki; Ando, Masahiko; Kawai, Tatsushi; Ban, Seiji

    2015-06-01

    Though zirconia has been used in dental implant fixtures, the biocompatibility of the zirconia surface is not optimal for the surrounding tissue, and many surface modifications have been attempted. We have developed a novel method for improving the biocompatibility of zirconia by incorporating Ca ions. Elemental analysis showed that calcium ions become thoroughly incorporated into the zirconia surface after firing with calcium acetate. Mechanical tests indicated that the Ca ions had little effect on the flexural strength and hardness. Moreover, incorporating Ca ions also dramatically improved the water wettability of specimens that had been soaked in a simulated body fluid. The surface of the Ca-modified zirconia demonstrated good initial cell attachment. PMID:25948140

  13. Glass ionomer ART sealant and fluoride-releasing resin sealant in fissure caries prevention – results from a randomized clinical trial

    PubMed Central

    2014-01-01

    Background The relative performance of ART sealant and fluoride-releasing resin sealant in preventing fissure caries in permanent molars was compared in a randomized clinical trial conducted in southern China (ClinicalTrials.gov NCT01829334). Methods After obtaining ethical approval, healthy schoolchildren who had permanent first molars with occlusal fissures which were sound but deep or presented with only incipient caries were recruited for the study. Included molars were randomly allocated into one of four parallel study groups in units of left/right teeth per mouth. Two of the four groups adopted the methods of ART or fluoride-releasing resin sealant placement while the other two groups adopted the topical fluoride application methods. Fissure status of the molars in each group was evaluated every 6 months. Development of dentine caries and sealant retention over 24 months in the molars in the two sealant-using groups was compared in this report. Outcome on cost-effectiveness of all four groups over 36 months will be reported elsewhere. Results At baseline, a total of 280 children (383 molars) with mean age 7.8 years were involved for the two sealant groups. After 24 months, 261 children (357 molars) were followed. Proportions of molars with dentine caries were 7.3% and 3.9% in the ART sealant and fluoride-releasing resin sealant groups, respectively (chi-square test, p?=?0.171). Life-table survival analysis showed that sealant retention (full and partial) rate over 24 months for the resin sealant (73%) was significantly higher than that (50%) for the ART sealant (p?

  14. A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys

    Microsoft Academic Search

    Waseem Haider; Norman Munroe; Chandan Pulletikurthi; Puneet K. Singh Gill; Sushma Amruthaluri

    2009-01-01

    Nitinol alloys are rapidly being utilized as the material of choice in a variety of applications in the medical industry.\\u000a It has been used for self-expanding stents, graft support systems, and various other devices for minimally invasive interventional\\u000a and endoscopic procedures. However, the biocompatibility of this alloy remains a concern to many practitioners in the industry\\u000a due to nickel sensitivity

  15. Cysteine modified polyaniline films improve biocompatibility for two cell lines.

    PubMed

    Yslas, Edith I; Cavallo, Pablo; Acevedo, Diego F; Barbero, César A; Rivarola, Viviana A

    2015-06-01

    This work focuses on one of the most exciting application areas of conjugated conducting polymers, which is cell culture and tissue engineering. To improve the biocompatibility of conducting polymers we present an easy method that involves the modification of the polymer backbone using l-cysteine. In this publication, we show the synthesis of polyaniline (PANI) films supported onto Polyethylene terephthalate (PET) films, and modified using cysteine (PANI-Cys) in order to generate a biocompatible substrate for cell culture. The PANI-Cys films are characterized by Fourier Transform infrared and UV-visible spectroscopy. The changes in the hydrophilicity of the polymer films after and before the modification were tested using contact angle measurements. After modification the contact angle changes from 86°±1 to 90°±1, suggesting a more hydrophylic surface. The adhesion properties of LM2 and HaCaT cell lines on the surface of PANI-Cys films in comparison with tissue culture plastic (TCP) are studied. The PANI-Cys film shows better biocompatibility than PANI film for both cell lines. The cell morphologies on the TCP and PANI-Cys film were examined by florescence and Atomic Force Microscopy (AFM). Microscopic observations show normal cellular behavior when PANI-Cys is used as a substrate of both cell lines (HaCaT and LM2) as when they are cultured on TCP. The ability of these PANI-Cys films to support cell attachment and growth indicates their potential use as biocompatible surfaces and in tissue engineering. PMID:25842107

  16. Evaluation of biocompatible products for managing cucurbit powdery mildew

    Microsoft Academic Search

    M. T McGrath; N Shishkoff

    1999-01-01

    The biocompatible products AQ10 (hyperparasitic fungus Ampelomyces quisqualis), JMS Stylet-Oil (medium viscosity mineral oil), M-Pede (potassium salts of fatty acids) and Kaligreen (82% potassium bicarbonate) suppressed powdery mildew (Sphaerotheca fusca) on winter squash, muskmelon, and pumpkin and increased yield compared with nontreated plants under field conditions. Applications were started after disease detection. JMS Stylet-Oil most effectively controlled powdery mildew. However,

  17. Characterization and biocompatibility of epoxy-crosslinked dermal sheep collagens

    Microsoft Academic Search

    Wachem van P. B; R. Zeeman; P. J. Dijkstra; J. Feijen; M. Hendriks; P. T. Cahalan; Luyn van M. J. A

    1999-01-01

    Dermal sheep collagen (DSC), which was crosslinked with 1,4-butanediol diglycidyl ether (BD) by using four different conditions, was characterized and its biocompatibility was evaluated after subcutaneous implantation in rats. Crosslinking at pH 9.0 (BD90) or with successive epoxy and carbodiimide steps (BD45EN) resulted in a large increase in the shrinkage temperature (Ts) in combination with a clear reduction in amines.

  18. Engineering Biomaterials to Integrate and Heal: The Biocompatibility Paradigm Shifts

    PubMed Central

    Bryers, James D.; Giachelli, Cecilia M.; Ratner, Buddy D.

    2012-01-01

    This article focuses on one of the major failure routes of implanted medical devices, the foreign body reaction (FBR)—that is, the phagocytic attack and encapsulation by the body of the so-called “biocompatible” biomaterials comprising the devices. We then review strategies currently under development that might lead to biomaterial constructs that will harmoniously heal and integrate into the body. We discuss in detail emerging strategies to inhibit the FBR by engineering biomaterials that elicit more biologically pertinent responses. PMID:22592568

  19. Biocompatibility Parameters of Different Dialysis Membranes Assessed during Systemic Inflammation

    Microsoft Academic Search

    F. Gueler; W. Gwinner; C. Schiborr; M. Martin; A. Klos; T. Kirsch; A. Fiebeler; H. Haller; D. Fliser

    2005-01-01

    Background: We explored whether biocompatible dialyzer membranes modulate the inflammatory response during blood contact in patients with systemic inflammation. Methods: 15 patients with end-stage renal disease and systemic inflammation (mean serum C-reactive protein 86 ± 4 mg\\/l) were randomly treated with Cuprophan (CU), polyamide (PA) and vitamin-E coated (VEC) membrane-based dialyzers. Results: Changes in blood pressure, capillary blood oxygen saturation

  20. Intermittency events in bio-compatible electrical contacts

    Microsoft Academic Search

    J. W. McBride; C. Maul

    2005-01-01

    This paper presents a study of the electrical contact performance of bio-compatible electrical connectors. In particular, the focus is on the performance of these devices under low frequency fretting conditions aimed to replicate the types of motion that may be experienced in-vivo. In the study, the contact materials selected include titanium, stainless-steel and cobalt-chromium alloys in various combinations. These materials

  1. Biocompatibility of Candidate Materials for the Realization of Medical Microdevices

    Microsoft Academic Search

    Pierre Pouponneau; L'Hocine Yahia; Yahye Merhi; Laura Mery Epure; Sylvain Martel

    2006-01-01

    The propulsion of ferromagnetic micro-carriers in the blood vessels by magnetic gradients generated from a magnetic resonance imaging (MRI) system is of special interest for targeted interventions such as chemotherapy or chemo-embolization. As such, Fe-Co alloys for its highest magnetization saturation, and single crystal Ni-Mn-Ga powder and Terfenol-D for their deformation in magnetic field are evaluated for their biocompatibility. The

  2. A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys

    PubMed Central

    Haider, Waseem; Munroe, Norman; Pulletikurthi, Chandan; Singh Gill, Puneet K.; Amruthaluri, Sushma

    2009-01-01

    Nitinol alloys are rapidly being utilized as the material of choice in a variety of applications in the medical industry. It has been used for self-expanding stents, graft support systems, and various other devices for minimally invasive interventional and endoscopic procedures. However, the biocompatibility of this alloy remains a concern to many practitioners in the industry due to nickel sensitivity experienced by many patients. In recent times, several new Nitinol alloys have been introduced with the addition of a ternary element. Nevertheless, there is still a dearth of information concerning the biocompatibility and corrosion resistance of these alloys. This study compared the biocompatibility of two ternary Nitinol alloys prepared by powder metallurgy (PM) and arc melting (AM) and critically assessed the influence of the ternary element. ASTM F 2129-08 cyclic polarization in vitro corrosion tests were conducted to evaluate the corrosion resistance in phosphate buffered saline (PBS). The growth of endothelial cells on NiTi was examined using optical microscopy. PMID:19956791

  3. A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys

    NASA Astrophysics Data System (ADS)

    Haider, Waseem; Munroe, Norman; Pulletikurthi, Chandan; Gill, Puneet K. Singh; Amruthaluri, Sushma

    2009-08-01

    Nitinol alloys are rapidly being utilized as the material of choice in a variety of applications in the medical industry. It has been used for self-expanding stents, graft support systems, and various other devices for minimally invasive interventional and endoscopic procedures. However, the biocompatibility of this alloy remains a concern to many practitioners in the industry due to nickel sensitivity experienced by many patients. In recent times, several new Nitinol alloys have been introduced with the addition of a ternary element. Nevertheless, there is still a dearth of information concerning the biocompatibility and corrosion resistance of these alloys. This study compared the biocompatibility of two ternary Nitinol alloys prepared by powder metallurgy (PM) and arc melting (AM) and critically assessed the influence of the ternary element. ASTM F 2129-08 cyclic polarization in vitro corrosion tests were conducted to evaluate the corrosion resistance in phosphate buffered saline (PBS). The growth of endothelial cells on NiTi was examined using optical microscopy.

  4. A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys.

    PubMed

    Haider, Waseem; Munroe, Norman; Pulletikurthi, Chandan; Singh Gill, Puneet K; Amruthaluri, Sushma

    2009-08-01

    Nitinol alloys are rapidly being utilized as the material of choice in a variety of applications in the medical industry. It has been used for self-expanding stents, graft support systems, and various other devices for minimally invasive interventional and endoscopic procedures. However, the biocompatibility of this alloy remains a concern to many practitioners in the industry due to nickel sensitivity experienced by many patients. In recent times, several new Nitinol alloys have been introduced with the addition of a ternary element. Nevertheless, there is still a dearth of information concerning the biocompatibility and corrosion resistance of these alloys. This study compared the biocompatibility of two ternary Nitinol alloys prepared by powder metallurgy (PM) and arc melting (AM) and critically assessed the influence of the ternary element. ASTM F 2129-08 cyclic polarization in vitro corrosion tests were conducted to evaluate the corrosion resistance in phosphate buffered saline (PBS). The growth of endothelial cells on NiTi was examined using optical microscopy. PMID:19956791

  5. Microscale investigation of arsenic distribution and species in cement product from cement kiln coprocessing wastes.

    PubMed

    Yang, Yufei; Xue, Jingchuan; Huang, Qifei

    2013-01-01

    To improve the understanding of the immobilization mechanism and the leaching risk of Arsenic (As) in the cement product from coprocessing wastes using cement kiln, distribution and species of As in cement product were determined by microscale investigation methods, including electron probe microanalysis (EPMA) and X-ray absorption spectroscopy. In this study, sodium arsenate crystals (Na3AsO412H2O) were mixed with cement production raw materials and calcined to produce cement clinker. Then, clinker was mixed water to prepare cement paste. EPMA results showed that As was generally distributed throughout the cement paste. As content in calcium silicate hydrates gel (C-S-H) was in low level, but higher than that in other cement mineral phases. This means that most of As is expected to form some compounds that disperse on the surfaces of cement mineral phases. Linear combination fitting (LCF) of the X-ray absorption near edge structure spectra revealed that As in the cement paste was predominantly As(V) and mainly existed as Mg3(AsO4)2, Ca3(AsO4)2, and Na2HAsO4. PMID:24223030

  6. Guide to Cement-Based Integrated Pavement Solutions

    E-print Network

    Cement- Modified Soils Roller- Com- pacted Con- crete EXTERNAL COMPACTION Concrete Recycling Full with cement, cement-modified soils, recycled concrete aggregates, and repair and restoration. Each application Conventional Overlays CRCP VIBRATORY COMPACTION Pervious Concrete Full-Depth Reclamation Cement- Treat- ed Base

  7. High-performance concretes from calcium aluminate cements

    Microsoft Academic Search

    Karen L. Scrivener; Jean-Louis Cabiron; Roger Letourneux

    1999-01-01

    Calcium aluminate cements have a radically different chemistry to Portland cements. Due principally to their higher cost, they do not compete directly with Portland cements. Nevertheless, concretes based on these cements have very high performance in specific applications. Two of these are discussed in this article: resistance to acid attack and particularly biogenic corrosion and abrasion resistance in hydraulic structures.

  8. Onset of cohesion in cement paste B. Jnsson1

    E-print Network

    Paris-Sud XI, Université de

    1 Onset of cohesion in cement paste B. Jönsson1 , H. Wennerström2 , A. Nonat3 , B. Cabane4 1 Abstract It is generally agreed that the cohesion of cement paste occurs through the formation of a network) or multivalent (Al or Fe hydroxide) ions. #12;2 Introduction Cohesion of cement paste When Portland cement

  9. A green chemistry approach for synthesizing biocompatible gold nanoparticles.

    PubMed

    Gurunathan, Sangiliyandi; Han, JaeWoong; Park, Jung Hyun; Kim, Jin-Hoi

    2014-01-01

    Gold nanoparticles (AuNPs) are a fascinating class of nanomaterial that can be used for a wide range of biomedical applications, including bio-imaging, lateral flow assays, environmental detection and purification, data storage, drug delivery, biomarkers, catalysis, chemical sensors, and DNA detection. Biological synthesis of nanoparticles appears to be simple, cost-effective, non-toxic, and easy to use for controlling size, shape, and stability, which is unlike the chemically synthesized nanoparticles. The aim of this study was to synthesize homogeneous AuNPs using pharmaceutically important Ganoderma spp. We developed a simple, non-toxic, and green method for water-soluble AuNP synthesis by treating gold (III) chloride trihydrate (HAuCl4) with a hot aqueous extract of the Ganoderma spp. mycelia. The formation of biologically synthesized AuNPs (bio-AuNPs) was characterized by ultraviolet (UV)-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the biocompatibility of as-prepared AuNPs was evaluated using a series of assays, such as cell viability, lactate dehydrogenase leakage, and reactive oxygen species generation (ROS) in human breast cancer cells (MDA-MB-231). The color change of the solution from yellow to reddish pink and strong surface plasmon resonance were observed at 520 nm using UV-visible spectroscopy, and that indicated the formation of AuNPs. DLS analysis revealed the size distribution of AuNPs in liquid solution, and the average size of AuNPs was 20 nm. The size and morphology of AuNPs were investigated using TEM. The biocompatibility effect of as-prepared AuNPs was investigated in MDA-MB-231 breast cancer cells by using various concentrations of AuNPs (10 to 100 ?M) for 24 h. Our findings suggest that AuNPs are non-cytotoxic and biocompatible. To the best of our knowledge, this is the first report to describe the synthesis of monodispersed, biocompatible, and soluble AuNPs with an average size of 20 nm using Ganoderma spp. This study opens up new possibilities of using an inexpensive and non-toxic mushroom extract as a reducing and stabilizing agent for the synthesis of size-controlled, large-scale, biocompatible, and monodispersed AuNPs, which may have future diagnostic and therapeutic applications. PMID:24940177

  10. Solidification of low-level radioactive wastes in masonry cement. [Masonry cement-boric acid waste forms

    Microsoft Academic Search

    H. Zhou; P. Colombo

    1987-01-01

    Portland cements are widely used as solidification agents for low-level radioactive wastes. However, it is known that boric acid wastes, as generated at pressurized water reactors (PWR's) are difficult to solidify using ordinary portland cements. Waste containing as little as 5 wt % boric acid inhibits the curing of the cement. For this purpose, the suitability of masonry cement was

  11. Phosphate-bonded calcium aluminate cements

    DOEpatents

    Sugama, T.

    1993-09-21

    A method is described for making a rapid-setting phosphate-bonded cementitious material. A powdered aluminous cement is mixed with an aqueous solution of ammonium phosphate. The mixture is allowed to set to form an amorphous cementitious material which also may be hydrothermally treated at a temperature of from about 120 C to about 300 C to form a crystal-containing phosphate-bonded material. Also described are the cementitious products of this method and the cement composition which includes aluminous cement and ammonium polyphosphate. 10 figures.

  12. Sulfate attack on hardened cement paste

    SciTech Connect

    Wang, J.G. (Shenzhen Univ. (China). Dept. of Applied Chemistry)

    1994-01-01

    Hardened cement paste specimens made with different cement types and varying water-cement ratios (w/c) were immersed in 5% sodium sulfate solution maintained at constant pH value of 6. The distribution curves for ettringite, gypsum, and portlandite phases were obtained by using layer by layer XRD analysis and interpreted in terms of material damage due to sulfate attack. The mechanism of sulfate attack is evaluated in regard to the leaching of Ca(OH)[sub 2] and formation of gypsum and ettringite.

  13. Sialite technology—sustainable alternative to portland cement

    Microsoft Academic Search

    Henghu Sun; Ravi Jain; Kennedy Nguyen; John Zuckerman

    2010-01-01

    The objective of this article is to describe the current state of the cement industry, its sustainability, and how it compares\\u000a to alternative cement technologies—specifically Sialite technology. The process for creating the most widely used cement,\\u000a portland cement, is an energy intensive process, which consumes considerable natural resources, such as limestone. In addition,\\u000a portland cement production releases harmful air pollutants,

  14. Interfacial interactions of structural adhesive components with cement pastes

    Microsoft Academic Search

    Inês Baeta Neves; Maud Chabut; Christian Perruchot; Mohamed M. Chehimi; Karim Benzarti

    2004-01-01

    The surface energy of hardened cement pastes, before and after treatment by organic coating, and two individual cement paste components (CSH and ettringite) have been characterized by inverse gas chromatography (IGC) at 35°C, using n-alkanes, 1-alkenes, benzene, chloroform and CCl4 molecular probes. The cement pastes were prepared by mixing an ordinary Portland cement (OPC) with water at a water\\/cement ratio

  15. General hydration model for portland cement and blast furnace slag cement

    SciTech Connect

    De Schutter, G.; Taerwe, L. [Magnel Laboratory for Concrete Research, Ghent (Belgium)] [Magnel Laboratory for Concrete Research, Ghent (Belgium)

    1995-04-01

    This paper focuses on the evolution of the heat of hydration of hardening concrete or cement based materials. Based on isothermal and adiabatic hydration tests a new general hydration model is developed, valid both for portland cement and blast furnace slag cement. This hydration model enables the calculation of the heat production rate as a function of the actual temperature and the degree of hydration.

  16. Factors affecting cement strains near the tip of a cemented femoral component

    Microsoft Academic Search

    Daniel M. Estok; Tracy E. Orr; William H. Harris

    1997-01-01

    A generic three-dimensional finite-element model of the upper half of the femur containing a cemented femoral stem of a total hip arthroplasty was developed to study those factors influencing cement strains near the tip of a cemented femoral component. This generic model was verified through another three-dimensional finite-element model that had been created based on the precise geometry of a

  17. Increased Antibiotic Release from a Bone Cement Containing Bacterial Cellulose

    PubMed Central

    Nakai, Takahisa; Enomoto, Koichi; Uchio, Yuji; Yoshino, Katsumi

    2010-01-01

    Background Major disadvantages of antibiotic bone cements include limited drug release and reduced strength resulting from the addition of high doses of antibiotics. Bacterial cellulose, a three-dimensional hydrophilic mesh, may retain antibiotics and release them gradually. We hypothesized that the addition of cellulose to antibiotic bone cement would improve mechanical strength and antibiotic release. Questions/purposes We therefore examined the mechanical strength and antibiotic release of cellulose antibiotic cement. Methods A high dose of antibiotics (5 g per 40 g cement powder) was incorporated into bacterial cellulose and then mixed with bone cement. We compared the compression strength, fracture toughness, fatigue life, and elution kinetics of this formulation with those of plain cement and a traditional antibiotic cement. Results The average values for compression strength, fracture toughness, and fatigue life of the cellulose antibiotic cement were 97%, 97%, and 78% of the values obtained for plain cement, respectively. The corresponding values for the traditional antibiotic cement were 79%, 82%, and 17%, respectively. The cumulative elution over 35 days was 129% greater from the cellulose antibiotic cement than from the traditional antibiotic cement. Conclusions With a high dose of antibiotics, incorporating cellulose into the bone cement prevented compression and fracture fragility, improved fatigue life, and increased antibiotic elution. Clinical Relevance Antibiotic cements containing cellulose may have applications in clinical situations that require high levels of antibiotic release and preservation of the mechanical properties of the cement. PMID:20945120

  18. Surface modification of iron oxide nanoparticles by biocompatible polymers for tissue imaging and targeting.

    PubMed

    Muthiah, Muthunarayanan; Park, In-Kyu; Cho, Chong-Su

    2013-12-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) are excellent MR contrast agents when coated with biocompatible polymers such as hydrophilic synthetic polymers, proteins, polysaccharides, and lipids, which improve their stability and biocompatibility and reduce their aggregation. Various biocompatible materials, coated or conjugated with targeting moieties such as galactose, mannose, folic acid, antibodies and RGD, have been applied to SPION surfaces to provide tissue specificity to hepatocytes, macrophages, and tumor regions in order to reduce non-specific uptake and improve biocompatibility. This review discusses the recent progress in the development of biocompatible and hydrophilic polymers for improving stability of SPIONs and describes the carbohydrates based biocompatible materials that are providing SPIONs with cell/tissue specificity as ligands. PMID:23528431

  19. Novel doped calcium phosphate-PMMA bone cement composites as levofloxacin delivery systems.

    PubMed

    Matos, Ana C; Marques, Catarina F; Pinto, Rosana V; Ribeiro, Isabel A C; Gonçalves, Lídia M; Vaz, Mário A; Ferreira, J M F; Almeida, António J; Bettencourt, Ana F

    2015-07-25

    Antibiotic-loaded acrylic bone cements (ALABCs) are well-established and cost-effective materials to control the occurrence of bone and joint infections. However, the inexistence of alternative antibiotics other than those already commercially available and the poor ability to bind to bone tissue hampering its biological function are still major drawbacks of ALABCs clinical application. The concept of this research work is to develop a novel bone cement (BC) drug delivery system composed by Mg- and Sr-doped calcium phosphate (CaP) particles as drug carriers loaded into a lactose-modified acrylic BC, which, to the best of our knowledge, has never been reported. CaP particles are known to promote bone ingrowth and current research is focused on using these carriers as antibiotic delivery systems for the treatment of bone infections, like osteomyelitis. Levofloxacin is a fluoroquinolone with anti-staphylococcal activity and adequate penetration into osteoarticular tissues and increasingly being recommended to manage bone-related infections. Also, the lactose-modified BC matrix, with a more porous structure, has already proved to enhance antibiotic release from the BC inner matrix. This novel BC composite biomaterial has shown improved mechanical integrity, biocompatibility maintenance, and sustained release of levofloxacin, with concentrations over the minimum inhibitory concentration values after a 48h while maintaining antibacterial activity over an 8-week period against Staphyloccocus aureus and Staphyloccocus epidermidis, common pathogens associated with bone infections. PMID:26002570

  20. A modified technique for extraoral cementation of implant retained restorations for preventing excess cement around the margins

    PubMed Central

    2014-01-01

    The major drawback of cement-retained restorations is the extrusion of the excess cement into the peri-implant sulcus, with subsequent complications. Insufficient removal of the excess cement may initiate a local inflammatory process, which may lead to implant failure. This article presents a method of controlling cement flow on implant abutments, minimizing the excess cement around implant-retained restorations. PMID:24843401

  1. A nanochemomechanical investigation of carbonated cement paste

    E-print Network

    Vanzo, James (James F.)

    2009-01-01

    Concrete, and in particular its principal component, cement paste, has an interesting relation with carbon dioxide. Concrete is a carbon dioxide generator-- it is estimated that 5-10% of atmospheric CO? comes from this ...

  2. Supply chain management in the cement industry

    E-print Network

    Agudelo, Isabel

    2009-01-01

    Traditionally supply chain management has played an operational role within cement and mineral extraction commodity companies. Recently, cost reduction projects have brought supply chain management into the limelight. In ...

  3. Stem Cells and Calcium Phosphate Cement Scaffolds for Bone Regeneration

    PubMed Central

    Wang, P.; Zhao, L.; Chen, W.; Liu, X.; Weir, M.D.; Xu, H.H.K.

    2014-01-01

    Calcium phosphate cements (CPCs) have excellent biocompatibility and osteoconductivity for dental, craniofacial, and orthopedic applications. This article reviews recent developments in stem cell delivery via CPC for bone regeneration. This includes: (1) biofunctionalization of the CPC scaffold, (2) co-culturing of osteoblasts/endothelial cells and prevascularization of CPC, (3) seeding of CPC with different stem cell species, (4) human umbilical cord mesenchymal stem cell (hUCMSC) and bone marrow MSC (hBMSC) seeding on CPC for bone regeneration, and (5) human embryonic stem cell (hESC) and induced pluripotent stem cell (hiPSC) seeding with CPC for bone regeneration. Cells exhibited good attachment/proliferation in CPC scaffolds. Stem-cell-CPC constructs generated more new bone and blood vessels in vivo than did the CPC control without cells. hUCMSCs, hESC-MSCs, and hiPSC-MSCs in CPC generated new bone and blood vessels similar to those of hBMSCs; hence, they were viable cell sources for bone engineering. CPC with hESC-MSCs and hiPSC-MSCs generated new bone two- to three-fold that of the CPC control. Therefore, this article demonstrates that: (1) CPC scaffolds are suitable for delivering cells; (2) hUCMSCs, hESCs, and hiPSCs are promising alternatives to hBMSCs, which require invasive procedures to harvest with limited cell quantity; and (3) stem-cell-CPC constructs are highly promising for bone regeneration in dental, craniofacial, and orthopedic applications. PMID:24799422

  4. Cemented backfilling performance of yellow phosphorus slag

    Microsoft Academic Search

    Jia-sheng Chen; Bin Zhao; Xin-min Wang; Qin-li Zhang; Li Wang

    2010-01-01

    The experiments on the cemented backfilling performance of yellow phosphorus slag, including physical-mechanical properties,\\u000a chemical compositions, optimized proportion, and cementation mechanisms, were carried out to make good use of yellow phosphorus\\u000a slag as well as tackle with environment problems, safety problems, geological hazards, and high-cost issues during mining\\u000a in Kaiyang Phosphorus Mine Group, Guizhou. The results show that yellow phosphorus

  5. Shrinkage of steel fibre reinforced cement composites

    Microsoft Academic Search

    P. S. Mangat; M. Motamedi Azari

    1988-01-01

    The paper presents results of an experimental investigation on the influence of steel fibres on the free shrinkage of cement-based\\u000a matrices. Shrinkage tests were carried out on cement paste, mortar and two types of concrete mixes for a period of up to 520\\u000a days. Melt extract, crimped and hooked steel fibres were used for reinforcement at volume fractions ranging between

  6. Field results of liner rotation during cementing

    SciTech Connect

    Lindsey, H.E.; Durham, K.S.

    1984-09-01

    Improving liner cementing success has been a constant objective of the industry for years. Recent developments in rotating liner hanger technology have made this primary cementing technique applicable to more wells than before. Presented here is an analysis of the results of 45 jobs over a year and a half. The study examines success ratios in light of liner size, depth, length, method of rotation, setting tool types, deviation, casing hardware (centralizers, scratchers, etc.), and bearing load.

  7. Analysis of rheological properties of bone cements

    Microsoft Academic Search

    M. K. D. Nicholas; M. G. J. Waters; K. M. Holford; G. Adusei

    2007-01-01

    The rheological properties of three commercially available bone cements, CMW 1, Palacos R and Cemex ISOPLASTIC, were investigated.\\u000a Testing was undertaken at both 25 and 37 C using an oscillating parallel plate rheometer. Results showed that the three high\\u000a viscosity cements exhibited distinct differences in curing rate, with CMW 1 curing in 8.7 min, Palacos R and Cemex ISOPLASTIC\\u000a in 13 min at

  8. Durability study of steel slag cement

    SciTech Connect

    Li Dongxue, Fu Xinhua; Wu Xuequan; Tang Mingshu [Nanjing Univ. of Chemical Technology, Jiangsu (China). Dept. of Materials Science and Engineering] [Nanjing Univ. of Chemical Technology, Jiangsu (China). Dept. of Materials Science and Engineering

    1997-07-01

    The properties of 525{number_sign} grade steel slag cements were investigated in the present research, including: long-term strength, sulphate attack, carbonation, sea water attack, and alkali-aggregate reaction. The study shows that steel slag cement is characterized by high later strength, slight expansion, good resistance to harmful materials such as sulphate, carbon dioxide, and sea water, reducing the alkali-aggregate reaction. Its pore structures have also been studied.

  9. Computational fluid dynamics improves liner cementing operation

    SciTech Connect

    Barton, N.A.; Archer, G.L. (British Gas plc, Newcastle upon Tyne (United Kingdom)); Seymour, D.A. (British Gas plc, Reading (United Kingdom))

    1994-09-26

    The use of computational fluid dynamics (CFD), an analytical tool for studying fluid mechanics, helped plan the successful cementing of a critical liner in a North Sea extended reach well. The results from CFD analysis increased the confidence in the primary cementing of the liner. CFD modeling was used to quantify the effects of increasing the displacement rate and of rotating the liner on the mud flow distribution in the annulus around the liner.

  10. Impedance spectra of hydrating cement pastes

    Microsoft Academic Search

    C. A. Scuderi; T. O. Mason; H. M. Jennings

    1991-01-01

    Complex impedance spectra were obtained over the frequency range 5 Hz to 13 MHz on Portland cement pastes with water\\/cement ratios of 0.3, 0.35, and 0.4 at various hydration times from 6 h to 24 days. Features of the spectra which could be associated with the bulk material and which could be separated from the electrode arc, were studied. The

  11. Mercury porosimetry of hardened cement pastes

    Microsoft Academic Search

    Raymond A. Cook; Kenneth C. Hover

    1999-01-01

    Mercury porosimetry was performed on 92 hardened cement paste specimens of water\\/cement (w\\/c) ratios 0.3, 0.4, 0.5, 0.6, and 0.7 and curing times of 1, 3, 7, 14, 28, and 56 days. This paper presents the experimental techniques, results, and their possible implications with respect to pore connectivity. As expected, longer curing times and lower w\\/c ratios resulted in smaller

  12. Yield stress of cemented tungsten carbide

    NASA Technical Reports Server (NTRS)

    Ruoff, A. L.; Wanagel, J.

    1975-01-01

    Cemented tungsten carbide yields plastically at room temperature in the presence of a large hydrostatic pressure component. By approximate analysis of the state of stress in supported opposed anvils and by measurement of the pressure at which the anvil tips exhibit a permanent deviation from planarity, we have obtained the yield stress of such materials. Our value for the yield stress of a 3% cobalt cemented tungsten carbide is 86 kbar.

  13. Biocompatibility and Surface Studies of Microwave CVD Diamond Films

    NASA Astrophysics Data System (ADS)

    Davis, Brian; Garguilo, J. M.; Koeck, F. A. M.; Nemanich, R. J.; Price, K. J.

    2002-03-01

    The structure and surface properties of a variety of diamond and diamond like carbon films were studied at the nano-scale, in an attempt to assess the biocompatibility of these surfaces. The process of microwave chemical vapor deposition was used to deposit undoped diamond, nitrogen doped diamond, diamond with a titanium monolayer, and diamond-like carbon samples. The contact angles of de-ionized water droplets on the surface of the samples were measured to analyze the surface energy of each film. The rms roughness values of the diamond films measured by atomic force microscopy were also used in determining surface characteristics. Surface treatments of hydrogen passivation, and oxidization were applied to the surface of each film. Hydrogen passivation of the undoped diamond, and nitrogen doped diamond surfaces increases the contact angle on average 30 degrees. Oxidation of the surface decreases the contact angle on average 20 degrees. The surface treatments did not significantly change the contact angle of the diamond like carbon films. Protein adsorption is the first event to take place at a tissue/material interface of an implant into the body, and fibrinogen is the major surface protein, which initiates coagulation and inflammation in the body. The adsorption of fibrinogen was used as an indicator of the biocompatibility of these diamond materials. Fibrinogen was applied to the diamond, and diamond like carbon films. A correlation between contact angle/surface energy, roughness, and the fibrinogen adsorption of these diamond surfaces is reported. There was no significant change in the contact angles following the application of fibrinogen to the surface of the films. This could indicate the biocompatibility of the diamond films. This work supported by the NSF REU program at NCSU and a Physical Sciences Student Research grant from MSU.

  14. Development, Characterizations and Biocompatibility Evaluations of Intravitreal Lipid Implants

    PubMed Central

    Tamaddon, Lana; Mostafavi, Abolfazl; Riazi-esfahani, Mohammad; Karkhane, Reza; Aghazadeh, Sara; Rafiee-Tehrani, Morteza; Abedin Dorkoosh, Farid; Asadi Amoli, Fahimeh

    2014-01-01

    Background: The treatment of posterior eye diseases is always challenging mainly due to inaccessibility of the region. Many drugs are currently delivered by repeated intraocular injections. Objectives: The purpose of this study was to investigate the potential applications of natural triglycerides as alternative carriers to synthetic polymers in terms of drug release profile and also biocompatibility for intraocular use. Materials and Methods: In vitro/in vivo evaluations of intravitreal implants fabricated from the physiological lipid, glyceride tripalmitate containing clindamycin phosphate as a model drug was performed. The micro-implants with average diameter of 0.4 mm were fabricated via a hot melt extrusion method. The extrudates were analyzed using scanning electron microscopy, differential scanning calorimetry, and in vitro drug dissolution studies. For biocompatibility, the implants were implanted into rabbit eyes. Clinical investigations including fundus observations, electroretinography as well as histological evaluations were performed. Results: In vitro tests guaranteed usefulness of the production method for preparing the homogenous mixture of the drug and lipid without affecting thermal and crystalinity characteristics of the components. In vitro releases indicated a bi-phasic pattern for lower lipid ratios, which were completed by the end of day three. With higher lipid ratios, more controlled release profiles were achieved until about ten days for a lipid ratio of 95%. Clinical observations did not show any abnormalities up to two months after implantation into the rabbit eye. Conclusions: These results suggest that although the implant could not adequately retard release of the present drug model yet, due to good physical characteristics and in vivo biocompatibility, it can represent a suitable device for loading wide ranges of therapeutics in treatment of many kinds of retinochoroidal disorders. PMID:24872944

  15. Green chemistry approach for the synthesis of biocompatible graphene

    PubMed Central

    Gurunathan, Sangiliyandi; Han, Jae Woong; Kim, Jin-Hoi

    2013-01-01

    Background Graphene is a single-atom thick, two-dimensional sheet of hexagonally arranged carbon atoms isolated from its three-dimensional parent material, graphite. One of the most common methods for preparation of graphene is chemical exfoliation of graphite using powerful oxidizing agents. Generally, graphene is synthesized through deoxygenation of graphene oxide (GO) by using hydrazine, which is one of the most widespread and strongest reducing agents. Due to the high toxicity of hydrazine, it is not a promising reducing agent in large-scale production of graphene; therefore, this study focused on a green or sustainable synthesis of graphene and the biocompatibility of graphene in primary mouse embryonic fibroblast cells (PMEFs). Methods Here, we demonstrated a simple, rapid, and green chemistry approach for the synthesis of reduced GO (rGO) from GO using triethylamine (TEA) as a reducing agent and stabilizing agent. The obtained TEA reduced GO (TEA-rGO) was characterized by ultraviolet (UV)–visible absorption spectroscopy, X-ray diffraction (XRD), particle size dynamic light scattering (DLS), scanning electron microscopy (SEM), Raman spectroscopy, and atomic force microscopy (AFM). Results The transition of graphene oxide to graphene was confirmed by UV–visible spectroscopy. XRD and SEM were used to investigate the crystallinity of graphene and the surface morphologies of prepared graphene respectively. The formation of defects further supports the functionalization of graphene as indicated in the Raman spectrum of TEA-rGO. Surface morphology and the thickness of the GO and TEA-rGO were analyzed using AFM. The presented results suggest that TEA-rGO shows significantly more biocompatibility with PMEFs cells than GO. Conclusion This is the first report about using TEA as a reducing as well as a stabilizing agent for the preparation of biocompatible graphene. The proposed safe and green method offers substitute routes for large-scale production of graphene for several biomedical applications. PMID:23940417

  16. Poly(ethyleneimines) in dermal applications: biocompatibility and antimicrobial effects.

    PubMed

    Wiegand, Cornelia; Bauer, Marius; Hipler, Uta-Christina; Fischer, Dagmar

    2013-11-01

    Cationic polyamines, such as poly(ethyleneimines) (PEIs), may recommend themselves for antimicrobial applications as they can interact with microbial membranes resulting in their disruption. The purpose of the study was the assessment of biocompatibility and antibacterial activity of PEIs with different architectures (branched (b) and linear (l)) and molar masses (0.8-750 kDa). lPEI and bPEI exhibited a strong antibacterial activity against Staphylococcus aureus and Escherichia coli with a more pronounced effect on the Gram-positive bacteria. lPEIs further demonstrated a higher antibacterial efficacy compared to bPEIs but no significant differences between 5 and 25 kDa were observed. In accordance, antibacterial activity of bPEI did not specifically depend on molar mass. Only slightly lower minimal inhibitory concentrations (MIC) were observed at 5 kDa (S. aureus) and 25 kDa (E. coli) in the tests. As PEIs are compelling candidates for use in antimicrobial treatment, two basic aspects have to be investigated: treatment effectiveness and safety. PEIs clearly induced molecular weight dependent cytotoxic effects in vitro. PEIs with low molecular weight (0.8 and 5 kDa) exhibited higher biocompatibility. Nonetheless, the results confirmed a low genotoxic potential of lPEI and bPEIs. In conclusion, 2.5 kDa-lPEI and 0.8 kDa-bPEI can be recommended for use as antimicrobial polymers in dermal applications due to their high biocompatibility with concomitant antibacterial efficacy. PMID:23948135

  17. Reducing the greenhouse effect through new cements

    SciTech Connect

    Malek, R.I.A.; Roy, D.M. [Pennsylvania State Univ., University Park, PA (United States)

    1996-12-31

    A novel approach to synthesize aluminosilicate cementitious materials according to the formula: has been developed. The new cement can reduce CO{sub 2} emission resulting from manufacture of Portland cement. In addition to its use as replacement for normal cement, the zeolitic nature of the new materials makes them particularly useful in trapping hazardous ions as in the case of radioactive waste disposal and tie-in of the alkali metal ions responsible for the alkali-silica reaction. The new cement utilizes large volume waste materials and industrial by products such as slags and fly ash and should provide significant economic and environmental benefits. Two systems were studied, namely, K-activated system composed of metakaolinite, class-F fly ash, potassium silicate and potassium hydroxide and K, Ca-activated system composed of metakaolinite, class-C fly ash, slag, potassium silicate and potassium hydroxide. Isothermal calorimetry experiments indicated an acceleration of hydration reaction and the compressive strength at 14 days is nearly equivalent to that of neat cement pastes. The pore structures of the new systems are finer than normal cement pastes and their reactivities towards alkali-silica reaction are minimal. The magic angle NMR studies indicate that Si/Al ratios are 1 and 1.3 for K, Ca-activated and K-activated systems, respectively.

  18. Analysis of rheological properties of bone cements.

    PubMed

    Nicholas, M K D; Waters, M G J; Holford, K M; Adusei, G

    2007-07-01

    The rheological properties of three commercially available bone cements, CMW 1, Palacos R and Cemex ISOPLASTIC, were investigated. Testing was undertaken at both 25 and 37 degrees C using an oscillating parallel plate rheometer. Results showed that the three high viscosity cements exhibited distinct differences in curing rate, with CMW 1 curing in 8.7 min, Palacos R and Cemex ISOPLASTIC in 13 min at 25 degrees C. Furthermore it was found that these curing rates were strongly temperature dependent, with curing rates being halved at 37 degrees C. By monitoring the change of viscosity with time over the entire curing process, the results showed that these cements had differing viscosity profiles and hence exhibit very different handling characteristics. However, all the cements reached the same maximum viscosity of 75 x 10(3) Pa s. Also, the change in elastic/viscous moduli and tan delta with time, show the cements changing from a viscous material to an elastic solid with a clear peak in the viscous modulus during the latter stages of curing. These results give valuable information about the changes in rheological properties for each commercial bone cement, especially during the final curing process. PMID:17277981

  19. Biocompatibility and applications of carbon nanotubes in medical nanorobots

    PubMed Central

    Popov, Andrei M; Lozovik, Yurii E; Fiorito, Silvana; Yahia, L’Hocine

    2007-01-01

    The set of nanoelectromechanical systems (NEMS) based on relative motion of carbon nanotubes walls is proposed for use in medical nanorobots. This set includes electromechanical nanothermometer, jet nanoengine, nanosyringe (the last can be used simultaneously as nanoprobe for individual biological molecules and drug nanodeliver). Principal schemes of these NEMS are considered. Operational characteristics of nanothermometer are analyzed. The possible methods of these NEMS actuation are considered. The present-day progress in nanotechnology techniques which are necessary for assembling of NEMS under consideration is discussed. Biocompatibility of carbon nanotubes is analyzed in connection with perspectives of their application in nanomedicine. PMID:18019835

  20. Surface Functionalized Biocompatible Magnetic Nanospheres for Cancer Hyperthermia

    Microsoft Academic Search

    Xianqiao Liu; Valentyn Novosad; Elena A. Rozhkova; Haitao Chen; Volodymyr Yefremenko; John Pearson; Michael Torno; Sam D. Bader; Axel J. Rosengart

    2007-01-01

    We report a simplified single emulsion (oil-in-water) solvent evaporation protocol to synthesize surface functionalized biocompatible magnetic nanospheres by using highly concentrated hydrophobic magnetite (gel) and a mixture of poly(D,L lactide-co-glycolide) (PLGA) and poly(lactic acid-block-polyethylene glycol-maleimide) (PLA-PEG-maleimide) (10:1 by mass) polymers. The as-synthesized particles are approximately spherical with an average diameter of 360-370 nm with polydispersity index of 0.12-0.18, are surface-functionalized

  1. Biocompatible implants and methods of making and attaching the same

    SciTech Connect

    Rowley, Adrian P; Laude, Lucien D; Humayun, Mark S; Weiland, James D; Lotfi, Atoosa; Markland, Jr., Francis S

    2014-10-07

    The invention provides a biocompatible silicone implant that can be securely affixed to living tissue through interaction with integral membrane proteins (integrins). A silicone article containing a laser-activated surface is utilized to make the implant. One example is an implantable prosthesis to treat blindness caused by outer retinal degenerative diseases. The device bypasses damaged photoreceptors and electrically stimulates the undamaged neurons of the retina. Electrical stimulation is achieved using a silicone microelectrode array (MEA). A safe, protein adhesive is used in attaching the MEA to the retinal surface and assist in alleviating focal pressure effects. Methods of making and attaching such implants are also provided.

  2. Dendritic polyglycerol: a new versatile biocompatible-material.

    PubMed

    Frey, Holger; Haag, Rainer

    2002-05-01

    Polyglycerol represents the first hyperbranched polymer that can be prepared in a controlled synthesis. It is characterized by the combination of a stable, biocompatible polyether scaffold, high-end group functionality and a compact, well-defined dendrimer-like architecture. These characteristics can be used to generate new materials properties and for biomedical applications to molecularly amplify or multiply effects or to create extremely high local concentrations of drugs, molecular labels, or probe moieties. Therefore, dendritic polyglycerols are expected to lead to new strategies for 'molecular medicine'. In this brief summary, the current state of the art in polyglycerol research is given, focusing on applications in life sciences. PMID:12071228

  3. Femtosecond pulsed laser deposition of biological and biocompatible thin layers

    Microsoft Academic Search

    B. Hopp; T. Smausz; G. Kecskeméti; A. Klini; Zs. Bor

    2007-01-01

    In our study we investigate and report the femtosecond pulsed laser deposition of biological and biocompatible materials. Teflon, polyhydroxybutyrate, polyglycolic-acid, pepsin and tooth in the form of pressed pellets were used as target materials. Thin layers were deposited using pulses from a femtosecond KrF excimer laser system (FWHM=450fs, ?=248nm, f=10Hz) at different fluences: 0.6, 0.9, 1.6, 2.2, 2.8 and 3.5J\\/cm2,

  4. Biodegradation and biocompatibility of a degradable chitosan vascular prosthesis

    PubMed Central

    Kong, Xiaoying; Xu, Wenhua

    2015-01-01

    An instrument made by ourselves was used to fabricate biodegradable chitosan-heparin artificial vascular prosthesis with small internal diameter (2 mm) and different crosslinking degree from biodegradable chitosan, chitosan derivates and heparin. In vivo and in vitro degradation studies, inflammatory analysis and electron microscope scanning of this artificial vascular prosthesis were performed. It was observed that 50% of the prosthesis decomposed in vivo and was replaced by natural tissues. The degradation process of the chitosan-heparin artificial vascular prosthesis of small diameter could be controlled by changing the crosslinking degree. This kind of artificial vascular prosthesis shows good biocompatibility that can be controllability designed to achieve desirable in vascular replacement application.

  5. Synthesis and characterization of self-curing hydrophilic bone cements for protein delivery.

    PubMed

    Franco-Marquès, E; Parra, J; Pèlach, M A; Méndez, J A

    2015-07-01

    New formulations of acrylic bone cements for bone defect reparation, based on self-hardening methyl methacrylate (MMA)/methacrylic acid (MAA), with a high capacity for protein delivery, have been developed. The self-curing formulations were prepared by partial substitution of solid phase PMMA microparticles by newly obtained PMAA microspheres. The PMAA microspheres were prepared by inverse suspension polymerization of their monomer and were cross-linked with N,N'-methylene-bis-acrylamide (MBA) (10-15 wt %) to produce stable systems in contact with aqueous media. PMAA microspheres were loaded with hydrolyzed collagen (HC) as a model protein to simulate bone morphogenetic protein delivery useful for hard tissue reconstruction. Solid phase PMMA microparticles in the formulation were partially substituted by new PMAA-HC microspheres and were characterized to determine viability as an acrylic bone cement in minimally invasive surgery. The incorporation of PMAA-HC microspheres decreased peak temperature by 20°C, which minimized thermal necrotic risk after implantation. Mechanical compression tests revealed a behavior, under dry conditions, close to ISO 5833 standard requirements. However, a drastic drop in mechanical strength, ?64%, was obtained after 15 days of immersion in simulated physiological conditions (37°C and pH 7.4) and was attributed to water absorption and a subsequent plasticizing effect. The increase in water uptake and retention enhanced the capability for controlled protein delivery. Finally, the biocompatibility of the cements was determined; some toxicity of the material during the first hours of culture incubation was observed. Later, toxicity was observed to decrease due to nonreacted monomer leaching, which ensured the low toxicity of the already polymerized phase. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 992-1001, 2015. PMID:25209322

  6. Hydration and properties of novel blended cements based on cement kiln dust and blast furnace slag

    Microsoft Academic Search

    Maria S. Konsta-Gdoutos; Surendra P. Shah

    2003-01-01

    The aim of the present paper is to address the key technical issues pertaining to the utilization of cement kiln dust (CKD) as an activator for ground granulated blast furnace slag (GGBFS) to create nonconventional cementitious binders for concrete. The relatively high alkaline content of CKD is the predominant factor preventing its recycling in cement manufacture. However, it was observed

  7. Cement clinker: A environmental sink for residues from hazardous waste treatment in cement kilns

    SciTech Connect

    Kleppinger, E.W. (EWK Consultants Inc., Washington, DC (United States))

    1993-01-01

    About 70% of all of the liquid and solid hazardous wastes commercially incinerated in the United States is being burned in cement kilns. The process inevitably results in residues, primarily heavy metals, entering the clinker and waste dusts (cement kiln dust, CKD) produced by these kilns. The effects of this trend on the nature and chemical composition of cement, actual and future, are discussed. The wastes burned by cement kilns are expected to increasingly have higher levels of heavy metals per Btu. In general, the effects are very simple to describe but have as yet unknown consequences. The present American Society for Testing and Materials (ASTM) standard does not effectively control hazardous waste burning residues in Portland Cement. The regulatory and economic pressures on CKD disposal suggest that much of it, and its heavy metal residues, will, in time, end up in the clinker and the resultant cement. The end point to the trend is the ability to make cement that passes the performance specifications while containing high levels of heavy metals. The only other alternative is to maximize the levels of heavy metals in the CKD, minimize the amount of CKD, and dispose of it as a hazardous waste. It is recommended that an effort to correlate heavy metal levels in clinker with adverse effects by undertaken, a new standard for cement containing hazardous and other waste residuals be developed, and labeling be required.

  8. Analysis of CCRL proficiency cements 151 and 152 using the Virtual Cement and Concrete Testing Laboratory

    SciTech Connect

    Bullard, Jeffrey W. [Materials and Construction Research Division, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899-8615 (United States)]. E-mail: jeffrey.bullard@nist.gov; Stutzman, Paul E. [Materials and Construction Research Division, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899-8615 (United States)

    2006-08-15

    To test the ability of the Virtual Cement and Concrete Testing Laboratory (VCCTL) software to predict cement hydration properties, characterization of mineralogy and phase distribution is necessary. Compositional and textural characteristics of Cement and Concrete Reference Laboratory (CCRL) cements 151 and 152 were determined via scanning electron microscopy (SEM) analysis followed by computer modeling of hydration properties. The general procedure to evaluate a cement is as follows: (1) two-dimensional SEM backscattered electron and X-ray microanalysis images of the cement are obtained, along with a measured particle size distribution (PSD); (2) based on analysis of these images and the measured PSD, three-dimensional microstructures of various water-to-cement ratios are created and hydrated using VCCTL, and (3) the model predictions for degree of hydration under saturated conditions, heat of hydration (ASTM C186), setting time (ASTM C191), and strength development of mortar cubes (ASTM C109) are compared to experimental measurements either performed at NIST or at the participating CCRL proficiency sample evaluation laboratories. For both cements, generally good agreement is observed between the model predictions and the experimental data.

  9. LIME AND CEMENT INDUSTRY PARTICULATE EMISSIONS: SOURCE CATEGORY REPORT. VOLUME 2. CEMENT INDUSTRY

    EPA Science Inventory

    The volume of the report gives results of the development of particulate emission factors, based on cutoff size for inhalable particles for the cement industry. After a review of available information characterizing particulate emissions from cement plants, the data were summariz...

  10. A thermodynamic model for blended cements. II: Cement hydrate phases; thermodynamic values and modelling studies

    NASA Astrophysics Data System (ADS)

    Bennett, D. G.; Read, D.; Atkins, M.; Glasser, F. P.

    1992-08-01

    Blended Portland cements are likely to form a substantial proportion of repository materials for the disposal of radioactive waste in the UK. A thermodynamic model has been developed therefore in order to predict the composition of the solid and aqueous phases in blended cements as a function of the bulk cement composition. The model is based on simplifying cement to the system CaO sbnd SiO 2sbnd Al 2O 3sbnd SO 4sbnd MgO sbnd H 2O, which constitutes 95% of most cement formulations. Solubility data for hydrogarnet and ettringite suggest that they dissolve congruently and that conventional solubility products can be used to model their dissolution. A solubility model for the siliceous hydrogarnet series, based on ideal solid solution on either side of an immiscibility gap, closely matches experimental solubility data. Solubility data for hydrotalcite and gehlenite hydrate are less consistent and indicative of more complex dissolution processes. On the basis of earlier work, an accurate solubility model is described for hydrated calcium silicate gels in the CaO sbnd SiO 2sbnd H 2O system. Together, these solubility models form a relatively complete thermodynamic model for blended cements. Model predictions for fully matured cement blends are compared to the compositions of pore fluids extracted from aged cement blends. Departures from expected behaviour occur in alkali-bearing systems and are discussed.

  11. Method of producing light weight cement for use of cementation of oil and gas wells

    SciTech Connect

    Skjeldal, S.

    1983-05-31

    A cement slurry of low specific density for cementation of oil and gas wells is produced by mixing oil-well cement with finely divided emission products comprising amorphous silica dust which has been obtained during the electrothermal preparation of ferrosilicon and/or silicon metal, water, and any desirable dispersion components, the emission products being added in an amount in the range of 1-50% of the total weight of dry material. The emission products can either be mixed with the cement while both components are in the dry state whereupon there is added a sufficient quantity of water in order to obtain a desired specific weight of the slurry or first mixed with water and any other desired dispersion components and this slurry is mixed with the oil-well cement.

  12. High concentration honey chitosan electrospun nanofibers: biocompatibility and antibacterial effects.

    PubMed

    Sarhan, Wessam A; Azzazy, Hassan M E

    2015-05-20

    Honey nanofibers represent an attractive formulation with unique medicinal and wound healing advantages. Nanofibers with honey concentrations of <10% were prepared, however, there is a need to prepare nanofibers with higher honey concentrations to increase the antibacterial and wound healing effects. In this work, chitosan and honey (H) were cospun with polyvinyl alcohol (P) allowing the fabrication of nanofibers with high honey concentrations up to 40% and high chitosan concentrations up to 5.5% of the total weight of the fibers using biocompatible solvents (1% acetic acid). The fabricated nanofibers were further chemically crosslinked, by exposure to glutaraldehyde vapor, and physically crosslinked by heating and freezing/thawing. The new HP-chitosan nanofibers showed pronounced antibacterial activity against Staphylococcus aureus but weak antibacterial activity against Escherichia coli. The developed HP-chitosan nanofibers revealed no cytotoxicity effects on cultured fibroblasts. In conclusion, biocompatible, antimicrobial crosslinked honey/polyvinyl alcohol/chitosan nanofibers were developed which hold potential as effective wound dressing. PMID:25817652

  13. Tailoring the stealth properties of biocompatible polysaccharide nanocontainers.

    PubMed

    Kang, Biao; Okwieka, Patricia; Schöttler, Susanne; Seifert, Oliver; Kontermann, Roland E; Pfizenmaier, Klaus; Musyanovych, Anna; Meyer, Ralf; Diken, Mustafa; Sahin, Ugur; Mailänder, Volker; Wurm, Frederik R; Landfester, Katharina

    2015-05-01

    Fundamental development of a biocompatible and degradable nanocarrier platform based on hydroxyethyl starch (HES) is reported. HES is a derivative of starch and possesses both high biocompatibility and improved stability against enzymatic degradation; it is used to prepare nanocapsules via the polyaddition reaction at the interface of water nanodroplets dispersed in an organic miniemulsion. The synthesized hollow nanocapsules can be loaded with hydrophilic guests in its aqueous core, tuned in size, chemically functionalized in various pathways, and show high shelf life stability. The surface of the HES nanocapsules is further functionalized with poly(ethylene glycol) via different chemistries, which substantially enhanced blood half-life time. Importantly, methods for precise and reliable quantification of the degree of functionalization are also introduced, which enable the precise control of the chemistry on the capsules' surface. The stealth properties of these capsules is studied both in-vitro and in-vivo. The functionalized nanocapsules serve as a modular platform for specific cell targeting, as they show no unspecific up-taken by different cell types and show very long circulating time in blood (up to 72 h). PMID:25725561

  14. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    SciTech Connect

    farquar, G; Leif, R

    2008-09-12

    Biocompatible polymers with hydrolyzable chemical bonds are being used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres are being produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. The advantages and disadvantages of each method will be presented and discussed in greater detail along with fluorescent and charge properties of the aerosols. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  15. Biocompatible shaped particles from dried multilayer polymer capsules.

    PubMed

    Chen, Jun; Kozlovskaya, Veronika; Goins, Allison; Campos-Gomez, Javier; Saeed, Mohammad; Kharlampieva, Eugenia

    2013-11-11

    We demonstrated a simple and facile approach to fabricate biocompatible monodisperse hollow microparticles of controlled geometry. The hemispherical, spherical, and cubical microparticles are obtained by drying multilayer capsules of hydrogen-bonded poly(N-vinylpyrrolidone)/tannic acid (PVPON/TA)n. Drying spherical capsules results in hemispherical particles if 15 < n < 20. This shape transformation is controlled by capsule stiffness, which is regulated by the layer number, capsule diameter, and PVPON molecular weight. Cubical and spherical hollow particles maintaining their three-dimensional shapes in the dry state are obtained if n ? 25.5. A 17-fold stiffness increase is required to lead from totally collapsed (PVPON/TA)5.5 to dried self-supporting (PVPON/TA)25.5 particles of 2 ?m in dimensions. All hollow particles could be further resuspended in aqueous solutions while retaining their shapes upon rehydration. The cell growth and viability studies using human cancer cells revealed noncytotoxic properties of the (PVPON/TA) multilayer particles. Both spherical and hemispherical capsules were internalized by macrophages with the uptake of the hemispherical particles per cell two times more efficient. The method presented here allows for a robust preparation of biocompatible shaped particles whose shape and dimensions can be easily tuned by controlling capsule size and wall thickness. The reported structures can be potentially useful for biomedical applications such as shape-controlled cellular uptake and flow dynamics. PMID:24063405

  16. Biocompatible fluorescent nanoparticles for in vivo stem cell tracking.

    PubMed

    Cova, Lidia; Bigini, Paolo; Diana, Valentina; Sitia, Leopoldo; Ferrari, Raffaele; Pesce, Ruggiero Maria; Khalaf, Rushd; Bossolasco, Patrizia; Ubezio, Paolo; Lupi, Monica; Tortarolo, Massimo; Colombo, Laura; Giardino, Daniela; Silani, Vincenzo; Morbidelli, Massimo; Salmona, Mario; Moscatelli, Davide

    2013-06-21

    Efficient application of stem cells to the treatment of neurodegenerative diseases requires safe cell tracking to follow stem cell fate over time in the host environment after transplantation. In this work, for the first time, fluorescent and biocompatible methyl methacrylate (MMA)-based nanoparticles (fluoNPs) were synthesized through a free-radical co-polymerization process with a fluorescent macromonomer obtained by linking Rhodamine B and hydroxyethyl methacrylate. We demonstrate that the fluoNPs produced by polymerization of MMA-Rhodamine complexes (1) were efficient for the labeling and tracking of multipotent human amniotic fluid cells (hAFCs); (2) did not alter the main biological features of hAFCs (such as viability, cell growth and metabolic activity); (3) enabled us to determine the longitudinal bio-distribution of hAFCs in different brain areas after graft in the brain ventricles of healthy mice by a direct fluorescence-based technique. The reliability of our approach was furthermore confirmed by magnetic resonance imaging analyses, carried out by incubating hAFCs with both superparamagnetic iron oxide nanoparticles and fluoNPs. Our data suggest that these finely tunable and biocompatible fluoNPs can be exploited for the longitudinal tracking of stem cells. PMID:23690139

  17. Polymeric barrier membranes for device packaging, diffusive control and biocompatibility

    NASA Astrophysics Data System (ADS)

    Wasikiewicz, J. M.; Roohpour, N.; Paul, D.; Grahn, M.; Ateh, D.; Rehman, I.; Vadgama, P.

    2008-11-01

    Current state-of-the-art implantable micron feature electronic devices are capable of monitoring and stimulating functions in vivo. Within an EU Framework VI project a further step was taken in developing key microsystem technologies and communication methods that could bring intelligence directly to the human interface, in the form of reactive medical implants and ambulatory measurement systems. Information from these devices is planned to be transmitted out into the wider environment for remote processing. However, the packaging of such state-of-the-art devices to enhance tissue biocompatibility, and to protect conducting elements from in vivo corrosion during extended use, along with protecting the body from toxins leaching from implant components, remains a concern. Candidate polymeric barriers as hydration resistant and solute impermeable interfaces to mitigate such major problems of chronic implantation were investigated. Materials studied included silicone rubber, PVC, polyurethane, and diamond-like carbon (DLC). Polymer permeability to water solutes was marginally improved through incorporation of lipid into these structures. Surface biocompatibility was assessed on the basis of protein film deposition in vitro and by cell viability studies in tissue culture. Short-term toxicity was not observed for any of the tested materials, though there were substantial differences in hydration. Additionally, polypyrrole over active electrodes shows feasibility for controlled tissue interfacing whilst retaining electrical conductivity.

  18. Biocompatible alginate from freshly collected Laminaria pallida for implantation.

    PubMed

    Jork, A; Thürmer, F; Cramer, H; Zimmermann, G; Gessner, P; Hämel, K; Hofmann, G; Kuttler, B; Hahn, H J; Josimovic-Alasevic, O; Fritsch, K G; Zimmermann, U

    2000-02-01

    A simple procedure is described for the extraction and purification of alginate from the inner stipes of the kelp Laminaria pallida. Alginate yield was about 10-15% of the dry mass, with a 70:30 mannuronic/guluronic acid ratio. Analysis of the purified alginate revealed a low polyphenol content while proteins were below detection level. The purified alginate was highly viscous, with 10-15 mPa s and 281 mPa s for a 0.1% and 0.5% solution, respectively, indicating a very high molecular mass (larger than 250 kDa). Bead formation occurred in the presence of divalent cations, but also in the presence of artificial serum (FCSIII) without added divalent cations. The biocompatibility of the alginate was tested with the in vitro mice lymphocyte test as well as by implantation of Ba2+ cross-linked beads beneath the kidney capsule of BB/OK rats. There was no evidence for significant mitogenic activity or fibrotic reaction. Biocompatibility of the alginate was also demonstrated by the encapsulation of human chondrocytes into Ca2+ cross-linked alginate beads. Immobilized chondrocytes grew and remained functional (i.e. they produced collagen). PMID:10709986

  19. Biocompatibility of orthodontic adhesives in rat subcutaneous tissue

    PubMed Central

    dos SANTOS, Rogério Lacerda; PITHON, Matheus Melo; FERNANDES, Alline Birra Nolasco; CABRAL, Márcia Grillo; RUELLAS, Antônio Carlos de Oliveira

    2010-01-01

    Objective The objective of the present study was to verify the hypothesis that no difference in biocompatibility exists between different orthodontic adhesives. Material and Methods Thirty male Wistar rats were used in this study and divided into five groups (n=6): Group 1 (control, distilled water), Group 2 (Concise), Group 3 (Xeno III), Group 4 (Transbond XT), and Group 5 (Transbond plus Self-Etching Primer). Two cavities were performed in the subcutaneous dorsum of each animal to place a polyvinyl sponge soaked with 2 drops of the respective adhesive in each surgical loci. Two animals of each group were sacrificed after 7, 15, and 30 days, and their tissues were analyzed by using an optical microscope. Results At day 7, Groups 3 (Transbond XT) and 4 (Xeno III) showed intense mono- and polymorphonuclear inflammatory infiltrate with no differences between them, whereas Groups 1 (control) and 2 (Concise) showed moderate mononuclear inflammatory infiltrate. At day 15, severe inflammation was observed in Group 3 (Transbond XT) compared to other groups. At day 30, the same group showed a more expressive mononuclear inflammatory infiltrate compared to other groups. Conclusion Among the orthodontic adhesive analyzed, it may be concluded that Transbond XT exhibited the worst biocompatibility. However, one cannot interpret the specificity of the data generated in vivo animal models as a human response. PMID:21085807

  20. A rheological and microscopical characterization of biocompatible ferrofluids

    NASA Astrophysics Data System (ADS)

    Nowak, J.; Wolf, D.; Odenbach, S.

    2014-03-01

    There is an increasing interest in suspensions of magnetic nanoparticles in the biomedical area. Those ferrofluids are e.g. used for magnetic resonance imaging and emerging research focuses on employing the fluids for magnetic drug targeting or magnetic particle heating as a potential treatment for cancer. For these applications the knowledge of the suspensions' thermophysical properties is of major interest to guarantee a safe and effective application. Therefore the flow behavior cannot be neglected as it might significantly influence the execution of the aforementioned applications. In this experimental study two biocompatible ferrofluids were investigated. Rheological measurements were carried out using rotational rheometry. To allow an interpretation of the fluids' behavior the microscopic make-up was investigated using dynamic light scattering and transmission electron microscopy. Measurements of diluted ferrofluids were carried out as a first step to simulate the rheological behavior reflecting the concentration of magnetic nanoparticles found in blood flow for most biomedical applications of such fluids. The detected strong effects show the potential to significantly influence application and handling of the biocompatible ferrofluids in the medical area and should therefore be taken into account for further research as well as for the application of such fluids.

  1. Mesh biocompatibility: effects of cellular inflammation and tissue remodelling.

    PubMed

    Junge, Karsten; Binnebösel, Marcel; von Trotha, Klaus T; Rosch, Raphael; Klinge, Uwe; Neumann, Ulf P; Lynen Jansen, Petra

    2012-02-01

    Mesh biocompatibility is basically determined by the foreign body reaction (FBR). In contrast to physiological wound healing and scar formation, the FBR at the host-tissue/biomaterial interface is present for the lifetime of the medical device. The cellular interactions at the mesh/tissue interface proceed over time ending up in a chronic inflammatory process. The time course of the FBR has been studied extensively and consists of three crucial steps that are protein absorption, cell recruitment and, finally, fibrotic encapsulation and extracellular matrix formation. Each of these steps involves a complex cascade of immune modulators including soluble mediators and various cell types. Recent research has focused on the cellular and molecular interactions of the distinct phases of the FBR offering a new basis for therapeutical strategies. The highly dynamic process of the FBR is considerably influenced by the biomaterial composition. Modifications of the type of polymer, the material weight, the filament structure and the pore size are realized and have substantial effects on the in vivo biocompatibility. Moreover, modern mesh technology aims to utilize the available implants as carrier systems for bioactive drugs. Studies in animal models account for the efficiency of these drugs that aim to reduce mesh-related infections or to minimize FBR by influencing inflammation or extracellular matrix remodelling. A thorough understanding of the molecular mechanisms of FBR provides a sophisticated background for the development of new biomaterials at least as carrier systems for bioactive reagents to reduce inflammation and to improve clinical outcome. PMID:21455703

  2. Kombucha-synthesized bacterial cellulose: preparation, characterization, and biocompatibility evaluation.

    PubMed

    Zhu, Changlai; Li, Feng; Zhou, Xinyang; Lin, Lin; Zhang, Tianyi

    2014-05-01

    Bacterial cellulose (BC) is a natural biomaterial with unique properties suitable for tissue engineering applications, but it has not yet been used for preparing nerve conduits to repair peripheral nerve injuries. The objectives of this study were to prepare and characterize the Kampuchea-synthesized bacterial cellulose (KBC) and further evaluate the biocompatibility of KBC with peripheral nerve cells and tissues in vitro and in vivo. KBC membranes were composed of interwoven ribbons of about 20-100 nm in width, and had a high purity and the same crystallinity as that of cellulose I?. The results from light and scanning electron microscopy, MTT assay, flow cytometry, and RT-PCR indicated that no significant differences in the morphology and cell function were observed between Schwann cells (SCs) cultured on KBC membranes and glass slips. We also fabricated a nerve conduit using KBC, which was implanted into the spatium intermusculare of rats. At 1, 3, and 6 weeks post-implantation, clinical chemistry and histochemistry showed that there were no significant differences in blood counts, serum biochemical parameters, and tissue reactions between implanted rats and sham-operated rats. Collectively, our data indicated that KBC possessed good biocompatibility with primary cultured SCs and KBC did not exert hematological and histological toxic effects on nerve tissues in vivo. PMID:23666905

  3. Hybrid polyglycerols with long blood circulation: synthesis, biocompatibility, and biodistribution.

    PubMed

    Imran ul-haq, Muhammad; Lai, Benjamin F L; Kizhakkedathu, Jayachandran N

    2014-10-01

    Multifunctional polymers with defined structure and biocompatibility are critical to the development of drug delivery systems and bioconjugates. In this article, the synthesis, in vitro blood compatibility, cell viability, in vivo circulation, biodistribution, and clearance of hybrid copolymers based on linear and branched polyglycerol are reported. Hybrid polyglycerols (M(n) ? 100 kDa) are synthesized with different compositions (15-80 mol% linear polyglycerol). Relatively small hydrodynamic size and radius of gyration of the hybrid polyglycerols suggest that they are highly compact functional nanostructures. The hybrid polyglycerols show excellent blood compatibility as determined by measuring their effects on blood coagulation, red blood cell aggregation, hemolysis, platelet, and complement activation. The cell viability in presence of hybrid polyglycerols is excellent up to 10 mg mL(-1) concentration and is similar to both dextran and polyvinyl alcohol. Furthermore, tritium labeled hybrid polyglycerol shows long blood circulation (t(1/2?)= 34 h) with minimal organ accumulation in mice. Multifunctionality, compact nature, biocompatibility, and the long blood circulation make these polymers attractive for the development of bioconjugates and drug delivery systems. PMID:25045070

  4. Wellbore cement fracture evolution at the cement–basalt caprock interface during geologic carbon sequestration

    SciTech Connect

    Jung, Hun Bok; Kabilan, Senthil; Carson, James P.; Kuprat, Andrew P.; Um, Wooyong; Martin, Paul F.; Dahl, Michael E.; Kafentzis, Tyler A.; Varga, Tamas; Stephens, Sean A.; Arey, Bruce W.; Carroll, KC; Bonneville, Alain; Fernandez, Carlos A.

    2014-08-01

    Composite Portland cement-basalt caprock cores with fractures, as well as neat Portland cement columns, were prepared to understand the geochemical and geomechanical effects on the integrity of wellbores with defects during geologic carbon sequestration. The samples were reacted with CO2-saturated groundwater at 50 ºC and 10 MPa for 3 months under static conditions, while one cement-basalt core was subjected to mechanical stress at 2.7 MPa before the CO2 reaction. Micro-XRD and SEM-EDS data collected along the cement-basalt interface after 3-month reaction with CO2-saturated groundwater indicate that carbonation of cement matrix was extensive with the precipitation of calcite, aragonite, and vaterite, whereas the alteration of basalt caprock was minor. X-ray microtomography (XMT) provided three-dimensional (3-D) visualization of the opening and interconnection of cement fractures due to mechanical stress. Computational fluid dynamics (CFD) modeling further revealed that this stress led to the increase in fluid flow and hence permeability. After the CO2-reaction, XMT images displayed that calcium carbonate precipitation occurred extensively within the fractures in the cement matrix, but only partially along the fracture located at the cement-basalt interface. The 3-D visualization and CFD modeling also showed that the precipitation of calcium carbonate within the cement fractures after the CO2-reaction resulted in the disconnection of cement fractures and permeability decrease. The permeability calculated based on CFD modeling was in agreement with the experimentally determined permeability. This study demonstrates that XMT imaging coupled with CFD modeling represent a powerful tool to visualize and quantify fracture evolution and permeability change in geologic materials and to predict their behavior during geologic carbon sequestration or hydraulic fracturing for shale gas production and enhanced geothermal systems.

  5. In vitro and in vivo studies on the toxicity of dental resin components: a review

    Microsoft Academic Search

    Michel Goldberg

    2008-01-01

    In vitro and in vivo studies have clearly identified that some components of restorative composite resins, adhesives, and\\u000a resin-modified glass ionomer cements are toxic. The mechanisms of cytotoxicity are related firstly to the short-term release\\u000a of free monomers occurring during the monomer–polymer conversion. Secondly, long-term release of leachable substances is generated\\u000a by erosion and degradation over time. In addition, ion

  6. Osteogenic proteins (bone sialoprotein and bone morphogenetic protein-7) and dental pulp mineralization

    Microsoft Academic Search

    F. Decup; J.-J. Lasfargues; E. Salih; M. Goldberg

    2002-01-01

    Bone sialoprotein (BSP) cross-linked to collagen\\/gelatin was implanted in the pulp of rat’s upper molars. Comparison was carried out with a sham group (non implanted), with a group of rats receiving the carrier alone, and a group of molars where the perforated pulps were capped with calcium hydroxide. The cavities were occluded with a glass-ionomer cement (GIC). After 8, 14

  7. One-step Continuous Synthesis of Biocompatible Gold Nanorods for Optical Coherence Tomography‡

    PubMed Central

    Sebastián, Víctor; Lee, Seung-Kon; Zhou, Chao; Kraus, Martin F.

    2012-01-01

    We present a novel one-step flow process to synthesize biocompatible gold nanorods with tunable absorption and biocompatible surface ligands. Photothermal optical coherence tomography (OCT) of human breast tissue is successfully demonstrated using tailored gold nanorods designed to have strong absorption in near-infrared range. PMID:22634612

  8. Effect of the membrane biocompatibility on nutritional parameters in chronic hemodialysis patients

    Microsoft Academic Search

    Tom F Parker; Rebecca L Wingard; Leigh Husni; T Alp Ikizler; Robert A Parker; Raymond M Hakim

    1996-01-01

    Effect of the membrane biocompatibility on nutritional parameters in chronic hemodialysis patients. Malnutrition is highly prevalent in chronic hemodialysis patients and is an important determinant of their morbidity and mortality. Several recent studies have suggested that the inflammatory response associated with the biocompatibility of the dialysis membranes is a potential contributing factor. In a prospective study of 159 new hemodialysis

  9. Biocompatible Silk Printed Optical Waveguides By Sara T. Parker, Peter Domachuk, Jason Amsden, Jason Bressner, Jennifer

    E-print Network

    Lewis, Jennifer

    implantable device, it may also be required that the components be biodegradable. Hence, the use for biomedical applications, silk fibroin has also been used to fabricate biocompatible and biodegradable of a biocompatible and biodegradable polymer to guide light would open new opportunities for biologically based

  10. New technology improves cement-slurry design

    SciTech Connect

    NONE

    1997-08-01

    A promising geothermal concession is located in a tea plantation on the island of Java. A drilling project was undertaken to evaluate and harness this resource for geothermal electricity generation. The program used two slimhole rigs to drill appraisal wells to establish the potential of the field. Geothermal wells present the most severe conditions to which cements are exposed. As a result, their performance requirements are among the most stringent. Geothermal cements are usually designed to provide at least 1,000 psi compressive strength and no more than 1.0-md water permeability. While casings with tight annular clearances require that good cementing practices be observed, they also create conditions that demand much greater care and control in slurry and procedure design than regular casing cementation. Free-water and thickening-time requirements are similar for geothermal and slimhole conditions, but the use of perlite and silica flour complicate the rheology required for geothermal wells. The paper describes liquid-cement premix, applications, laboratory testing, field pilot testing, and field operations.

  11. Reinforcing of Cement Composites by Estabragh Fibres

    NASA Astrophysics Data System (ADS)

    Merati, A. A.

    2014-04-01

    The influence of Estabragh fibres has been studied to improve the performance characteristics of the reinforced cement composites. The concrete shrinkage was evaluated by counting the number of cracks and measuring the width of cracks on the surface of concrete specimens. Although, the Estabragh fibres lose their strength in an alkali environment of cement composites, but, the ability of Estabragh fibres to bridge on the micro cracks in the concrete matrix causes to decrease the width of the cracks on the surface of the concrete samples in comparison with the plain concrete. However, considering the mechanical properties of specimens such as bending strength and impact resistance, the specimens with 0.25 % of Estabragh fibre performed better in all respects compared to the physical and mechanical properties of reinforced cement composite of concrete. Consequently, by adding 0.25 % of Estabragh fibres to the cement composite of concrete, a remarkable improvement in physical and mechanical properties of fibre-containing cement composite is achieved.

  12. Sulfate attack on cement-stabilized sand

    SciTech Connect

    Rollings, R.S.; Burkes, J.P.; Rollings, M.P. [Army Engineer Waterways Experiment Station, Vicksburg, MS (United States)] [Army Engineer Waterways Experiment Station, Vicksburg, MS (United States)

    1999-05-01

    A 3.5-km (2.2 mi) section of a road in Georgia developed unexpected transverse bumps within 6 months after construction. The source of the bumps appeared to be expansion within the cement-stabilized base course. Laboratory examination of samples from areas showing distress revealed the presence of ettringite, a calcium sulfoaluminate the formation of which can be accompanied by severe expansion. This expansive materials was the probable cause of the volume changes causing the transverse bumps. The calcium and alumina needed to form ettringite ware available from the portland cement and the stabilized soil`s clay minerals. The source of the sulfur was identified as the well water that was mixed with the cement-stabilized base. Sulfate attack of cement-stabilized soils is a relatively infrequent problem, but it is highly destructive when it occurs. Currently, there are no firm criteria for identifying when sulfate attack of a cement-stabilized soil is a potential problem nor are there established methods of preventing the attack.

  13. Identification of Concrete Incompatibilities Using Cement Paste Rheology 

    E-print Network

    Jang, Se Hoon

    2010-07-14

    as well as heat evolution abnormalities. The objectives of the present study were to examine the applicability of the dynamic shear rheometer (DSR) to measure cement paste rheology, and to identify cement and mineral/chemical admixture incompatibilities...

  14. Comparison of the Strength of Barnacle and Commercial Dental Cements

    Microsoft Academic Search

    R. R. Despain; K. L. De Vries; R. D. Luntz; M. L. Williams

    1973-01-01

    The strength of barnacle cement was compared with commercial dental polymeric restorative materials and cements by use of a fracture mechanics approach in conjunction with a blister technique. Barnacles were \\

  15. Microemulsions for use as spaces in well cementation

    SciTech Connect

    Carriay, J.; De Lautrec, J.

    1980-09-23

    New application of microemulsions as buffers between the slurry and the cement in the cementation of oil wells. The microemulsions contain an amphoteric surfactant selected from the group of alkyl dimethyl betaines.

  16. Bone Cement Dislodgement: One of Complications Following Bone Cement Augmentation Procedures for Osteoporotic Spinal Fracture.

    PubMed

    Ha, Kee-Yong; Kim, Young-Hoon; Yoo, Sung-Rim; Molon, Jan Noel

    2015-05-01

    Bone cement augmentation procedures have been getting more position as a minimally invasive surgical option for osteoporotic spinal fractures. However, complications related to these procedures have been increasingly reported. We describe a case of bone cement dislodgement following cement augmentation procedure for osteoporotic spinal fracture by reviewing the patient's medical records, imaging results and related literatures. A 73-year-old woman suffering back and buttock pain following a fall from level ground was diagnosed as an osteoporotic fracture of the 11th thoracic spine. Percutaneous kyphoplasty was performed for this lesion. Six weeks later, the patient complained of a recurrence of back and buttock pain. Radiologic images revealed superior dislodgement of bone cement through the 11th thoracic superior endplate with destruction of the lower part of the 10th thoracic spine. Staged anterior and posterior fusion was performed. Two years postoperatively, the patient carries on with her daily living without any significant disability. Delayed bone cement dislodgement can occur as one of complications following bone cement augmentation procedure for osteoporotic spinal fracture. It might be related to the presence of intravertebral cleft, lack of interdigitation of bone cement with the surrounding trabeculae, and possible damage of endplate during ballooning procedure. PMID:26113965

  17. Bone Cement Dislodgement: One of Complications Following Bone Cement Augmentation Procedures for Osteoporotic Spinal Fracture

    PubMed Central

    Ha, Kee-Yong; Yoo, Sung-Rim; Molon, Jan Noel

    2015-01-01

    Bone cement augmentation procedures have been getting more position as a minimally invasive surgical option for osteoporotic spinal fractures. However, complications related to these procedures have been increasingly reported. We describe a case of bone cement dislodgement following cement augmentation procedure for osteoporotic spinal fracture by reviewing the patient's medical records, imaging results and related literatures. A 73-year-old woman suffering back and buttock pain following a fall from level ground was diagnosed as an osteoporotic fracture of the 11th thoracic spine. Percutaneous kyphoplasty was performed for this lesion. Six weeks later, the patient complained of a recurrence of back and buttock pain. Radiologic images revealed superior dislodgement of bone cement through the 11th thoracic superior endplate with destruction of the lower part of the 10th thoracic spine. Staged anterior and posterior fusion was performed. Two years postoperatively, the patient carries on with her daily living without any significant disability. Delayed bone cement dislodgement can occur as one of complications following bone cement augmentation procedure for osteoporotic spinal fracture. It might be related to the presence of intravertebral cleft, lack of interdigitation of bone cement with the surrounding trabeculae, and possible damage of endplate during ballooning procedure.

  18. Magnesia modification of alkali-activated slag fly ash cement

    Microsoft Academic Search

    Weiguo Shen; Yiheng Wang; Tao Zhang; Mingkai Zhou; Jiasheng Li; Xiaoyu Cui

    2011-01-01

    A new type of magnesia modification alkali-activated cement was prepared, the strength, setting time, shrinkage ratio and\\u000a cracking behavior, as well as the composition and structure of the hydration product were investigated. The results indicate\\u000a that the setting time of this cement is similar to that of the ordinary commercial cements; its strength reaches the standard\\u000a of 42.5 degree cement,

  19. Stability evaluation for cement package containing radioactive waste

    SciTech Connect

    Chino, K.; Kawamura, F.

    1988-04-01

    In order to provide stable cement packages, ettringite formation, a major cause of cement deterioration, was studied theoretically and experimentally. A computer program was developed to calculate the chemical equilibrium compositions of a complex cement system. Higher curing temperature and the addition of NaOH were identified as effective methods to avoid ettringite formation. These findings were confirmed by measuring the amount of ettringite in solidified cement by an X-ray diffraction method.

  20. CO2 laser on apical seal of retrofilled teeth

    NASA Astrophysics Data System (ADS)

    Aun, Carlos E.; Gavini, Giulio; Clasen, Naya F.; Silva Kfouri, Luciana

    1997-05-01

    The CO2 laser has been suggested for occlusion of dentinal tubuli and sterilization of the beveled root surfaces, avoiding degrees of irritants from the root canal system into periapical tissues. This study has evaluated marginal leakage in 40 human single rooted teeth divided into 4 groups of 8 teeth which received retrofillings, and 2 control groups of 4 teeth each. Group A: Super EBA; group B: Super EBA and CO2 laser irradiation; group C: Glass Ionomer Cement; group D: Glass ionomer Cement and laser; group E: positive control; group F: negative control. In groups B and D the power set was 2 watts, 20 msec, with a CT3105 ceramic point. Teeth were placed in 5 percent methylene blue dye for 24 hs and the dye penetration was lower in B. The higher penetration was seen in C. Analysis of variance found statistical difference between groups. In this study the laser irradiation was able to change the amount of dye penetration. It can be assumed that Super EBA and Glass Ionomer Cement have their sealing abilities improved by laser irradiation.

  1. Transmittance of a bioceramic dental restorative material based on calcium aluminate.

    PubMed

    Engqvist, Håkan; Lööf, Jesper; Uppström, Stina; Phaneuf, Mike W; Jonsson, Jacob C; Hermansson, Leif; Ahnfelt, Nils-Otto

    2004-04-15

    This article investigates the transmittance of a new ceramic filling material as a function of time, thickness, wavelength, and addition of pigments. In the hardened state the ceramic material is composed of hydrates, calcium aluminate, and glass fillers. The radiopacity of the investigated material is also measured. The results of the transmittance are compared to a commercial glass ionomer cement (Fuji II) and resin composite (Tetric Ceram). The transmittance increased with time from low values after 1 h to values close to the glass ionomer cements after 1 week. The resin composite had almost twice the transmittance as the calcium aluminate material and the glass ionomer cement. The amount of light passing through the material was dependent on both the sample thickness and the wavelength. Samples of 0.5-mm thickness transmitted almost twice as much as 1-mm-thick samples. Regarding the wavelength, blue light was scattered very effectively (low transmittance), whereas red light was not (high transmittance). Addition of pigments lowered the transmittance. The radiopacity was slightly higher than that of enamel. PMID:15015216

  2. Hydration kinetics of cement composites with varying water-cement ratio using terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Ray, Shaumik; Dash, Jyotirmayee; Devi, Nirmala; Sasmal, Saptarshi; Pesala, Bala

    2015-03-01

    Cement is mixed with water in an optimum ratio to form concrete with desirable mechanical strength and durability. The ability to track the consumption of major cement constituents, viz., Tri- and Dicalcium Silicates (C3S, C2S) reacting with water along with the formation of key hydration products, viz., Calcium-Silicate-Hydrate (C-S-H) which gives the overall strength to the concrete and Calcium Hydroxide (Ca(OH)2), a hydration product which reduces the strength and durability, using an efficient technique is highly desirable. Optimizing the amount of water to be mixed with cement is one of the main parameters which determine the strength of concrete. In this work, THz spectroscopy has been employed to track the variation in hydration kinetics for concrete samples with different water-cement ratios, viz., 0.3, 0.4, 0.5 and 0.6. Results show that for the sample with water-cement ratio of 0.3, significant amount of the C3S and C2S remain unreacted even after the initial hydration period of 28 days while for the cement with water-cement ratio of 0.6, most of the constituents get consumed during this stage. Analysis of the formation of Ca(OH)2 has been done which shows that the concrete sample with water-cement ratio of 0.6 produces the highest amount of Ca(OH)2 due to higher consumption of C3S/C2S in presence of excess water which is not desirable. Samples with water-cement ratio of 0.4 and 0.5 show more controlled reaction during the hydration which can imply formation of an optimized level of desired hydration products resulting in a more mechanically strong and durable concrete.

  3. Hospital waste ashes in Portland cement mortars

    SciTech Connect

    Genazzini, C.; Zerbino, R.; Ronco, A.; Batic, O.; Giaccio, G

    2003-10-01

    Nowadays, most concretes incorporate mineral additions such as pozzolans, fly ash, silica fume, blast furnace slag, and calcareous filler among others. Although the technological and economical benefits were the main reasons for the use of mineral additions, the prevention of environmental contamination by means of proper waste disposal becomes a priority. The chance of incorporating hospital waste ashes in Portland cement-based materials is presented here. Ash characterization was performed by chemical analysis, X-ray diffraction, radioactive material detection, and fineness and density tests. Conduction calorimetry and setting time tests were developed on pastes including ash contents from 0% to 100%. Mortars were prepared including ash contents up to 50% of cement. The results of setting time, temperature development, flexural and compressive strengths, water absorption, density, and leachability are analyzed. Results indicate that Portland cement systems could become an alternative for the disposal of this type of ashes.

  4. In vitro and in vivo evaluation of SU-8 biocompatibility

    PubMed Central

    Nemani, Krishnamurthy V.; Moodie, Karen L.; Brennick, Jeoffry B.; Su, Alison; Gimi, Barjor

    2013-01-01

    SU-8 negative photoresist is a high tensile strength polymer that has been used for a number of biomedical applications that include cell encapsulation and neuronal probes. Chemically, SU-8 comprises, among other components, an epoxy based monomer and antimony salts, the latter being a potential source of cytotoxicity. We report on the in vitro and in vivo evaluation of SU-8 biocompatibility based on leachates from various solvents, at varying temperature and pH, and upon subcutaneous implantation of SU-8 substrates in mice. MTT cell viability assay did not exhibit any cytotoxic effects from the leachates. The hemolytic activity of SU-8 is comparable to that of FDA approved implant materials such as silicone elastomer, Buna-S and medical steel. In vivo histocompatibility study in mice indicates a muted immune response to subcutaneous SU-8 implants. PMID:23910365

  5. In-Plane Biocompatible Microfluidic Interconnects for Implantable Microsystems

    PubMed Central

    Johnson, Dean G.; Frisina, Robert D.; Borkholder, David A.

    2011-01-01

    Small mammals, particularly mice, are very useful animal models for biomedical research. Extremely small anatomical dimensions, however, make design of implantable microsystems quite challenging. A method for coupling external fluidic systems to microfluidic channels via in-plane interconnects is presented. Capillary tubing is inserted into channels etched in the surface of a Si wafer with a seal created by Parylene-C deposition. Prediction of Parylene-C deposition into tapered channels based on Knudsen diffusion and deposition characterizations allows for design optimization. Low-volume interconnects using biocompatible, chemical resistant materials have been demonstrated and shown to withstand pressure as high as 827 kPa (120 psi) with an average pull test strength of 2.9 N. Each interconnect consumes less than 0.018 mm3 (18 nL) of volume. The low added volume makes this an ideal interconnect technology for medical applications where implant volume is critical. PMID:21147591

  6. [Initial results of the biocompatibility, cytotoxicity and genotoxicity of Aramid].

    PubMed

    Wening, J V; Langendorff, U; Delling, G; Marquardt, H; Hoffmann, M; Jungbluth, K H

    1989-10-01

    Tissue biocompatibility of aramid fibres was tested over up to 16 weeks after subcutaneous (A = nine) and intraarticular (B = twelve animals) implantation in the rabbit. Histologically all specimens showed connective tissue ingrowth with interspersed mesenchymal cells. Foreign body giant cells were numerous and demonstrated intracellular dye or aramid particles. Following implantation into the knee joint the aramid ligament was invaded by longitudinally arranged, stress-oriented collagen fibres as soon as four weeks postoperatively. In spite of reactive new bone formation a functional bony anchorage in the bore holes did not take place during the 16 week period. Additional investigations in bacteria (particularly the Salmonella-microsome Assay according to Ames) and mammalian cell cultures showed no evidence for any cyto- or genotoxic effects of aramid fibres. PMID:2694563

  7. Interfacing microbial styrene production with a biocompatible cyclopropanation reaction.

    PubMed

    Wallace, Stephen; Balskus, Emily P

    2015-06-01

    The introduction of new reactivity into living organisms is a major challenge in synthetic biology. Despite an increasing interest in both the development of small-molecule catalysts that are compatible with aqueous media and the engineering of enzymes to perform new chemistry in vitro, the integration of non-native reactivity into metabolic pathways for small-molecule production has been underexplored. Herein we report a biocompatible iron(III) phthalocyanine catalyst capable of efficient olefin cyclopropanation in the presence of a living microorganism. By interfacing this catalyst with E.?coli engineered to produce styrene, we synthesized non-natural phenyl cyclopropanes directly from D-glucose in single-vessel fermentations. This process is the first example of the combination of nonbiological carbene-transfer reactivity with cellular metabolism for small-molecule production. PMID:25925138

  8. Properties of silver nanostructure-coated PTFE and its biocompatibility

    PubMed Central

    2013-01-01

    Silver nanolayers were sputtered on polytetrafluoroethylene (PTFE) and subsequently transformed into discrete nanoislands by thermal annealing. The Ag/PTFE composites prepared under different conditions were characterized by several complementary methods (goniometry, UV-visible spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy), and new data on the mechanism of Ag layer growth and Ag atom clustering under annealing were obtained. Biocompatibility of selected Ag/PTFE composites was studied in vitro using vascular smooth muscle cell (VSMC) cultures. Despite of the well-known inhibitory properties of silver nanostructures towards broad spectrum of bacterial strains and cells, it was found that very thin silver coating stimulates both adhesion and proliferation of VSMCs. PMID:24044426

  9. Biocompatible surgical meshes based on decellularized human amniotic membrane.

    PubMed

    Shi, Peina; Gao, Mengna; Shen, Qiuxia; Hou, Lei; Zhu, Yabin; Wang, Jun

    2015-09-01

    Meshes play important roles to repair human tissue defect. In this work, human amniotic membrane (HAM) was decellularized and explored the efficacy as an implantable biological mesh. Surfactant, hypertonic saline, lipase and DNAase were used individually or collectively to remove all cell components and remain the extracellular matrix. Results of H&E and DAPI staining demonstrated that the method of surfactant and lipase combining with DNAase is the most effective treatment for HAM decellularization. Primary smooth muscle cells were seeded to evaluate the decellularized HAM's (dHAM) in vitro cytocompatibility. The in vivo test was performed via implantation at rabbits' uterus with clinic polypropylene mesh (PP) as the control. The results indicated that dHAM possessed good biocompatibility and will be a potential candidate for biological mesh. PMID:26046274

  10. The role of materials biocompatibility for functional electrical stimulation applications.

    PubMed

    Plenk, Hanns

    2011-03-01

    The biocompatibility of all metallic, polymeric, or ceramic materials used for functional electrical stimulation is governed by the inevitable inflammatory tissue response, but possibly also by immunological reactions to the bulk material or released constituents. Besides chemical, physical, and corrosion properties of the conductive electrode materials, increased surface area and roughness of the electrode can influence tissue contact and signal delivery, and can also affect electrode-tissue impedance due to increased connective tissue encapsulation. The polymeric materials used for electrode insulation and those for leads and stimulator packaging seem more or less compatible in an aggressive biological environment. For the long-term performance of electrodes and leads, the relative motion in the various implant bed situations also has to be considered. PMID:21401666

  11. Label-free cellular manipulation and sorting via biocompatible ferrofluids

    PubMed Central

    Kose, Ayse R.; Fischer, Birgit; Mao, Leidong; Koser, Hur

    2009-01-01

    We present a simple microfluidic platform that uses biocompatible ferrofluids for the controlled manipulation and rapid separation of both microparticles and live cells. This low-cost platform exploits differences in particle size, shape, and elasticity to achieve rapid and efficient separation. Using microspheres, we demonstrate size-based separation with 99% separation efficiency and sub-10-?m resolution in <45 s. We also show continuous manipulation and shape-based separation of live red blood cells from sickle cells and bacteria. These initial demonstrations reveal the potential of ferromicrofluidics in significantly reducing incubation times and increasing diagnostic sensitivity in cellular assays through rapid separation and delivery of target cells to sensor arrays. PMID:19995975

  12. Biocompatible optical needle array for antibacterial blue light therapy

    NASA Astrophysics Data System (ADS)

    Guimarães, Caio; An, Jeesoo; Humar, Matjaz; Goth, Will; Yun, Andy

    2015-03-01

    Biocompatible Optical Needle Array (BONA) is showing to be a powerful tool complementing the novel antibacterial blue light therapy. BONA is able to deliver light to deeper skin tissue layers successfully as shown in experiments. In this study, we will discuss BONA's design, mechanical and optical properties, production method, plus propose improvements to optimize it all. A special skin phantom with photosensitizer was developed in order to investigate how light is delivered inside the tissue. The phantom shows the light scattering pattern through photobleach, allowing us to determine length, thickness and spacing between needles. Other quantitative optical properties as penetration depth were determined using a different phantom (using PDMS). Mechanical properties as needle resistance were determined using one axis of a custom biaxial tensile strain device. The results led us to conclude that besides the great results, there is still room for improvements regarding tip sharpness and manufacturing time and cost, which would be solved with the enhanced fabrication method proposed.

  13. Does vacuum mixing of bone cement affect heat generation? Analysis of four cement brands.

    PubMed

    Wang, J S; Franzén, H; Toksvig-Larsen, S; Lidgren, L

    1995-01-01

    Four different brands of bone cement (Palacos R, Simplex P, Sulfix, CMW 1) were tested for exothermic changes during polymerization at atmospheric pressure and under partial vacuum of 0.2 bar. Palacos R was also mixed at four pressure levels (1.0, 0.2, 0.12, and 0.05 bar). The peak temperature in the bone cement was 46 to 124 degrees C, depending on the measuring point. There was no difference in peak temperature or duration of temperature increase above 50 degrees C during the curing of cement whether mixed at atmospheric pressure or under partial vacuum at different pressure levels. PMID:7640436

  14. Adsorption characteristics of superplasticizers on cement component minerals

    Microsoft Academic Search

    Kazuhiro Yoshioka; Ei-ichi Tazawa; Kenji Kawai; Tomoyuki Enohata

    2002-01-01

    Adsorption characteristics of various superplasticizers on portland cement component minerals were investigated. Adsorption isotherms of various types of superplasticizers and ?-potentials of cement component minerals at the maximum adsorption of the superplasticizers were measured. The value of the adsorption isotherm was calculated from the amount of the superplasticizer adsorbed on a cement component mineral in an equilibrated solution. The maximum

  15. Shear and tensile bond testing for resin cement evaluation

    Microsoft Academic Search

    Yuichi Kitasako; Michael F. Burrow; Toru Nikaido; Naoko Harada; Shigehisa Inokoshi; Toshimoto Yamada; Toshio Takatsu

    1995-01-01

    Objectives. The aim of this study was to compare the tensile and shear bond strengths of one experimental and four commercially available resin cements following the ISO document TR 110405 for bond measurement.Methods. Tensile and shear bond tests were performed using bovine enamel and dentin as the tooth substrate with each of the resin cements. Resin composite rods were cemented

  16. Control of in vivo mineral bone cement degradation.

    PubMed

    Kanter, Britta; Geffers, Martha; Ignatius, Anita; Gbureck, Uwe

    2014-07-01

    The current study aimed to prevent the formation of hydroxyapatite reprecipitates in brushite-forming biocements by minimizing the availability of free Ca(2+) ions in the cement matrix. This was achieved by both maximizing the degree of cement setting to avoid unreacted, calcium-rich cement raw materials which can deliver Ca(2+) directly to the cement matrix after dissolution, and by a reduction in porosity to reduce Ca(2+) diffusion into the set cement matrix. In addition, a biocement based on the formation of the magnesium phosphate mineral struvite (MgNH4PO4·6H2O) was tested, which should prevent the formation of low-solubility hydroxyapatite reprecipitates due to the high magnesium content. Different porosity levels were fabricated by altering the powder-to-liquid ratio at which the cements were mixed and the materials were implanted into mechanically unloaded femoral defects in sheep for up to 10 months. While the higher-porosity brushite cement quantitatively transformed into crystalline octacalcium phosphate after 10 months, slowing down cement resorption, a lower-porosity brushite cement modification was found to be chemically stable with the absence of reprecipitate formation and minor cement resorption from the implant surface. In contrast, struvite-forming cements were much more degradable due to the absence of mineral reprecipitates and a nearly quantitative cement degradation was found after 10 months of implantation. PMID:24769112

  17. Properties of volcanic pumice based cement and lightweight concrete

    Microsoft Academic Search

    Khandaker M Anwar Hossain

    2004-01-01

    The results of investigations on the suitability of using volcanic pumice (VP) as cement replacement material and as coarse aggregate in lightweight concrete production are reported. Tests were conducted on cement by replacing 0% to 25% of cement by weight and on concrete by replacing 0% to 100% of coarse aggregate by volume. The physical and chemical properties of VP

  18. A Novel Oil Well Cementing Technology Using Natural Fibers

    Microsoft Academic Search

    M. M. Al-Darbi; N. O. Saeed; L. O. Ajijolaiya; M. R. Islam

    2006-01-01

    In many industrial processes, the pipeline systems are lined with a protective layer of cement mortar. In petroleum wells, cement slurry is placed in a wellbore to be hardened into an impermeable mass that seals the annulus from fluid flow and protects the casing from corrosion for the life of the well. When uniform linings of neat cement fail in

  19. Durability of gamma irradiated polymer-impregnated blended cement pastes

    Microsoft Academic Search

    Magdy M. Khattab; H. A. Abdel-Rahman; M. M. Younes

    2011-01-01

    This study is focusing on durability of the neat blended cement paste as well as those of the polymer-impregnated paste towards seawater and various concentrations of magnesium sulfate solutions up to 6months of curing. The neat blended cement paste was prepared by a partial substitution of ordinary Portland cement with 5% of active rice husk ash (RHA). These samples were

  20. Model for the developing microstructure in Portland cement pastes

    Microsoft Academic Search

    Hamlin M. Jennings; Paul D. Tennis

    1994-01-01

    A method is proposed for quantitatively predicting the volume of the major phases in hydrated cement pastes as a function of (1) the composition of the cement, (2) the degree of reaction, and (3) the initial water: cement ratio. This procedure is then used to develop a quantitative model for the surface area and volume of porosity that is accessible

  1. Delayed ettringite formation in 4-year old cement pastes

    Microsoft Academic Search

    R. Yang; C. D. Lawrence; J. H. Sharp

    1996-01-01

    Cement paste prisms (40 × 40 × 160 mm) made from portland cement have been cured at 100 °C for 3 hours, followed by extended water storage at room temperature. Large expansions have been observed after 212 years for prisms made with a certain portland cement. Backscattered electron imaging (bse) in a scanning electron microscope (SEM), combined with x-ray microanalysis

  2. Development of Angle Ply Cement Based Composite Laminates

    E-print Network

    Mobasher, Barzin

    as shown in Figure 2. The impregnation chamber consists of a tube filled with cement paste that coatsDevelopment of Angle Ply Cement Based Composite Laminates A. Pivacek, G. J. Haupt, and B. Mobasher cement based materials with improved structural and mechanical properties are developed. High fiber

  3. Communication Electric polarization in carbon fiber-reinforced cement

    E-print Network

    Chung, Deborah D.L.

    -reinforced cement paste during resistivity measurement. The effect was diminished by increasing the conductivity of the cement paste through the use of carbon fibers that were more crystalline, the increase of the fiber Science Ltd. All rights reserved. Keywords: Fiber reinforcement; Cement paste; Electrical properties

  4. Communication Seebeck effect in steel fiber reinforced cement

    E-print Network

    Chung, Deborah D.L.

    Abstract Cement pastes containing short steel fibers, which contribute to electron conduction, exhibit with temperature difference (up to 65°C). In contrast, cement pastes containing short carbon fibers, which power. D 2000 Elsevier Science Ltd. All rights reserved. Keywords: Fiber reinforcement; Cement Paste

  5. Electrical Conduction Behavior of Cement-Matrix Composites

    E-print Network

    Chung, Deborah D.L.

    -matrix composites. 2. Resistive Behavior Cement paste is electrically conductive, with DC resistivity at 28 days the cement paste and the aggregate enhances the conductivity.[4] Whether aggregates (sand and stonesElectrical Conduction Behavior of Cement-Matrix Composites D.D.L. Chung (Submitted 26 March 2000

  6. Master Thesis: Simulation of plastic deformation in cemented carbide inserts

    E-print Network

    Haviland, David

    Master Thesis: Simulation of plastic deformation in cemented carbide inserts Background Sandvik in cemented carbide, high-speed steel and other hard materials such as diamond, cubic boron nitride in cemented carbide inserts will be performed using the FEM software Ansys and AdvantEdge. The work

  7. Particle erosion of cemented carbides with low Co content

    Microsoft Academic Search

    U Beste; L Hammerström; H Engqvist; S Rimlinger; S Jacobson

    2001-01-01

    Cemented carbides are well known for their high erosion resistance and are therefore used in many demanding applications involving erosion, such as grit blasting nozzles. A number of investigations on the erosive wear resistance of conventional cemented carbides have been published. The present paper is aimed at investigating the erosion resistance of a series of modern cemented carbides containing no

  8. Tribofilm formation on cemented carbides in dry sliding conformal contact

    Microsoft Academic Search

    H Engqvist; H Högberg; G. A Botton; S Ederyd; N Axén

    2000-01-01

    The friction properties and the tribofilm formation of a binderless cemented carbide and two conventional cemented carbides have been evaluated in an unlubricated sliding contact in either air or nitrogen surroundings. A continuously varied normal load and two rotational speeds were used. The tribofilms were analysed with SEM, XPS, TEM and EELS.For all cemented carbides, friction was lower at higher

  9. 30 CFR 250.1608 - Well casing and cementing.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...purpose of this subpart, the several casing strings in order of normal installation are...cement all wells with a sufficient number of strings of casing cemented in a manner...minimum of 100 feet into the previous casing string. (2) Sufficient cement shall be...

  10. 30 CFR 250.1608 - Well casing and cementing.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...purpose of this subpart, the several casing strings in order of normal installation are...cement all wells with a sufficient number of strings of casing cemented in a manner...minimum of 100 feet into the previous casing string. (2) Sufficient cement shall be...

  11. 30 CFR 250.1608 - Well casing and cementing.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...purpose of this subpart, the several casing strings in order of normal installation are...cement all wells with a sufficient number of strings of casing cemented in a manner...minimum of 100 feet into the previous casing string. (2) Sufficient cement shall be...

  12. Hemocompatibility and biocompatibility of antibacterial biomimetic hybrid films

    SciTech Connect

    Coll Ferrer, M. Carme [Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Eckmann, Uriel N. [Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA 19104 (United States); Composto, Russell J. [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Eckmann, David M., E-mail: eckmanndm@uphs.upenn.edu [Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA 19104 (United States)

    2013-11-01

    In previous work, we developed novel antibacterial hybrid coatings based on dextran containing dispersed Ag NPs (? 5 nm, DEX-Ag) aimed to offer dual protection against two of the most common complications associated with implant surgery, infections and rejection of the implant. However, their blood-material interactions are unknown. In this study, we assess the hemocompatibility and biocompatibility of DEX-Ag using fresh blood and two cell lines of the immune system, monocytes (THP-1 cells) and macrophages (PMA-stimulated THP-1 cells). Glass, polyurethane (PU) and bare dextran (DEX) were used as reference surfaces. PU, DEX and DEX-Ag exhibited non-hemolytic properties. Relative to glass (100%), platelet attachment on PU, DEX and DEX-Ag was 15%, 10% and 34%, respectively. Further, we assessed cell morphology and viability, pro-inflammatory cytokines expression (TNF-? and IL-1?), pro-inflammatory eicosanoid expression (Prostaglandin E{sub 2}, PGE{sub 2}) and release of reactive oxygen species (ROS, superoxide and H{sub 2}O{sub 2}) following incubation of the cells with the surfaces. The morphology and cell viability of THP-1 cells were not affected by DEX-Ag whereas DEX-Ag minimized spreading of PMA-stimulated THP-1 cells and caused a reduction in cell viability (16% relative to other surfaces). Although DEX-Ag slightly enhanced release of ROS, the expression of pro-inflammatory cytokines remained minimal with similar levels of PGE{sub 2}, as compared to the other surfaces studied. These results highlight low toxicity of DEX-Ag and hold promise for future applications in vivo. - Highlights: • We examined specific blood-contact reactions of dextran doped with Ag NPs coatings. • Biocompatibility was assessed with THP-1 cells and PMA-stimulated THP-1 cells. • Glass, polyurethane and dextran were used as reference surfaces. • Hybrid coatings exhibited non-hemolytic properties. • Low toxicity, inflammatory response and ROS suggest potential for in vivo use.

  13. Rotate liners for a successful cement job

    SciTech Connect

    Lindsey, H.E. Jr.

    1986-10-01

    Until recently, few liners were moved-rotated or reciprocated-during the cementing process, because of difficulties inherent in liner placement. Now rotation or reciprocation is practiced on an estimated 20% of all liner jobs, and rotation is becoming an increasingly popular technique. Successful rotation has even been accomplished from floating drilling vessels in holes deviated as much as 47/sup 0/. This article discusses equipment and techniques that will allow rotation throughout the cementing process and overcome usual causes of rotation job failure.

  14. The effect of centrifuging bone cement.

    PubMed

    Davies, J P; Jasty, M; O'Connor, D O; Burke, D W; Harrigan, T P; Harris, W H

    1989-01-01

    We have tested the porosity and fatigue life of five commonly used bone cements: Simplex P, LVC, Zimmer regular, CMW and Palacos R. Tests were conducted with and without centrifugation and with the monomer at room temperature and, except for LVC, at 0 degrees C. We found that the fatigue life of different specimens varied by a factor of nearly 100. It did not depend on porosity alone, but was more influenced by the basic composition of the cement. Simplex P when mixed with monomer at 0 degrees C and centrifuged for 60 seconds had the highest fatigue life and was still sufficiently liquid to use easily. PMID:2915001

  15. The accelerated testing of cements in brines

    SciTech Connect

    Krumhansl, J.L.

    1993-12-31

    Cementitious materials may be employed in settings where they face prolonged exposure to Mg-rich brines. This study evaluated the possibility of using high temperatures to accelerate brine-cement reaction rates. Class-H cement coupons were tested in Mg-K-Na-C1- SO{sub 4} brines to 100{degrees}C. MgC1{sub 2}-NaC1 solutions were also employed in a test sequence that extended to 200{degrees}C. It was found that accelerated testing could be used successfully to evaluate the compatability of cementitious materials with such brines.

  16. Chloride ingress in cement paste and mortar

    SciTech Connect

    Jensen, O.M.; Hansen, P.F.; Coats, A.M.; Glasser, F.P.

    1999-09-01

    In this paper chloride ingress in cement paste and mortar is followed by electron probe microanalysis. The influence of several paste and exposure parameters on chloride ingress are examined (e.g., water-cement ratio, silica fume addition, exposure time, and temperature). The measurements are modelled on Fick's law modified by a term for chloride binding. Inclusion of chloride binding significantly improves the profile shape of the modelled ingress profiles. The presence of fine aggregate and formation of interfacial transition zones at paste-aggregate boundaries does not significantly affect diffusion rates.

  17. Durability of pulp fiber-cement composites

    NASA Astrophysics Data System (ADS)

    Mohr, Benjamin J.

    Wood pulp fibers are a unique reinforcing material as they are non-hazardous, renewable, and readily available at relatively low cost compared to other commercially available fibers. Today, pulp fiber-cement composites can be found in products such as extruded non-pressure pipes and non-structural building materials, mainly thin-sheet products. Although natural fibers have been used historically to reinforce various building materials, little scientific effort has been devoted to the examination of natural fibers to reinforce engineering materials until recently. The need for this type of fundamental research has been emphasized by widespread awareness of moisture-related failures of some engineered materials; these failures have led to the filing of national- and state-level class action lawsuits against several manufacturers. Thus, if pulp fiber-cement composites are to be used for exterior structural applications, the effects of cyclical wet/dry (rain/heat) exposure on performance must be known. Pulp fiber-cement composites have been tested in flexure to examine the progression of strength and toughness degradation. Based on scanning electron microscopy (SEM), environmental scanning electron microscopy (ESEM), energy dispersive spectroscopy (EDS), a three-part model describing the mechanisms of progressive degradation has been proposed: (1) initial fiber-cement/fiber interlayer debonding, (2) reprecipitation of crystalline and amorphous ettringite within the void space at the former fiber-cement interface, and (3) fiber embrittlement due to reprecipitation of calcium hydroxide filling the spaces within the fiber cell wall structure. Finally, as a means to mitigate kraft pulp fiber-cement composite degradation, the effects of partial portland cement replacement with various supplementary cementitious materials (SCMs) has been investigated for their effect on mitigating kraft pulp fiber-cement composite mechanical property degradation (i.e., strength and toughness losses) during wet/dry cycling. SCMs have been found to be effective in mitigating composite degradation through several processes, including a reduction in the calcium hydroxide content, stabilization of monosulfate by maintaining pore solution pH, and a decrease in ettringite reprecipitation accomplished by increased binding of aluminum in calcium aluminate phases and calcium in the calcium silicate hydrate (C-S-H) phase.

  18. Properties of cement made by partially replacing cement raw materials with municipal solid waste ashes and calcium carbide waste

    Microsoft Academic Search

    P Krammart; S Tangtermsirikul

    2004-01-01

    An investigation on using municipal solid waste incinerator bottom ash (MSWI) and calcium carbide waste (CCW) as a part of the cement raw materials was performed. Cement raw meals were replaced by 5% and 10% of MSWI and CCW to study properties of the laboratory produced MSWI and CCW cements. Chemical composition, setting times, compressive strength and expansion in sulfate

  19. Effect of bleaching agents on sealing properties of different intraorifice barriers and root filling materials

    PubMed Central

    Canoglu, Ebru; Gulsahi, Kamran; Sahin, Cem; Altundasar, Emre

    2012-01-01

    Objective: To evaluate the effect of intracoronal bleaching agents on the sealing properties of different intraorifice barriers and root filling materials. Study Design: The root canals of extracted human premolars (n=180) were prepared by using System GT rotary files and filled with either gutta-percha+AH Plus or Resilon+Epiphany sealer. In both groups, the coronal 3mm of root filling was removed and replaced with one of the following materials applied as intraorifice barriers (n=30/group): 1. ProProot-MTA; 2. Conventional Glass ionomer cement; and 3. Hybrid resin composite. In each subgroup, intracoronal bleaching was performed using either sodium perborate with distilled water or 35% hydrogen peroxide gel for 3 weeks. The leakage of specimens was measured using fluid-filtration and dye penetration tests. The data were analyzed statistically with One-way ANOVA, Repeated Measures t-test and Independent Samples t-test (p=0.05). Results: The fluid conductance values of the test groups were not influenced by the type of the bleaching agent, the intraorifice barrier, or the root filling material (all p>0.05). However, the extent of dye leakage was significantly affected by the type of intraorifice barrier material (p<0.05), which showed the following statistical ranking: glass ionomer cement > resin composite > ProRoot-MTA (p<0.05). Conclusions: The effect of 35% hydrogen peroxide gel or sodium perborate/distilled water on the sealing properties of tested intraorifice barriers and root filling materials varied conforming leakage assessment. These properties were not affected by using fluid filtration test, while the glass ionomer barrier showed the greatest amount of dye leakage in both gutta-percha and Resilon root-filled teeth. Key words:Tooth Bleaching, root canal filling materials, glass ionomer cement, mineral trioxide aggregate, micro leakage PMID:22322509

  20. The skeletal response to matt and polished cemented femoral stems.

    PubMed

    Barker, D S; Wang, A W; Yeo, M F; Nawana, N S; Brumby, S A; Pearcy, M J; Howie, D W

    2000-11-01

    We studied the effect of the surface finish of the stem on the transfer of load in the proximal femur in a sheep model of cemented hip arthroplasty. Strain-gauge analysis and corresponding finite-element (FE) analysis were performed to assess the effect of friction and creep at the cement-stem interface. No difference was seen between the matt and polished stems. FE analysis showed that the effects of cement creep and friction at the stem-cement interface on femoral strain were small compared with the effect of inserting a cemented stem. PMID:11132284

  1. Cement-Implant Interface Contamination: Possible Reason of Inferior Clinical Outcomes for Rough Surface Cemented Stems

    PubMed Central

    Wang, Tian; Pelletier, Matthew H; Bertollo, Nicky; Crosky, Alan; Walsh, William R

    2013-01-01

    Background: Shape-closed cemented implants rely on a stronger bond and have displayed inferior clinical outcomes when compared to force-closed designs. Implant contamination such as saline, bone marrow and blood prior to cement application has the potential to affect the cement-implant bond. The consequences of implant contamination were investigated in this study. Methods: Fifty Titanium alloy (Ti-6Al-4V) dowels were separated into ten groups based on surface roughness and contaminant, and then cemented in polyvinyl chloride tubes. Push-out testing was performed at 1mm per minute. The roughness of the dowel surface was measured before and after the testing. The dowel surface and cement mantel were analyzed using a Scanning Electron Microscopy (SEM) to determine the distribution and characteristics of any debris and contaminants on the surface. Results: Contaminants largely decreased stem-cement interfacial shear strength, especially for rough surfaces. Saline produced the greatest decrease, followed by blood. The effect of bone marrow was less pronounced and similar to that of oil. Increasing surface roughness increased the interfacial bonding strength, even with contaminants. There was a non-significant increase in mean bonding strength for smooth surfaces with bone marrow and oil contamination. SEM showed that contaminants influence the interfacial bond by different mechanisms. More debris was found on rough samples following testing. Conclusions: The results of this study underscore the importance of keeping an implant free from contamination, and suggest if contamination does occur, a saline rinse may further decrease the stability of an implant. The deleterious effects of contamination on rough surface cement bonding were considerable, and indicate that contamination at the time of surgery may, in part, contribute to inferior clinical outcomes for rough surfaced cemented stems. PMID:23898352

  2. A New Biocompatible and Antibacterial Phosphate Free Glass-Ceramic for Medical Applications

    NASA Astrophysics Data System (ADS)

    Cabal, Belén; Alou, Luís; Cafini, Fabio; Couceiro, Ramiro; Sevillano, David; Esteban-Tejeda, Leticia; Guitián, Francisco; Torrecillas, Ramón; Moya, José S.

    2014-06-01

    In the attempt to find valid alternatives to classic antibiotics and in view of current limitations in the efficacy of antimicrobial-coated or loaded biomaterials, this work is focused on the development of a new glass-ceramic with antibacterial performance together with safe biocompatibility. This bactericidal glass-ceramic composed of combeite and nepheline crystals in a residual glassy matrix has been obtained using an antimicrobial soda-lime glass as a precursor. Its inhibitory effects on bacterial growth and biofilm formation were proved against five biofilm-producing reference strains. The biocompatibility tests by using mesenchymal stem cells derived from human bone indicate an excellent biocompatibility.

  3. A New Biocompatible and Antibacterial Phosphate Free Glass-Ceramic for Medical Applications

    PubMed Central

    Cabal, Belén; Alou, Luís; Cafini, Fabio; Couceiro, Ramiro; Sevillano, David; Esteban-Tejeda, Leticia; Guitián, Francisco; Torrecillas, Ramón; Moya, José S.

    2014-01-01

    In the attempt to find valid alternatives to classic antibiotics and in view of current limitations in the efficacy of antimicrobial-coated or loaded biomaterials, this work is focused on the development of a new glass-ceramic with antibacterial performance together with safe biocompatibility. This bactericidal glass-ceramic composed of combeite and nepheline crystals in a residual glassy matrix has been obtained using an antimicrobial soda-lime glass as a precursor. Its inhibitory effects on bacterial growth and biofilm formation were proved against five biofilm-producing reference strains. The biocompatibility tests by using mesenchymal stem cells derived from human bone indicate an excellent biocompatibility. PMID:24961911

  4. How gelation affects oil well cements

    SciTech Connect

    Kieffer, J.; Rae, P.

    1987-05-01

    One of the most common problems seen in the oil industry is that of cement gelation. Gelation can be defined as a premature viscosification or a gel-strength buildup of the cement slurry. This can have important consequences in field operations and may be so severe as to cause job failure. One of the principal difficulties encountered in dealing with cement gelation is the unpredictable nature of the phenomenon and the fact that it may manifest itself under a variety of field conditions. Thus, it may occur immediately after mixing or during the displacement when the slurry has reached circulating temperature; it occasionally is seen only during shutdowns, when the slurry is in static condition, but may appear during pumping when the slurry is under continual shear. The fact that the physico-chemical bases of gelation are complex probably accounts for the broad spectrum of conditions under which gelation can occur. Factors involved include the chemical composition of the cement powder itself, its fineness, its microstructure, the mixwater quality, the types (if any) of additive used, the rate of heat flux into the slurry as well as the final temperature to which the slurry is exposed.

  5. USE OF ASBESTOS-CEMENT PIPE

    EPA Science Inventory

    Concerning the use of asbestos-cement (A/C) pipe for the distribution of drinking water, the status of the ingested asbestos health research underway in the U.S. Environmental Protection Agency is briefly described. At the present time there are no U.S. standards for asbestos in ...

  6. Halting the calcium aluminate cement hydration process

    Microsoft Academic Search

    A. P. Luz; V. C. Pandolfelli

    2011-01-01

    Calcium aluminate cement reactions with water result in anhydrous phases dissolution, followed by nucleation and crystal growth of hydrate compounds. Due to the dynamic characteristics of this process and in order to evaluate the phase transformation kinetics of such materials, suitable methods to halt hydration are required. In this work, the use of acetone and microwave drying, aiming to withdraw

  7. The Kosmosdale expansion project [cement plant upgrade

    Microsoft Academic Search

    A. Rowley; D. Babel

    2002-01-01

    Kosmos Cement Company, a partnership between Southdown (now CEMEX, responsible for operation) and Lonestar Industries (now Heidelberger) decided in 1998 to increase the clinker production of the Kosmosdale plant from 2500 stpd to 4700 stpd. To achieve this capacity increase of almost 90%, extensive additions and modifications had to be made in almost all manufacturing areas. These main areas were

  8. PULSED LASER ABLATION OF CEMENT AND CONCRETE

    EPA Science Inventory

    Laser ablation was investigated as a means of removing radioactive contaminants from the surface and near-surface regions of concrete from nuclear facilities. We present the results of ablation tests on cement and concrete samples using a pulsed Nd:YAG laser with fiber optic beam...

  9. Replacement kit for cement mill gearboxes

    Microsoft Academic Search

    D. Chetelat

    2000-01-01

    Improvements to cement mill operation via installation of planetary gearboxes as “replacement kits”, have recently proven to be very successful, due to quick return on investments thanks to the immediate achievement of higher efficiency and improvement in mill operation. The installation of a “replacement kit” gearbox in most cases includes the utilization of the existing foundation by installation of “tailor

  10. Reducing Machinery Noise in Cement Plants

    Microsoft Academic Search

    George L. Koonsman

    1970-01-01

    Industrial noise (a pollutant) can cause various kinds of health damage, including temporary or permanent hearing loss. By obscuring conversation it can be a safety hazard. Laws protecting workers consider only audible sounds, intensity, and duration of exposure. However, hearing damage is also influenced by frequency. Infrasonic and ultrasonic noises may be damaging as well. Cement plant noise up to

  11. Particulate Analysis Instrumentation for the Cement Industry

    Microsoft Academic Search

    Emil C. Muly; Harold N. Frock; Donald L. Grammes

    1979-01-01

    At present, even though most cement plants are computer controlled, they depend on manual particle analysis and feed settings. Automatic process control through the use of continuous particle size analysis can provide the maximum obtainable throughput at optimum particle size. A new particle size measurement technology using a helium-neon laser and a unique optical filtering system has been reported previously.

  12. Cement paste–epoxy adhesive interactions

    Microsoft Academic Search

    Fatma Djouani; Carole Connan; Michel Delamar; Mohamed M. Chehimi; Karim Benzarti

    2011-01-01

    In the field of civil engineering, the durability of concrete assemblies using adhesives is widely conditioned by the properties of the interface between the resin and the mineral support (concrete). In this context we studied first the molecular interactions at the interface between an epoxy resin and cement pastes by several approaches based on XPS and IR spectroscopies, DSC, and

  13. Abrasion of cemented carbides by small grits

    Microsoft Academic Search

    H Engqvist; N Axén

    1999-01-01

    The abrasion properties of a series of cemented carbides with different carbide grain sizes, different amounts and types of binder phases have been investigated under varied conditions. Abrasion results from other works are also incorporated for comparison reasons. The results are interpreted in the light of a previously published model for the abrasion properties of multiphase materials, although this is

  14. Materials science of cemented carbides — an overview

    Microsoft Academic Search

    G. S Upadhyaya

    2001-01-01

    The processing and properties of cemented carbides are highly dependent on the basic nature of the component, i.e. hard carbide and soft metal binder phases. The present overview covers the nature of refractory carbides and binders, phase equilibria, and sintering and mechanical properties. The role of microstructural evolution during sintering is also highlighted.

  15. Nondestructive evaluation of bone cement and bone cement/metal interface failure.

    PubMed

    Browne, M; Jeffers, J R T; Saffari, N

    2010-02-01

    To quantify the failure mechanisms related to the loosening of cemented hip joint replacements, novel techniques, capable of monitoring, nondestructively, the initiation and progression of failure during in vitro fatigue tests, were employed. Fatigue testing of model cement and cement-stem test pieces was monitored using acoustic emission (AE) sensors. Once damage was detected, an ultrasonic imaging system was used to obtain an image of the damage site and to measure the stiffness of the affected region. This method of examination provided a detailed insight into the internal crack propagation and delamination patterns. Initial work was conducted on bulk cement specimens subjected to bending and tension. The second stage of the work examined a model stem-cement interface under tensile opening loading conditions. A novel ultrasonic technique was used to measure the bond quality at the cement-metal interface. Progressive delamination was identified over time, and the AE technique was able to identify critical areas of delamination before they could be identified conclusively by ultrasonic imaging. The work has demonstrated the potential of the AE technique as a tool for the preclinical assessment of total hip replacements. PMID:19927335

  16. Porosity of various preparations of acrylic bone cements.

    PubMed

    Jasty, M; Davies, J P; O'Connor, D O; Burke, D W; Harrigan, T P; Harris, W H

    1990-10-01

    The total porosity and mean pore sizes of various bone cement preparations were measured using image analysis. The porosity in different commercial bone cements varied from 5% to 16% when these cements were prepared in the usual fashion. Centrifugation for 30 seconds resulted in a substantial reduction in the overall porosity of Simplex P, AKZ, Zimmer Regular, and CMW bone cements by reducing both the mean pore size and the number of pores per unit area. In contrast, the porosity of LVC, Palacos R, and Palacos R with gentamicin bone cements was not significantly decreased by centrifugation. Chilling the monomer before mixing resulted in higher porosity of both the centrifuged and uncentrifuged Simplex P, Zimmer Regular, and CMW bone cements. Simplex P mixed with chilled monomer and centrifuged for 120 seconds has one of the lowest porosities of the various cements, while retaining good handling characteristics and excellent fatigue strength. PMID:2208846

  17. Monitoring and repairing geothermal casing cement: a case history

    SciTech Connect

    Pettitt, R.A.

    1980-01-01

    A manmade geothermal reservoir has been created by drilling a deep hole into relatively impermeable hot rocks, creating a large surface area for heat transfer by hydraulic fracturing, then drilling a second hole to intersect the fracture to complete the closed circulation loop. A second generation system, presently being drilled, will entail creating multiple, parallel, vertical fractures between a pair of inclined boreholes. The original completion of injection Hole EE-1, consisting of a conventional high-temperature formulation of Class B portland cement, stabilized with 40% silica sand, did not withstand the cyclic stresses, and rapid deterioration of casing-to-cement and cement-to-formation bonds occurred, which allowed significant flow in the resulting microannulus. The performance history of the casing cement for the existing HDR EE-1 injection well, the subsequent remedial cementing program, the cement bond logs, and the radioactive isotope tracer injections tests, used to monitor the condition of the casing cement is described. (MHR)

  18. Optical evaluation on the setting of cement paste

    NASA Astrophysics Data System (ADS)

    De León Martínez, H. A.; Bernal, J. J. Soto; González Mota, R.; Rosales-Candelas, I.

    2015-01-01

    In the construction area, one of the most widely used cement is the CPC 30R, it is a hydraulic binder consisting of CaO, SiO2, Al2O3 and Fe2O3, when mixed with water forms cement pastes and its four crystallographic phases start to hydrate. The diffuse reflection on cement paste can give an indication of the behaviour on optical properties on the hydration of the cement and early formation products. In this study, Portland cement (CPC) pastes were prepared with 0.45 a water to cement ratio (w/c). This work is aimed to evaluate the optical properties of cement pastes on the hydration reaction during the first 24 hours by measuring the intensity of diffuse reflection changes.

  19. Performance studies of mud converted to cement (blast furnace slag cement), DEA-87. Final report, December 1994

    SciTech Connect

    Pavlich, J.P.; Benton, W.; Bodenhamer, W.; Choi, H.J.; Edwards, T.

    1994-12-01

    This paper summarizes the results of a Joint Industry Project investigating the performance of mud converted to cement using Blast Furnace Slag (BFS). This paper compares BFS/muds to conventional Portland cements in various simulated cementing applications. The poject covers the test results from converting dispersed and PHPA drilling fluids to cement, in comparison to conventional low fluid loss Portland cements. The tests simulated a geopressured gas well by use of a large scale physical model. In addition, the dimensional stability of the BFS/mud is presented.

  20. Improving the biocompatibility and stability of gold nanorods(GNRs) as bioimaging tags through silica coating

    Microsoft Academic Search

    Qiuqiang Zhan; Jun Qian; Xin Li; Sailing He

    2009-01-01

    We report a facile method to coat GNRs by silica shell, which greatly improves GNRs' biocompatibility and chemical stability in applications without any obvious side effect on their attractive optical properties.

  1. Microstructure, mechanical property, corrosion behavior, and in vitro biocompatibility of ZrMo alloys

    E-print Network

    Zheng, Yufeng

    Microstructure, mechanical property, corrosion behavior, and in vitro biocompatibility of Zr Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 Abstract: In this study, the microstructure, mechanical prop- erties, corrosion behaviors, and in vitro

  2. The Chemistry of Modern Dental Filling Materials

    NASA Astrophysics Data System (ADS)

    Nicholson, John W.; Anstice, H. Mary

    1999-11-01

    The chemistry underpinning modern tooth-colored dental fillings is described. Two broad groups of material are covered, the so-called composite resins and the glass-ionomer cements. Composite resins consist of bulky difunctional monomers together with high loadings of powdered inorganic fillers, and they set by addition polymerization. Glass-ionomers consist of aqueous polymeric acids, such as polyacrylic acid, plus basic glass powders. They set by a neutralization reaction, but leave a substantial amount of the glass unreacted, to act as reinforcing filler. Various attempts have been made to combine the attractive properties of these materials, and the different types of hybrids of them are described. The importance of chemistry to this important branch of health care is emphasized.

  3. Fabrication of porous scaffolds by three-dimensional plotting of a pasty calcium phosphate bone cement under mild conditions.

    PubMed

    Lode, Anja; Meissner, Katrin; Luo, Yongxiang; Sonntag, Frank; Glorius, Stefan; Nies, Berthold; Vater, Corina; Despang, Florian; Hanke, Thomas; Gelinsky, Michael

    2014-09-01

    The major advantage of hydroxyapatite (HA)-forming calcium phosphate cements (CPCs) used as bone replacement materials is their setting under physiological conditions without the necessity for thermal treatment that allows the incorporation of biological factors. In the present study, we have combined the biocompatible consolidation of CPCs with the potential of rapid prototyping (RP) techniques to generate calcium phosphate-based scaffolds with defined inner and outer morphology. We demonstrate the application of the RP technique three-dimensional (3D) plotting for the fabrication of HA cement scaffolds. This was realized by utilizing a paste-like CPC (P-CPC) which is stable as a malleable paste and whose setting reaction is initiated only after contact with aqueous solutions. The P-CPC showed good processability in the 3D plotting process and allowed the fabrication of stable?3D structures of different geometries with adequate mechanical stability and compressive strength. The cytocompatibility of the plotted P-CPC scaffolds was demonstrated in a cell culture experiment with human mesenchymal stem cells. The mild conditions during 3D plotting and post-processing and the realization of the whole procedure under sterile conditions make this approach highly attractive for fabrication of individualized implants with respect to patient-specific requirements by simultaneous plotting of biological components. PMID:22933381

  4. Corrosion-resistant Foamed Cements for Carbon Steels

    SciTech Connect

    Sugama T.; Gill, S.; Pyatina, T., Muraca, A.; Keese, R.; Khan, A.; Bour, D.

    2012-12-01

    The cementitious material consisting of Secar #80, Class F fly ash, and sodium silicate designed as an alternative thermal-shock resistant cement for the Enhanced Geothermal System (EGS) wells was treated with cocamidopropyl dimethylamine oxide-based compound as foaming agent (FA) to prepare numerous air bubble-dispersed low density cement slurries of and #61603;1.3 g/cm3. Then, the foamed slurry was modified with acrylic emulsion (AE) as corrosion inhibitor. We detailed the positive effects of the acrylic polymer (AP) in this emulsion on the five different properties of the foamed cement: 1) The hydrothermal stability of the AP in 200 and #61616;C-autoclaved cements; 2) the hydrolysis-hydration reactions of the slurry at 85 and #61616;C; 3) the composition of crystalline phases assembled and the microstructure developed in autoclaved cements; 4) the mechanical behaviors of the autoclaved cements; and, 5) the corrosion mitigation of carbon steel (CS) by the polymer. For the first property, the hydrothermal-catalyzed acid-base interactions between the AP and cement resulted in Ca-or Na-complexed carboxylate derivatives, which led to the improvement of thermal stability of the AP. This interaction also stimulated the cement hydration reactions, enhancing the total heat evolved during cement’s curing. Addition of AP did not alter any of the crystalline phase compositions responsible for the strength of the cement. Furthermore, the AP-modified cement developed the porous microstructure with numerous defect-free cavities of disconnected voids. These effects together contributed to the improvement of compressive-strength and –toughness of the cured cement. AP modification of the cement also offered an improved protection of CS against brine-caused corrosion. There were three major factors governing the corrosion protection: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS surfaces; 2) inhibiting the cathodic reactions at the corrosion site of CS; 3) extending the coverage of cement over CS surfaces; and, 4) improving the adherence of the cement to CS surfaces. Thus, the CS’s corrosion rate of 176 milli inch/per year (mpy) for 1 wt% FA-foamed cement without AP was considerably reduced to 69 mpy by adding only 2 wt% AP. Addition of AP at 10 wt% further reduced this rate to less than 10 mpy.

  5. Magnetron Enhanced Plasma-Polymerization for Biocompatible Sensor Coatings and Membranes on Polymeric Based Materials

    Microsoft Academic Search

    F. Olcaytug; L. Ledernez; G. Dame; P. Zahn; H. Yasuda; G. Urban

    One of the key questions in the application of miniaturized sensors and actuators for acute and\\/or chronic use in living-body\\u000a environment is the biocompatibility. In case of gas sensors additionally a very fine balance between the biocompatibility\\u000a of the device and the gas (e.g. O2, NO, CO) permeability of its coating must be maintained. In many sensor configurations\\u000a polymeric substrate

  6. Preparation of the acellular scaffold of the spinal cord and the study of biocompatibility

    Microsoft Academic Search

    S-Z Guo; X-J Ren; B Wu; T Jiang

    2010-01-01

    Study design:Acellular spinal cord was prepared through chemical extraction, and its biocompatibility was studied.Objective:Acellular scaffolds have been developed from various materials for tissue reconstruction, except for spinal cord. The objective of this study was to prepare acellular spinal cord and examine the biocompatibility of the scaffold.Setting:This study was conducted at the Department of Orthopedics, Xinqiao Hospital, The Third Military Medical

  7. Novel Immunosuppressant Agents Targeting Activated Lymphocytes by Biocompatible MPC Polymer Conjugated with Interleukin2

    Microsoft Academic Search

    N. Chiba; M. Ueda; T. Shimada; H. Jinno; J. Watanabe; K. Ishihara; M. Kitajima

    2007-01-01

    The immunopharmacological profile of novel biocompatible water-soluble interleukin-2 (IL-2)-conjugated 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer immunosuppressive agents was established. MPC-co-n- butyl methacrylate (BMA)-co-p-nitrophenylcarbonyloxyethyl methacrylate (NPMA) (PMBN) was prepared as a backbone for these novel agents. PMBN contained MPC as a biocompatible unit, BMA as a hydrophobic domain in water, and NPMA as an immobilizable unit with IL-2. This research showed that proliferation

  8. Investigation of Ion-Peptide Interactions Using a Biocompatible Nanopore Probe 

    E-print Network

    Bard, Sean

    2012-07-16

    of Department, David H. Russell May 2012 Major Subject: Chemistry iii ABSTRACT Investigation of Ion-Peptide Interactions Using a Biocompatible Nanopore Probe. May 2012 Sean Blount Bard, B.S. Rice University Chair of Advisory Committee: Dr... INVESTIGATION OF ION-PEPTIDE INTERACTIONS USING A BIOCOMPATIBLE NANOPORE PROBE A Thesis by SEAN BLOUNT BARD Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements...

  9. Optimal selection of organic solvents for biocompatible extraction of ?-carotene from Dunaliella salina

    Microsoft Academic Search

    M. Mojaat; A. Foucault; J. Pruvost; J. Legrand

    2008-01-01

    In the aim of ?-carotene biocompatible extraction, toxicity of various pure solvents belonging to different homologous series has been investigated for Dunaliella salina. The results showed that solvents having logPoct>5 or having a molecular weight over 150g\\/mol can be considered biocompatible for this microalga. The membrane critical solvent concentration for each series of solvents has been calculated applying Osborne's model,

  10. Biocompatibility of chemically cross-linked gelatin hydrogels for ophthalmic use

    Microsoft Academic Search

    Jui-Yang Lai

    2010-01-01

    Biocompatibility is a major requirement for the development of functional biomaterials for ophthalmic applications. In this\\u000a study, we investigated the effect of cross-linker functionality on ocular biocompatibility of chemically modified gelatin\\u000a hydrogels. The test materials were cross-linked with glutaraldehyde (GTA) or 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide\\u000a (EDC), and were analyzed using in vitro and in vivo assays. Primary rat iris pigment epithelial cultures

  11. Biocompatibility of iron filled carbon nanotubes in vitro.

    PubMed

    Taylor, Arthur; Lipert, Kamil; Krämer, Kai; Hampel, Silke; Füssel, Susanne; Meye, Axel; Klingeler, Rüdiger; Ritschel, Manfred; Leonhardt, Albrecht; Büchner, Bernd; Wirth, Manfred P

    2009-10-01

    Due to their particular magnetic properties, nanoparticles of metallic iron are promising candidates for magnetic fluid hyperthermia when compared to the commonly used iron oxides. However, the difficulty of handling these structures in ambient conditions without oxidation hinders its practical application. In this work, iron filled carbon nanotubes non-covalently functionalized by human serum albumin are studied as potential agents for hyperthermia. Here the iron is encapsulated inside of the carbon shells and protected from reactions with its environment. Besides protecting the iron and biological environment against each other, the carbon shells can also work as an interface for conjugation with other biological molecules of interest. In order to assess if such structures could induce any toxic effect in human cell cultures, we have probed its biocompatibility on a dosage and time dependent manner by measuring metabolic activity, cell proliferation, cell cycle distribution and apoptosis. Our results have shown that those nanotubes strongly associate with cells within a short incubation period and do not pose any significant toxic effect. The magnetic properties of iron filled carbon nanotubes in biological environment, i.e., associated to cells, have been studied and a possible rotation as a function of the applied magnetic field is discussed. Our initial findings encourage the further study of these structures as potential hyperthermia agents. PMID:19908442

  12. Reinforcement of bacterial cellulose aerogels with biocompatible polymers

    PubMed Central

    Pircher, N.; Veigel, S.; Aigner, N.; Nedelec, J.M.; Rosenau, T.; Liebner, F.

    2014-01-01

    Bacterial cellulose (BC) aerogels, which are fragile, ultra-lightweight, open-porous and transversally isotropic materials, have been reinforced with the biocompatible polymers polylactic acid (PLA), polycaprolactone (PCL), cellulose acetate (CA), and poly(methyl methacrylate) (PMMA), respectively, at varying BC/polymer ratios. Supercritical carbon dioxide anti-solvent precipitation and simultaneous extraction of the anti-solvent using scCO2 have been used as core techniques for incorporating the secondary polymer into the BC matrix and to convert the formed composite organogels into aerogels. Uniaxial compression tests revealed a considerable enhancement of the mechanical properties as compared to BC aerogels. Nitrogen sorption experiments at 77 K and scanning electron micrographs confirmed the preservation (or even enhancement) of the surface-area-to-volume ratio for most of the samples. The formation of an open-porous, interpenetrating network of the second polymer has been demonstrated by treatment of BC/PMMA hybrid aerogels with EMIM acetate, which exclusively extracted cellulose, leaving behind self-supporting organogels. PMID:25037381

  13. Reinforcement of bacterial cellulose aerogels with biocompatible polymers.

    PubMed

    Pircher, N; Veigel, S; Aigner, N; Nedelec, J M; Rosenau, T; Liebner, F

    2014-10-13

    Bacterial cellulose (BC) aerogels, which are fragile, ultra-lightweight, open-porous and transversally isotropic materials, have been reinforced with the biocompatible polymers polylactic acid (PLA), polycaprolactone (PCL), cellulose acetate (CA), and poly(methyl methacrylate) (PMMA), respectively, at varying BC/polymer ratios. Supercritical carbon dioxide anti-solvent precipitation and simultaneous extraction of the anti-solvent using scCO2 have been used as core techniques for incorporating the secondary polymer into the BC matrix and to convert the formed composite organogels into aerogels. Uniaxial compression tests revealed a considerable enhancement of the mechanical properties as compared to BC aerogels. Nitrogen sorption experiments at 77K and scanning electron micrographs confirmed the preservation (or even enhancement) of the surface-area-to-volume ratio for most of the samples. The formation of an open-porous, interpenetrating network of the second polymer has been demonstrated by treatment of BC/PMMA hybrid aerogels with EMIM acetate, which exclusively extracted cellulose, leaving behind self-supporting organogels. PMID:25037381

  14. Biocompatibility and characterization of renewable agricultural residues and polyester composites.

    PubMed

    Wu, Chin-San; Hsu, Yi-Chiang; Yeh, Jen-taut; Liao, Hsin-Tzu; Jhang, Jheng-Jie; Sie, Yong-Yu

    2013-04-15

    Composites of sesame husk and glycidyl methacrylate-grafted polytrimethylene terephthalate (PTT-g-GMA/SH) exhibit noticeably superior mechanical properties compared to PTT/SH composites due to greater compatibility between the two components. The dispersion of SH in the PTT-g-GMA matrix is highly homogeneous as a result of condensation reaction formations. Human lung fibroblasts (FBs) were seeded on these two series of composites to characterize the biocompatibility properties. In a time-dependent course, the FB proliferation results demonstrated higher performance from the PTT/SH series of composites than from the PTT-g-GMA/SH composites. In addition, collagen production by FBs present in the PTT/SH series was 20% higher than in regular culture-plates after 7 days of incubation. The water resistance of PTT-g-GMA/SH was higher than that of PTT/SH, although the weight loss of both composites buried in soil compost indicated that they were both biodegradable, especially at higher levels of SH substitution. The PTT/SH and PTT-g-GMA/SH composites were more biodegradable than pure PTT, implying a strong connection between SH content and biodegradability. PMID:23544578

  15. PCL-PGLA composite tubular scaffold preparation and biocompatibility investigation.

    PubMed

    Mo, X; Weber, H-J; Ramakrishna, S

    2006-08-01

    The objective of this paper was to fabricate a biodegradable tubular scaffold for small diameter (d<6 mm) blood vessel tissue engineering. The tube scaffold needed a porous wall for cell attachment, proliferation and tissue regeneration with its degradation. A novel method given in this paper was to coat a porous layer of poly (epsilon-caprolactone) (PCL) on the outside of a poly (glycolic-co-lactic acid) (PGLA with GA:LA=90:10) fiber braided tube to give a PCL-PGLA composite. The PGLA tube was fabricated using a braiding machine by inserting a Teflon tube with the desired diameter in center of the 20 spindles, which are the carriers of PGLA fibers. Changing the diameter of the Teflon tube can vary the inner diameter of a braided PGLA tube. Thermally induced phase separation method was used for PCL solution coating on the surface of the PGLA braided tube. Controlling the polymer concentration, non-solvent addition and quenching temperature generated the pore structures, with pore sizes ranging from 10-30 microm. The fibroblast cells were seeded on the tubular scaffold and cultured in vitro for the biocompatibility investigation. Histology results showed that the fibroblast cells proliferated on the interconnected pore of the PCL porous layer in 1 week. PMID:16969757

  16. Ocular biocompatibility of polyquaternium 10 gel: functional and morphological results.

    PubMed

    Alasino, Roxana Valeria; Garcia, Luciana Guadalupe; Gramajo, Ana Laura; Pusterla, Juan Pablo; Beltramo, Dante Miguel; Luna, José Domingo

    2015-02-01

    This paper deals with the characterization study of topical and intraocular biocompatibility and toxicity of cationic hydroxyethylcellulose Polyquaternium 10 (PQ10). It also evaluates the rheological properties of gels. The cytotoxicity assays were done in two cell lines: HEp-2 and VERO (human larynx epidermoid carcinoma cell and African green monkey kidney cells respectively). For the in vivo study, New Zealand albino rabbits were used. The in vitro cytotoxic activity of PQ10 shows no statistically significant differences in relation to the control of hydroxypropylmethylcellulose (HPMC) in any of the cell lines used in this study. Similarly, the signs of inflammation observed after treatment showed no significant difference between the groups of animals treated with the polymer compared to the control group. Normal histological characteristics were seen in both groups with no histological inflammatory reaction. After 1 month of the intracameral application of 2% PQ10 (treatment group) or 0.3% HPMC (control group), electroretinograms showed similar levels of a- and b-waves latencies and amplitude. In summary, PQ10 gel was well tolerated in these experiments, with proper monitoring, it could stand as a new alternative in the development of ophthalmic viscosurgical devices. PMID:25631258

  17. In vivo biocompatibility of the PLGA microparticles in parotid gland

    PubMed Central

    Cantín, Mario; Miranda, Patricio; Suazo Galdames, Iván; Zavando, Daniela; Arenas, Patricia; Velásquez, Luis; Vilos, Cristian

    2013-01-01

    Poly(lactic-co-glycolic acid) (PLGA) microparticles are used in various disorders for the controlled or sustained release of drugs, with the management of salivary gland pathologies possible using this technology. There is no record of the response to such microparticles in the glandular parenchyma. The purpose of this study was to assess the morphological changes in the parotid gland when injected with a single dose of PLGA microparticles. We used 12 adult female Sprague Dawley rats (Rattus norvegicus) that were injected into their right parotid gland with sterile vehicle solution (G1, n=4), 0.5 mg PLGA microparticles (G2, n=4), and 0.75 mg PLGA microparticles (G3, n=4); the microparticles were dissolved in a sterile vehicle solution. The intercalar and striated ducts lumen, the thickness of the acini and the histology aspect in terms of the parenchyma organization, cell morphology of acini and duct system, the presence of polymeric residues, and inflammatory response were determined at 14 days post-injection. The administration of the compound in a single dose modified some of the morphometric parameters of parenchyma (intercalar duct lumen and thickness of the glandular acini) but did not induce tissue inflammatory response, despite the visible presence of polymer waste. This suggests that PLGA microparticles are biocompatible with the parotid tissue, making it possible to use intraglandular controlled drug administration. PMID:24228103

  18. An effective and biocompatible antibiofilm coating for central venous catheter.

    PubMed

    Silva Paes Leme, Annelisa Farah; Ferreira, Aline Siqueira; Alves, Fernanda Aparecida Oliveira; de Azevedo, Bruna Martinho; de Bretas, Liza Porcaro; Farias, Rogerio Estevam; Oliveira, Murilo Gomes; Raposo, Nádia Rezende Barbosa

    2015-05-01

    The aim of this study was to investigate the in vitro and in vivo efficacy and the tissue reaction of an antibiofilm coating composed of xylitol, triclosan, and polyhexamethylene biguanide. The antimicrobial activity was analyzed by a turbidimetric method. Scanning electron microscopy was used to evaluate the antiadherent property of central venous catheter (CVC) fragments impregnated with an antibiofilm coating (I-CVC) in comparison with noncoated CVC (NC-CVC) fragments. Two in vivo assays using subcutaneous implantation of NC-CVC and I-CVC fragments in the dorsal area of rats were performed. The first assay comprised hematological and microbiological analysis. The second assay evaluated tissue response by examining the inflammatory reactions after 7 and 21 days. The formulation displayed antimicrobial activity against all tested strains. A biofilm disaggregation with significant reduction of microorganism's adherence in I-CVC fragments was observed. In vivo antiadherence results demonstrated a reduction of early biofilm formation of Staphylococcus aureus ATCC 25923, mainly in an external surface of the I-CVC, in comparison with the NC-CVC. All animals displayed negative hemoculture. No significant tissue reaction was observed, indicating that the antibiofilm formulation could be considered biocompatible. The use of I-CVC could decrease the probability of development of localized or systemic infections. PMID:25826042

  19. Conversion of bulk seashells to biocompatible hydroxyapatite for bone implants.

    PubMed

    Vecchio, Kenneth S; Zhang, Xing; Massie, Jennifer B; Wang, Mark; Kim, Choll W

    2007-11-01

    Strombus gigas (conch) shells and Tridacna gigas (Giant clam) shells have dense, tailored structures that impart excellent mechanical properties to these shells. In this investigation, conch and clam seashells were converted to hydroxyapatite (HAP) by a hydrothermal method at different temperatures and for different conversion durations. Dense HAP structures were created from these shells throughout the majority of the samples at the relative low temperature of approximately 200 degrees C. The average fracture stress was found to be approximately 137-218MPa for partially converted conch shell samples and approximately 70-150MPa for original and converted clamshell samples, which is close to the mechanical strength of compact human bone. This indicates that the converted shell samples can be used as implants in load-bearing cases. In vivo tests of converted shell samples were performed in rat femoral defects for 6 weeks. The microtomography images at 6 weeks show that the implants did not move, and untreated control defects remain empty with no evidence of a spontaneous fusion. Histological study reveals that there is newly formed bone growing up to and around the implants. There is no evidence of a fibrosis tissue ring around the implants, also indicating that there is no loosening of the implants. In contrast, the untreated controls remain empty with some evidence of a fibrosis ring around the defect hole. These results indicate good biocompatibility and bioactivity of the converted shell implants. PMID:17684000

  20. Solution behavior of PEO : the ultimate biocompatible polymer.

    SciTech Connect

    Curro, John G.; Frischknecht, Amalie Lucile

    2004-11-01

    Poly(ethylene oxide) (PEO) is the quintessential biocompatible polymer. Due to its ability to form hydrogen bonds, it is soluble in water, and yet is uncharged and relatively inert. It is being investigated for use in a wide range of biomedical and biotechnical applications, including the prevention of protein adhesion (biofouling), controlled drug delivery, and tissue scaffolds. PEO has also been proposed for use in novel polymer hydrogel nanocomposites with superior mechanical properties. However, the phase behavior of PEO in water is highly anomalous and is not addressed by current theories of polymer solutions. The effective interactions between PEO and water are very concentration dependent, unlike other polymer/solvent systems, due to water-water and water-PEO hydrogen bonds. An understanding of this anomalous behavior requires a careful examination of PEO liquids and solutions on the molecular level. We performed massively parallel molecular dynamics simulations and self-consistent Polymer Reference Interaction Site Model (PRISM) calculations on PEO liquids. We also initiated MD studies on PEO/water solutions with and without an applied electric field. This work is summarized in three parts devoted to: (1) A comparison of MD simulations, theory and experiment on PEO liquids; (2) The implementation of water potentials into the LAMMPS MD code; and (3) A theoretical analysis of the effect of an applied electric field on the phase diagram of polymer solutions.

  1. Biocompatibility and gelation of chitosan-glycerol phosphate hydrogels.

    PubMed

    Ahmadi, Raheleh; de Bruijn, Joost D

    2008-09-01

    The aim of this study was to evaluate the cytotoxicity and gelation of thermosensitive chitosan-beta-glycerol phosphate (GP) solutions, which undergo sol-gel transition around body temperature. Chitosan 0.5-2% (w/v) mixed with GP 5-20% (w/v) solutions all gel at 37 degrees C and possess pH around the physiological range. High GP and chitosan concentrations result in faster gelation time. Extracts of all chitosan concentrations mixed with or without 5% (w/v) GP and 2% (w/v) chitosan combined with 10% (w/v) GP demonstrated up to 34% increase in proliferation rate of goat bone marrow derived mesenchymal stem cells when compared with control medium. Extracts from all other chitosan-GP combinations resulted in reduced cell proliferation relative to control medium. Increasing GP content in the gel resulted in a linear increase in the osmolality of the extracts in contact with the gels. The results of this study indicate that chitosan-GP is a biocompatible hydrogel, extracts of which can stimulate mesenchymal stem cell proliferation at certain concentrations. This material is therefore a promising vehicle for cell encapsulation and injectable tissue-engineering applications. PMID:18041728

  2. Biocompatible anionic polyelectrolyte for improved liposome based gene transfection.

    PubMed

    Chen, Ming; Zeng, Zhiying; Qu, Xiaohuan; Tang, Yaqin; Long, Qipeng; Feng, Xuli

    2015-07-25

    Cationic liposomes have been widely used as efficient gene carriers. However, the serious cytotoxicity caused by exposed positive charges restricts the further application of those kinds of gene vectors. Thus, it is challenging to develop biocompatiable non-positive charge carriers to achieve high gene transfection efficiencies. Herein, we report a novel design by pasting biocompatible anionic polyelectrolyte, namely alginic acid, hyaluronic acid, pectin and polyglutamic acid, to the positive charge surface of liposome/pDNA complex. Through shielding the positive charges, the new gene carriers show decreased cytotoxicity while still maintaining high transfection efficiency. To be noted, the complex formed by coating polyglutamic acid to the surface of liposome/pDNA greatly enhanced the transfection efficiency in HepG2 cells, and the use of pectin shows increased transfection in MCF-7 cells. Hemolysis assay proved a possible mechanism that when the new gene complex was internalized into cells, as acidity increases, more side chains become hydrophobic, and thus destabilizing the endosomal membrane to accelerate DNA escape. The present results suggest that such anionic polyelectrolyte covered liposome based carrier possess promising application for clinical gene delivery. PMID:26004001

  3. Designing biocompatible Ti-based metallic glasses for implant applications.

    PubMed

    Calin, Mariana; Gebert, Annett; Ghinea, Andreea Cosmina; Gostin, Petre Flaviu; Abdi, Somayeh; Mickel, Christine; Eckert, Jürgen

    2013-03-01

    Ti-based metallic glasses show high potential for implant applications; they overcome in several crucial respects their well-established biocompatible crystalline counterparts, e.g. improved corrosion properties, higher fracture strength and wear resistance, increased elastic strain range and lower Young's modulus. However, some of the elements required for glass formation (e.g. Cu, Ni) are harmful for the human body. We critically reviewed the biological safety and glass forming tendency in Ti of 27 elements. This can be used as a basis for the future designing of novel amorphous Ti-based implant alloys entirely free of harmful additions. In this paper, two first alloys were developed: Ti(75)Zr(10)Si(15) and Ti(60)Nb(15)Zr(10)Si(15). The overheating temperature of the melt before casting can be used as the controlling parameter to produce fully amorphous materials or bcc-Ti-phase reinforced metallic glass nano-composites. The beneficial effect of Nb addition on the glass-formation and amorphous phase stability was assessed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. Crystallization and mechanical behavior of ribbons are influenced by the amount and distribution of the nano-scaled bcc phase existing in the as-cast state. Their electrochemical stability in Ringer's solution at 310 K was found to be significantly better than that of commercial Ti-based biomaterials; no indication for pitting corrosion was recorded. PMID:25427501

  4. Development of monetite-nanosilica bone cement: a preliminary study.

    PubMed

    Zhou, Huan; Luchini, Timothy J F; Agarwal, Anand K; Goel, Vijay K; Bhaduri, Sarit B

    2014-11-01

    In this paper, we reported the results of our efforts in developing DCPA/nanosilica composite orthopedic cement. It is motivated by the significances of DCPA and silicon in bone physiological activities. More specifically, this paper examined the effects of various experimental parameters on the properties of such composite cements. In this work, DCPA cement powders were synthesized using a microwave synthesis technique. Mixing colloidal nanosilica directly with synthesized DCPA cement powders can significantly reduce the washout resistance of DCPA cement. In contrast, a DCPA-nanosilica cement powder prepared by reacting Ca(OH)2 , H3 PO4 and nanosilica together showed good washout resistance. The incorporation of nanosilica in DCPA can improve compressive strength, accelerate cement solidification, and intensify surface bioactivity. In addition, it was observed that by controlling the content of NaHCO3 during cement preparation, the resulting composite cement properties could be modified. Allowing for the development of different setting times, mechanical performance and crystal features. It is suggested that DCPA-nanosilica composite cement can be a potential candidate for bone healing applications. PMID:24652701

  5. Current attitudes to cementing techniques in British hip surgery.

    PubMed

    Hashemi-Nejad, A; Birch, N C; Goddard, N J

    1994-11-01

    Aseptic loosening is the major problem in hip joint replacement. Improved cementing techniques have been shown to improve the long-term survival of implants significantly. To assess the use of modern cementing techniques in British surgeons, a detailed questionnaire was sent to all Fellows of The British Orthopaedic Association (BOA) regarding cement preparation, bone preparation, cementing technique and prostheses used in total hip arthroplasty. Excluding retired fellows, surgeons who use no cement, and those who had filled in forms inadequately, 668 responded, who between them performed 43,680 hip arthroplasties per year. In this survey, 21 different types of hip prostheses were implanted by the surgeons; 48% of hips implanted were Charnley type. Of the surgeons, 46% used Palacos with gentamicin as their cement for both the femur and acetabulum. For the femur, 44% of surgeons remove all cancellous bone, 40% use pulse lavage, 59% use a brush to clear debris, 94% dry the femur, 97% plug the femur, 76% use a cement gun and 70% pressurise the cement. For the acetabulum, 88% of surgeons retain the subchondral bone, 40% use pulse lavage, 100% dry the acetabulum, 22% use hypotensive anaesthesia and 58% pressurise the cement. Overall only 25% of surgeons (26% of hips implanted) use 'modern' cementing techniques. This has implications for the number of arthroplasties that may require early revision. PMID:7702322

  6. Microhardness Measurements on Chemically and Mechanically Altered Well Bore Cements

    NASA Astrophysics Data System (ADS)

    Du, H.; Radonjic, M.

    2014-12-01

    The focus of this research was to investigate the effect of water to cement ratio (w/c), water salinity and additives on its microstructure and mechanical properties. Microhardness test was utilized to evaluate the change in cement mechanical properties. Nanovea® Nano/Micro-Indenter is based on the standards for instrumented indentation, ASTM E2546 and ISO 14577. The indenter tip with a known geometry (Vickers Diamond) is driven into the cement sample to be tested, by applying an increasing normal load. Analysis of indentation test results on the cement samples showed: (a) a decrease of both Young's modulus and hardness after increasing w/c and/or water salinity, and (b) additives have a significant impact on both hardness and Yong's modulus. The most likely mechanism behind all changes in cement structure and its properties is that the difference of cement components resulted in a change of the cement matrix porosity and grain size. Scanning Electron Microscopy (SEM) imaging also indicated changes in cement, as can be observed from micrographs of control and altered cement taken at the same magnification. This unique research provides an important insight to the understanding of mechanical properties of cement

  7. Alkali-slag cements for the immobilization of radioactive wastes

    SciTech Connect

    Shi, C. [Wastewater Technology Centre, Burlington, Ontario (Canada); Day, R.L. [Univ. of Calgary, Alberta (Canada). Dept. of Civil Engineering

    1996-12-31

    Alkali-slag cements consist of glassy slag and an alkaline activator and can show both higher early and later strengths than Type III Portland cement, if a proper alkaline activator is used. An examination of microstructure of hardened alkali-slag cement pastes with the help of XRD and SEM with EDAX shows that the main hydration product is C-S-H (B) with low C/S ratio and no crystalline substances exist such as Ca(OH){sub 2}, Al (OH){sub 3} and sulphoaluminates. Mercury intrusion tests indicate that hardened alkali-slag cement pastes have a lower porosity than ordinary Portland cement, and contain mainly gel pores. The fine pore structure of hardened alkali-slag cement pastes will restrict the ingress of deleterious substances and the leaching of harmful species such as radionuclides. The leachability of Cs{sup + } from hardened alkali-slag cement pastes is only half of that from hardened Portland cement. From all these aspects, it is concluded that alkali-slag cements are a better solidification matrix than Portland cement for radioactive wastes.

  8. Mechanical properties and drug release behavior of bioactivated PMMA cements.

    PubMed

    Vorndran, Elke; Spohn, Nikola; Nies, Berthold; Rössler, Sophie; Storch, Sandra; Gbureck, Uwe

    2012-01-01

    Septic loosening of cemented implants represents an unresolved long-term problem of total hip endoprostheses. Common treatments of infected prostheses involve the use of temporary antibiotic-loaded PMMA spacer-implants or antibiotic-loaded cements. The latter are either provided by a manufacturer or are obtained by simply mixing specific antibiotic powders according to a microbial sensitivity test with PMMA cement. This study is aimed to investigate the antibiotic release behavior and mechanical properties of novel modified PMMA cements, which were bioactivated by chemical modification of commercial cements with either 0.5% hydroxyethylmethacrylate-phosphate (HEMA-P) or 0.5% hydroxyethylmethacrylate-phosphate + calcium chloride and sodium carbonate as buffer. Tobramycin release experiments from the cements were performed statically by immersion of the drug-loaded samples in PBS buffer following liquid change after different periods of time or during cyclic mechanical loading of the cement samples. Cement modification did not significantly alter the mechanical properties of the cements, but affected the release rate from the matrix. While the unmodified cement released approximately 0.33 mg/cm(2) tobramycin after 48 h independent of the testing regime, modification with both HEMA-P and salt buffer increased the antibiotic release to 37-50 mg/cm(2) when tested under cyclical mechanical loading. PMID:20819922

  9. Injectable citrate-modified Portland cement for use in vertebroplasty.

    PubMed

    Wynn-Jones, Gareth; Shelton, Richard M; Hofmann, Michael P

    2014-11-01

    The injectability of Portland cement (PC) with several citrate additives was investigated for use in clinical applications such as vertebroplasty (stabilization of a fractured vertebra with bone cement) using a syringe. A 2-wt % addition of sodium or potassium citrate with PC significantly improved cement injectability, decreased cement setting times from over 2 h to below 25 min, while increasing the compressive strength to a maximum of 125 MPa. Zeta-potential measurements indicated that the citrate anion was binding to one or more of the positively charged species causing charged repulsion between cement particles which dispersed aggregates and caused the liquefying effect of the anion. Analysis of the hydrating phases of PC indicated that the early strength producing PC phase (ettringite) developed within the first 2 h of setting following addition of the citrate anion, while this did not occur in the control cement (PC only). Within 24 h ettringite developed in PC as well as calcium-silicate-hydrate (C-S-H), the major setting phase of PC, whereas cements containing citrate did not develop this phase. The evidence suggested that in the presence of citrate the cements limited water supply appeared to be utilized for ettringite formation, producing the early strength of the citrate cements. The present study has demonstrated that it is possible to modify PC with citrate to both improve the injectability and crucially reduce the setting times of PC while improving the strength of the cement. PMID:24711245

  10. Creep behavior comparison of CMW1 and palacos R-40 clinical bone cements

    Microsoft Academic Search

    C. Liu; S. M. Green; N. D. Watkins; P. J. Gregg; A. W. McCaskie

    2002-01-01

    The restrained dynamic creep behaviors of two clinical bone cements, Palacos R-40 and CMW1 have been investigated at room temperature and body temperature. It was found that the two cements demonstrated significantly different creep deformations, with Palacos R-40 bone cement demonstrating higher creep strain than CMW1 bone cement at each loading cycle. For both cements, two stages of creep were

  11. Retrieval of Cement Embolus from Inferior Vena Cava After Percutaneous Vertebroplasty

    SciTech Connect

    Athreya, S., E-mail: sathreya@stjoes.c [St. Joseph's Healthcare, Department of Radiology (Canada); Mathias, N. [Gartnavel General Hospital, Department of Radiology (United Kingdom); Rogers, P. [Gartnavel General Hospital, Department of Surgery (United Kingdom); Edwards, R. [Gartnavel General Hospital, Department of Radiology (United Kingdom)

    2009-07-15

    Percutaneous vertebroplasty is an accepted treatment for painful vertebral compression fractures caused by osteoporosis and malignant disease. Venous leakage of cement and pulmonary cement embolism have been reported complications. We describe a paravertebral venous cement leak resulting in the deposition of a cement cast in the inferior vena cava and successful retrieval of the cement embolus.

  12. Double percolation in the electrical conduction in carbon fiber reinforced cement-based materials

    E-print Network

    Chung, Deborah D.L.

    conduction in carbon fiber cement-based materials. It involves fiber percolation and cement paste percolation.% fibers in the paste portion. The cement paste percolation threshold is between 70 and 76 vol.% carbon fiber cement paste in the mortar. A sand volume fraction of 24% or less (i.e., a sand/cement ratio of 0

  13. Retrieval of Cement Embolus from Inferior Vena Cava After Percutaneous Vertebroplasty

    Microsoft Academic Search

    S. Athreya; N. Mathias; P. Rogers; R. Edwards

    2009-01-01

    Percutaneous vertebroplasty is an accepted treatment for painful vertebral compression fractures caused by osteoporosis and malignant disease. Venous leakage of cement and pulmonary cement embolism have been reported complications. We describe a paravertebral venous cement leak resulting in the deposition of a cement cast in the inferior vena cava and successful retrieval of the cement embolus.

  14. In Vitro Models in Biocompatibility Assessment for Biomedical-Grade Chitosan Derivatives in Wound Management

    PubMed Central

    Keong, Lim Chin; Halim, Ahmad Sukari

    2009-01-01

    One of the ultimate goals of wound healing research is to find effective healing techniques that utilize the regeneration of similar tissues. This involves the modification of various wound dressing biomaterials for proper wound management. The biopolymer chitosan (?-1,4-D-glucosamine) has natural biocompatibility and biodegradability that render it suitable for wound management. By definition, a biocompatible biomaterial does not have toxic or injurious effects on biological systems. Chemical and physical modifications of chitosan influence its biocompatibility and biodegradability to an uncertain degree. Hence, the modified biomedical-grade of chitosan derivatives should be pre-examined in vitro in order to produce high-quality, biocompatible dressings. In vitro toxicity examinations are more favorable than those performed in vivo, as the results are more reproducible and predictive. In this paper, basic in vitro tools were used to evaluate cellular and molecular responses with regard to the biocompatibility of biomedical-grade chitosan. Three paramount experimental parameters of biocompatibility in vitro namely cytocompatibility, genotoxicity and skin pro-inflammatory cytokine expression, were generally reviewed for biomedical-grade chitosan as wound dressing. PMID:19399250

  15. In vitro and in vivo ocular biocompatibility of electrospun poly(?-caprolactone) nanofibers.

    PubMed

    Da Silva, Gisele Rodrigues; Lima, Tadeu Henrique; Oréfice, Rodrigo Lambert; Fernandes-Cunha, Gabriella Maria; Silva-Cunha, Armando; Zhao, Min; Behar-Cohen, Francine

    2015-06-20

    Biocompatibility is a requirement for the development of nanofibers for ophthalmic applications. In this study, nanofibers were elaborated using poly(?-caprolactone) via electrospinning. The ocular biocompatibility of this material was investigated. MIO-M1 and ARPE-19 cell cultures were incubated with nanofibers and cellular responses were monitored by viability and morphology. The in vitro biocompatibility revealed that the nanofibers were not cytotoxic to the ocular cells. These cells exposed to the nanofibers proliferated and formed an organized monolayer. ARPE-19 and MIO-M1 cells were capable of expressing GFAP, respectively, demonstrating their functionality. Nanofibers were inserted into the vitreous cavity of the rat's eye for 10days and the in vivo biocompatibility was investigated using Optical Coherence Tomography (OCT), histology and measuring the expression of pro-inflammatory genes (IL-1?, TNF-?, VEGF and iNOS) (real-time PCR). The OCT and the histological analyzes exhibited the preserved architecture of the tissues of the eye. The biomaterial did not elicit an inflammatory reaction and pro-inflammatory cytokines were not expressed by the retinal cells, and the other posterior tissues of the eye. Results from the biocompatibility studies indicated that the nanofibers exhibited a high degree of cellular biocompatibility and short-term intraocular tolerance, indicating that they might be applied as drug carrier for ophthalmic use. PMID:25797289

  16. Ion release and pH of a new endodontic cement, MTA and Portland cement

    PubMed Central

    Amini Ghazvini, Sara; Abdo Tabrizi, Maryam; Kobarfard, Farzad; Akbarzadeh Baghban, Alireza; Asgary, Saeed

    2009-01-01

    INTRODUCTION: This in vitro study measured and compared pH and phosphate and calcium ions release of a new endodontic material (CEM cement), mineral trioxide aggregate (MTA), and Portland cement (PC) using UV-visible technique, atomic absorption spectrophotometry methods, and pH meter, respectively. MATERIALS AND METHODS: Each material was placed in a plastic tube (n=10) and immersed in a glass flask containing deionized water. Half of the samples were tested for determining pH and released ions after 1h, 3h, 24h, 48h, 7d and 28d. Remaining samples (n=5), were evaluated after 28d. Data was analyzed using one way ANOVA and Tukey tests. RESULTS: Results indicated that all materials were highly alkaline and released calcium and low concentration of phosphate ions in all the time intervals. CEM cement released considerably higher concentration of phosphate during the first hour (P<0.05). CONCLUSION: This novel endodontic cement promoted alkaline pH in a similar manner to MTA and released calcium and phosphate. These conditions can stimulate the calcification process and explain the basic physico-chemical mechanisms of hard tissue regeneration of CEM cement. PMID:23940490

  17. Cement clinker structure during plasma-chemical synthesis and its influence on cement properties

    NASA Astrophysics Data System (ADS)

    Sazonova, N.; Skripnikova, N.; Lucenko, A.; Novikova, L.

    2015-01-01

    The aim of this study was to determine the degree of influence of cement clinker cooling modes, synthesized in a low-temperature plasma, its structure and physico-mechanical properties. The raw mixture consisting of marble, sand, ash from thermal power plants and py- rite cinders were used, which are characterized by saturation factor (1,045); silicate (2,35) and alumina (1,22) modules. It was found that the use of different cooling rates of fused cement clinker entails changes associated with the mineralogical composition (increase of alite of 8.719,2 %), morphology (variation of the mineral alite aspect ratio of 6,7-17,5), density of the structure (change in distance between the minerals from 1 to 7,5 microns), grindability, specific surface area (2600-3650 cm2/g) and, in consequence, the activity of cement (56,973,2 MPa). Disorientation of alite mineral blocks against each other, a significant amount of microcracks, affect the increase in cement specific surface area of 14,3-21,6 %, which leads to activity growth of the system. Along with this, with the rapid cooling of the samples, alite 54CaO- 16SiO2-Al2O3 MgO is formed, with single units of the structure, more deformed relatively to C3S, which has a positive effect on the hydraulic cement activity.

  18. Influence of carbonation on the acid neutralization capacity of cements and cement-solidified/stabilized electroplating sludge.

    PubMed

    Chen, Quanyuan; Zhang, Lina; Ke, Yujuan; Hills, Colin; Kang, Yanming

    2009-02-01

    Portland cement (PC) and blended cements containing pulverized fuel ash (PFA) or granulated blast-furnace slag (GGBS) were used to solidify/stabilize an electroplating sludge in this work. The acid neutralization capacity (ANC) of the hydrated pastes increased in the order of PC > PC/GGBS > PC/PFA. The GGBS or PFA replacement (80 wt%) reduced the ANC of the hydrated pastes by 30-50%. The ANC of the blended cement-solidified electroplating sludge (cement/sludge 1:2) was 20-30% higher than that of the hydrated blended cement pastes. Upon carbonation, there was little difference in the ANC of the three cement pastes, but the presence of electroplating sludge (cement/sludge 1:2) increased the ANC by 20%. Blended cements were more effective binders for immobilization of Ni, Cr and Cu, compared with PC, whereas Zn was encapsulated more effectively in the latter. Accelerated carbonation improved the immobilization of Cr, Cu and Zn, but not Ni. The geochemical code PHREEQC, with the edited database from EQ3/6 and HATCHES, was used to calculate the saturation index and solubility of likely heavy metal precipitates in cement-based solidification/stabilization systems. The release of heavy metals could be related to the disruption of cement matrices and the remarkable variation of solubility of heavy metal precipitates at different pH values. PMID:19062068

  19. Effect of stem preheating and precooling on residual stress formation at stem/cement interface for cemented hip implants.

    PubMed

    Madrala, A; Nuño, N

    2010-04-01

    PMMA polymerization is an exothermic phenomenon during which stresses and porosity are observed. An experimental model is devised to directly measure radial forces, to be converted to radial stresses, at the stem/cement interface, and temperatures at both interfaces during cement curing. The effects of stem and bone cement initial temperatures (preheating or precooling vs. room temperature) as well as mixing method (hand vs. vacuum mixing) and cement type (Simplex P vs. Palacos R) on radial stress and temperatures are investigated. Compressive radial residual stresses at the stem/cement interface are measured for hand mixed PMMA with preheated stem, with a maximum magnitude of 1.0 MPa. No radial residual stresses are observed when the stem is initially at room temperature or precooled, suggesting that during curing, bone cement can polymerize away from the stem/cement interface generating radial stress in tension or gaps. The results demonstrate the reverse direction of polymerization for preheated stems. Stem preheating significantly increases transient temperatures at the bone/cement interface and also the risk of bone thermal necrosis, because the exposure time to high temperature is prolonged. The results provide interfacial characteristics for accurate modeling of bone cement polymerization to better understand the debonding process of cemented hip prostheses. PMID:20091924

  20. Quantitative characterization of the microstructure of fresh cement paste via random packing of polydispersed Platonic cement particles

    NASA Astrophysics Data System (ADS)

    Xu, W. X.; Chen, H. S.

    2012-10-01

    On a microscopic scale, fresh cement paste is composed of random packing of irregular cement particles, and their initial packing behavior plays an important role in microstructural evolution. The preponderance of previous works has focused on the microstructure model by random packing of three-dimensional spheroidal particles, and little is known about non-spheroidal particles. In this paper, a modified cement particle size distribution function is used to facilitate the particle size distribution of convex polyhedral cement particles. Based on an overlapping detection algorithm, the microstructure model of fresh cement paste is simulated by the random sequential packing of Platonic cement particles of various sizes. Applying stereological tools and the serial sectioning analysis technique, the modeling microstructure composed of polydispersed Platonic cement particles is characterized and compared with that of ellipsoidal cement particles with various aspect ratios. The statistical results are investigated to evaluate the influence of cement particle shape on the microstructure of fresh cement paste. Finally, with the derived experimental and numerical results of microstructural parameters, the reliability of the statistical results is verified.

  1. Synthesis and hardening of fluoralinite cement

    Microsoft Academic Search

    A. KANTAUTAS; G. VAICKELIONIS PALUBINSKAIT

    The synthesis of fluoralinite cement and its hydration properties are presented. It was determined that fluoralinite is obtained after 4 hrs of burning at 1100 °C by using an initial composition of 0.89% Al2O3, 1.78% MgO, and 0.89% Fe2O3 additions. Specimens formed from fluoralinite clinker and ground sand (with a mass ratio of 1:3), hydrothermally cured at 175 °C for

  2. Mortality and cancer morbidity among cement workers.

    PubMed Central

    Jakobsson, K; Horstmann, V; Welinder, H

    1993-01-01

    OBJECTIVE--To explore associations between exposure to cement dust and cause specific mortality and tumour morbidity, especially gastrointestinal tumours. DESIGN--A retrospective cohort study. SUBJECTS AND SETTING--2400 men, employed for at least 12 months in two Swedish cement factories. MAIN OUTCOME MEASURES--Cause specific morality from death certificates (1952-86). Cancer morbidity from tumour registry information (1958-86). Standardised mortality rates (SMRs; national reference rates) and standardised morbidity incidence rates (SIRs; regional reference rates) were calculated. RESULTS--An increased risk of colorectal cancer was found > or = 15 years since the start of employment (SIR 1.6, 95% confidence interval (95% CI) 1.1-2.3), mainly due to an increased risk for tumours in the right part of the colon (SIR 2.7, 95% CI 1.4-4.8), but not in the left part (SIR 1.0, 95% CI 0.3-2.5). There was a numerical increase of rectal cancer (SIR 1.5, 95% CI 0.8-2.5). Exposure (duration of blue collar employment)-response relations were found for right sided colon cancer. After > or = 25 years of cement work, the risk was fourfold (SIR 4.3, 95% CI 1.7-8.9). There was no excess of stomach cancer or respiratory cancer. Neither total mortality nor cause specific mortality were significantly increased. CONCLUSIONS--Diverging risk patterns for tumours with different localisations within the large bowel were found in the morbidity study. Long term exposure to cement dust was a risk factor for right sided colon cancer. The mortality study did not show this risk. PMID:8457494

  3. Cement Kiln Flue Gas Recovery Scrubber Project

    SciTech Connect

    National Energy Technology Laboratory

    2001-11-30

    The Cement Kiln Flue Gas Recovery Scrubber Project was a technical success and demonstrated the following: CKD can be used successfully as the sole reagent for removing SO2 from cement kiln flue gas, with removal efficiencies of 90 percent or greater; Removal efficiencies for HCl and VOCs were approximately 98 percent and 70 percent, respectively; Particulate emissions were low, in the range of 0.005 to 0.007 grains/standard cubic foot; The treated CKD sorbent can be recycled to the kiln after its potassium content has been reduced in the scrubber, thereby avoiding the need for landfilling; The process can yield fertilizer-grade K2SO4, a saleable by-product; and Waste heat in the flue gas can provide the energy required for evaporation and crystallization in the by-product recovery operation. The demonstration program established the feasibility of using the Recovery Scrubber{trademark} for desulfurization of flue gas from cement kilns, with generally favorable economics, assuming tipping fees are available for disposal of ash from biomass combustion. The process appears to be suitable for commercial use on any type of cement kiln. EPA has ruled that CKD is a nonhazardous waste, provided the facility meets Performance Standards for the Management of CKD (U.S. Environmental Protection Agency 1999d). Therefore, regulatory drivers for the technology focus more on reduction of air pollutants and pollution prevention, rather than on treating CKD as a hazardous waste. Application of the Recovery Scrubbe{trademark} concept to other waste-disposal operations, where pollution and waste reductions are needed, appears promising.

  4. Dry electrical discharge machining of cemented carbide

    Microsoft Academic Search

    ZhanBo Yu; Takahashi Jun; Kunieda Masanori

    2004-01-01

    Dry electrical discharge machining (dry EDM) has characteristics of high work removal rate and low tool electrode wear ratio. Hence dry EDM is suitable for three-dimensional milling of difficult-to-cut materials, such as cemented carbide. We compared machining characteristics between dry EDM milling, oil EDM milling and oil die sinking EDM and found that dry EDM milling is most advantageous to

  5. Friction and wear behaviour of cemented carbides

    Microsoft Academic Search

    Jüri Pirso; Sergei Letunovitš; Mart Viljus

    2004-01-01

    In this paper the friction and sliding wear of WC–Co cemented carbides are studied. Friction and wear tests were carried out using six different WC–Co alloys (Co ranging from 6 to 20wt.%) under unlubricated conditions against steel (0.45wt.% C) disk. Tests were performed at sliding velocity of 2.2ms?1 and normal load of 40 and 180N. Sliding wear tests were carried

  6. Effective Permeability Change in Wellbore Cement with Carbon Dioxide Reaction

    SciTech Connect

    Um, Wooyong; Jung, Hun Bok; Martin, Paul F.; McGrail, B. Peter

    2011-11-01

    Portland cement, a common sealing material for wellbores for geological carbon sequestration was reacted with CO{sub 2} in supercritical, gaseous, and aqueous phases at various pressure and temperature conditions to simulate cement-CO{sub 2} reaction along the wellbore from carbon injection depth to the near-surface. Hydrated Portland cement columns (14 mm diameter x 90 mm length; water-to-cement ratio = 0.33) including additives such as steel coupons and Wallula basalt fragments were reacted with CO{sub 2} in the wet supercritical (the top half) and dissolved (the bottom half) phases under carbon sequestration condition with high pressure (10 MPa) and temperature (50 C) for 5 months, while small-sized hydrated Portland cement columns (7 mm diameter x 20 mm length; water-to-cement ratio = 0.38) were reacted with CO{sub 2} in dissolved phase at high pressure (10 MPa) and temperature (50 C) for 1 month or with wet CO{sub 2} in gaseous phase at low pressure (0.2 MPa) and temperature (20 C) for 3 months. XMT images reveal that the cement reacted with CO{sub 2} saturated groundwater had degradation depth of {approx}1 mm for 1 month and {approx}3.5 mm for 5 month, whereas the degradation was minor with cement exposure to supercritical CO{sub 2}. SEM-EDS analysis showed that the carbonated cement was comprised of three distinct zones; the innermost less degraded zone with Ca atom % > C atom %, the inner degraded zone with Ca atom % {approx} C atom % due to precipitation of calcite, the outer degraded zone with C atom % > Ca atom % due to dissolution of calcite and C-S-H, as well as adsorption of carbon to cement matrix. The outer degraded zone of carbonated cement was porous and fractured because of dissolution-dominated reaction by carbonic acid exposure, which resulted in the increase in BJH pore volume and BET surface area. In contrast, cement-wet CO{sub 2}(g) reaction at low P (0.2 MPa)-T (20 C) conditions for 1 to 3 months was dominated by precipitation of micron-sized calcite on the outside surface of cement, which resulted in the decrease in BJH pore volume and BET surface area. Cement carbonation and pore structure change are significantly dependent on pressure and temperature conditions as well as the phase of CO{sub 2}, which controls the balance between precipitation and dissolution in cement matrix. Geochemical modeling result suggests that ratio of solid (cement)-to-solution (carbonated water) has a significant effect on cement carbonation, thus the cement-CO{sub 2} reaction experiment needs to be conducted under realistic conditions representing the in-situ wellbore environment of carbon sequestration field site. Total porosity and air permeability for a duplicate cement column with water-to-cement ratio of 0.38 measured after oven-drying by Core Laboratories using Boyle's Law technique and steady-state method were 31% and 0.576 mD. A novel method to measure the effective liquid permeability of a cement column using X-ray micro-tomography images after injection of pressurized KI (potassium iodide) is under development by PNNL. Preliminary results indicate the permeability of a cement column with water-to-cement ratio of 0.38 is 4-8 mD. PNNL will apply the method to understand the effective permeability change of Portland cement by CO{sub 2}(g) reaction under a variety of pressure and temperature conditions to develop a more reliable well-bore leakage risk model.

  7. Antibiotic-Loaded Cement in Orthopedic Surgery: A Review

    PubMed Central

    Bistolfi, Alessandro; Massazza, Giuseppe; Verné, Enrica; Massè, Alessandro; Deledda, Davide; Ferraris, Sara; Miola, Marta; Galetto, Fabrizio; Crova, Maurizio

    2011-01-01

    Infections in orthopaedic surgery are a serious issue. Antibiotic-loaded bone cement was developed for the treatment of infected joint arthroplasties and for prophylaxes in total joint replacement in selected cases. Despite the widespread use of the antibiotic-loaded bone cement in orthopedics, many issues are still unclear or controversial: bacterial adhesion and antibiotic resistance, modification of mechanical properties which follows the addition of the antibiotic, factors influencing the release of the antibiotic from the cement and the role of the surface, the method for mixing the cement and the antibiotic, the choice and the effectiveness of the antibiotic, the combination of two or more antibiotics, and the toxicity. This review discusses all these topics, focusing on properties, merits, and defects of the antibiotic loaded cement. The final objective is to provide the orthopaedic surgeons clear and concise information for the correct choice of cement in their clinical practice. PMID:24977058

  8. Class G cement in Brazil - A statistical approach

    SciTech Connect

    Rosa, F.C.; Coelho, O. Jr.; Parente, F.J. (Petrobras S.A., Rio de Janeiro (Brazil))

    1993-09-01

    Since 1975, Petrobras has worked with Brazilian Portland cement manufacturers to develop high-quality Class G cements. The Petrobras R and D Center has analyzed each batch of Class G cement manufactured by prequalified producers to API Spec. 10 standards and to Brazilian Assoc. of Technical Standards (ABNT) NBR 9831 standards. As a consequence, the Drilling Dept. at Petrobras now is supplied by three approved Class G cement factories strategically located in Brazil. This paper statistically analyzes test results on the basis of physical parameters of these Class G cements over 3 years. Statistical indices are reported to evaluate dispersion of the physical properties to obtain a reliability index for each Class G cement.

  9. Field measurements of annular pressure and temperature during primary cementing

    SciTech Connect

    Cooke, C.E.; Kluck, M.P.; Medrano, R.

    1983-03-01

    This paper investigates the causes of fluid migration behind the well casing after primary cementing through methods of pressure and temperature measurement in the annulus of seven wells during cementing operations. A variety of logging methods are used. The pressure data resulting from these measurements could be used to determine conditions that either prevented or allowed fluid entry into the wellbore. The temperature measurements in the annulus were used to monitor the setting of the cement and the accompanying evolution of heat. These field data confirm laboratory data that show a pressure decline in a cement column as the cement cures. Conditions more likely to lead to annular fluid migration before the cement sets and steps that can be taken to decrease the likelihood of these occurrences can be identified from the field results. The acronym FILAP is suggested for the phenomenon of flow induced by the loss of annular pressure.

  10. Treating root-surface caries

    Microsoft Academic Search

    John O. Burgess; John R. Gallo

    2002-01-01

    Gingival recession associated with aging and periodontal therapy exposes root surfaces, which are then susceptible to root caries. Resin-modified glass ionomer, glass ionomer, compomer, composite resin, and amalgam restora- tive materials are frequently used to restore carious root lesions. Amalgam continues to be used successfully to restore root caries. Resin composites, compomers, glass ionomers, and resin-modified glass ionomers are increas-

  11. Shrinkage deformation of cement foam concrete

    NASA Astrophysics Data System (ADS)

    Kudyakov, A. I.; Steshenko, A. B.

    2015-01-01

    The article presents the results of research of dispersion-reinforced cement foam concrete with chrysotile asbestos fibers. The goal was to study the patterns of influence of chrysotile asbestos fibers on drying shrinkage deformation of cement foam concrete of natural hardening. The chrysotile asbestos fiber contains cylindrical fiber shaped particles with a diameter of 0.55 micron to 8 microns, which are composed of nanostructures of the same form with diameters up to 55 nm and length up to 22 microns. Taking into account the wall thickness, effective reinforcement can be achieved only by microtube foam materials, the so- called carbon nanotubes, the dimensions of which are of power less that the wall pore diameter. The presence of not reinforced foam concrete pores with perforated walls causes a decrease in its strength, decreases the mechanical properties of the investigated material and increases its shrinkage. The microstructure investigation results have shown that introduction of chrysotile asbestos fibers in an amount of 2 % by weight of cement provides the finely porous foam concrete structure with more uniform size closed pores, which are uniformly distributed over the volume. This reduces the shrinkage deformation of foam concrete by 50%.

  12. Properties and hydration of blended cements with calcareous diatomite

    Microsoft Academic Search

    D. Kastis; G. Kakali; S. Tsivilis; M. G. Stamatakis

    2006-01-01

    In this paper the effect of diatomite addition on blended cement properties and hydration was studied. Calcareous diatomaceous rocks of Zakynthos Island, Ionian Sea, containing mainly CaCO3 and amorphous silica of biogenic origin with the form of opal-A were used. Cement mortars and pastes, with 0%, 10%, 20% and 35% replacement of cement with the specific diatomite, were examined. Strength

  13. The use of vancomycin and tobramycin in acrylic bone cement

    Microsoft Academic Search

    John Klekamp; John M. Dawson; David W. Haas; David DeBoer; Michael Christie

    1999-01-01

    We examined the effects of vancomycin on the compressive strength and fatigue life of bone cement and the pharmacokinetics and antimicrobial activity against methicillin-resistant Staphylococcus aureus of vancomycin eluted from bone cement, both alone and in combination with tobramycin. Two cements, Palacos and Simplex, were tested. Three antibiotic preparations were tested: lyophilized vancomycin (vancomycin-L), vancomycin powder (vancomycin-P), and tobramycin powder

  14. Brazilian waste fibres as reinforcement for cement-based composites

    Microsoft Academic Search

    H Savastano; P. G Warden; R. S. P Coutts

    2000-01-01

    Fibre reinforced cement-based composites were prepared using kraft pulps from sisal and banana waste and from Eucalyptus grandis pulp mill residues. The study adapted conventional chemical pulping conditions for the non-wood strands and a slurry vacuum de-watering method for composite preparation followed by air-curing. Plain cement paste and Pinus radiata kraft reinforced cement composites were used as reference materials. Mechanical

  15. Thermal characterization of PMMA-based bone cement curing.

    PubMed

    Li, Chaodi; Mason, James; Yakimicki, Don

    2004-01-01

    In thermal characterization tests of polymethylmethacrylate bone cement performed according to the ASTM Standard Specification for Acrylic Bone Cement, time-temperature profiles of bone cement were observed to be sensitive to the thickness of the cement patty and the mold material. Due to the heat transfer from cement to the surrounding mold, such tests might underestimate the exothermic temperature of bone cement. Developing test methods to better characterize cement thermal behavior is necessary for accurate cement curing simulations. In this paper, the effects of the mold material and geometry on experimental measurements of bone cement setting temperature and setting time were evaluated by conducting the polymerization in different test molds. Finite element (FE) numerical simulations were also performed to provide a further understanding of these effects. It was found that the mold material and geometry significantly influence the values of the parameters measured using the ASTM standard. Results showed that the setting temperature measured was about 50 degrees C lower in a polytetrafluoroethylene (PTFE) mold than in a polyurethane (PU) foam mold for the 6 mm thickness cement. The measured peak temperature using PTFE molds varied about 75 degrees C for different mold heights (6mm vs. 40 mm), but only by 28 degrees C with PU molds. The measured setting time with PTFE molds varied by about 740 s for different mold heights (6 mm vs. 40 mm), while only by about 130 s for PU molds. Using PU foam materials for the test mold decreases cement heat transfer effects due to the poor heat conductivity of PU foam and provides more consistent measured results. FE parametric studies also support these observations. Poor conductivity materials, like PU foam, make better molds for the characterization of bone cement thermal behavior. PMID:15338595

  16. Feasibility of using recycled glass in architectural cement mortars

    Microsoft Academic Search

    Tung-Chai Ling; Chi-Sun Poon; Shi-Cong Kou

    2011-01-01

    The feasibility of using 100% recycled glass (RG) as a fine aggregate replacement in architectural white cement mortar was investigated. All the cement mortar mixtures were proportioned with a fixed water to binder ratio of 0.40. The dosage of superplasticizer was varied to produce highly workable recycled glass self-compacting white cement mortar (RG-SCWM) mixtures. Metakaolin (MK) was used in the

  17. Aseptic loosening of BonelocR cemented hip prostheses.

    PubMed

    Wedderkopp, N; Andersen-Ranberg, F; Andersen, M B; Termansen, N B

    1997-01-01

    We present a systematic clinical and radiographic study of 147 patients who had total hip replacements from February 1992 to May 1993. BonelocR cement was used in 108, and PalacosR cement with gentamicin in 39 patients who had an increased risk of infection. At follow-up after 24 to 39 months, 26 cases with BonelocR cement had failed; there were no clinical failures in the PalacosR group. PMID:9195259

  18. Characterisation of cement pastes by inverse gas chromatography

    Microsoft Academic Search

    Victor Oliva; Béchir Mrabet; Maria Inês Baeta Neves; Mohamed M. Chehimi; Karim Benzarti

    2002-01-01

    Two cement pastes, commonly used in concrete formulations, were characterised by IGC at 35–80°C before and after coating with an epoxy resin and a hardener. The cements are mixtures of hydrates in various proportions, such as calcium silicate hydrate (CaO–SiO2–H2O) and calcium hydroxide Ca(OH)2. Apolar and polar probes were used to determine the dispersive and acid–base characteristics of the cement

  19. Injectable acrylic bone cements for vertebroplasty with improved properties

    Microsoft Academic Search

    2004-01-01

    Currently commercially available acrylic bone cements lack adequate radiopacity and viscosity when they are used in percutaneous vertebroplasty (PVP). In this work improved formulations of radiopaque and injectable poly(methyl methacrylate) bone cements were prepared with different amounts (10 -50 wt.%) of BaTiO3 or SrTiO3 particles as the ra- diopaque agent. Two sets of cements were prepared by using untreated or

  20. Physical structure of hardened cement paste. A classical approach

    Microsoft Academic Search

    Torben C. Hansen

    1986-01-01

    It is explained how the classical model of the structure of hardened Portland cement paste was deduced by T.C. Powers and\\u000a coworkers from data on water vapor adsorption isotherms. Moreover, it is shown how the fractional volumes of all major constituents\\u000a in the physical structure of room temperature cured Portland cement paste can be estimated from information on water-cement\\u000a ratio

  1. Full density processing of complex WC-based cemented carbides

    Microsoft Academic Search

    S. K. Bhaumik; G. S. Upadhyaya; M. L. Vaidya

    1996-01-01

    The present investigation was a study of the densification behaviour of some complex WC-based cemented carbides containing TiC\\/TiN. Sintering experiments showed that a fully dense product can be obtained from cemented carbides containing TiC by liquid phase sintering, but TiC addition to WC-10 Co-cemented carbide necessitated modification of the binder phase cobalt by incorporating nickel and molybdenum in order to

  2. Calorimetric Study of Frost Attack During Cement Hardening

    Microsoft Academic Search

    A. Usherov-Marshak; O. Zlatkovski; V. Sopov

    2002-01-01

    This report deals with practical and experimental studies of the effects of frost attack on hardening cement stone and concrete.\\u000a The basic component of concrete, cement stone, is a typical capillary-porous material formed from solid, liquid and gaseous\\u000a phases. The level of knowledge on the effects of frost attack on cement stone and concrete hardening is insufficient, due\\u000a to the

  3. Chitosan implants in the rat spinal cord: biocompatibility and biodegradation.

    PubMed

    Kim, Howard; Tator, Charles H; Shoichet, Molly S

    2011-06-15

    Biomaterials are becoming increasingly popular for use in spinal cord repair, but few studies have investigated their long-term biocompatibility in central nervous system tissue. In this study, chitosan was compared with two commercial materials, degradable polyglycolide (vicryl and polyglactin 910) and nondegradable expanded poly(tetrafluoroethylene) (Gore-Tex and ePTFE), in terms of host tissue response and biodegradation in the rat spinal cord in two different spinal cord implantation models. In an uninjured model, implants were placed in the spinal cord intrathecal space for up to 6 months. At 1 month, vicryl implants elicited an elevated macrophage/microglia response compared to chitosan and Gore-Tex, which subsided in all groups by 6 months. Fibrous encapsulation was observed for all three materials. At 6 months, the in vivo degradation of vicryl was complete, while Gore-Tex showed no signs of degradation, as assessed by mass loss and SEM. Chitosan implants showed evidence of chain degradation at 6 months as demonstrated by differential hematoxylin and eosin staining; however, this did not result in mass loss. In the second model, implants were placed directly into the spinal cord for up to 12 months. This resulted in increased immune and inflammatory responses but did not alter degradation profiles. The same trends observed for the materials in the intrathecal space were mirrored in the spinal cord tissue. These results demonstrate that chitosan is a relatively inert biomaterial that does not elicit a chronic immune response and is suitable for long-term applications for repair of the spinal cord. PMID:21465644

  4. HEMOCOMPATIBILITY AND BIOCOMPATIBILITY OF ANTIBACTERIAL BIOMIMETIC HYBRID FILMS

    PubMed Central

    Ferrer, M. Carme Coll; Eckmann, Uriel N.; Composto, Russell J.; Eckmann, David M.

    2013-01-01

    In previous work, we developed novel antibacterial hybrid coatings based on dextran containing dispersed Ag NPs (~5nm, DEX-Ag) aimed to offer dual protection against two of the most common complications associated with implant surgery, infections and rejection of the implant. However, their blood-material interactions are unknown. In this study, we assess the hemocompatibility and biocompatibility of DEX-Ag using fresh blood and two cell lines of the immune system, monocytes (THP-1 cells) and macrophages (PMA-stimulated THP-1 cells). Glass, polyurethane (PU) and bare dextran (DEX) were used as reference surfaces. PU, DEX and DEX-Ag exhibited non-hemolytic properties. Relative to glass (100%), platelet attachment on PU, DEX and DEX-Ag was 15%, 10% and 34%, respectively. Further, we assessed cell morphology and viability, pro-inflammatory cytokines expression (TNF-? and IL-1?), pro-inflammatory eicosanoid expression (Prostaglandin E2, PGE2) and release of reactive oxygen species (ROS, superoxide and H2O2) following incubation of the cells with the surfaces. The morphology and cell viability of THP-1 cells were not affected by DEX-Ag whereas DEX-Ag minimized spreading of PMA-stimulated THP-1 cells and caused a reduction in cell viability (16% relative to other surfaces). Although DEX-Ag slightly enhanced release of ROS, the expression of pro-inflammatory cytokines remained minimal with similar levels of PGE2, as compared to the other surfaces studied. These results highlight low toxicity of DEX-Ag and hold promise for future applications in vivo. PMID:23933530

  5. An alternative to Portland Cement for waste encapsulation--the calcium sulfoaluminate cement system.

    PubMed

    Zhou, Q; Milestone, N B; Hayes, M

    2006-08-10

    Currently, Portland Cement (PC) is used extensively in the solidification/stabilisation of a wide variety of wastes. In the nuclear industry, low and intermediate level radioactive wastes are encapsulated or immobilised within composite PC cement systems based on high replacement with blast furnace slag or fly ash. However, the high alkalinity of these PC-based systems will corrode reactive metals found in some wastes releasing hydrogen and forming expansive corrosion products. Alternative cement systems could provide a different hydration chemistry, which would allow wastes containing these metals to be encapsulated with lower reactivity. Calcium sulfoaluminate (CS A) cement is one such cement. It combines economy of cost and low emission of CO(2) with rapid strength gain and compatibility with other construction materials. Hydration provides an internal pore solution where the pH is considerably lower than that of PC. The main hydration product, ettringite, can incorporate a number of ions into its crystal structure, making it an ideal candidate for waste immobilisation. This paper details some results from a commercial CS A system that examines aspects of mixing, hydration of different formulations and aluminium corrosion behaviour. The fluidity of mixes can be adjusted by changing the formulations. All designed mixes were set within 24 h with little bleeding and the pH values were in the range of 10-11.5. In addition, a significant reduction in Al corrosion was observed compared to a composite OPC system. Although these results provide encouragement for the idea that CS A cement can provide a possible alternative to PC in the immobilisation of difficult and reactive wastes, further investigation is needed. PMID:16406289

  6. Identification of active agents for tetrachloroethylene degradation in Portland cement slurry containing ferrous iron 

    E-print Network

    Ko, Sae Bom

    2006-08-16

    -EDS) were used to identify minerals in chemical mixtures that have high activities. Results indicate that active agents for PCE degradation in Portland cement slurries and in cement extracts might be one of several AFm phases. However, systems without cement...

  7. 21 CFR 888.3100 - Ankle joint metal/composite semi-constrained cemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Ankle joint metal/composite semi-constrained cemented prosthesis... § 888.3100 Ankle joint metal/composite semi-constrained cemented prosthesis...Identification. An ankle joint metal/composite semi-constrained cemented...

  8. 30 CFR 250.422 - When may I resume drilling after cementing?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false When may I resume drilling after cementing? 250...AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Drilling Operations Casing and Cementing...422 When may I resume drilling after cementing?...

  9. 30 CFR 250.422 - When may I resume drilling after cementing?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false When may I resume drilling after cementing? 250...AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Drilling Operations Casing and Cementing...422 When may I resume drilling after cementing?...

  10. Mechanical properties of WC10Co cemented carbides sintered from nanocrystalline spray conversion processed powders

    E-print Network

    Hong, Soon Hyung

    Mechanical properties of WC±10Co cemented carbides sintered from nanocrystalline spray conversion properties and microstructures of nanocrystalline WC±10Co cemented carbides were investigated. The nanocrys- talline WC±10Co cemented carbide powders were manufactured by reduction and carbonization

  11. Radiographic and histologic analysis of cemented double tapered femoral stems.

    PubMed

    Brumby, S A; Howie, D W; Pearcy, M J; Wang, A W; Nawana, N S

    1998-10-01

    The macroscopic, radiographic, and histologic features of the prosthesis-cement and cementbone interfaces and adjacent bone were studied in 21 cemented hemiarthroplasties in sheep that had lived until sacrifice at 9 months. The features were compared with those immediately after implantation of the stem in the contralateral femur. The femoral stem was a double taper that was either polished collarless, matte collarless, or matte collared. There was no prosthesis to cement debonding or cement to bone radiolucent line immediately after implantation, and there was excellent interdigitation at the cement-bone interface. After 9 months there was no evidence of prosthesis to cement debonding and no stem with definite loosening. At 9 months after implantation there was evidence of bone remodeling with new bone filling what were presumed to be gaps at the cement-bone interface from immediately after implantation. Radiolucent lines at the cement-bone interface were found to represent trabeculation of the cortical bone rather than the presence of a complete fibrous interface, which was not seen. There was no difference between stem types. Sheep have been shown to be useful in a model of cemented hip arthroplasty and, although no differences were seen between stem types at 9 months after implantation, long term differences cannot be excluded. PMID:9917608

  12. Electrically induced temperature difference and deformation in hardened cement pastes

    SciTech Connect

    Sun Mingqing [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China)]. E-mail: sunmingqing@yahoo.com; Wang Xiaoying [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China); Zhao Kairui [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China); Li Zhuoqiu [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China)

    2006-12-15

    Electromechanical effect of hardened cement paste beam is investigated in this paper. When an external electrical current is applied to the electrodes attached to opposite surfaces of a cement beam, it is found that temperature on the positive electrode is always higher than that on the negative electrode. The sign of electrically induced temperature difference is determined by the direction of applied electrical current. Electrically induced temperature difference makes the beam bend towards the surface with a higher temperature. Both electrically induced temperature difference and electroosmosis lead to electromechanical effect of hardened cement paste. Finally, electromechanical effect becomes more obvious by adding NaCl to cement paste.

  13. Soft X-ray Microscopy of Green Cements

    SciTech Connect

    Monteiro, P. J. M.; Mancio, M.; Chae, R.; Ha, J. [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States); Kirchheim, A. P. [Department of Civil Engineering, Federal University of Rio Grande do Sul, Porto Alegre, RS, 90035-190 (Brazil); Fischer, P. [Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley CA, 94720 (United States); Tyliszczak, T. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley CA, 94720 (United States)

    2011-09-09

    The present status of the cement and concrete industry is not sustainable. The production of Portland cement is responsible for 7% of the CO{sub 2} emissions in the world and existing reinforced concrete infrastructure is deteriorating at a fast pace. The change in the existing technology requires new developments in our understanding of the nanostructure of hydration products and the complex deterioration reactions. We have been developing an elaborate research program to advance the existing cement and concrete science by characterizing its nanostructure by synchrotron radiation. A new generation of green cements is being studied using high-resolution soft x-ray microscopy at the nano-level.

  14. Sorption of radionuclides onto cement materials altered by hydrothermal reaction

    SciTech Connect

    Sugiyama, D.; Fujita, T.

    1999-07-01

    The sorption of radionuclides onto cement materials is a very important parameter when considering the release of radionuclides from radioactive wastes. Once the composition or crystallinity of the constituent minerals of a cement material is changed by alteration in the disposal environment, its sorption ability might be affected. In this study, the effect of hydrothermal alteration on the sorption properties of two cement grouts and Calcium Silicate Hydrogels (CSH-gels) is investigated by using the batch sorption technique. In the case of strontium (a model cation) sorption, the distribution ratio for Ordinary Portland Cement (OPC) and OPC/Blast Furnace Slag blended cement (OPC/BFS) decreased as the alteration temperature increased. This is mainly caused by the decrease of sorption onto CSH-gel which is a constituent of cement materials. In the case of selenium (selenite, a model anion) sorption, the distribution ratio decreased as the alteration temperature increased for OPC treated in both distilled water and groundwater, and for OPC/BFS in groundwater. This is attributed to the decomposition of ettringite which sorbs anions. The distribution ratio for OPC/BFS in distilled water increased as the alteration temperature increased, although ettringite decomposed. This is attributed to the formation of monosulfate which also sorbs anions. These results show that the hydrothermal alteration of cement mineral phases in a disposal environment may cause changes which could increase or decrease the sorption of radionuclides onto cements depending on the cement composition and radionuclide speciation.

  15. Results: Blended Cements Survey -2012 Recently, ASTM and AASHTO have approved changes to their blended cement specifications, ASTM C595 and AASHTO M 240,

    E-print Network

    Results: Blended Cements Survey - 2012 Recently, ASTM and AASHTO have approved changes to their blended cement specifications, ASTM C595 and AASHTO M 240, respectively. The changes allow for a new type cement. CO: Our DOT has had several projects ASTM C1157 cement with positive results. WI: Need more field

  16. Lehigh Southwest Cement Company: Compressed Air System Improvement Saves Energy at a Lehigh Southwest Cement Plant

    SciTech Connect

    Not Available

    2003-10-01

    In 2001, Lehigh Southwest Cement Company improved the compressed air system at its cement plant in Tehachapi, California. Consequently, the system was able to operate more efficiently with less compressor capacity and at a lower system pressure. The project yielded total annual savings of 895,000 kWh and $199,000. The initial project cost was $417,000, but Southern California Edison provided a $90,000 incentive payment to reduce the cost to $327,000. Simple payback was about 20 months.

  17. Influence of polymer on cement hydration in SBR-modified cement pastes

    SciTech Connect

    Wang Ru [Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, School of Materials Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China) and Institute of Cement-Based Materials, School of Materials Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China)]. E-mail: wr_irene@163.com; Li Xingui [Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, School of Materials Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Institute of Cement-Based Materials, School of Materials Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Wang Peiming [Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, School of Materials Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Institute of Cement-Based Materials, School of Materials Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

    2006-09-15

    The influence of styrene-butadiene rubber (SBR) latex on cement hydrates Ca(OH){sub 2}, ettringite, C{sub 4}AH{sub 13} and C-S-H gel and the degree of cement hydration is studied by means of several measure methods. The results of DSC and XRD show that the Ca(OH){sub 2} content in wet-cured SBR-modified cement pastes increases with polymer-cement ratio (P/C) and reaches a maximum when P/C is 5%, 10% and 10% for the pastes hydrated for 3 d, 7 d and 28 d, respectively. With wet cure, appropriate addition of SBR promotes the hydration of cement, while the effect of SBR on the content of Ca(OH){sub 2} and the degree of cement hydration is not remarkable in mixed-cured SBR-modified cement pastes. XRD results illustrate that SBR accelerates the reaction of calcium aluminate with gypsum, and thus enhances the formation and stability of the ettringite and inhibits the formation of C{sub 4}AH{sub 13}. The structure of aluminum-oxide and silicon-oxide polyhedron is characterized by {sup 27}Al and {sup 29}Si solid state NMR spectrum method, which shows that tetrahedron and octahedron are the main forms of aluminum-oxide polyhedrons in SBR-modified cement pastes. There are only [SiO{sub 4}]{sup 4-} tetrahedron monomer and dimer in the modified pastes hydrated for 3 d, but there appears three-tetrahedron polymer in the modified pastes hydrated for 28 d. The effect of low SBR dosage on the structure of aluminum-oxide and silicon-oxide polyhedron is slight. However, the combination of Al{sup 3+} with [SiO{sub 4}]{sup 4-} is restrained when P/C is above 15%, and the structure of Al{sup 3+} is changed obviously. Meantime, the polymerization of the [SiO{sub 4}]{sup 4-} tetrahedron in C-S-H gel is controlled.

  18. Shear Properties of Bilaminar Polymethylmethacrylate Cement Mantles in Revision Hip Joint Arthroplasty

    Microsoft Academic Search

    Patrick C. Weinrauch; Cameron Bell; Lance Wilson; Ben Goss; Cameron Lutton; Ross W. Crawford

    2007-01-01

    Although cement-within-cement revision arthroplasty minimizes the complications associated with removal of secure PMMA, failure at the interfacial region between new and old cement mantles remains a theoretical concern. This article assesses the variability in shear properties of bilaminar cement mantles related to duration of postcure and the use of antibiotic cements.Bilaminar cement mantles were 15% to 20% weaker than uniform

  19. A comparison of retentive strength of implant cement depending on various methods of removing provisional cement from implant abutment

    PubMed Central

    Keum, Eun-Cheol

    2013-01-01

    PURPOSE This study evaluated the effectiveness of various methods for removing provisional cement from implant abutments, and what effect these methods have on the retention of prosthesis during the definitive cementation. MATERIALS AND METHODS Forty implant fixture analogues and abutments were embedded in resin blocks. Forty cast crowns were fabricated and divided into 4 groups each containing 10 implants. Group A was cemented directly with the definitive cement (Cem-Implant). The remainder were cemented with provisional cement (Temp-Bond NE), and classified according to the method for cleaning the abutments. Group B used a plastic curette and wet gauze, Group C used a rubber cup and pumice, and Group D used an airborne particle abrasion technique. The abutments were observed using a stereomicroscope after removing the provisional cement. The tensile bond strength was measured after the definitive cementation. Statistical analysis was performed using one-way analysis of variance test (?=.05). RESULTS Group B clearly showed provisional cement remaining, whereas the other groups showed almost no cement. Groups A and B showed a relatively smooth surface. More roughness was observed in Group C, and apparent roughness was noted in Group D. The tensile bond strength tests revealed Group D to have significantly the highest tensile bond strength followed in order by Groups C, A and B. CONCLUSION A plastic curette and wet gauze alone cannot effectively remove the residual provisional cement on the abutment. The definitive retention increased when the abutments were treated with rubber cup/pumice or airborne particle abraded to remove the provisional cement. PMID:24049563

  20. Structure and properties of thermoplastic polyurethanes based on poly(dimethylsiloxane): assessment of biocompatibility.

    PubMed

    Pergal, Marija V; Nestorov, Jelena; Tovilovi?, Gordana; Ostoji?, Sanja; Go?evac, Dejan; Vasiljevi?-Radovi?, Dana; Djonlagi?, Jasna

    2014-11-01

    Properties and biocompatibility of a series of thermoplastic poly(urethane-siloxane)s (TPUSs) based on ?,?-dihydroxy ethoxy propyl poly(dimethylsiloxane) (PDMS) for potential biomedical application were studied. Thin films of TPUSs with a different PDMS soft segment content were characterized by (1) H NMR, quantitative (13) C NMR, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), contact angle, and water absorption measurements. Different techniques (FTIR, AFM, and DMA) showed that decrease of PDMS content promotes microphase separation in TPUSs. Samples with a higher PDMS content have more hydrophobic surface and better waterproof performances, but lower degree of crystallinity. Biocompatibility of TPUSs was examined after attachment of endothelial cells to the untreated copolymer surface or surface pretreated with multicomponent protein mixture, and by using competitive protein adsorption assay. TPUSs did not exhibit any cytotoxicity toward endothelial cells, as measured by lactate dehydrogenase and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assays. The untreated and proteins preadsorbed TPUS samples favored endothelial cells adhesion and growth, indicating good biocompatibility. All TPUSs adsorbed more albumin than fibrinogen in competitive protein adsorption experiment, which is feature regarded as beneficial for biocompatibility. The results indicate that TPUSs have good surface, thermo-mechanical, and biocompatible properties, which can be tailored for biomedical application requirements by adequate selection of the soft/hard segments ratio of the copolymers. PMID:24376027