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1

Biocompatibility of glass ionomer cements with and without chlorhexidine  

PubMed Central

Objective: The aim of the present study is to evaluate the biocompatibility of glass ionomer cements (GICs) with and without chlorhexidine (CHX) as well as coated with varnish or not using in vitro cytotoxicity test. Materials and Methods: Biocompatibility of Fuji IX, Fuji IX with varnish, Fuji IX with 1% CHX diacetate and Fuji IX with 1% CHX diacetate with varnish was determined with in vitro cytotoxicity assay by using L929 mouse connective tissue fibroblasts. After 72 h, cell viabilities were evaluated by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay to determine the effects of the cements on the mitochondrial function and microscopic images were taken by scanning electron microscopy. Results: Statistical analysis was performed by one-way analysis of variance followed by the Bonferroni post-hoc test at a significance level of P < 0.05. 72 h after treatment, there were statistically significant differences between Fuji IX and Fuji IX-CHX (P < 0.001). In addition, the reduction of the cytotoxicity by coating the GICs with varnish was indicative and increased the cell viability ratio (P < 0.001). Conclusions: Fuji IX coated with varnish was found to be the most biocompatible one among others. Thus adding CHX significantly reduced the cell viability, it is assumed that, due to the leakage of CHX and the other components of the GICs to the cell culture medium, the cell viabilities were decreased, so it is highly recommended to use varnish not only to reduce the water loss from the GICs, but also to reduce the cytotoxicity of the GICs. PMID:24966735

Iz, Sultan Gulce; Ertugrul, Fahinur; Eden, Ece; Gurhan, S. Ismet Deliloglu

2013-01-01

2

Glass ionomer cements  

Microsoft Academic Search

Glass ionomer cements have been used in pediatric restorative dentistry for 20 years. Their usefulness in pediatric restorative dentistry is preferential relative to other materi- als because of their fluoride release, chemical adhesion to tooth structure, and availability to use in a variety of clinical scenarios. This paper reviews the use of glass ionomer ma- terials in pediatric restorative dentistry.

Joel H. Berg

2002-01-01

3

Interaction of Glass-ionomer Cements with Moist Dentin  

Microsoft Academic Search

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.

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

2004-01-01

4

Biodegradation of dental composites/glass-ionomer cements.  

PubMed

Studies of the degradation processes, types of tests, and measurements and analyses of substances leaching out from resin-based composite materials and glass-ionomer cements are reviewed. For both types of materials, the initial release rate rapidly decreases to a low, but nearly constant, level. For composites, various types of degradation processes have been demonstrated. Elements from filler particles and degradation products from the resin (e.g., formaldehyde) leak out. Many substances are not properly identified. It is, however, difficult for in vitro and in vivo degradation to be compared. For glass ionomers, a total disintegration of a surface layer is observed, together with a slow release of elements from the bulk. Of the elements released, fluoride is the most interesting. Marked differences have been shown between in vitro and in vivo solubility tests. PMID:1292463

Oilo, G

1992-09-01

5

Reconsidering glass-ionomer cements for direct restorations.  

PubMed

Glass-ionomer cements (GICs) have been used in dentistry for a number of applications, primarily as a base or liner under other direct filling materials or indirect restorative materials, for crown buildup/foundation restorations, or as luting cements for indirect restorations. However, GICs have many unique attributes that make them useful for either a full-contour restoration or sandwich/hybrid restorations where they are synergistic with composite resins. This article, which includes two brief case reports, discusses the potential advantages of GIC for some direct applications where composite resin or other materials may not be the most ideal choice. PMID:24571524

Pitel, Mark L

2014-01-01

6

In-vitro Comparison of the Antimicrobial Properties of Glass Ionomer Cements with Zinc Phosphate Cements  

PubMed Central

White spot lesions are observed in nearly 50% of patients undergoing orthodontic treatment. Long-lasting antibacterial properties of orthodontic cements can reduce this phenomenon. The aim of this research was to compare antimicrobial activity of three commercial glass ionomer cements with three commercial zinc phosphate cements, over time, against streptococcus mutans and candida albicans. Direct contact test (DCT) was used to evaluate the antibacterial and antifungal activity of products after 48 h and 7 days of incubation. The results demonstrated that all the cements presented antibacterial activity but the antibacterial activity of glass ionomer cements was more than that of zinc phosphate cements. Counts of C. albicans after 48 h were lower and statistically different in the GIC group in relation to the control groups. But no differences were observed between GIC and control groups at 7 days. Based on the results of this study, the antimicrobial and mainly antifungal effects of all the cements were so short.

Vahid Dastjerdie, Elaheh; Oskoui, Mahvash; Sayanjali, Elham; Tabatabaei, Fahimeh Sadat

2012-01-01

7

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

PubMed Central

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.

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

8

Glass-ionomer cement restorative materials: a sticky subject?  

PubMed

Glass-ionomer cement (GIC) materials have been in clinical use since their inception 40 years ago. They have undergone several permutations to yield different categories of these materials. Although all GICs share the same generic properties, subtle differences between commercial products may occur. They have a wide range of uses such as lining, bonding, sealing, luting or restoring a tooth. In general, GICs are useful for reasons of adhesion to tooth structure, fluoride release and being tooth-coloured although their sensitivity to moisture, inherent opacity, long-term wear and strength are not as adequate as desired. They are useful in situations where they are not disadvantaged by their comparatively lower physical properties, such as where there is adequate remaining tooth structure to support the material and where they are not subject to heavy occlusal loading. The last decade has seen the use of these materials being extended. However, they are likely to retain their specific niches of clinical application. PMID:21564113

Sidhu, S K

2011-06-01

9

Micronucleus, alkaline, and human 8-oxoguanine glycosylase 1 modified comet assays evaluation of glass-ionomer cements - in vitro.  

PubMed

The purpose of this study was to evaluate the genotoxic potential of components leached from two conventional self-curing glass-ionomer cements (Fuji IX and Ketac Molar), and light-curing, resin modified glass-ionomer cements (Vitrebond, Fuji II LC). Evaluation was performed on human lymphocytes using alkaline and hOGG1 modified comet, and micronucleus assays. Each material, polymerised and unpolymerised, was eluted in extracellular saline (1 cm2 mL-1) for 1 h, 1 day, and 5 days. Cultures were treated with eluates using final dilutions of 10(-2), 10(-3), and 10(-4). Alkaline comet assay did not detect changes in DNA migration of treated cells regardless of the ionomer tested, polymerisation state, and elution duration. Glass ionomers failed to significantly influence micronucleus frequency. No oxidative DNA damage in treated lymphocytes was observed using hOGG1 modified comet assay. Obtained results indicate high biocompatibility of all tested materials used in the study under experimental conditions. PMID:24846952

Gali?, Elizabeta; Tadin, Antonija; Gali?, Nada; Kašuba, Vilena; Mladini?, Marin; Rozgaj, Ružica; Bio?ina-Lukenda, Dolores; Gali?, Ivan; Zelježi?, Davor

2014-06-01

10

Orthodontic bracket bonding with a plasma-arc light and resin-reinforced glass ionomer cement.  

PubMed

Developments in light-curing technology have led to the introduction of a plasma-arc light-curing unit that delivers high-intensity output for faster curing. The purposes of this study were to determine the shear bond strengths of light-cured resin-reinforced glass ionomer cement cured with a plasma-arc light-curing unit and to evaluate the durability of the resultant bond strength with thermal cycling. Comparisons were made between light-cured resin-reinforced glass ionomer cement and light-cured composite resin. Two light-curing units were used in this study: a plasma-arc light-curing unit and a conventional light-curing unit. The mean shear bond strengths of light-cured resin-reinforced glass ionomer cement with the plasma-arc and the conventional light-curing units were 20.3 MPa and 26.0 MPa, respectively. An analysis of variance showed no statistically significant differences between the plasma-arc and the conventional light-curing units. Light-cured resin-reinforced glass ionomer cement and light-cured composite resin demonstrated similar bond strengths and exhibited no statistical differences. There was no statistical difference in bond strength between the teeth that were thermal cycled and those that were not. Failure sites for the brackets bonded with light-cured resin-reinforced glass ionomer cement appeared to be predominantly at the bracket-adhesive interface. The SDs of light-cured composite resin were high for both light-curing units. Whereas the coefficients of variation for light-cured resin-reinforced glass ionomer cement ranged from 20% to 30%, those of light-cured composite resin ranged from 40% to 60%. The bond strength of light-cured resin-reinforced glass ionomer cement cured with either a conventional light-curing unit or a plasma-arc light-curing unit surpassed the clinically required threshold. The plasma-arc light-curing unit may be an advantageous alternative to the conventional light-curing unit for orthodontic bracket bonding with both light-cured resin-reinforced glass ionomer cement and light-cured composite resin. PMID:11455379

Ishikawa, H; Komori, A; Kojima, I; Ando, F

2001-07-01

11

Minimal intervention dentistry II: part 7. Minimal intervention in cariology: the role of glass-ionomer cements in the preservation of tooth structures against caries.  

PubMed

Glass-ionomer cements (GICs) are essential materials in clinical practice because of their versatility, self-adhesion to enamel and dentine, and good biocompatibility. In addition, being chemically cured, with no shrinkage stress, makes them well suited for minimally invasive restorative techniques. This article looks at some of the clinical situations where the chemical adhesion and high biocompatibility of GIC are important for clinical success: excavation of deep carious lesions, fissure sealing and protection of root surfaces against caries. PMID:24852986

Ngo, H; Opsahl-Vital, S

2014-05-01

12

Water sorption characteristics of resin-modified glass-ionomer cements  

Microsoft Academic Search

When restorative materials take up water, their dimensions and structural integrity may be affected. This study determined, using gravimetric measurements, the water sorption characteristics of four resin-modified glass-ionomer cements (RMGICs) immersed in either distilled water or artificial saliva. The dimensional changes on water storage were also determined. The RMGICs exhibited differing characteristics as they absorbed water. Percentage water uptake and

Widchaya Kanchanavasita; H. M. Anstice; Gavin J. Pearson

1997-01-01

13

The Effect of Glass Ionomer and Adhesive Cements on Substance P Expression in Human Dental Pulp  

PubMed Central

Objectives: The purpose of this study was to quantify the effect of glass ionomer and adhesive cements on SP expression in healthy human dental pulp. Study Design: Forty pulp samples were obtained from healthy premolars where extraction was indicated for orthodontic reasons. In thirty of these premolars a Class V cavity preparation was performed and teeth were equally divided in three groups: Experimental Group I: Glass Ionomer cement was placed in the cavity. Experimental Group II: Adhesive Cement was placed in the cavity. Positive control group: Class V cavities only. The remaining ten healthy premolars where extracted without treatment and served as a negative control group. All pulp samples were processed and SP was measured by radioimmunoassay. Results: Greater SP expression was found in the adhesive cement group, followed by the glass ionomer and the positive control groups. The lower SP values were for the negative control group. ANOVA showed statistically significant differences between groups (p<0.0001). Tukey HSD post hoc tests showed statistically significant differences in SP expression between negative control group and the 3 other groups (p<0.01). Differences between the cavity-only group and the two experimental groups were also statistically significant (p<0.05 and p<0.01 respectively). There is also a statistically significant difference between the two experimental groups (p<0.01). Conclusions: These findings suggest that adhesive cements provoke a greater SP expression when compared with glass ionomer. Key words:Glass Ionomer, adhesive cement, Substance P, human dental pulp. PMID:23722145

Ariza-Garcia, German; Camelo, Patricia; Mejia, Monica; Ojeda, Karyn; Azuero-Holguin, Maria M.; Abad-Coronel, Dunia; Munoz, Hugo R.

2013-01-01

14

Antibacterial activity of resin adhesives, glass ionomer and resin-modified glass ionomer cements and a compomer in contact with dentin caries samples.  

PubMed

A total of 103 clinical samples of carious dentin were used to study the antibacterial action of different dental resin adhesive materials (Gluma 2000, Syntac, Prisma Universal Bond 3, Scotchbond Multi-Purpose and Prime&Bond 2.0) glass ionomer cements (Ketac-Cem, Ketac-Bond, Ketac-Silver, Ketac-Fil) resin-modified glass ionomer cements (Fuji II LC, Vitremer and Vitrebond) and a compomer (Dyract). The agar plate diffusion method was used for the microbial cultures and a chlorhexidine control. The growth of the caries-producing microorganisms was effectively inhibited by the Vitremer and Vitrebond cements, and to a lesser extent by the Scotchbond Multi-Purpose adhesive system. Overall, there were statistically significant differences in the antibacterial activity of the products tested. PMID:11203829

Herrera, M; Castillo, A; Bravo, M; Liébana, J; Carrión, P

2000-01-01

15

Antimicrobial Effects of Dental Luting Glass Ionomer Cements on Streptococcus mutans  

PubMed Central

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

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

2014-01-01

16

Antibacterial activity of glass-ionomer restorative cements exposed to cavity-producing microorganisms.  

PubMed

The antibacterial activity of the glass-ionomer restorative cements Ketac-Fil, Ketac-Silver, Fuji II LC, and Vitremer was studied in vitro, in conjunction with a total of 32 strains of five bacterial genera that may be associated with dental caries: Streptococcus spp, Lactobacillus spp, Actinomyces spp, Porphyromonas spp, and Clostridium spp. Agar plate diffusion was the method used for the bacterial cultures, which included a chlorhexidine control. All four glass-ionomer cements were found to inhibit bacterial growth, though with noteworthy differences in their spheres of action. Vitremer was the cement determined to have the greatest antibacterial effects, whereas Ketac-Silver presented the least inhibitory action. PMID:10823075

Herrera, M; Castillo, A; Baca, P; Carrión, P

1999-01-01

17

In vitro fluoride release from a different kind of conventional and resin modified glass-ionomer cements.  

PubMed

Fluoride release is important characteristic of glass-ionomer cements. Quantity of fluoride ions released from the glass-ionomer cements has major importance in definition of their biological activity. The objectives of this study were to define the quantity of fluoride ions released from the experimental glass-ionomer cements and to define the effect of fluoride ions released from the experimental glass-ionomer cements on their cytotoxicity. Concentrations of the fluoride ions released in the evaluated glass-ionomer cements were measured indirectly, by the fluoride-selective WTW, F500 electrode potential, combined with reference R503/D electrode. Statistical analyses of F-ion concentrations released by all glass-ionomers evaluated at two time points, after 8 and after 24 hours, show statistically higher fluoride releases from RMGICs: Vitrebond, Fuji II LC and Fuji Plus, when compared to conventional glass-ionomer cements: Fuji Triage, Fuji IX GP Fast and Ketac Silver, both after 8 and after 24 hours. Correlation coefficient between concentrations of fluoride ion released by evaluated glass-ionomer cements and cytotoxic response of UMR-106 osteoblast cell-line are relatively high, but do not reach levels of biological significance. Correlation between concentrations of fluoride ion released and cytotoxic response of NIH3T3 mouse fibroblast cell line after 8 hours is high, positive and statistically significant for conventional GICs, Fuji Triage and Fuji IX GP Fast, and RMGIC, Fuji II LC. Statistically significant Correlation coefficient between concentrations of fluoride ion released and cytotoxic response of NIH3T3 cell line after 24 hours is defined for RMGIC Fuji II LC only. PMID:23988173

Selimovi?-Dragaš, Mediha; Hasi?-Brankovi?, Lajla; Kora?, Fehim; ?apo, Nermin; Huseinbegovi?, Amina; Kobašlija, Sedin; Leki?, Meliha; Hatibovi?-Kofman, Šahza

2013-08-01

18

[IR study of the hardening and maturation of glass ionomer cement].  

PubMed

The set reaction of glass ionomer cement has been investigated by means of IR spectra. It has been found that the band intensity around 1413 cm(-1) due to the vibration of polyacrylate salt increased with aging, and the shoulder band at 950 cm(-1) due to the stretching vibration of Si-OH still appeared during the periods studied. The results are consistent with that of mechanical determination of compressive strength, which suggested that the crosslink density increase resulting from the slow diffusion of Ca2+ and Al3+ is responsible for compressive strength increasing with aging, and forming and maturing of interface layer comprising of silica gel also have a significant effect on the properties of glass ionomer cements. PMID:16329489

Cheng, Han-ting; Liu, Han-xing; Xiao, Qun

2005-08-01

19

Effects of extraction media upon fluoride release from a resin-modified glass-ionomer cement  

Microsoft Academic Search

Previous studies have shown that various factors such as ionic composition or pH of the extraction medium may significantly\\u000a influence leaching of components from restorative materials. Therefore, it was the aim of this investigation to determine\\u000a the release of fluoride from a resin-modified glass-ionomer cement (GIC) following storage in various extraction media, including\\u000a an esterase buffer. Specimens of the resin-modified

W. Geurtsen; P. Bubeck; G. Leyhausen; F. Garcia-Godoy

1998-01-01

20

Effect of water on the physical properties of resin-modified glass ionomer cements  

Microsoft Academic Search

Objectives: Resin-modified glass ionomer cements (GIC) are available for clinical use as restorative materials or as liners and bases. This work was conducted to study the effect of water sorption on the physical properties of several resin-modified GIC, by changing the samples’ storage conditions.Methods: The water sorption, the flexural strength, the flexural elastic modulus, the Vickers hardness and the dimensional

M.-A Cattani-Lorente; V Dupuis; J Payan; F Moya; J.-M Meyer

1999-01-01

21

Effects of etching and adhesive applications on the bond strength between composite resin and glass-ionomer cements  

PubMed Central

Objective This study determined the effects of various surface treatment modalities on the bond strength of composite resins to glass-ionomer cements. Material and Methods Conventional (KetacTM Molar Quick ApplicapTM) or resin-modified (PhotacTM Fil Quick AplicapTM) glass-ionomer cements were prepared. Two-step etch-rinse & bond adhesive (AdperTM Single Bond 2) or single-step self-etching adhesive (AdperTM PromptTM L-PopTM) was applied to the set cements. In the etch-rinse & bond group, the sample surfaces were pre-treated as follows: (1) no etching, (2) 15 s of etching with 35% phosphoric acid, (3) 30 s of etching, and (4) 60 s of etching. Following the placement of the composite resin (FiltekTM Z250), the bond strength was measured in a universal testing machine and the data obtained were analyzed with the two-way analysis of variance (ANOVA) followed by the Tukey's HSD post hoc analysis (p=0.05). Then, the fractured surfaces were examined by scanning electron microscopy. Results The bond strength of the composite resin to the conventional glass-ionomer cement was significantly lower than that to the resin-modified glass-ionomer cement (p<0.001). No significant differences were determined between the self-etching and etch-rinse & bond adhesives at any etching time (p>0.05). However, a greater bond strength was obtained with 30 s of phosphoric acid application. Conclusions The resin-modified glass-ionomer cement improved the bond strength of the composite resin to the glass-ionomer cement. Both etch-rinse & bond and self-etching adhesives may be used effectively in the lamination of glass-ionomer cements. However, an etching time of at least 30 s appears to be optimal. PMID:23329245

PAMIR, Tijen; SEN, Bilge Hakan; EVCIN, Ozgur

2012-01-01

22

The influence of water sorption on the development of setting shrinkage stress in traditional and resin-modified glass ionomer cements  

Microsoft Academic Search

Objectives. The aim of this study was to determine the setting stress development for some traditional and resin-modified glass ionomer cements and to assess the effect of early water exposure to this stress. Methods. The development of the setting stress of the glass ionomer cements was determined in a tensilometer set-up as described earlier by Feilzer et al. (1987). Results.

Albert J. Feilzer; Afrodite I. Kakaboura; Anton J. de Gee; Carel L. Davidson

1995-01-01

23

Surgical management of invasive cervical resorption using resin-modified glass ionomer cement.  

PubMed

Invasive cervical resorption is an external resorption that begins below the epithelial attachment. It is caused primarily by dental trauma, orthodontic treatment, or dental bleaching. This case report involved an invasive Class III cervical resorption resulting from trauma to the superior right central incisor. Root canal treatment was followed by surgical intervention. The resorptive defect was debrided, and part of the tooth was restored with resin-modified glass ionomer cement. Postoperative follow-up revealed complete healing and healthy gingival attachment. PMID:24192742

Tavares, Warley Luciano Fonseca; Lopes, Renata Carvalho Portes; Oliveira, Ricardo Reis; Souza, Rodrigo Goncalves de; Henriques, Luiz Carlos Feitosa; Ribeiro-Sobrinho, Antonio Paulino

2013-01-01

24

Evaluation of the mechanical properties of dental adhesives and glass-ionomer cements  

Microsoft Academic Search

Adhesives and lining\\/base materials should relieve the stresses concentrated at the tooth\\/restoration interface. The study\\u000a aimed at comparing the mechanical properties of eight adhesives and six glass-ionomer cements (GICs). The adhesives were applied\\u000a on dentin disks, whereas 2 mm?×?3 mm?×?2 mm GICs specimens were prepared in a teflon mold. Vicker’s hardness (VH), elastic\\u000a modulus (E), creep (Cr) and elastic work (We\\/Wtot) were measured

Elisa Magni; Marco Ferrari; Reinhard Hickel; Nicoleta Ilie

2010-01-01

25

Ultrasonically set novel NVC-containing glass-ionomer cements for applications in restorative dentistry  

Microsoft Academic Search

The objective of this study is to investigate the effects of application of ultrasound on the physical properties of a novel\\u000a NVC (N-vinylcaprolactam)-containing conventional glass-ionomer cement (GIC). Experimental GIC (EXP) samples were made from the acrylic\\u000a acid (AA)–itaconic acid (IA)–NVC synthesized terpolymer with Fuji IX powder in a 3.6:1 P\\/L ratio as recommended by the manufacturer.\\u000a Specimens were mixed and

Alireza Moshaverinia; Sahar Ansari; Maryam Moshaverinia; Scott R. Schricker; Winston W. L. Chee

26

Influence of air abrasion preparation on microleakage in glass ionomer cement restorations.  

PubMed

The aim of this study was to assess microleakage in class V cavities prepared by air abrasion or high-speed dental bur and restored with different glass ionomer cements. Sixty bovine incisors were equally divided into 6 groups: I, II and III (preparation by high-speed) and IV, V and VI (preparation by air abrasion). Groups I and IV were restored with Fuji IX; groups II and V with Ketac Molar; and groups III and VI with Vitremer. After 24 h (37 degrees C), specimens were thermocycled, isolated with nail varnish, immersed in a 0.2% Rhodamine B solution for 24 hours, sectioned longitudinally and analyzed for microleakage using an optical microscope connected to a digital camera and a computer. The images were digitized and a software allowed the quantitative evaluation of microleakage in millimeters. Data were analyzed by Wilcoxon and Kruskal-Wallis tests. It was observed that there were significant differences (p < 0.05) between incisal (enamel) and cervical (dentine/cementum) margins, mainly for Ketac Molar; there was no difference (p > 0.05) between preparation methods, except for group II (high-speed/Ketac Molar) that showed higher infiltration; regarding the materials, Ketac Molar demonstrated the highest microleakage values (p < 0.05), and only Vitremer sealed completely both margins of restorations. It was concluded that air abrasion preparation did not influence microleakage in class V restorations with the employed glass ionomer cements. PMID:15880930

Reis, Lucia da Silva; Chinelatti, Michelle A; Corona, Silmara A M; Palma-Dibb, Regina G; Borsatto, Maria Cristina

2004-11-01

27

Microleakage of glass-ionomer cement placed in association with non-setting calcium hydroxide.  

PubMed

The purpose of this investigation was to determine whether non-setting calcium hydroxide [Ca (OH)2] cement placed in the root canal system of premolar teeth would affect the subsequent microleakage of a glass-ionomer restoration (GIC). Following selection, 62 human premolar teeth extracted for orthodontic reasons were accessed and root canals prepared according to a standardized procedure. The specimens were then allocated randomly into two major groups each of 30 teeth. Two other teeth were used as a positive and a negative control. The control group was restored with glass-ionomer cement following drying of the canal and placement of a cotton wool pledget. The test group had all canals dressed with non-setting Ca(OH)2 and then was subdivided, one set (n = 22) being restored following conditioning of the access cavity margins, the other (n = 8) having the margins cleaned with a hand excavator. Samples were assessed for microleakage using a two-point scoring system (leakage or no leakage) in conjunction with a clearing technique using AgNO3. Using Fisher's exact test, a statistically significant difference was found between the control and test groups (P < 0.05) but there was no significant difference between the excavated and conditioned cavities (P=0.55). It is concluded that contamination of access cavity margins with Ca(OH)2 during medication of a root canal interferes with the bond of GIC, resulting in increased microleakage in vitro. PMID:15842248

Mahmood, S A; Wood, D J; Boyle, E L; Jarad, F D; Youngson, C C

2005-05-01

28

The effect of etching on a number of glass ionomer cements.  

PubMed

In view of the continuing interest in the use of glass ionomer cements as a dentine substitute or base under composite resins, further investigations were carried out on the effects of the length of time of etching of the surface of the cement prior to the placement of the resin. A number of cements are available on the Australian market which are advocated for use in this technique. Each of them was subjected to etching for periods of 15, 30, 45, or 60 seconds and then stored in water for one week. Examination under a dissecting microscope and a scanning electron microscope revealed some variation in results between the different cements. It would appear that not all those materials presently marketed for this purpose are entirely suitable. Whilst 15 seconds is the preferred time for most cements, some require times up to 60 seconds to achieve the best result. Also, some of the cements showed signs of cracking, expansion and distortion after they had been stored in water for one week to allow for maturation before being prepared for viewing under the SEM. It is suggested that this group of cements is not suitable for the 'sandwich' technique. PMID:2275652

Fuss, J; Mount, G J; Makinson, O F

1990-08-01

29

Effects of enamel deproteinization on bracket bonding with conventional and resin-modified glass ionomer cements.  

PubMed

The objective of this study was to test the effects of enamel deproteinization on bracket bonding with conventional and resin-modified glass ionomer cement (RMGIC). One hundred premolars, extracted for orthodontic reasons, were divided into five groups (n = 20). Group 1 (control): enamel was etched with 35 per cent phosphoric acid, a thin layer of adhesive was applied, and the brackets were bonded with Transbond XT. Group 2: enamel was etched with 10 per cent polyacrylic acid and the brackets were bonded with conventional glass ionomer cement (GIC). Group 3: enamel was treated with 5.25 per cent NaOCl, etched with 10 per cent polyacrylic acid, and the brackets were bonded with conventional GIC. Group 4: enamel was etched with 10 per cent polyacrylic acid and the brackets were bonded with RMGIC. Group 5: enamel was treated with 5.25 per cent NaOCl, etched with 10 per cent polyacrylic acid, and the brackets were bonded with RMGIC. The teeth were stored in distilled water for 24 hours before they were submitted to shear testing. The results demonstrated that bond strength values of group 1 (17.08 ± 6.39 MPa) were significantly higher in comparison with the other groups. Groups 2 (3.43 ± 1.94 MPa) and 3 (3.92 ± 1.57 MPa) presented values below the average recommended in the literature. With regard to adhesive remnant index, the groups in which the enamel was treated with NaOCl showed a behaviour similar to that of the resin composite. It is conclude with enamel treatment with NaOCl increased bonding strength of brackets bonded with GIC and RMGIC, but increased bond strength was not statistically significant when compared to the untreated groups. PMID:22379131

Pereira, Tatiana Bahia Junqueira; Jansen, Wellington Corrêa; Pithon, Matheus Melo; Souki, Bernardo Quiroga; Tanaka, Orlando Motohiro; Oliveira, Dauro Douglas

2013-08-01

30

Microleakage Evaluation of Class V Restorations with Conventional and Resin-modified Glass Ionomer Cements.  

PubMed

The aim of this study was to evaluate in vitro the marginal microleakage of conventional Glass Ionomer Cements (GIC) and Resin Modified Glass Ionomer Cements (RMGIC). The tested materials were grouped as follows: GIC category - G1 (Vidrion R - SSWhite); G2 (Vitro Fill - DFL); G3 (Vitro Molar - DFL); G4 (Bioglass R - Biodinâmica); and G5 (Ketac Fill - 3M/ESPE); and RMGIC category - G6 (Vitremer - 3M/ESPE); G7 (Vitro Fill LC - DFL); and G8 (Resiglass - Biodinâmica). Therefore, 80 class V cavities (2.0X2.0 mm) were prepared in bovine incisors, either in the buccal face. The samples were randomly divided into 8 groups and restored using each material tested according to the manufacturer. The root apices were then sealed with acrylic resin. The teeth were stored for 24 h in 100% humidity at 37°C. After storage, the specimens were polished with extra-slim burs and silicon disc (Soft-lex - 3M/ESPE), then were isolated with cosmetic nail polish up to 1 mm around the restoration. Then, the samples were immersed in 50% AgNO3 solution for 12 h and in a developing solution for 30 min. They were rinsed and buccal-lingual sectioned. The evaluation of the microleakage followed scores from 0 to 3. The Kruskal-Wallis test and Dunn method test were applied (a=0.05). The results showed that there was no difference between the enamel and dentin margins. However, GIC materials presented more microleakage than RMGIC. PMID:25284528

Pontes, Danielson Guedes; Guedes-Neto, Manoel Valcacio; Cabral, Maria Fernanda Costa; Cohen-Carneiro, Flávia

2014-09-01

31

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

PubMed Central

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

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

2013-01-01

32

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

PubMed Central

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

Khoroushi, Maryam; Keshani, Fateme

2013-01-01

33

Mechanical behavior of glass ionomer cements as a function of loading condition and mixing procedure.  

PubMed

With a view to comparing conventional (CGIC) and resin-modified glass ionomer cements (RMGIC) in terms of mechanical properties, these materials were subjected to different loading conditions for evaluation. In addition, this study investigated the assumption that capsulated systems possess superior mechanical properties compared to the hand-mixed systems, owing to the former's better material homogeneity and a more precise adjustment of the powder-liquid ratio. In view of the aims of this study, the following mechanical properties were determined: strength and modulus of elasticity in flexural test, diametric tensile and compressive strengths, as well as variation of hardness and modulus of elasticity with depth. In all macroscopic strength tests, the RMGICs performed significantly better than the CGICs. In microhardness evaluation, the differences were levelled out. In particular, the mechanical properties of RMGICs were comparable to those of microfilled and packable composites. The effect of mixing was closely intertwined with material property. The tested CGICs performed better when they were hand-mixed, whereas RMGICs fared better in the capsulated form. PMID:17886457

Ilie, Nicoleta; Hickel, Reinhard

2007-07-01

34

Antibacterial activity and physical properties of glass-ionomer cements containing antibiotics.  

PubMed

This study evaluated the antibacterial effects, physical properties and bonding strengths of conventional glass-ionomer cements (GICs) containing antibiotics and determined the optimal concentration of antibiotics addition for use with the ART approach. Fuji IX GIC was used as a control. Three antibiotic mixtures, ciprofloxacin, metronidazole and minocycline, were added to powdered GIC (Fuji IX) to obtain concentration ratios of 1.5, 3.0 and 4.5% w/w. The antibacterial activity of each GIC was evaluated against Streptococcus mutans or Lactobacillus casei using agar-diffusion methods. The release of antibiotics was analyzed by high-performance liquid chromatography (HPLC). The compressive strength and bonding strength to dentin were measured and compared with those of control samples. The results were analyzed using the Mann-Whitney test and Wilcoxon test. All tested groups showed a significantly greater inhibition with growth of the selected bacteria in comparison to the control groups (p < 0.01). However, the 3% and 4.5% concentration ratios of antibiotics had significantly lower compressive strength and lower bond strength to dentin than the control group (p = 0.003). The GIC-containing antibiotics were effective in inhibiting S Mutans and L Casei. The addition of a 1.5% antibiotic mixture was optimal to giving appropriate physical and bonding properties. PMID:19192833

Yesilyurt, Cemal; Er, Kursat; Tasdemir, Tamer; Buruk, Kurtulus; Celik, Davut

2009-01-01

35

Inhibitory effects on selected oral bacteria of antibacterial agents incorporated in a glass ionomer cement.  

PubMed

The objectives of the study were to investigate the antimicrobial efficacy, over time, of combining antibacterial agents with a glass ionomer cement (GIC). This was assessed using an agar diffusion test. Chlorhexidine hydrochloride, cetylpyridinium chloride, cetrimide and benzalkonium chloride were added to Fuji IX GIC at 0, 1, 2 and 4% w/w. Antibacterial-GIC specimens were placed onto agar plates inoculated with one of six bacterial species (Streptococcis, Lactobacillus, and Actinomyces, two each) and the area of inhibition calculated after 24 h incubation. The experiment was repeated weekly and at week 11 the surface of the specimen was abraded prior to replacing on inoculated agar plates. Control specimens of the GIC produced no bacterial inhibition. The antibacterial-GIC combination specimens showed significant inhibition which decreased at different rates over the test period. Resurfacing of the specimens showed a dramatic increase of antibacterial action similar to levels produced on week 1. CT-GIC showed the greatest (p < 0.005) inhibitory effect throughout the experimental period for 4 out of 6 test bacteria. The addition of antibacterial agents to Fuji IX creates a GIC material with significant antimicrobial action in vitro which is dependent on concentration and type of antibacterial agent, and appears to be associated primarily with a release of the antibacterial from the surface layer of the specimen. PMID:12652048

Botelho, Michael G

2003-01-01

36

Effect of green propolis addition to physical-mechanical properties of glass ionomer cements  

PubMed Central

Objective This study investigated the mechanical properties of glass ionomer cements (GICs) combined with propolis as a natural antimicrobial substance Material and Methods Typified green propolis, as an ethanolic extract (EEP) or in the lyophilized form (powder), was incorporated to specimens of Ketac Fil Plus, ChemFlex and Ketac Molar Easymix GICs. For each test, 8 specimens of each material were prepared. For water sorption and solubility tests, specimens were subjected to dehydration, hydration and re-dehydration cycles until a constant mass was obtained for each step. Measurements were recorded using a digital balance of 10-4 g precision. For the diametral tensile strength test, specimens were tested in a universal test machine at 0.5 mm/min crosshead speed after 24 h storage in deionized water. Data were evaluated by one-way ANOVA and Tukey’s tests (p<0.05). Results The addition of propolis to GIC clearly increased water sorption compared to pure material. Solubility was material-dependent and was not clearly evident. For the diametral tensile strength test, association with propolis altered negatively only Chemflex. Conclusion It may be concluded that incorporation of propolis to GICs alters some properties in a material-dependent condition. PMID:21552709

TROCA, Valéria Barros Pereira Barbosa; FERNANDES, Karen Barros Parron; TERRILE, Amélia Elena; MARCUCCI, Maria Cristina; de ANDRADE, Flaviana Bombarda; WANG, Linda

2011-01-01

37

Sealing furcation perforations with silver glass ionomer cement: an in vitro evaluation.  

PubMed

Furcation perforations sealed with silver glass ionomer cement (Chelon Silver) were evaluated in vitro compared with amalgam. Access cavities were prepared in 25 extracted human molar teeth. The coronal orifices of the root canals were sealed with amalgam and varnish. Naturally occurring coronal leakage through the intact pulp chamber floor was determined quantitatively for each tooth, using a modified fluid transport model, under pressure of 1.2 Atm. Each tooth was then disconnected from the system, perforated at the furcation, and the perforation sealed with either Chelon Silver (10 teeth) or amalgam (10 teeth); five remaining teeth served as a negative control. After incubation for 24 h at 37 degrees C in 100% humidity, teeth were reconnected to the modified fluid transport system, and coronal leakage under pressure was evaluated at 1, 2, 6, 15, and 24 h. Leakage through each tooth was compared with that of its own intact pulp chamber floor before perforation and the groups compared with each other. No significant difference was found between the mean leakage of the intact pulp chamber floors of the two groups. Chelon Silver had a significantly better sealing ability than amalgam (p < 0.01): leakage rate of 0.007 and 0.017 microliter/min, respectively. It is concluded that Chelon Silver could be an adequate sealer for furcation perforations. PMID:11199781

Fuss, Z; Abramovitz, I; Metzger, Z

2000-08-01

38

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

PubMed Central

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

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

2013-01-01

39

Mechanical performance of encapsulated restorative glass-ionomer cements for use with Atraumatic Restorative Treatment (ART)  

PubMed Central

The Atraumatic Restorative Treatment (ART) approach was suggested to be a suitable method to treat enamel and dentine carious lesions in patients with disabilities. The use of a restorative glass-ionomer with optimal mechanical properties is, therefore, very important. Objective: To test the null-hypotheses that no difference in diametral tensile, compressive and flexural strengths exists between: (1) The EQUIA system and (2) The Chemfil Rock (encapsulated glass-ionomers; test materials) and the Fuji 9 Gold Label and the Ketac Molar Easymix (hand-mixed conventional glass-ionomers; control materials); (3) The EQUIA system and Chemfil Rock. Material and Methods: Specimens for testing flexural (n=240) and diametral tensile (n=80) strengths were prepared according to standardized specifications; the compressive strength (n=80) was measured using a tooth-model of a class II ART restoration. ANOVA and Tukey B tests were used to test for significant differences between dependent and independent variables. Results: The EQUIA system and Chemfil Rock had significantly higher mean scores for all the three strength variables than the Fuji 9 Gold Label and Ketac Molar Easymix (?=0.05). The EQUIA system had significant higher mean scores for diametral tensile and flexural strengths than the Chemfil Rock (?=0.05). Conclusion: The two encapsulated high-viscosity glass-ionomers had significantly higher test values for diametral tensile, flexural and compressive strengths than the commonly used hand-mixed high-viscosity glass-ionomers. PMID:23857657

MOLINA, Gustavo Fabián; CABRAL, Ricardo Juan; MAZZOLA, Ignacio; BRAIN LASCANO, Laura; FRENCKEN, Jo. E.

2013-01-01

40

A long term study of fluoride release from metal-containing conventional and resin-modified glass-ionomer cements.  

PubMed

The objective of this study was to determine long term release of fluoride from a resin-modified glass-ionomer cement (RMGIC) (Fuji II LC (FLC)) compared with that from two conventional acid-base setting cements (HiDense (HD) and KetacSilver (KS)) marketed for similar restorative purposes. Fluoride release from discs of cement immersed in water or artificial saliva was measured for 2.7 years using an ion selective electrode technique. The RMGIC was affected by water if immersed immediately after setting. This is similar to conventional acid-base cements and the experimental method was designed to allow for this. Over the 2.7-year period, the RMGIC and HD released similar amounts of fluoride into both water and artificial saliva. In water, the RMGIC released the most fluoride, while in artificial saliva the highest release was from HD. KS released the least amount of fluoride in both immersing liquids. In artificial saliva, release was reduced to 17-25% of that found in water, with the RMGIC showing the greatest reduction. Both acid-base cured cements showed changes in colour over the 2.7-year span, while the colour of the RMGIC was stable. It was concluded that the RMGIC released equivalent or greater amounts of fluoride than the two acid-base cure glass-ionomers over a period of 2.7 years. PMID:11298908

Williams, J A; Billington, R W; Pearson, G J

2001-01-01

41

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

PubMed Central

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

2014-01-01

42

Effect of different root caries treatments on the sealing ability of conventional glass ionomer cement restorations.  

PubMed

In this study we compared the microleakage of conventional glass ionomer cement (GIC) restorations following the use of different methods of root caries removal. In vitro root caries were induced in 75 human root dentin samples that were divided in five groups of 15 each according to the method used for caries removal: in group 1 spherical carbide burs at low speed were used, in group 2 a hand-held excavator was used, and in groups 3 to 5 an Er,Cr:YSGG laser was used at 2.25 W, 40.18 J/cm(2) (group 3), 2.50 W, 44.64 J/cm(2) (group 4) and 2.75 W, 49.11 J/cm(2) (group 5). The air/water cooling during irradiation was set to 55%/65% respectively. All cavities were filled with GIC. Five samples from each group were evaluated by scanning electron microscopy (SEM) and the other ten samples were thermocycled and submitted to a microleakage test. The data obtained were compared by ANOVA followed by Fisher's test (p?0.05). Group 4 showed the lowest microleakage index (56.65 6.30; p<0.05). There were no significant differences among the other groups. On SEM images samples of groups 1 and 2 showed a more regular interface than the irradiated samples. Demineralized dentin below the restoration was observed, that was probably affected dentin. Group 4 showed the lowest microleakage values compared to the other experimental groups, so under the conditions of the present study the method that provided the lowest microleakage was the Er,Cr:YSGG laser with a power output of 2.5 W yielding an energy density of 44.64 J/cm(2). PMID:20886360

Geraldo-Martins, Vinicius R; Lepri, Cesar P; Palma-Dibb, Regina G

2012-01-01

43

The erosion kinetics of conventional and resin-modified glass-ionomer luting cements in acidic buffer solutions.  

PubMed

This study investigated the erosion kinetics of conventional and resin-modified glass-ionomer luting cements in acidic buffer solutions as a function of time. Disc shaped specimens were prepared from conventional (Ketac-Cem: KTC) and resin-modified glass ionomer cements (Fuji Plus: FP) and immersed in three acidic buffer solutions (0.01 M) namely, acetic acid/sodium acetate (AA(B)), lactic acid/sodium lactate (LA(B)) and citric acid/sodium citrate (CA(B)) with a constant pH of 4.1 and stored for 1, 8, 24, 48, 80, 120 and 168 h. F concentration was determined using ion-specific electrode. Si, Ca and Al concentrations were determined by atomic absorption spectroscopy. Ca, Al, Si and F solubility rates in both FP and KTC were the highest in CA(B) solution. The erosion rates of both FP and KTC in all buffer solutions increased as a function of immersion time. The amount of F eluted from FP was more than that of KTC. The total amount of elements released from FP was less than KTC in all solutions. PMID:23207217

Hazar-Yoruc, Binnaz; Bavbek, Andac Barkin; Özcan, Mutlu

2012-01-01

44

Mechanical properties of a resin-modified glass ionomer cement for luting: effect of adding spherical silica filler.  

PubMed

This study investigated the effects of spherical silica filler (SSF) on the workability and mechanical properties of resin-modified glass ionomer cements for luting (RMGICL). Varying powder/liquid ratios (P/L=2.0, 2.2, 2.4, and 2.6) of a commercially available glass ionomer cement (Fuji Lute, GC Corp.) were mixed with SSF at different weight percentages (5, 7.5, and 10%). On film thickness, statistically significant effects of SSF addition were noted at 2.5 minutes after mixing started, notably at P/L=2.4 and 2.6 when 7.5 and 10 wt% of SSF were added. The same result was also obtained for consistency evaluation. On mechanical and bonding strengths to the tooth substrate, no statistically significant differences were observed among all the SSF weight percentages within each P/L ratio. SSF-added RMGICL at a higher powder/liquid ratio exhibited increased mechanical and bonding strengths when compared to a control without SSF addition, but nonetheless maintained the film thickness with no further increase. PMID:20484829

E, Lihua; Irie, Masao; Nagaoka, Noriyuki; Yamashiro, Takashi; Suzuki, Kazuomi

2010-05-01

45

Reactions in glass ionomer cements: V. Effect of incorporating tartaric acid in the cement liquid.  

PubMed

A description is give of the effect on the ASPA cement reaction of tartaric acid incorporated in the cement liquid. Tartaric acid acts as an accelerator that aids in the extraction of ions from the aluminosilicate glass and facilitates their binding to the polyanion chains. Postgelation hardening is significantly increased. Working time is unaffected possibly because cations are initially present as complexes. PMID:187629

Crisp, S; Wilson, A D

1976-01-01

46

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

PubMed Central

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

FONSECA, Rodrigo Borges; BRANCO, Carolina Assaf; QUAGLIATTO, Paulo Sergio; GONCALVES, Luciano de Souza; SOARES, Carlos Jose; CARLO, Hugo Lemes; CORRER-SOBRINHO, Lourenco

2010-01-01

47

Effect of moisture protective coatings on the strength of a modern metal-reinforced glass-ionomer cement.  

PubMed

The strength of a modern, low metal:glass ratio, metal-reinforced glass-ionomer cement was measured evaluating a number of protective barriers: one light-cured resin, two solvent-based dental varnishes and petroleum jelly. The cement was exposed to water at 10 and 60 min from start of mix. The results obtained with these protecting agents were compared with those obtained where no protection was applied. A comparison of uniaxial flexural strength and biaxial flexural strength showed the latter to be more discriminating. Proprietary dental varnishes were superior to petroleum jelly, producing similar strengths of 50 MPa. Petroleum jelly was, however, preferable to no protection. Moisture protection during the first 30 min was found to be beneficial, thereafter no further strength increase was found. A second material, a cement which has a high metal:glass ratio, was found to be more moisture resistant but weaker in strength than the modern material, with a biaxial strength of 39 MPa. PMID:9722100

Williams, J A; Billington, R W; Pearson, G J

1998-07-01

48

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

PubMed

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

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

2014-01-01

49

Comparative evaluation of effect of polymerizable and non-polymerizable desensitizing agents on crown-retentive-strength of zinc-phosphate, glass-ionomer and compomer cements.  

PubMed

The Purpose of this study was to evaluate the effect of polymerizable and non-polymerizable dentine desensitizers on retention of complete cast crowns cemented with three different types of cements. Freshly extracted human molars (n = 90) were prepared for standardized crown preparation (6-degree taper 4-mm height). The axial surface area of each preparation was determined and specimens were distributed equally among groups (n = 10). Dentine desensitizers, cementing agents, glass ionomer cement and compomer cement. Teeth were prepared and individual castings were made using high noble porcelain-metal alloy. Castings were cemented, thermo-cycled and removed along the path of insertion using a universal testing machine. Tooth surface as well as inner surface of the casting was examined and nature of cement failure was determined. Compomer cement exhibited the highest retentive strength and all dentine treatments resulted in significantly different retentive values. Zinc phosphate was the least retentive. Crown retentive values of Compomer cement were improved with Prime & Bond NT and Gluma Desensitizer Retentive values of zinc phosphate cement with Prime & Bond NT were decreased and not affected with Gluma Desensitizer Retentive values of Glass ionomer cement were not affected by any of the desensitizers used in the study. PMID:23101176

Patil, P G; Parkhedkar, R D; Patil, S P; Bhowmik, H S

2012-09-01

50

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

PubMed Central

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

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

2013-01-01

51

Comparative evaluation of microleakage of three restorative glass ionomer cements: An in vitro study  

PubMed Central

Purpose: The aim of this study was to compare the microleakage of glass ionomers (conventional and resin modified) with that of recently introduced nanoionomers. Materials and Methods: Standardized class I and class V cavities were prepared on 120 young permanent teeth. Samples were equally divided into group I (class I restorations) and group II (class V restorations), and further divided into subgroups. The subgroups were restored with Fuji IX, Fuji II LC, and newly introduced Ketac™ N 100 (KN 100). Samples were thermocycled and submerged in Acridine dye for 24 h. Samples were sectioned to view under fluorescent microscope and marginal leakage was evaluated by Chi-square and Kruskal — Wallis test. Results: Fuji IX showed the maximum leakage, followed by LC II and the least was observed in KN 100. In class I restorations, there was significant difference while comparing Fuji IX with Fuji LC II and KN 100 and nonsignificant difference between LC II and KN100. In class V restorations, Fuji IX and KN100, KN 100 and LC II showed significant difference. Fuji IX and LC II showed nonsignificant difference. Conclusion: Within the limitations of this study, Fuji IX showed the maximum microleakage. KN 100 showed minimum leakage, better sealing ability, and was more consistent. PMID:25097418

Diwanji, Amish; Dhar, Vineet; Arora, Ruchi; Madhusudan, A.; Rathore, Ambika Singh

2014-01-01

52

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

PubMed Central

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

2011-01-01

53

Microleakage after Thermocycling of Three Self-Etch Adhesives under Resin-Modified Glass-Ionomer Cement Restorations  

PubMed Central

This study was designed to evaluate microleakage that appeared on Resin-Modified Glass-Ionomer Cement (RMGIC) restorations. Sixty class V cavities (h × w × l = 2?mm × 2?mm × 3?mm) were cut on thirty extracted third molars, which were randomly allocated to three experimental groups. All the buccal cavities were pretreated with polyacrylic acid, whereas the lingual cavities were treated with three one-step Self-Etch adhesives, respectively, Xeno III (Dentsply Detrey GmbH, Konstanz, Germany), iBond exp (Heraeus Kulzer gmbH & Co. KG, Hanau, Germany), and Adper Prompt-L-Pop (3M ESPE AG, Dental products Seefeld, Germany). All cavities were completely filled with RMGIC, teeth were thermocycled for 800 cycles, and leakage was evaluated. Results were expressed as means ± standard deviations (SDs). Microleakage scores were analysed by means of generalized linear mixed models (GLMMs) assuming an ordinal logistic link function. All results were considered to be significant at the 5% critical level (P < .05). The results showed that bonding RMGIC to dentin with a Self-Etch adhesive rather than using polyacrylic acid did not influence microleakage scores (P = .091), except for one tested Self-Etch adhesive, namely, Xeno III (P < .0001). Nevertheless, our results did not show any significant difference between the three tested Self-Etch adhesive systems. In conclusion, the pretreatment of dentin with Self-Etch adhesive system, before RMGIC filling, seems to be an alternative to the conventional Dentin Conditioner for the clinicians as suggested by our results (thermocycling) and others (microtensile tests). PMID:20628510

Geerts, Sabine O.; Seidel, Laurence; Albert, Adelin I.; Gueders, Audrey M.

2010-01-01

54

Nanoclays reinforced glass ionomer cements: dispersion and interaction of polymer grade (PG) montmorillonite with poly(acrylic acid).  

PubMed

Montmorillonite nanoclays (PGV and PGN) were dispersed in poly(acrylic acid) (PAA) for utilization as reinforcing filler in glass ionomer cements (GICs). Chemical and physical interaction of PAA and nanoclay (PGV and PGN) was studied. PAA–PGV and PAA–PGN solutions were prepared in different weight percent loadings of PGV and PGN nanoclay (0.5-8.0 wt%) via exfoliation-adsorption method. Characterization was carried out by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and fourier transform infrared (FTIR) spectroscopy. XRD results of PAA–PGN demonstrated that the interlayer space expanded from 12.83 to 16.03 Å indicating intercalation whereas the absence of the peak at d(001) in PAA–PGV indicated exfoliation. XPS scans of PGV and PGN nanoclays depicted the main peak of O 1s photoelectron due to Si–O–M (M = Mg, Al, Fe) whereas, Si–O–Al linkages were identified by Si 2p or Si 2s and Al 2p or Al 2s peaks. The disappearance of the Na peak confirmed that PAA molecules exchanged sodium ions present on surface of silicate layers and significantly reduced the electrostatic van-der-Waals forces between silicate plates resulting in intercalation or exfoliation. FTIR spectra of PAA–nanoclay suspensions demonstrated the presence of a new peak at 1,019 cm(-1) associated with Si–O– stretching vibrations which increased with increasing nanoclays concentration. Information concerning the dispersion of nanoclay in PAA aqueous solutions, chemical reaction and increase interlayer space in montmorillonite nanoclay is particularly useful regarding dispersion and reinforcement of nanoclay in PAA. PMID:24077996

Fareed, Muhammad A; Stamboulis, Artemis

2014-01-01

55

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

PubMed Central

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

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

2013-01-01

56

Comparison of bracket debonding force between two conventional resin adhesives and a resin-reinforced glass ionomer cement: an in vitro and in vivo study.  

PubMed

The purpose of this study was to compare the debonding force of orthodontic brackets bonded with two conventional resin adhesives (Resilience L3 and Light Bond) and a resin-reinforced glass ionomer cement (Fuji Ortho LC). For the in vitro part of the study, 80 extracted premolars were randomly divided into four groups. In groups A and B, brackets were bonded to unetched enamel using Fuji Ortho LC cement in wet and dry conditions, respectively. In groups C and D, brackets were bonded to etched enamel using Resilience L3 and Light Bond, respectively. Debonding force was determined using a servohydraulic testing machine at a crosshead speed of 1 mm/min. Data was analyzed using the ANOVA and Tukey-Kramer multiple comparison test at p<0.05. A significant difference was found in debonding force between unetched Fuji Ortho LC and the two conventional resins. There was no significant difference between the two conventional resins or between unetched resin-reinforced glass ionomer in the wet and dry conditions. For the in vivo part of the study, 30 patients were randomly assigned to one of the three bonding material groups. Bracket survival rates and distributions were obtained by following these patients for 1.2 years. Data was analyzed using the Kaplan-Meier product-limit estimates of survivorship function. Bond failure interface was determined using a modified adhesive remnant index (ARI). These results showed no significant difference between survival rates and distributions among the three bonding materials with respect to the type of malocclusion, type of orthodontic treatment, or location of bracket. There were significant differences between survival distributions of males and females in the unetched Fuji Ortho LC group and among type of teeth in the conventional resin groups. The predominant mode of bracket failure for the unetched Fuji Ortho LC cement was at the enamel-adhesive interface, and for conventional resins, the enamel-adhesive interface and the bracket-adhesive interface. These results suggest that resin-reinforced glass ionomer cement can withstand occlusal and orthodontic forces despite having a bond strength lower than that of conventional resin adhesives. PMID:10515145

Shammaa, I; Ngan, P; Kim, H; Kao, E; Gladwin, M; Gunel, E; Brown, C

1999-10-01

57

Evaluation of shear bond strength of two resin-based composites and glass ionomer cement to pure tricalcium silicate-based cement (Biodentine®)  

PubMed Central

Objectives Tricalcium silicate is the major constituent phase in mineral trioxide aggregate (MTA). It is thus postulated that pure tricalcium silicate can replace the Portland cement component of MTA. The aim of this study was to evaluate bond strength of methacrylate-based (MB) composites, silorane-based (SB) composites, and glass ionomer cement (GIC) to Biodentine® and mineral trioxide aggregate (MTA). Material and Methods Acrylic blocks (n=90, 2 mm high, 5 mm diameter central hole) were prepared. In 45 of the samples, the holes were fully filled with Biodentine® and in the other 45 samples, the holes were fully filled with MTA. The Biodentine® and the MTA samples were randomly divided into 3 subgroups of 15 specimens each: Group-1: MB composite; Group-2: SB composite; and Group-3: GIC. For the shear bond strength (SBS) test, each block was secured in a universal testing machine. Results The highest (17.7±6.2 MPa) and the lowest (5.8±3.2 MPa) bond strength values were recorded for the MB composite-Biodentine® and the GIC-MTA, respectively. Although the MB composite showed significantly higher bond strength to Biodentine (17.7±6.2) than it did to MTA (8.9±5.7) (p<0.001), the SB composite (SB and MTA=7.4±3.3; SB and Biodentine®=8.0±3,6) and GIC (GIC and MTA=5.8±3.2; GIC and Biodentine=6.7±2.6) showed similar bond strength performance with MTA compared with Biodentine (p=0.73 and p=0.38, respectively). Conclusions The new pure tricalcium-based pulp capping, repair, and endodontic material showed higher shear bond scores compared to MTA when used with the MB composite. PMID:25141202

CANTEKIN, Kenan; AVCI, Serap

2014-01-01

58

In vitro quantitative evaluation of marginal microleakage in Class II restorations confected with a glass ionomer cement and two composite resins.  

PubMed

This study evaluated, in vitro, marginal microleakage in class II restorations confected with the glass ionomer cement Vitremer and with the composite resins Ariston pHc and P-60. The aims of the study were to assess the effect of thermocycling on those materials and to evaluate two methods utilized in the analysis of dye penetration. Sixty premolars divided in three groups were utilized; the teeth had proximal cavities whose cervical walls were located 1 mm below the cementoenamel junction. Half of the test specimens from each group underwent thermocycling; the other half remained in deionized water, at 37 degrees C. The specimens were immersed, for 24 hours, in a basic 0.5% fuchsin solution at 37 degrees C. For the analysis of microleakage, the specimens were sectioned in a mesio-distal direction, and the observation was carried out with the software Imagetools. The results were evaluated through the 2-way ANOVA and through the Tukey's test. All groups presented marginal microleakage. The smallest values were obtained with Vitremer, followed by those obtained with the composite resins P-60 and Ariston pHc. There was no statistically significant difference caused by thermocycling, and the method of maximum infiltration was the best for detecting the extension of microleakage. PMID:11787314

Bijella, M F; Bijella, M F; da Silva, S M

2001-01-01

59

Compound changes and tooth mineralization effects of glass ionomer cements containing bioactive glass (S53P4), an in vivo study.  

PubMed

In this study, modifications of glass ionomer cements (GICs) were made by adding bioactive glass (BAG) to GIC to obtain bioactive restorative materials. This study used SEM, EDS and visual analysis to examine the bioactivity and the ability of the study materials to mineralize dentin. Conventional cure and resin-modified light-curing GIC were used. The materials consisted of powder and liquid. Three experimental materials were made by mixing 10-30 wt% of BAG powder with GIC powders. Commercially available GIC without BAG were used as controls. Class III restorations were made in altogether 62 intact beagle dog teeth, and the operation was performed under general anesthesia. The restorations were followed clinically for 1, 3 or 6 weeks. Resin-modified GIC containing BAG showed uniform CaP surface formation on the restorations. Mineral depositions in the close vicinity of the restoration-dentin interface and in deeper parts of dentin tubules were also noticed in resin-modified GIC containing BAG particles. It can be concluded that resin-modified GIC containing BAG have good potential in clinical applications where enhanced mineralization is expected. PMID:15958240

Yli-Urpo, Helena; Närhi, Matti; Närhi, Timo

2005-10-01

60

Effect of different surface treatments on the shear and microtensile bond strength of resin-modified glass ionomer cement to dentin.  

PubMed

Abstract Objective. The aim of this study was to evaluate the effect of different surface treatments on the microtensile bond strength (?TBS) and shear bond strength (SBS) of resin-modified glass ionomer cement (RMGIC) to dentin. Materials and methods. Fifty-two extracted human molars were flattened to obtain dentin surfaces. For SBS assessment 40 teeth were divided into four groups according to their surface treatments (acid etching, Er:YAG laser QSP mode, Er:YAG laser MSP mode and control-SiC) (n = 10). A plastic cylinder was placed over the differently treated dentin surfaces and RMGIC was placed into the rings and polymerized. Twelve teeth were used for the ?TBS test. The treated dentin surfaces described above were restored with 4 mm high RMGIC and light cured; then, the specimens were sectioned into serial sticks (n = 15) and ?TBS and SBS were tested for failure in a testing machine with a 1 mm/min crosshead speed. The data were analyzed by one-way ANOVA and Tukey HSD tests (? = 0.05). Results. Acid etching showed significantly higher SBS than the other groups (p < 0.05). Er:YAG QSP and MSP-treated groups showed higher SBS values than the control group, but the difference was not statistically significant (p > 0.05). Er:YAG MSP showed the highest ?TBS value followed by acid etching, whereas the control group exhibited the lowest value (p < 0.05) and the differences between the control group and Er:YAG QSP were not significant (p > 0.05). Conclusions. The application of Er:YAG MSP mode and acid etching to dentin can be used for improving the bond strength of RMGIC. PMID:24844786

Altunsoy, Mustafa; Botsali, Murat Selim; Korkut, Emre; Kucukyilmaz, Ebru; Sener, Yagmur

2014-11-01

61

The effects of ambient temperature and mixing time of glass ionomer cement material on the survival rate of proximal ART restorations in primary molars  

PubMed Central

Objective: Temperature fluctuations and material mixing times are likely to affect the consistency and integrity of the material mixture, and hence the restoration made out of it. The purpose of the present study was to determine the influence of the ambient temperature and the mixing time of glass ionomer cement (GIC) restorative material on the survival rate of proximal atraumatic restorative treatment (ART) restorations placed in primary molars. Materials and Methods: A total of 804 restorations were placed in the primary molars of 6-8-year-olds using the ART approach. The restorations were then followed for a period of 2 years and evaluated at given intervals. The data collected were analyzed using SPSS computer statistical program, and the results tested and compared using the Chi-square, Kaplan Meier survival analysis and Cox Proportional hazard statistical tests. Results: The cumulative survival rate of the restorations dropped from the initial 94.4% to 30.8% at the end of 2 years. The higher survival rate of the restorations was associated with the experienced operators and assistants when using the rubber dam isolation method. However, there was no statistically significant difference in the survival rate of the restorations when related to the room temperature and the mixing time of the GIC materials used in spite of the variations in the temperature recoded and the methods used in mixing the materials. Conclusion: The ambient temperature and mixing time of GIC did not have a significant effect on the survival of the proximal ART restorations. PMID:24808692

Kemoli, Arthur M

2014-01-01

62

Local and Systemic Responses To Dental Composites and Glass Ionomers  

Microsoft Academic Search

For many years, the dental profession worked mainly with rather inert restorative materials that had a limited contact with vital tissue, and the opportunity for local and systemic complications was minimal. However, conditions have changed in recent years where the two leading non-mercury-containing materials, resin composites and glass-ionomer cements, are chemically active compounds and can have detrimental effects on pulp

Harold R. Stanley

1992-01-01

63

Evaluation and Comparison of the Effect of Different Surface Preparations on Bond Strength of Glass Ionomer Cement with Nickel–Chrome Metal–Ceramic Alloy: A Laboratory Study  

Microsoft Academic Search

Retention of fixed partial dentures is mostly dependent upon the bond between metal and cement as well as cement and tooth\\u000a structure. However, most of the time clinical failure of bond has been observed at metal and cement interface. The treatment\\u000a of metal surface, prior to luting, plays a crucial role in bonding cement with the metal. This study is

Kalpana Hasti; H. G. Jagadeesh; Narendra P. Patil

2011-01-01

64

Comparative wear resistance of reinforced glass ionomer restorative materials.  

PubMed

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

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

2001-01-01

65

Failure of a Glass Ionomer to Remineralize Apatite-depleted Dentin  

Microsoft Academic Search

Remineralization of demineralized dentin lesions adjacent to glass-ionomer cements (GICs) has been reported in the literature. This study tested the hypothesis that a strontium-based GIC can remineralize completely demineralized dentin by nucleation of new apatite crystallites within an apatite-free dentin matrix. Human dentin specimens were acid-etched, bonded with Fuji IXGP, and immersed in a calcium-and-phosphate-containing 1.5X simulated body fluid (SBF)

Y. K. Kim; C. K. Y. Yiu; J. R. Kim; L. Gu; S. K. Kim; R. N. Weller; D. H. Pashley; F. R. Tay

2010-01-01

66

Fluoride release and bioactivity evaluation of glass ionomer: Forsterite nanocomposite  

PubMed Central

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

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

2013-01-01

67

Cytotoxicity of dental glass ionomers evaluated using dimethylthiazol diphenyltetrazolium and neutral red tests.  

PubMed

The purpose of this study was to assess the cytotoxicity of some commonly used glass ionomers. Three chemically cured glass ionomers (Fuji II, Lining cement, and Ketac Silver) and one light-cured (Fuji II LC) were tested. Extracts of mixed non-polymerized materials and polymerized specimens were prepared in accordance with ISO standard 10993-12. The polymerized specimens were cured and placed either directly in the medium (freshly cured), left for 24 h (aged), or aged plus ground before being placed in the medium. The cytotoxicity of extracts was evaluated on mouse fibroblasts (L, 929), using dimethylthiazol diphenyltetrazolium (MTT) and neutral red (NR) assays. Further, the concentrations of aluminum, arsenic and lead were analyzed in aqueous extracts from freshly cured and aged samples, and the fluoride levels analyzed in aqueous extracts from freshly cured samples. All extracts except that of non-polymerized Ketac Silver were rated as severely cytotoxic in both assays. Extracts of polymerized material were significantly more cytotoxic than extracts of non-polymerized material. All freshly cured glass ionomers released aluminum and fluoride concentrations far above what is considered cytotoxic (aluminum >0.2 ppm and fluoride >20 ppm). Extracts from freshly cured Lining Cement contained the highest concentrations of aluminum and fluoride (215 ppm and 112 ppm). Extracts from freshly cured Ketac Silver had the lowest concentrations of aluminum and fluoride but the highest of lead (100 ppm). It can be concluded that all extracts from non-cured, freshly cured, and aged glass ionomers contained cytotoxic levels of substances. Curing did not reduce the toxicity significantly. PMID:11318043

Lönnroth, E C; Dahl, J E

2001-02-01

68

Mechanical properties of dental luting cements  

Microsoft Academic Search

Statement of problem. Dental luting cements fail by microcrack formation and bacterial ingress or by gross failure and crown dislodgment. Both of these failure modes are related to mechanical properties and deformation. Purpose. This study evaluated those mechanical properties of cements. Methods and material. Elastic modulus for 8 representative cements (zinc phosphate, polycarboxylate, glass ionomer, encapsulated glass ionomer, resin-modified glass

Zhen Chun Li; Shane N. White

1999-01-01

69

Thermal characterization of glass ionomer/vinyl IPN composites  

SciTech Connect

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.

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

70

The effect of low dose teicoplanin-loaded acrylic bone cement on biocompatibility of bone cement.  

PubMed

Antibiotic-loaded acrylic bone cement (polymethylmethacrylate, PMMA) is used to prevent or treat infection in total joint replacement surgery. The purpose of this study was to investigate biocompatibility and cytotoxicity of the teicoplanin-loaded acrylic bone cement. Cytotoxicity examination of acrylic bone cement balls and 400 mg teicoplanin added acrylic bone cement balls conducted by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. SEM (Scanning electron microscopy) was used to observe adhesion and spreading of cells on surface of the balls. Cytotoxicity examination conducted by MTT assay on acrylic bone cement balls and teicoplanin-added acrylic bone cement balls revealed no cytotoxicity. SEM analysis put forward that cells started to proliferate and adhere on surface of the samples in both groups as a result of 48-hour incubation and that the cell proliferation over acrylic bone cement and teicoplanin-added acrylic bone cement was similar. As a consequence, there was no cytotoxicity in acrylic bone cement and teicoplanin-added acrylic bone cement groups according to results of MTT assay. On the other hand, results of SEM showed that biocompatibility of both groups was similar. In conclusion, teicoplanin-loaded bone cement did not change biocompatibility of bone cement in studied dose. PMID:23827744

Öztemür, Zekeriya; Sümer, Zeynep; Tunç, Tutku; Pazarcé, Özhan; Bulut, Okay

2013-06-01

71

Clinical Evaluation of Resin Composite and Resin Modified Glass Ionomer in Class III Restorations of Primary Maxillary Incisors: A Comparative In Vivo Study  

PubMed Central

Restoration of primary teeth continues to be an important facet of restorative dentistry. In comparison to restorations in permanent dentition, the longevity of those in primary teeth is significantly different for all materials. This makes the assessment of these fillings as a separate group meaningful. As there is lack of supporting clinical data with regard to the restoration of primary incisors, it would be judicious to consider why this is so and determine if studies can be designed to gain new information. The purpose of this study was therefore to evaluate and compare the clinical efficacy of composite resins and resin-modified glass ionomer cement restorations of primary incisors, over a period of one year. Methods: The study group consisted of 40 patients (3½- 5 ½ years of age) with at least one pair of similar sized lesions in the middle1/3 of the same proximal surface of contralateral primary maxillary incisors. Composite resin and resinmodified glass ionomer cement restorations were placed in primary maxillary incisors using split-mouth design. The restorations were evaluated at different intervals of 3,6,9, months and 1 year using Ryge’s criteria. Data obtained was analyzed using Mann-Whitney test. Results: The results revealed no statistical significance in the difference of clinical characteristics between the two restorative materials. Interpretation and conclusion: (1) Resin-modified glass ionomer cement and composite resin restorative materials showed acceptable clinical performance after 1 year in primary teeth. (2) Resin-modified glass ionomer cement and composite resin restorative materials functioned well as class III restorative materials in primary teeth.

Mohan Das, Usha; Viswanath, Deepak; Azher, Umme

2009-01-01

72

Microleakage of high-strength glass ionomer: resin composite restorations in minimally invasive treatment.  

PubMed

Atraumatic Restorative Treatment (ART) has been investigated as an alternative caries treatment. The technique involves removal of loose tooth structure with a spoon excavator, followed by placement of an adhesive restorative material, often a high-strength glass ionomer. This study compares the microleakage of a high-strength glass ionomer/resin composite and two occlusal resin composite restoration techniques. PMID:12061017

Platt, J A; Rhodes, B

73

Improvement of enamel bond strengths for conventional and resin-modified glass ionomers: acid-etching vs. conditioning*  

PubMed Central

Objective: This study deals with the effect of phosphoric acid etching and conditioning on enamel micro-tensile bond strengths (?TBSs) of conventional and resin-modified glass ionomer cements (GICs/RMGICs). Methods: Forty-eight bovine incisors were prepared into rectangular blocks. Highly-polished labial enamel surfaces were either acid-etched, conditioned with liquids of cements, or not further treated (control). Subsequently, two matching pre-treated enamel surfaces were cemented together with one of four cements [two GICs: Fuji I (GC), Ketac Cem Easymix (3M ESPE); two RMGICs: Fuji Plus (GC), RelyX Luting (3M ESPE)] in preparation for ?TBS tests. Pre-treated enamel surfaces and cement-enamel interfaces were analyzed by scanning electron microscopy (SEM). Results: Phosphoric acid etching significantly increased the enamel ?TBS of GICs/RMGICs. Conditioning with the liquids of the cements produced significantly weaker or equivalent enamel ?TBS compared to the control. Regardless of etching, RMGICs yielded stronger enamel ?TBS than GICs. A visible hybrid layer was found at certain enamel-cement interfaces of the etched enamels. Conclusions: Phosphoric acid etching significantly increased the enamel ?TBSs of GICs/RMGICs. Phosphoric acid etching should be recommended to etch the enamel margins before the cementation of the prostheses such as inlays and onlays, using GICs/RMGICs to improve the bond strengths. RMGICs provided stronger enamel bond strength than GICs and conditioning did not increase enamel bond strength. PMID:24190447

Zhang, Ling; Tang, Tian; Zhang, Zhen-liang; Liang, Bing; Wang, Xiao-miao; Fu, Bai-ping

2013-01-01

74

Clinical and microbiological performance of resin-modified glass-ionomer liners after incomplete dentine caries removal.  

PubMed

The aims of this study were to evaluate clinically and microbiologically the effects of two resin-modified glass-ionomer cements (RMGICs) used as liners after incomplete dentine caries removal and to identify Streptococcus mutans and Streptococcus sobrinus strains isolated from dentine samples, before and after indirect pulp treatment. Twenty-seven primary molars with deep carious lesions, but without signs and symptoms of irreversible pulpitis, were submitted to indirect pulp treatment. Treatment consisted of incomplete excavation of the carious dentine, application of one of the RMGICs (Vitrebond or Fuji Lining LC) or calcium hydroxide cement (Dycal), and sealing for 3 months. Clinical evaluation (consistency, color, and wetness of dentine) and carious dentine collects were performed before temporary sealing and after the experimental period. Microbiological samples were cultivated in specific media for subsequent counting of mutans streptococci (MS) and lactobacilli (LB). MS colonies were selected for identification of S. mutans and S. sobrinus by polymerase chain reaction. After 3 months, the remaining dentine was hard and dry, and there was a significant decrease in the number of MS and LB, in all groups, although complete elimination was not achieved in 33% and 26% of the teeth for MS and LB, respectively. From 243 MS colonies selected, 216 (88.9%) were identified as S. mutans and only 2 (0.8%) as S. sobrinus. The use of resin-modified glass-ionomer liners after incomplete caries removal, as well as a calcium hydroxide cement, promoted significant reduction of the viable residual cariogenic bacteria in addition to favorable clinical changes in the remaining carious dentine. PMID:19548010

Duque, Cristiane; Negrini, Thais de Cássia; Sacono, Nancy Tomoko; Spolidorio, Denise Madalena Palomari; de Souza Costa, Carlos Alberto; Hebling, Josimeri

2009-12-01

75

Stoichiometry of the leaching process of fluoride-containing aluminosilicate glass-ionomer glasses.  

PubMed

Dental glass-ionomer cements (GIC) set by an acid-base reaction between a polyalkenoic acid and an ion-leachable glass. The exact relationship between the glass composition and the setting and final properties of GIC is not yet fully elucidated. As part of a systematic study of this relationship, we studied the leaching stoichiometry of glasses used in commercial formulations to correlate the glass composition with its leaching properties. The leaching experiments were performed in acetic acid solutions at pH = 3.4 by means of a pH-stat method. After predetermined time intervals, the suspension was filtered and the filtrate was analyzed for the glass constituents. The usefulness of the pH-stat method for the determination of glass reactivity was corroborated. The deviation of the leaching stoichiometry with respect to the pure glass stoichiometry decreased with increasing relative content of mono- and bivalent glass network dwellers and modifiers. Indications were found that the latter can be leached out independently and preferentially, while the leaching of network dwellers is coupled with the aluminum release. The F content as well as the reactivity of the glass affect the amount of fluoride available for release from a set GIC. It could be concluded that the leaching stoichiometry of GIC glasses can be correlated with their absolute and relative composition. PMID:10403458

De Maeyer, E A; Verbeeck, R M; Vercruysse, C W

1999-07-01

76

An in vitro comparative SEM study of marginal adaptation of IRM, light- and chemically-cured glass ionomer, and amalgam in furcation perforations.  

PubMed

The furcation regions of 30 human mandibular molars were perforated and sealed using four different materials: IRM, light- and chemically-cured glass ionomer cement (GIC), and amalgam. The materials were compared for marginal gaps in coronal, mid, and apical regions after routine SEM processing. While light-cured GIC showed the smallest gaps in the three regions, in mid and coronal regions chemically-cured GIC, and in apical regions amalgam, showed the largest gaps. IRM cases showed the highest rate of fillings with a good "fit", whereas the majority of amalgam cases and none of the chemically-cured GIC cases were overfilled. PMID:12360666

Rajablou, N; Azimi, S

2001-12-01

77

A novel star-shaped poly(carboxylic acid) for resin-modified glass-ionomer restoratives.  

PubMed

We have developed a novel glass-ionomer cement (GIC) system composed of photo-curable star-shaped poly(acrylic acid-co-itaconic acid)s. These polyacids were synthesized via a chain-transfer radical polymerization using a newly synthesized multi-arm chain-transfer agent. The star-shaped polyacids showed significantly lower viscosities in water as compared to the linear polyacids. Due to the lower viscosities, the molecular weight (MW) of the polyacids can be significantly increased for enhancing the mechanical strengths while keeping the ease of mixing and handling. The effects of MW, GM-tethering ratio, P/L ratio, and aging on the compressive properties of the experimental cements were significant. The light-cured experimental cements showed significantly improved mechanical strengths i.e. 49% in yield strength, 41% in modulus, 25% in CS, 20% in DTS, and 36% in FS, higher than commercial Fuji II LC. After aging in water for 1 month, the compressive strength of the novel light-cured experimental cement reached 343?MPa, which was 34% and 42% higher than Fuji II and Fuji II LC, respectively. This one-month aged experimental cement was also 23% higher than itself after one day aging, indicating that aging in water can significantly enhance salt-bridge formation for this novel star-shaped polyacid-comprised GIC. PMID:24865692

Weng, Y; Howard, L; Xie, D

2014-07-01

78

Bioglass: A novel biocompatible innovation  

PubMed Central

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

Krishnan, Vidya; Lakshmi, T.

2013-01-01

79

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

PubMed Central

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

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

2014-01-01

80

Effect of surface treatments on the bond strength of glass ionomers to enamel  

Microsoft Academic Search

Objectives: The objective of this study was to evaluate the effect of various surface treatments on the bond strength of several glass ionomers to enamel, and to examine the resulting bond interface.Methods: Ground bovine enamel specimens were divided into groups which were pretreated with one of the following: (1) no pretreatment, (2) Vitremer primer, (3) 10% polyacrylic acid or (4)

Eileen A. Glasspoole; Robert L. Erickson; Carel L. Davidson

2002-01-01

81

Biocompatibility of mineral trioxide aggregate and three new endodontic cements: An animal study  

PubMed Central

Background: Introducing new endodontic cements should await comprehensive investigations and new formulations have to be tested in vivo before applying in human beings. So, the purpose of this study was to compare the biocompatibility of new endodontic cements, calcium aluminate ?-aluminate cement (CAAC), calcium aluminate ?-aluminate plus cement (CAAC plus), and a mixture of wollastonite and CAAC cement (WOLCA) and mineral trioxide aggregate (MTA), in subcutaneous connective tissue of rats. Materials and Methods: Twenty-seven Wistar rats were divided into three groups of 7, 14, and 30 experimental days. Sterile polyethylene tubes were filled with MTA, CAAC, CAAC Plus, and WOLCA cement and implanted subcutaneously. Empty tubes were implanted as negative control. After the experimental periods, animals were sacrificed by anesthetic overdosing. The occurrence of inflammatory responses was scored according to the previously established scores. Data were statistically analyzed using Friedman, Wilcoxon, Kruskal-Wallis, and Mann-Whitney tests. The level of significance was 5% (P<0.05). Results: There was a statistically significant difference between experimental and negative control sites in each group (P<0.05). CAAC Plus showed the highest mean scores of inflammation, compared with MTA, CAAC, and WOLCA cement sits at the end of all periods (P<0.05). There were no statistically significant differences between inflammatory scores of each site in different experimental groups, except CAAC plus sites, in which inflammation increased significantly with time (P<0.05). Conclusion: According to the results of the current study, biocompatibility of CAAC and WOLCA cement were comparable with that of MTA, but CAAC Plus induced an inflammatory response higher than MTA, therefore is not biocompatible. PMID:22363364

Aminozarbian, Mohammad-Ghasem; Barati, Masoud; Salehi, Iman; Mousavi, Seyed Behrouz

2012-01-01

82

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

PubMed Central

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.

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

2014-01-01

83

Biocompatibility in vitro tests of mineral trioxide aggregate and regular and white Portland cements.  

PubMed

Mineral trioxide aggregate (MTA) and Portland cement are being used in dentistry as root end-filling materials. However, biocompatibility data concerning genotoxicity and cytotoxicity are needed for complete risk assessment of these compounds. In the present study, genotoxic and cytotoxic effects of MTA and Portland cements were evaluated in vitro using the alkaline single cell gel (comet) assay and trypan blue exclusion test, respectively, on mouse lymphoma cells. The results demonstrated that the single cell gel (comet) assay failed to detect DNA damage after a treatment of cells by MTA and Portland cements for concentrations up to 1000 microg/ml. Similarly, results showed that none of the compounds tested were cytotoxic. Taken together, these results seem to indicate that MTA and Portland cements are not genotoxins and do not induce cellular death. PMID:16044045

Ribeiro, Daniel Araki; Duarte, Marco Antonio Hungaro; Matsumoto, Mariza Akemi; Marques, Mariangela Esther Alencar; Salvadori, Daisy Maria Favero

2005-08-01

84

Phase composition, mechanical performance and in vitro biocompatibility of hydraulic setting calcium magnesium phosphate cement.  

PubMed

Brushite (CaHPO(4) x 2H(2)O)-forming calcium phosphate cements are of great interest as bone replacement materials because they are resorbable in physiological conditions. However, their short setting times and low mechanical strengths limit broad clinical application. In this study, we showed that a significant improvement of these properties of brushite cement could be achieved by the use of magnesium-substituted beta-tricalcium phosphate with the general formula Mg(x)Ca((3-x))((PO(4))(2) with 0 < x < 3 as cement reactants. The incorporation of magnesium ions increased the setting times of cements from 2 min for a magnesium-free matrix to 8-11 min for Mg(2.25)Ca(0.75)(PO(4))(2) as reactant. At the same time, the compressive strength of set cements was doubled from 19 MPa to more than 40 MPa after 24h wet storage. Magnesium ions were not only retarding the setting reaction to brushite but were also forming newberyite (MgHPO(4) x 3H(2)O) as a second setting product. The biocompatibility of the material was investigated in vitro using the osteoblast-like cell line MC3T3-E1. A considerable increase of cell proliferation and expression of alkaline phosphatase, indicating an osteoblastic differentiation, could be noticed. Scanning electron microscopy analysis revealed an obvious cell growth on the surface of the scaffolds. Analysis of the culture medium showed minor alterations of pH value within the physiological range. The concentrations of free calcium, magnesium and phosphate ions were altered markedly due to the chemical solubility of the scaffolds. We conclude that the calcium magnesium phosphate (newberyite) cements have a promising potential for their use as bone replacement material since they provide a suitable biocompatibility, an extended workability and improved mechanical performance compared with brushite cements. PMID:19837194

Klammert, Uwe; Reuther, Tobias; Blank, Melanie; Reske, Isabelle; Barralet, Jake E; Grover, Liam M; Kübler, Alexander C; Gbureck, Uwe

2010-04-01

85

Evaluation of the biocompatibility of experimentally manufactured portland cement: An animal study  

PubMed Central

Objectives: The purpose of this study was to evaluate the biocompatibility of MTA and the experimentally manufactured portland cement (EMPC). Study design: Twenty one Sprague Dawley (SD) rats were allocated to testing of three groups. Group I and Group II included ProRoot MTA and the EMPC. The materials were mixed with distilled water and placed in polyethylene tubes. The tubes were implanted subcutaneously in the dorsal region of the animals. Group III served as control; the implanted polyethylene tubes remained empty. At 7, 14, and 28 days after the implantation, the animals were sacrificed and the implants were removed with the surrounding tissues. The specimens were prepared for histological examination to evaluate the inflammatory response. Results: No significant difference was found between tissue reactions against the tested materials (p>0.05). Also, control group showed similar results (p>0.05). Conclusions: Results suggest that the EMPC has the potential to be used in clinical conditions in which ProRoot MTA is indicated. MTA and the EMPC show comparable biocompatibility when evaluated in vivo. Although the results are supportive for the EMPC, more studies are required before the safe clinical use of the EMPC. Key words:Mineral trioxide aggregate, portland cement, subcutanous implantation. PMID:24596630

Erten, Hulya; Baris, Emre; Turk, Serkan; Alacam, Tayfun

2014-01-01

86

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

PubMed Central

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

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

2014-01-01

87

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

PubMed

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

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

2013-12-01

88

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

PubMed Central

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

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

2012-01-01

89

Comparison of the push-out shear bond strength of four types of glass ionomers when used to bond amalgam: An in vitro study  

PubMed Central

Background: Dental amalgam is the primary direct posterior restorative material used worldwide, but it have certain shortcomings due to the lack of adhesiveness to the cavity. The introduction of the concept of bonded amalgam helped improve the use of amalgam as a restorative material. Aim: Evaluation of the comparative push-out shear bond strength of four types of conventional glass ionomers used to bond amalgam to tooth in simulated class I situations. Materials and Methods: Four chemical cure glass ionomers are used: GC Fuji I, GC Fuji II, GC Fuji III and GC Fuji VII, and are compared with unbonded amalgam. The push-out bond strength was tested using the Instron Universal Testing Machine at a crosshead speed of 0.5 mm/min. Statistical Analysis: One-way ANOVA and post hoc Bonferroni tests were used to analyze the data. Results: The results showed that the use of glass ionomer to bond amalgam resulted in an increase in the bond strength of amalgam. The Type VII glass ionomer showed the highest bond strength in comparison with the other glass ionomers. Conclusions: Conventional glass ionomer bonds to amalgam and shows a beneficial increase in the bond strength of the restoration in comparison with unbonded amalgam. PMID:22144798

Mathew, Vinod Babu; Ramachandran, S; Indira, R; Shankar, P

2011-01-01

90

Highly sensitive amperometric biosensor based on a biocompatible calcium phosphate cement.  

PubMed

Brushite is a biocompatible calcium phosphate mineral with properties of solid electrolyte. In this study we take advantage of this characteristic to develop an enzymatic amperometric biosensor based on brushite cement. The biosensor was prepared by immobilizing tyrosinase (PPO) on a brushite cement layer which was subsequently cross-linked with glutaraldehyde (GA) on the surface of a glassy carbon electrode. The system was optimized for the detection of phenolic compounds in both aqueous and non-aqueous solutions. Several variables involved in the enzyme immobilization method such as glutaraldehyde cross-linking time, PPO/brushite ratio and thickness of the brushite film were investigated. Furthermore, the effects of the pH, temperature and applied potential on the biosensor performance were also optimized. On the other hand, the biosensor analytical properties were studied in presence of different organic solvents: dioxane, acetonitrile and ethanol. In both, phosphate buffer solution (PBS) and acetonitrile/PBS solution, the biosensor exhibits a rapid response (12 s); a wide linear range (0.001-3 microM and 0.007-2 microM respectively); low detection limit (1 and 2 nM respectively); and high sensitivity (46.6 and 28.6 A M(-1) cm(-2) respectively). The performance of the biosensor in the analysis of phenols in real samples was successful. PMID:19211238

Sánchez-Paniagua López, M; Tamimi, F; López-Cabarcos, E; López-Ruiz, B

2009-04-15

91

The Effect of Temperature on Viscoelastic Properties of Glass Ionomer Cements and Compomers  

E-print Network

of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece 2 of Athens, School of Dentistry, Department of Biomaterials Received 14 February 2006; revised 9 April 2006.interscience.wiley.com). DOI: 10.1002/jbm.b.30618 Abstract: The objective of this study was to determine the viscoelastic

Lakes, Roderic

92

An evaluation of microleakage of various glass ionomer based restorative materials in deciduous and permanent teeth: An in vitro study  

PubMed Central

Aim To evaluate the microleakage of recently available glass ionomer based restorative materials (GC Fuji IX GP, GC Fuji VII, and Dyract) and compare their microleakage with the previously existing glass ionomer restorative materials (GC Fuji II LC) in primary and permanent teeth. Method One hundred and fifty (75 + 75) non-carious deciduous and permanent teeth were restored with glass ionomer based restorative materials after making class I cavities. Samples were subjected to thermocycling after storing in distilled water for 24 h. Two coats of nail polish were applied 1 mm short of restorative margins and samples sectioned buccolingually after storing in methylene blue dye for 24 h. Microleakage was assessed using stereomicroscope. Result Significant differences (P < 0.05) were found when inter group comparisons were done. Except when GC Fuji VII (Group III) was compared with GC Fuji II LC (Group II) and Dyract (Group IV), non-significant differences (P > 0.05) were observed. It was found that there was no statistically significant difference when the means of microleakage of primary teeth were compared with those of permanent teeth. Conclusions GC Fuji IX GP showed maximum microleakage and GC Fuji VII showed least microleakage. PMID:23960526

Singla, Teena; Pandit, I.K.; Srivastava, Nikhil; Gugnani, Neeraj; Gupta, Monika

2011-01-01

93

Long-term fluoride release from resin-reinforced orthodontic cements following recharge with fluoride solution.  

PubMed

The aim of this study was to test the hypothesis that there is no difference in the fluoride release behavior of resin-reinforced glass ionomer cements before or after fluoride recharge. The materials were divided into 5 groups: 2 resin-reinforced glass ionomer cements used for attaching orthodontic bands, that is, group FOB (Fuji Ortho Band) and group MCB (Multi-Cure Glass Ionomer Orthodontic Band Cement); 2 resin-reinforced glass ionomer cements and a composite used for bonding orthodontic brackets, that is, group OGLC (Ortho Glass LC), group FOLC (Fuji Ortho LC), and group TXT (Transbond XT), respectively. Fluoride release was measured during a 60-day period by using selective ion electrodes connected to an ionic analyser. After 4 weeks, the samples were exposed to 0.221% sodium fluoride solution. The results showed that cements achieved a maximum fluoride release 24 h after initial setting. No statistically significant differences were observed between groups FOB and OGLC regarding the amount of released fluoride following fluoride recharge from day 31 to day 36 (p>0.05). In conclusion, FOB and OGLC cements showed a higher capacity of capturing and releasing fluoride compared to the other cements studied. PMID:20640354

dos Santos, Rogério Lacerda; Pithon, Matheus Melo; Vaitsman, Delmo Santiago; Araújo, Mônica Tirre de Souza; de Souza, Margareth Maria Gomes; Nojima, Matilde Gonçalves da Cunha

2010-01-01

94

Repairability of three resin-modified glass-ionomer restorative materials.  

PubMed

The purpose of this study was to evaluate the repair shear bond strengths of three resin-modified glass-ionomer restorative materials repaired at two different times. Thirty specimens of Fuji II LC, Vitremer, and Photac-Fil were prepared in cavities (2 mm x 7 mm) cut into acrylic resin cylinders. After the initial fill, half of the specimens were repaired 5 minutes later and half 1 week later. The specimens were stored in 37 degrees C distilled water when not being repaired or tested. Repairs were made without any surface preparation of the initial fill. Each specimen was mixed according to the manufacturer's directions, placed in the preparation in 1-mm increments and photocured for 40 seconds. The last increment was covered with a plastic strip and a glass slide before curing to create a smooth surface. Repairs were accomplished by drying the specimen for 10 seconds, then adding the new material to the unprepared surface using a 3-mm-thick polytetrafluoroethylene mold. The specimens were thermocycled 500 times, stored in 37 degrees C distilled water for 1 week, then loaded to failure in shear at a rate of 0.5 mm/min. Data were analyzed using a one-way ANOVA and Z-value multiple comparison test to determine significant differences at the 0.05 significance level. Vitremer showed no significant difference in shear bond strength for 5-minute and 1-week repair periods, while Fuji II LC and Photac-Fil did. Repair bond strength of Vitremer was significantly greater than Fuji II LC and Photac-Fil at both repair times. This study showed that time of repair significantly affected the bond strength of two of the materials tested. PMID:9760918

Shaffer, R A; Charlton, D G; Hermesch, C B

1998-01-01

95

Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement  

PubMed Central

Objectives To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement. Material and Methods White Portland cement (WPC) was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6). The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p<0.05). Results The results showed an increase of the pH level after 15 days, followed by a slight increase after 30 days and a decrease after 60 days. There were no significant statistical differences among the groups (p>0.05). For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05). The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05). Conclusions The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated. PMID:25141197

MARCIANO, Marina Angelica; GARCIA, Roberto Brandao; CAVENAGO, Bruno Cavalini; MINOTTI, Paloma Gagliardi; MIDENA, Raquel Zanin; GUIMARAES, Bruno Martini; ORDINOLA-ZAPATA, Ronald; DUARTE, Marco Antonio Hungaro

2014-01-01

96

Atraumatic restorative treatment and glass-ionomer sealants in a school oral health programme in Zimbabwe: evaluation after 1 year.  

PubMed

An oral health care programme in secondary schools using the atraumatic restorative treatment (ART) technique for dental caries was started in 1993. Glass-ionomer was used as the restorative and sealant material. Sealants were placed using the "press finger' technique. Results after 1 year revealed a survival percentage for one-surface ART restorations of 93.4 whilst the complete and partial retention percentages for sealants were 60.3 and 13.4, respectively. No caries was observed in teeth restored using ART, and only 0.8% of surfaces diagnosed as having early enamel lesions at the start of the programme and sealed consequently had progressed into active dentinal lesions after 1 year. The sealant retention percentage and the survival percentage of ART restorations were influenced by an operator effect. The majority of restorations were carried out without administering local anaesthesia. The mean treatment time for one-surface ART restorations was 22.1 min (range per operator of 19.8-23.6 min), whilst the mean time for placing sealants was 9.4 min (range per operator of 8.2-10.8 min). Post-operative sensitivity was reported for 6% of the teeth restored. 95% of the students were satisfied with ART as a treatment modality. It is concluded that ART may in part be the answer to the unavailability of restorative care for many population groups globally. PMID:8946101

Frencken, J E; Makoni, F; Sithole, W D

1996-01-01

97

Fluoride release and recharge characteristics of denture base resins containing surface pre-reacted glass-ionomer filler.  

PubMed

The flexural strength, flexural modulus, and the amount of fluoride released from four experimental denture base resins containing 5, 10, 20 and 30 wt% surface pre-reacted glass-ionomer (S-PRG) filler added to the powder were evaluated. The mean flexural strength of the experimental resins, except the 30 wt%, and the flexural modulus of all the resins, complied with ISO 1567 requirements. In the 20 wt% resin, the amount of fluoride released in the initial phase was 1.88 microg/cm2/day, after which the level decreased. After recharging in a 9000 ppm fluoride solution for eight hours, the level of released fluoride increased markedly to 40.21 microg/cm2/16 hrs. Our results show that fluoride levels increased as a function of the S-PRG filler content. After the almost completely discharged resins were recharged, similar fluoride release occurred again. These results suggest that denture base resins containing S-PRG filler have great recharge and release capabilities which may assist in preventing root caries of abutment teeth. PMID:19496404

Kamijo, Kazuko; Mukai, Yoshiharu; Tominaga, Takatoshi; Iwaya, Izumi; Fujino, Fukue; Hirata, Yukio; Teranaka, Toshio

2009-03-01

98

Comparison of Shear Bond Strength of Resin-Modified Glass Ionomer and Composite Resin to Three Pulp Capping Agents  

PubMed Central

Background and aims. Present study was designed to compare the bonding strength of resin-modified glass ionomer (RMGI) and composite resin to mineral trioxide aggregate (MTA), MTA mixed with Na2HPO4 (NAMTA), and calcium-enriched mixture (CEM). Materials and methods. Thirty specimens of each CEM, NAMTA, and MTA were prepared. Composite and RMGI restorations were then placed on the samples (15 samples in six subgroups). Shear bond strength was assessed using universal testing machine. Data were analyzed with two-way ANOVA and post-hoc Tukey test. To compare the bond strength in subgroups, one-away ANOVA was applied. Significance level was set at P < 0.05. Results. Bond strength was significantly higher to composite samples compared to RMGI samples (p<0.001). The difference in bond strength of composite samples between MTA and CEM subgroups (P=0.026) as well as MTA and NAMTA subgroups (P= 0.019) was significant, but the difference between NAMTA and CEM subgroups (P=0.56) was not significant. The differences in bond strength in subgroups of RMGI group were not significant (P>0.05). Conclusion. Regarding shear bond strength to the tested substrates, composite was shown to be superior to RMGI. The bond of resin composite to MTA was weaker than that to CEM and NAMTA. PMID:24082988

Ajami, Amir Ahmad; Jafari Navimipour, Elmira; Savadi Oskoee, Siavash; Abed Kahnamoui, Mehdi; Lotfi, Mehrdad; Daneshpooy, Mehdi

2013-01-01

99

Maximum bond strength of dental luting cement to amalgam alloy.  

PubMed

Although dental amalgam is used frequently under artificial crowns for restoration of severely damaged teeth, there is little information available on the bond between luting cements and this alloy. This study was designed for determination of the strength of the bond between a dental amalgam alloy and three crown-luting cements. Cylinders of dental amalgam were joined in pairs, with use of a zinc-phosphate, a glass-ionomer, and an acrylic-adhesive resin cement. The tensile-fracture stress of 45 samples of each cement was measured with a universal testing machine, and subjected to a Weibull analysis. The fractured surfaces were examined under low magnification with use of a light microscope, and at low and high magnifications with use of a scanning electron microscope, for evaluation of the appearance of the fractured joints. The Weibull analysis demonstrated that the adhesive resin cement provided a stronger and more predictable bond than either the zinc-phosphate or the glass-ionomer cement. The appearance of the fractured surfaces gave no indication of the strength of the joints, a feature that is common to brittle materials. The results suggest that crowns placed on teeth offering a large amalgam-alloy surface could be retained more predictably with an adhesive resin cement. PMID:2685070

Mojon, P; Hawbolt, E B; MacEntee, M I; Belser, U C

1989-11-01

100

Evaluation of fit of cement-retained implant-supported 3-unit structures fabricated with direct metal laser sintering and vacuum casting techniques.  

PubMed

This study evaluated the vertical discrepancy of implant-fixed 3-unit structures. Frameworks were constructed with laser-sintered Co-Cr, and vacuum-cast Co-Cr, Ni-Cr-Ti, and Pd-Au. Samples of each alloy group were randomly luted in standard fashion using resin-modified glass-ionomer, self-adhesive, and acrylic/urethane-based cements (n = 12 each). Discrepancies were SEM analyzed. Three-way ANOVA and Student-Newman-Keuls tests were run (P < 0.05). Laser-sintered structures achieved the best fit per cement tested. Within each alloy group, resin-modified glass-ionomer and acrylic/urethane-based cements produced comparably lower discrepancies than the self-adhesive agent. The abutment position did not yield significant differences. All misfit values could be considered clinically acceptable. PMID:22075754

Oyagüe, Raquel Castillo; Sánchez-Turrión, Andrés; López-Lozano, José Francisco; Montero, Javier; Albaladejo, Alberto; Suárez-García, María Jesús

2012-07-01

101

[Effect of vibration for the rheology of some luting cements].  

PubMed

Vibrant load is known to be effective to thin the film thickness of various luting cements. In this study, a vibrator which can change various conditions such as frequency, form of wave were made, and the changes of viscosity, film thickness and bond strength were tested statistically. Furthermore, the most effective condition for the slurry of some luting cements (i.e. domestic two zinc phosphate cements, one polycarboxylate cement and one glass ionomer cement) were investigated. The results obtained were as follows. 1) When vibrant load was applied to the slurry of cement in the setting process, the rise in viscosity was apt to be slower than the same case of static load. 2) The effect of vibration appears in the early sixty seconds especially, and the effect varied with the kind of cement, frequency or form of wave. 3) Vibration was also effective for the increase of compressive strength and of bond strength. PMID:2637503

Kaburagi, K

1989-05-01

102

A Comparative Evaluation of the Effect of Resin based Sealers on Retention of Crown Cemented with Three Types of Cement – An In Vitro Study  

PubMed Central

Aim: In an effort to control postoperative sensitivity, dentin sealers are being applied following crown preparations, with little knowledge of how crown retention might be affected. A previous study demonstrated no adverse effect when using a gluteraldehyde-based sealer, and existing studies have shown conflicting results for resin-based products. This study determined the retention of the casting cemented with three types of cement, with and without use of resin sealers and it determined the mode of failure. Materials and Methods: Extracted human molars (n=60) were prepared with a flat occlusal, 20-degree taper, and 4-mm axial length. The axial surface area of each preparation was determined and specimens were distributed equally among groups (n=10). A single-bottle adhesive system (one step single bottle adhesive system) was used to seal dentin, following tooth preparation. Sealers were not used on the control specimens. The test castings were prepared by using Ni-Cr alloy for each specimen and they were cemented with a seating force of 20 Kg by using either Zinc Phosphate (Harvard Cement), Glass Ionomer (GC luting and lining cement,GC America Inc.) and modified-resin cement (RelyXTMLuting2). Specimens were thermocycled for one month and were then removed along the path of insertion by using a Universal Testing Machine at 0.5 mm/min. A single-factor ANOVA was used with a p value of .05. The nature of failure was recorded and the data was analyzed by using Chi-square test. Results: Mean dislodgement stress for Zinc phosphate (Group A) was 24.55±1.0 KgF and that for zinc phosphate with sealer (Group D) was 14.65±0.8 KgF. For glass ionomer (Group B) without sealer, the mean value was 32.0±1.0 KgF and mean value for glass ionomer with sealer (Group E) was 37.90±1.0 KgF. The mean value for modified resin cement (Group C) was 44.3±1.0KgF and that for modified resins with sealer (Group F) was 57.2±1.2 KgF. The tooth failed before casting dislodgement in 8 to 10 specimens cemented with modified-resin cement. Conclusion: Resin sealer decreased casting retentive stress by 46% when it was used with Zinc phosphate. However, sealer use resulted in 60% increased retention when it was used with Glass ionomer cement. The modified-resin cement produced the highest mean dislodgement stress, which nearly always exceeded the strength of the tooth. PMID:24783150

Sharma, Sumeet; Patel, J.R.; Sethuraman, Rajesh; Singh, Sarbjeet; Wazir, Nikhil Dev; Singh, Harvinder

2014-01-01

103

Biocompatibility of posterior restorative materials.  

PubMed

Biocompatibility of dental materials is an important consideration for the patient, clinician, laboratory technician and manufacturer. This paper examines biocompatibility testing methods and the biocompatibility of posterior restorative materials, including amalgam, casting alloys, resin composites, dentin bonding agents, cements, porcelains and ceramics. PMID:9120609

Schuster, G S; Lefebvre, C A; Wataha, J C; White, S N

1996-09-01

104

Evaluation of the sealing ability of resin cement used as a root canal sealer: An in vitro study  

PubMed Central

Aim: This study was designed to evaluate the apical seal of root canals obturated with resin cement as a root canal sealer and compare with that of the glass ionomer and zinc oxide eugenol sealers using a cold lateral condensation gutta-percha technique. Background: Successful root canal treatment requires three-dimensional obturation of the root canal system with nonirritating biomaterials. None of the available materials are capable of providing a fluid tight seal. Materials and Methods: The prepared teeth were randomly divided into three groups of 15 each to be obturated using three different sealers. Group I: zinc oxide eugenol (Tubliseal), Group II: Glass ionomer (Ketac Endo), and Group III: resin cement (C & B Superbond). All the specimens were stored in 100% relative humidity at 37° for 24 h. The specimens were placed in 2% methylene blue dye for 48 h and sectioned. The dye penetration was evaluated under a stereomicroscope. Results: The “Kruskal” Wallis test was carried out to test the equality of mean. All the specimens showed dye leakage, and there was a statistically significant difference (P < 0.0001) among the groups. The specimens in Group III showed a minimal leakage and the specimens in Group I showed a maximum leakage. Conclusion: Resin cement sealed the root canals significantly better when compared with zinc oxide eugenol and glass ionomer sealers. PMID:22876018

Kumar, R Vinod; Shruthi, CS

2012-01-01

105

Comparing the effect of a resin based sealer on crown retention for three types of cements: an in vitro study.  

PubMed

To determine the effect of resin based sealer on retention of casting cemented with three different luting agents. 55 extracted molar teeth were prepared with a flat occlusal surface, 20° taper and 4 mm axial height. The axial surface of each specimen was determined. The specimen were then distributed into five groups based on decreasing surface area, so each cementation group contained 11 specimens with similar mean axial surface area. A two-step, single bottle universal adhesive system (One-Step-Resinomer, Bisco) was used to seal dentin after the tooth preparation. Sealer was not used on the control specimens except for the modified-resin cement (Resinomer, Bisco) specimens that required use of adhesive with cementation. Using ceramometal (Wirobond(®), BEGO), a casting was produced for each specimen and cemented with either zinc phosphate (Harvard), glass ionomer (Vivaglass) or modified resin cement (Resinomer) with single bottle adhesive. All the castings were cemented with a force of 20 kg. Castings were thermal cycled at 5 and 55 °C for 2,500 cycles and were then removed along the path of insertion using a universal testing machine at 0.5 mm/min. A single-factor ANOVA was used with a = 0.05. The nature of failure was also recorded. The mean stress removal for non sealed zinc phosphate, sealed zinc phosphate, non sealed glass ionomer, sealed glass ionomer and modified resin cement was found to be 3.56, 1.92, 2.40, 4.26, 6.95 MPa respectively. Zinc phosphate cement remained principally on the castings when the tooth surface was treated with the sealer and was found on both the tooth and the casting when the sealer was not used. Fracture of root before dislodgement was seen in 9 of 11 specimens with modified resin cement. Resin sealer decreases the retention of the castings when used with zinc phosphate and increases it when used with glass ionomer cement. The highest mean dislodgement force was measured with modified resin cement. PMID:24431752

Patel, Pankaj; Thummar, Mansukh; Shah, Dipti; Pitti, Varun

2013-09-01

106

Effect of light-cure initiation time on polymerization and orthodontic bond strength with a resin-modified glass-ionomer  

NASA Astrophysics Data System (ADS)

Introduction: The polymerization and acid-base reactions in resin-modified glass-ionomers (RMGI) are thought to compete with and inhibit one another. The objective of this study was to examine the effect of visible light-cure (VLC) delay on the polymerization efficiency and orthodontic bond strength of a dual-cured RMGI. Methods: An RMGI light-cured immediately, 2.5, 5, or 10 minutes after mixing comprised the experimental groups. Isothermal and dynamic temperature scan differential scanning calorimetry (DSC) analysis of the RMGI was performed to determine extents of VLC polymerization and acid-base reaction exotherms. Human premolars (n = 18/group) were bonded with the RMGI. Shear bond strength and adhesive remnant index (ARI) scores were determined. Results: DSC results showed the 10 minute delay RMGI group experienced significantly (P <0.05) lower VLC polymerization compared to the other groups. Acid-base reaction exotherms were undetected in all groups except the 10 minute delay group. No significant differences (P >0.05) were noted among the groups for mean shear bond strength. A chi-square test showed no significant difference (P = 0.428) in ARI scores between groups. Conclusions: Delay in light-curing may reduce polymerization efficiency and alter the structure of the RMGI, but orthodontic shear bond strength does not appear to be compromised.

Thomas, Jess

107

A review of chemical-approach and ultramorphological studies on the development of fluoride-releasing dental adhesives comprising new pre-reacted glass ionomer (PRG) fillers.  

PubMed

This paper reviews our recent studies on fluoride-releasing adhesives and the related studies in this field based on information from original research papers, reviews, and patent literatures. A revolutionary PRG (pre-reacted glass ionomer) filler technology--where fillers were prepared by the acid-base reaction of a fluoroaluminosilicate glass with polyalkenoic acid in water, was newly developed, and a new category as "Giomer" was introduced into the market. On fluoride release capability, SIMS examination revealed in vitro fluoride ion uptake by dentin substrate from the PRG fillers in dental adhesive. On bonding durability, it was found that the improved durability of resin-dentin bonds might be achieved not only via the strengthened dentin due to fluoride ion uptake from the PRG-Ca fillers, but also due to retention of relatively insoluble 4-AETCa formed around remnant apatite crystallites within the hybrid layer in 4-AET-containing self-etching adhesives. On ultramorphological study of the resin-dentin interface, TEM images of the PRG-Ca fillers revealed that the dehydrated hydrogel was barely distinguishable from normal glass fillers, if not for the concurrent presence of remnant, incompletely reacted glass cores. In conclusion, it was expected that uptake of fluoride ions with cariostatic effect from PRG-Ca fillers would endow dentin substrates with the benefit of secondary caries prevention, together with an effective and durable adhesion to dentin. PMID:18717159

Ikemura, Kunio; Tay, Franklin R; Endo, Takeshi; Pashley, David H

2008-05-01

108

In vitro degradation, biocompatibility, and in vivo osteogenesis of poly(lactic-co-glycolic acid)/calcium phosphate cement scaffold with unidirectional lamellar pore structure.  

PubMed

The aim of this study was to investigate the in vitro degradation, cytocompatibility, and in vivo osteogenesis of poly(lactic-co-glycolic acid) (PLGA)/calcium phosphate cement (CPC) scaffold with unidirectional lamellar pore structure. CPC-based scaffold was fabricated by unidirectional freeze casting, and PLGA was used to improve the mechanical properties of the CPC-based scaffold, which covered the surface of the pore wall as coating. The in vitro degradation results demonstrated that the PLGA/CPC scaffold had good degradability. The degradation of PLGA film on the surface of the scaffold made the CPC matrix exposed, which facilitated cell response and osteogenesis. Rat bone mesenchymal stem cells (rMSCs) were seeded on the PLGA/CPC composite scaffold. Cell viability, proliferation, and differentiation on the PLGA/CPC composite scaffold were evaluated. The results showed that viable rMSCs attached on the surface of pore wall gradually penetrated into the internal pores of the scaffold as prolongation of culture time. In addition, the rMSCs seeded on the scaffold exhibited good proliferation and growing alkaline phosphatase activity. The scaffold was implanted in the defects in distal end of femora of New Zealand white rabbits. Histological evaluation indicated that the PLGA/CPC scaffold with unidirectional lamellar pore structure had good biocompatibility and effective osteogenesis. These results suggest PLGA/CPC composite scaffold with unidirectional lamellar pore structure is a promising scaffold for bone tissue engineering. PMID:22733543

He, Fupo; Ye, Jiandong

2012-12-01

109

Comparison of the Effect of Three Cements on Prevention of Enamel Demineralization Adjacent to Orthodontic Bands  

PubMed Central

Background and aims This in vitro study was designed to compare enamel demineralization depths adjacent to bands cemented with zinc polycarboxylate, glass ionomer (GI) and resin-modified glass ionomer (RMGI), in order to achieve minimal enamel demineralization during orthodontic treatment. Materials and methods Sixty fully developed extracted third molars were randomly divided into three testgroups each containing 20 samples, used to cement orthodontic bands with zinc polycarboxylate, GI and RMGI. All samples were demineralized using White method using hydroxyapatite, latic acid and Carbapol for in vitro caries simulation, and then, immersed in 10% solution of methylene blue. The mean depth of dye penetration was assessed up to 0.1 millimeter, reflect-ing the depth of enamel demineralization. One way ANOVA and LSD statistical tests were employed to evaluate significant differences among groups. Results The highest dye penetration depth was seen in zinc polycarboxylate group, followed by GI, and RMGI groups, respectively, with significant differences among each two groups (P < 0.05). Conclusion The use of RMGI cement seems to present significantly better prevention of enamel demineralization adja-cent to orthodontics bands. PMID:22991644

Kashani, Mehdi; Farhadi, Sareh; Rastegarfard, Neda

2012-01-01

110

Evaluation of pH at the bacteria-dental cement interface.  

PubMed

Physiochemical assessment of the parasite-biomaterial interface is essential in the development of new biomaterials. The purpose of this study was to develop a method to evaluate pH at the bacteria-dental cement interface and to demonstrate physiochemical interaction at the interface. The experimental apparatus with a well (4.0 mm in diameter and 2.0 mm deep) was made of polymethyl methacrylate with dental cement or polymethyl methacrylate (control) at the bottom. Three representative dental cements (glass-ionomer, zinc phosphate, and zinc oxide-eugenol cements) were used. Each specimen was immersed in 2 mM potassium phosphate buffer for 10 min, 24 hrs, 1 wk, or 4 wks. The well was packed with Streptococcus mutans NCTC 10449, and a miniature pH electrode was placed at the interface between bacterial cells and dental cement. The pH was monitored after the addition of 1% glucose, and the fluoride contained in the cells was quantified. Glass-ionomer cement inhibited the bacteria-induced pH fall significantly compared with polymethyl methacrylate (control) at the interface (10 min, 5.16 ± 0.19 vs. 4.50 ± 0.07; 24 hrs, 5.20 ± 0.07 vs. 4.59 ± 0.11; 1 wk, 5.34 ± 0.14 vs. 4.57 ± 0.11; and 4 wks, 4.95 ± 0.27 vs. 4.40 ± 0.14), probably due to the fluoride released from the cement. This method could be useful for the assessment of pH at the parasite-biomaterial interface. PMID:21933936

Mayanagi, G; Igarashi, K; Washio, J; Nakajo, K; Domon-Tawaraya, H; Takahashi, N

2011-12-01

111

Invivo comparative evaluation of tertiary dentin deposit to three different luting cements a histopathological study.  

PubMed

The aim of the study is to evaluate histopathologically the amount of tertiary dentin deposit stimulated by three different luting cements. With the informed consent for fifteen patients crown preparation was done for maxillary and mandibular premolar teeth which were scheduled for orthodontic extraction. Copings were cemented with three different luting cements zinc oxide eugenol, glass ionomer and zinc polycarboxylate which were classified as Groups A, B and C respectively. The teeth were later extracted and histopathologically analysed for pulpodentinal reactions using a control study group. Statistically Tukey-HSD procedure was used to identify the significant group and one way ANNOVA was used to analyse the thickness of tertiary dentin among the study group. Tertiary dentin was seen in most of the specimens. When the three groups were compared zinc oxide eugenol helps in stimulation of tertiary dentin formation. PMID:24431735

Yogesh, P B; Preethi, M; Babu, Hari; Malathi, N

2013-09-01

112

Comparison of the clinical and preclinical biocompatibility testing of dental materials: are the ISO usage tests meaningful?  

PubMed

International Organization for Standardization (ISO 10993 and 7405) guidelines recommends the preclinical screening of dental materials using non-human primates. The literature contains no comparisons of responses to dental materials. To test the accuracy of preclinical screening tests for predicting human clinical responses, 106 class V pulp exposed cavities were prepared in human and non-human primate teeth. Teeth were restored with calcium hydroxide and amalgam, zinc oxide eugenol or resin-modified glass ionomer. Teeth were extracted after 10-163 days and prepared for histological analysis. Pulp cell numbers were compared and their reactionary dentin activity measured in response to cavity preparation. Pulp inflammatory activity was categorized according to ISO standards. There were no statistically significant differences between human and non-human primate teeth in terms of pulp reactions to dental materials. The use of non-human primates for preclinical biocompatibility investigation provided an accurate method of evaluating clinical responses to dental materials. PMID:17109428

Murray, Peter E; Garcia-Godoy, Franklin

2007-04-01

113

Surface roughness of orthodontic band cements with different compositions  

PubMed Central

Objectives The present study evaluated comparatively the surface roughness of four orthodontic band cements after storage in various solutions. Material and Methods eight standardized cylinders were made from 4 materials: zinc phosphate cement (ZP), compomer (C), resin-modified glass ionomer cement (RMGIC) and resin cement (RC). Specimens were stored for 24 h in deionized water and immersed in saline (pH 7.0) or 0.1 M lactic acid solution (pH 4.0) for 15 days. Surface roughness readings were taken with a profilometer (Surfcorder SE1200) before and after the storage period. Data were analyzed by two-way ANOVA and Tukey's test (comparison among cements and storage solutions) or paired t-test (comparison before and after the storage period) at 5% significance level. Results The values for average surface roughness were statistically different (p<0.001) among cements at both baseline and after storage. The roughness values of cements in a decreasing order were ZP>RMGIC>C>R (p<0.001). After 15 days, immersion in lactic acid solution resulted in the highest surface roughness for all cements (p<0.05), except for the RC group (p>0.05). Compared to the current threshold (0.2 µm) related to biofilm accumulation, both RC and C remained below the threshold, even after acidic challenge by immersion in lactic acid solution. Conclusions Storage time and immersion in lactic acid solution increased the surface roughness of the majority of the tested cements. RC presented the smoothest surface and it was not influenced by storage conditions. PMID:21625737

van de SANDE, Françoise Hélène; da SILVA, Adriana Fernandes; MICHELON, Douver; PIVA, Evandro; CENCI, Maximiliano Sérgio; DEMARCO, Flávio Fernando

2011-01-01

114

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

PubMed

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

Hafiz, Gunter

2005-01-01

115

Injectable bone cement based on mineralized collagen.  

PubMed

A novel injectable bone cement based on mineralized collagen was reported in this paper. The cement was fabricated by introducing calcium sulfate hemihydrate (CaSO(4).1/2H(2)O, CSH) into nano-hydroxyapatite/collagen (nHAC). The workability, in vitro degradation, in vitro and in vivo biocompatibility of the cement (nHAC/CSH) were studied. The comparative tests via in vitro and in vivo showed that the nHAC/CSH composite cement processed better biocompatibiltiy than that of pure CSH cement. The results implied that this new injectable cement should be very promising for bone repair. PMID:20336741

Liu, Xi; Wang, Xiu-Mei; Chen, Zonggang; Cui, Fu-Zhai; Liu, Huan-Ye; Mao, Keya; Wang, Yan

2010-07-01

116

Carboxymethylation of ulvan and chitosan and their use as polymeric components of bone cements.  

PubMed

Ulvan, extracted from the green algae Ulva lactuca, and chitosan, extracted from Loligo forbesis squid-pen, were carboxymethylated, yielding polysaccharides with an average degree of substitution of ?98% (carboxymethyl ulvan, CMU) and ?87% (carboxymethyl chitosan, N,O-CMC). The carboxymethylation was confirmed by Fourier transform infrared spectroscopy and quantified by conductimetric titration and 1H nuclear magnetic resonance. The average molecular weight increased with the carboxymethylation (chitosan, Mn 145?296 kDa and Mw 227?416 kDa; ulvan, Mn 139?261 kDa and Mw 368?640 kDa), indicating successful chemical modifications. Mixtures of the modified polysaccharides were tested in the formulation of polyacrylic acid-free glass-ionomer bone cements. Mechanical and in vitro bioactivity tests indicate that the inclusion of CMU in the cement formulation, i.e. 0.50:0.50 N,O-CMC:CMU, enhances its mechanical performance (compressive strength 52.4±8.0 MPa and modulus 2.3±0.3 GPa), generates non-cytotoxic cements and induces the diffusion of Ca and/or P-based moieties from the surface to the bulk of the cements. PMID:23816652

Barros, A A A; Alves, A; Nunes, C; Coimbra, M A; Pires, R A; Reis, R L

2013-11-01

117

Influence of polymeric additives on the mechanical properties of alpha-tricalcium phosphate cement.  

PubMed

Recently, great attention has been paid to calcium phosphate cements, because of their advantages in comparison with conventional calcium phosphate bioceramics employed for bone repairing, regarding in situ handling, and shaping abilities. Nevertheless, the calcium phosphate cements exhibit relatively low mechanical strength. The aim of this work was the improvement of the compressive strength of alpha-tricalcium phosphate-based cement. The hydraulic setting reaction of this system produces a calcium-deficient hydroxyapatite phase suitable for bone repairing: alpha-Ca3(PO4)2 + H2O --> Ca9(HPO4)(PO4)5OH. Mechanical strength can be improved using technological solutions developed for other applications, such as Portland cement and dual-setting glass-ionomers, by using polymeric additives. The additives used in this work were sodium alginate, sodium polyacrylate, and an in situ polymerization system resulting in a polyacrylamide crosslinked hydrogel. Parameters evaluated were setting time, compressive strength before and after immersion in simulated body fluid, density, porosity, crystalline phases, and microstructure. Sodium alginate and sodium polyacrylate were deleterious to both setting time and mechanical strength. When the in situ polymerization system was added, two setting reactions progressed in parallel: the conventional hydraulic reaction and the copolymerization of acrylamide and crosslinking water-soluble monomers. The initial and final setting times of the "dual-setting" cement were 9 and 35 min, respectively, and they can be regulated varying the initiator, catalyst, and monomers concentrations. The initial compressive strength of the dual-setting cement (6.8 MPa at 0 h, and 15.2 MPa at 24 h) is higher than that of unmodified cement. The major crystalline phase after setting is hydroxyapatite. The dual-setting cement seems to be suitable for clinical applications in bone repairing and remodeling. PMID:10458286

dos Santos, L A; De Oliveria, L C; Rigo, E C; Carrodeguas, R G; Boschi, A O; De Arruda, A C

1999-08-01

118

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

PubMed

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

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

119

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

PubMed Central

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

Bagheri, R

2013-01-01

120

Criteria of biocompatibility of materials for bone defect repair.  

PubMed

We analyzed and systematized the criteria of biocompatibility of materials intended for reconstruction of bone defects on the basis of previously studied synthetic, natural, and composite biomaterials (carbonate hydroxyapatite, calcium phosphate cement, silica, natural corals, freshwater pearls, chitosan/carbonate hydroxyapatite) in the model of subcutaneous implantation to small laboratory animals. PMID:25257441

Sergeeva, N S; Sviridova, I K; Frank, G A; Kirsanova, V A; Akhmedova, S A; Popov, A A

2014-09-01

121

Biomaterials and biocompatibility.  

PubMed

This review attempts to assess the present status of biomaterials, especially in relation to their interaction with tissue. The terms biomaterial and biocompatibility are defined and both the present areas of clinical application and the requirements of biomaterials for these applications discussed. The types of biomaterials in clinical use and those under development are briefly described. Problems associated with implant functionality are covered, dealing with fatigue, wear and membrane permeability. Of more importance are the problems relating to biocompatibility and metallic corrosion, polymer and ceramic degradation, local tissue changes, systemic effects, infection, implant loosening, blood compatibility and the assessment of biocompatibility. PMID:792673

Williams, D F

1976-07-20

122

Microdrilling of Biocompatible Materials  

E-print Network

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...

Mohanty, Sankalp

2012-02-14

123

Mineral trioxide aggregate and portland cement for direct pulp capping in dog: a histopathological evaluation.  

PubMed

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

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

2014-01-01

124

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

PubMed Central

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.

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

2014-01-01

125

Bone cement  

PubMed Central

The knowledge about the bone cement is of paramount importance to all Orthopaedic surgeons. Although the bone cement had been the gold standard in the field of joint replacement surgery, its use has somewhat decreased because of the advent of press-fit implants which encourages bone in growth. The shortcomings, side effects and toxicity of the bone cement are being addressed recently. More research is needed and continues in the field of nanoparticle additives, enhanced bone–cement interface etc.

Vaishya, Raju; Chauhan, Mayank; Vaish, Abhishek

2013-01-01

126

Influence of different drying methods on microtensile bond strength of self-adhesive resin cements to dentin.  

PubMed

Abstract Objective. This study investigated the effect of different drying methods of dentin surface on the bonding efficacy of self-adhesive resin cements (SRCs). Materials and methods. Three SRCs (RelyX U200, RU; Maxcem Elite, ME; and BisCem, BC) and one resin-modified glass ionomer cement (RelyX Luting 2, RL) were used. The characteristics of the materials were evaluated using thermogravimetric analysis and surface roughness and contact angle measurements. Human dentin surfaces were finished with 600-grit silicon carbide paper and assigned to three groups according to these drying methods: ethanol dehydration, drying by waiting for 10 s after blot-drying and blot-drying. The four cements were used for luting composite overlays to the dried dentin. After 24 h storage at 37°C and 100% relative humidity, stick-shaped specimens with a cross-sectional area of 0.8 mm(2) were prepared and stressed to failure in tension at a crosshead speed of 0.5 mm/min (n = 27). Failure modes of fractured specimens were assessed by optical and scanning electron microscopy. Results. RL was the most hydrophilic, followed by BC and ME and then RU. All the luting cements luted to ethanol-dehydrated dentin showed zero bond strengths. For the three SRCs, drying by waiting produced higher microtensile bond strengths than blot-drying. RU showed the best bonding performance in the above two dentin conditions. RL showed significantly higher bond strength in blot-drying condition than in drying-by-waiting (p < 0.001). Conclusions. This study suggests that dentin surface moisture has a crucial effect on the bond strength of SRCs. PMID:24922092

Kim, Young Kyung; Min, Bong Ki; Son, Jun Sik; Kim, Kyo-Han; Kwon, Tae-Yub

2014-11-01

127

Flouride release from various restorative materials.  

PubMed

Fluoride release from six light-activated restorative materials, including two resinmodified glass-ionomers, two composites, and two compomers, was evaluated and compared with one conventional acid-based glass-ionomer cement. The amount and rate of release varied among the tested materials. Both resin-modified glass-ionomers and the conventional acid-base glass-ionomer cements released more fluoride then the composites and compomers (p < 0.05). Additionally, composite materials released less fluoride than compomer materials (p < 0.05). Release of fluoride by the tested materials showed a significant decrease after all the tested time intervals. PMID:9354026

Bala, O; Uçta?li, M; Can, H; Türköz, E; Can, M

1997-09-01

128

Biocompatibility of composite resins  

PubMed Central

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

Mousavinasab, Sayed Mostafa

2011-01-01

129

Porosity, MicroHardness and Morphology of White and Gray Portland Cements in Relation to Their Potential in the Development of New Dental Filling Materials  

Microsoft Academic Search

Purpose: Portland cements may be used in dentistry due to their excellent biocompatibility, sealing ability and potential osteogenic induction. The aim of the present study was to identify the structural and physical properties of two basic Portland cements for their development as potential new dental filling materials. Methods: The two Portland cements, White Portland (WPC) and Gray Portland (GPC), were

Boris De Carlo; Salvatore Sauro; Sanjukta Deb; Giuseppe Pitzolu; Federico Foschi; Francesco Mannocci; Silvano Zanna; Romano Mongiorgi

2012-01-01

130

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

PubMed Central

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

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

2013-01-01

131

Cement-based thermocouples  

Microsoft Academic Search

A cement-based thermocouple in the form of a junction between dissimilar cement pastes and exhibiting thermocouple sensitivity 70±7 ?V\\/°C is provided. The dissimilar cement pastes are steel fiber cement paste (n-type) and carbon-fiber silica-fume cement paste (p-type). The junction is made by pouring the cement pastes side by side.

Sihai Wen; D. D. L. Chung

2001-01-01

132

Electrospinning of Biocompatible Nanofibers  

NASA Astrophysics Data System (ADS)

Artificial scaffolds for growing cells can have a wide range of applications including wound coverings, supports in tissue cultures, drug delivery, and organ and tissue transplantation. Tissue engineering is a promising field which may resolve current problems with transplantation, such as rejection by the immune system and scarcity of donors. One approach to tissue engineering utilizes a biodegradable scaffold onto which cells are seeded and cultured, and ideally develop into functional tissue. The scaffold acts as an artificial extracellular matrix (ECM). Because a typical ECM contains collagen fibers with diameters of 50-500 nm, electrostatic spinning (electrospinning) was used to mimic the size and structure of these fibers. Electrospinning is a novel way of spinning a nonwoven web of fibers on the order of 100 nm, much like the web of collagen in an ECM. We are investigating the ability of several biocompatible polymers (e.g., chitosan and polyvinyl alcohol) to form defect-free nanofiber webs and are studying the influence of the zero shear rate viscosity, molecular weight, entanglement concentration, relaxation time, and solvent on the resulting fiber size and morphology.

Coughlin, Andrew J.; Queen, Hailey A.; McCullen, Seth D.; Krause, Wendy E.

2006-03-01

133

Biocompatible nanoparticles and biopolyelectrolytes  

NASA Astrophysics Data System (ADS)

The research presented in this manuscript encompasses a merger of two research directions: a study of aqueous nanoparticle colloids and a study of biological polyelectrolytes. The majority of biomedical applications of nanoparticles require stable aqueous colloids of nanoparticles as a starting point. A new one-step method of preparation of aqueous solutions of ultra-fine ferroelectric barium titanate nanoparticles was developed and generalized to the preparation of stable aqueous colloids of semiconductor nanoparticles. This high-energy ball milling technique is low cost, environmentally friendly, and allows for control of nanoparticle size by changing milling time. Aqueous colloids of BaTiO3 nanoparticles are stable over time, maintain ferroelectricity and can be used as second harmonic generating nanoprobes for biomedical imaging. Biopolyelectrolytes exhibit a variety of novel liquid-crystalline phases in aqueous solutions where their electrolytic nature is a driving force behind phase formation. We study medically relevant mixtures of F-actin, DNA and oppositely charged ions (such as multivalent salts and antibiotic drugs) and map out phase diagrams and laws that govern phase transitions. We combine these research directions in studies of the condensation behavior in aqueous solutions of biocompatible nanoparticles and biopolyelectrolytes.

Zribi, Olena

134

Rheology of foamed cement  

Microsoft Academic Search

Foams are being used in a number of petroleum industry applications that exploit their high viscosity and low density. Foamed cement slurries can have superior displacement properties relative to non-foamed cement slurries. This article presents results of an experimental study of foamed cement rheology. Viscosity curves of foamed cements were obtained using a flow-through rotational viscometer. Foamed cements with different

R. M. Ahmed; N. E. Takach; U. M. Khan; S. Taoutaou; S. James; A. Saasen; R. Godøy

2009-01-01

135

Lunar cement  

NASA Technical Reports Server (NTRS)

With the exception of water, the major oxide constituents of terrestrial cements are present at all nine lunar sites from which samples have been returned. However, with the exception of relatively rare cristobalite, the lunar oxides are not present as individual phases but are combined in silicates and in mixed oxides. Lime (CaO) is most abundant on the Moon in the plagioclase (CaAl2Si2O8) of highland anorthosites. It may be possible to enrich the lime content of anorthite to levels like those of Portland cement by pyrolyzing it with lunar-derived phosphate. The phosphate consumed in such a reaction can be regenerated by reacting the phosphorus product with lunar augite pyroxenes at elevated temperatures. Other possible sources of lunar phosphate and other oxides are discussed.

Agosto, William N.

1992-01-01

136

Method of making biocompatible electrodes  

DOEpatents

A process of improving the sensing function of biocompatible electrodes and the product so made are disclosed. The process is designed to alter the surfaces of the electrodes at their tips to provide increased surface area and therefore decreased contact resistance at the electrode-tissue interface for increased sensitivity and essentially includes rendering the tips atomically clean by exposing them to bombardment by ions of an inert gas, depositing an adhesion layer on the cleaned tips, forming a hillocked layer on the adhesion layer by increasing the temperature of the tips, and applying a biocompatible coating on the hillocked layer. The resultant biocompatible electrode is characterized by improved sensitivity, minimum voltage requirement for organ stimulation and a longer battery life for the device in which it is employed.

Wollam, John S. (Acton, MA)

1992-01-01

137

ULTRA-LIGHTWEIGHT CEMENT  

SciTech Connect

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, a comparison study of the three cement systems examined the effect that cement drillout has on the three cement systems. Testing to determine the effect of pressure cycling on the shear bond properties of the cement systems was also conducted. This report discusses testing that was performed to analyze the alkali-silica reactivity of ULHS in cement slurries.

Fred Sabins

2002-07-30

138

ULTRA-LIGHTWEIGHT CEMENT  

SciTech Connect

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.

Fred Sabins

2003-10-31

139

Alex Benson Cement Plants  

E-print Network

Alex Benson ATOC 3500 Cement Plants 4 Step Production Line: o Mine the Limestone: Cement plants of generating electricity by coal. o From Kiln Combustion CO2 ­ 2nd largest CO2 emitter behind electricity health effects Relative News; o "EPA Clamps down on Cement Plant Pollution" http

Toohey, Darin W.

140

Application of HS-SPME in the determination of potentially toxic organic compounds emitted from resin-based dental materials.  

PubMed

Leaching of volatile substances from resin-based dental materials may have a potential impact on the biocompatibility as well as safety of these materials. Information from manufacturers on ingredients in the materials is very often incomplete. Patients and dentists may be in contact with components emitted from cured dental fillings or from substrates applied in their preparation. Therefore, determination of the components of these materials is necessary for better prevention from possible harmful effects caused by dental fillings. The aim of this work was the isolation and identification of organic compounds evolved from four commercial resin-modified glass-ionomer cements (resin-based dental materials applied in dentistry) by using an alternative method of volatile compounds analysis-HS-SPME (headspace-solid phase microextraction). Dental materials were heated in closed vial at various temperatures and volatile substances released into the headspace phase above the sample were isolated on a thin polymeric fibre placed in SPME syringe. Identification was performed by using the GC-MS (gas chromatography-mass spectrometry) technique. Almost 50 RMGIC (resin-modified glass-ionomer cement) components (monomers and additives) were identified. The main identified leachables were: iodobenzene (DPICls-diphenyliodonium chloride degradation product), camphorquinone (photo-initiator), tert-butyl-p-hydroxyanisole (inhibitor), 4-(dimethylamino)ethyl benzoate (co-initiator), ethylene glycol dimethacrylate (monomer). PMID:16528422

Rogalewicz, Rafal; Voelkel, Adam; Kownacki, Ireneusz

2006-03-01

141

Enhanced Biocompatibility of Porous Nitinol  

PubMed Central

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

Munroe, Norman; Pulletikurthi, Chandan; Haider, Waseem

2009-01-01

142

Biocompatible polysaccharide-based cryogels.  

PubMed

This study focuses on the development of novel biocompatible macroporous cryogels by electron-beam assisted free-radical crosslinking reaction of polymerizable dextran and hyaluronan derivatives. As a main advantage this straightforward approach provides highly pure materials of high porosity without using additional crosslinkers or initiators. The cryogels were characterized with regard to their morphology and their basic properties including thermal and mechanical characteristics, and swellability. It was found that the applied irradiation dose and the chemical composition strongly influence the material properties of the resulting cryogels. Preliminary cytotoxicity tests illustrate the excellent in vitro-cytocompatibility of the fabricated cryogels making them especially attractive as matrices in tissue regeneration procedures. PMID:24411364

Reichelt, Senta; Becher, Jana; Weisser, Jürgen; Prager, Andrea; Decker, Ulrich; Möller, Stephanie; Berg, Albrecht; Schnabelrauch, Matthias

2014-02-01

143

ULTRA-LIGHTWEIGHT CEMENT  

SciTech Connect

The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Issues, Task 2: Review Russian Ultra-Lightweight Cement Literature, Task 3: Test Ultra-Lightweight Cements, and Task 8: Develop Field ULHS Cement Blending and Mixing Techniques. Results reported this quarter include: preliminary findings from a literature review focusing on problems associated with ultra-lightweight cements; summary of pertinent information from Russian ultra-lightweight cement literature review; laboratory tests comparing ULHS slurries to foamed slurries and sodium silicate slurries for two different applications; and initial laboratory studies with ULHS in preparation for a field job.

Fred Sabins

2001-07-18

144

ULTRA-LIGHTWEIGHT CEMENT  

SciTech Connect

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, a comparison study of the three cement systems examined the effect that cement drillout has on the three cement systems. Testing to determine the effect of pressure cycling on the shear bond properties of the cement systems was also conducted. This report discusses testing that will be performed for analyzing the alkali-silica reactivity of ULHS in cement slurries, as well as the results of Field Tests 1 and 2.

Fred Sabins

2002-10-31

145

Fiber-enriched double-setting calcium phosphate bone cement.  

PubMed

Calcium phosphate bone cements are useful in orthopedics and traumatology, their main advantages being their biocompatibility and bioactivity, which render bone tissue osteoconductive, providing in situ hardening and easy handling. However, their low mechanical strength, which, in the best of cases, is equal to the trabecular bone, and their very low toughness are disadvantages. Calcium phosphate cement compositions with mechanical properties more closely resembling those of human bone would broaden the range of applications, which is currently limited to sites subjected to low loads. This study investigated the influence of added polypropylene, nylon, and carbon fibers on the mechanical properties of double setting alpha-tricalcium phosphate-based cement, using calcium phosphate cement added to an in situ polymerizable acrylamide-based system recently developed by the authors. Although the addition of fibers was found to reduce the compression strength of the double-setting calcium phosphate cement because of increased porosity, it strongly increased the cement's toughness (J(IC)) and tensile strength. The composites developed in this work, therefore, have a potential application in shapes subjected to flexure. PMID:12734819

dos Santos, Luís Alberto; Carrodéguas, Raúl Garcia; Boschi, Anselmo Ortega; Fonseca de Arruda, Antônio Celso

2003-05-01

146

Mineral of the month: cement  

USGS Publications Warehouse

Hydraulic cement is a virtually ubiquitous construction material that, when mixed with water, serves as the binder in concrete and most mortars. Only about 13 percent of concrete by weight is cement (the rest being water and aggregates), but the cement contributes all of the concrete’s compressional strength. The term “hydraulic” refers to the cement’s ability to set and harden underwater through the hydration of the cement’s components.

van Oss, Hendrik G.

2006-01-01

147

ULTRA-LIGHTWEIGHT CEMENT  

SciTech Connect

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.

Fred Sabins

2001-01-15

148

A Novel Injectable Borate Bioactive Glass Cement as an Antibiotic Delivery Vehicle for Treating Osteomyelitis  

PubMed Central

Background A novel injectable cement composed of chitosan-bonded borate bioactive glass (BG) particles was evaluated as a carrier for local delivery of vancomycin in the treatment of osteomyelitis in a rabbit tibial model. Materials and Methods The setting time, injectability, and compressive strength of the borate BG cement, and the release profile of vancomycin from the cement were measured in vitro. The capacity of the vancomycin-loaded BG cement to eradicate methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis in rabbit tibiae in vivo was evaluated and compared with that for a vancomycin-loaded calcium sulfate (CS) cement and for intravenous injection of vancomycin. Results The BG cement had an injectability of >90% during the first 3 minutes after mixing, hardened within 30 minutes and, after hardening, had a compressive strength of 18±2 MPa. Vancomycin was released from the BG cement into phosphate-buffered saline for up to 36 days, and the cumulative amount of vancomycin released was 86% of the amount initially loaded into the cement. In comparison, vancomycin was released from the CS cement for up 28 days and the cumulative amount released was 89%. Two months post-surgery, radiography and microbiological tests showed that the BG and CS cements had a better ability to eradicate osteomyelitis when compared to intravenous injection of vancomycin, but there was no significant difference between the BG and CS cements in eradicating the infection. Histological examination showed that the BG cement was biocompatible and had a good capacity for regenerating bone in the tibial defects. Conclusions These results indicate that borate BG cement is a promising material both as an injectable carrier for vancomycin in the eradication of osteomyelitis and as an osteoconductive matrix to regenerate bone after the infection is cured. PMID:24427311

Cui, Xu; Gu, Yi-Fei; Jia, Wei-Tao; Rahaman, Mohamed N.; Wang, Yang; Huang, Wen-Hai; Zhang, Chang-Qing

2014-01-01

149

Water sorption and mechanical behaviour of cosmetic direct restorative materials in artificial saliva  

Microsoft Academic Search

Objectives: To evaluate the water sorption and mechanical behaviour of a compomer in comparison with those of its nominal forerunners, a filled resin restorative material and a conventional glass ionomer cement.Method: Compomer (Dyract AP) (D-AP), filled resin (SureFil) (SF), and glass ionomer (ChemFlex) (CF) (all Dentsply, Addlestone, UK) restorative materials were tested. Forty bar specimens (26×1.5×1.0mm3) of each material were

L. Musanje; M. Shu; B. W. Darvell

2001-01-01

150

Corrosion resistant cemented carbide  

Microsoft Academic Search

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,

Hong

1990-01-01

151

Making periclase cement waterproof  

Microsoft Academic Search

Conclusions Waterproofing of pure periclase cement with 1.5% petroleum resin is due to its lower capillary and sorption water absorption; the treatment also prevents caking. The activity of periclase cement that has been waterproofed with petroleum resin remains practically unaltered during storage.

L. B. Khoroshavin; T. A. Drozdova; P. N. D'yachov

1967-01-01

152

ULTRA-LIGHTWEIGHT CEMENT  

SciTech Connect

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: foamed and sodium silicate slurries. Comparison studies of the three cement systems examined several properties: tensile strength, Young's modulus, water permeability, and shear bond. Testing was also done to determine the effect that temperature cycling has on the shear bond properties of the cement systems. In addition, analysis was carried out to examine alkali silica reactivity of slurries containing ULHS. Data is also presented from a study investigating the effects of mixing and pump circulation on breakage of ULHS. Information is also presented about the field application of ULHS in cementing a 7-in. intermediate casing in south Texas.

Fred Sabins

2002-01-23

153

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

PubMed

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

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

2014-12-01

154

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

PubMed Central

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

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

155

Cement penetration after patella venting  

Microsoft Academic Search

There is a high rate of patellofemoral complications following total knee arthroplasty. Optimization of the cement–bone interface by venting and suction of the tibial plateau has been shown to improve cement penetration. Our study was designed to investigate if venting the patella prior to cementing improved cement penetration.Ten paired cadaver patellae were allocated prior to resurfacing to be vented or

Christopher W. Jones; Li-On Lam; Adam Butler; David J. Wood; William R. Walsh

2009-01-01

156

Titaniumcarboxonitride layer increased biocompatibility of medical polyetherurethanes.  

PubMed

Polyetherurethane (PEU) is in use for blood-contacted devices because of its excellent mechanical properties. However, poor hemocompatibility of the hydrophobic material required surface modification or endothelialization. To increase the biocompatibility of PEU, the polymer was coated with a titaniumcarboxonitride [Ti(C,N,O)] layer by a plasma-activated chemical vapor deposition (PACVD) process. Biocompatibility of titaniferously coated PEU was verified using static and dynamic cell culture techniques. Titaniferous coating significantly improved proliferation and mitochondrial activity of human endothelial cells on PEU. These cells captured significantly less mononuclear cells and platelets. Under shear stress for up to 72 hours, titaniferous coating increased endothelial cell adhesion, spreading, and cell density to form an organized monolayer covering the whole luminal surface of vascular PEU grafts. In summary, coating of PEU surfaces with Ti(C,N,O) might be a promising strategy to improve the biocompatibility of biomedical biomaterials. PMID:23853113

Riescher, Sebastian; Wehner, Daniel; Schmid, Thomas; Zimmermann, Hanngoerg; Hartmann, Björn; Schmid, Christof; Lehle, Karla

2014-01-01

157

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

PubMed

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

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

2014-04-01

158

Thermokineticanalysis of the hydration process of calcium phosphate cement  

Microsoft Academic Search

A microcalorimeter (Setaram c-80) was used\\u000a to study the thermokinetics of the hydration process of calcium phosphate\\u000a cement (CPC), a biocompatible biomaterial used in bone repair. The hydration\\u000a enthalpy was determined to be 35.8 J g–1\\u000a at 37.0°C when up to 80 mg CPC was dissolved in 2 mL of citric buffer.\\u000a In the present study, parameters related to time

W. Y. Gao; Y. W. Wang; L. M. Dong

2006-01-01

159

Cement for passive damping  

NASA Astrophysics Data System (ADS)

Multifunctional concretes capable of both structural and non- structural functions are made possible by appropriate admixtures. The use of acid treated silica fume (15% by weight of cement), latex (20 - 30% by weight of cement) or methylcellulose (0.4 - 0.8% by weight of cement) as an admixture gave the vibration damping function (with loss tangent up to 0.18, i.e., up to 390% increase, and loss modulus up to 2.2 GPa, i.e., up to 2200% increase, at 0.2 - 2 Hz loading).

Fu, Xuli; Li, Xiaohui; Chung, Deborah D. L.

1998-06-01

160

Thermodynamics and cement science  

SciTech Connect

Thermodynamics applied to cement science has proved to be very valuable. One of the most striking findings has been the extent to which the hydrate phases, with one conspicuous exception, achieve equilibrium. The important exception is the persistence of amorphous C-S-H which is metastable with respect to crystalline calcium silicate hydrates. Nevertheless C-S-H can be included in the scope of calculations. As a consequence, from comparison of calculation and experiment, it appears that kinetics is not necessarily an insuperable barrier to engineering the phase composition of a hydrated Portland cement. Also the sensitivity of the mineralogy of the AFm and AFt phase compositions to the presence of calcite and to temperature has been reported. This knowledge gives a powerful incentive to develop links between the mineralogy and engineering properties of hydrated cement paste and, of course, anticipates improvements in its performance leading to decreasing the environmental impacts of cement production.

Damidot, D., E-mail: damidot@ensm-douai.fr [Universite Lille Nord de France (France); EM Douai, LGCgE-MPE-GCE, Douai (France); Lothenbach, B. [Empa, Lab. Concrete and Construction Chemistry, Duebendorf (Switzerland); Herfort, D. [Cementir Holding (Denmark); Glasser, F.P. [Chemistry Department, University of Aberdeen, Aberdeen (United Kingdom)

2011-07-15

161

[Allergy towards bone cement].  

PubMed

Bone cements based on polymethylmethacrylate are typically used for fixation of artificial joints. Intolerance reactions to endoprostheses not explained by infection or mechanical failure may lead to allergological diagnostics, which mostly focuses on metal allergy. However, also bone cement components may provoke hypersensitivity reactions leading to eczema, implant loosening, or fistula formation. Elicitors of such reactions encompass acrylates and additives such as benzoyl peroxide, N,N-dimethyl-p-toluidine, hydroquinone, or antibiotics (particularly gentamicin). Upon repeated contact with bone cement components, e.g., acrylate monomers, also in medical personnel occasionally hand eczema or even asthma may develop. Therefore, in the case of suspected hypersensitivity reactions to arthroplasty, the allergological diagnostics should include bone cement components. PMID:16865384

Thomas, P; Schuh, A; Summer, B; Mazoochian, F; Thomsen, M

2006-09-01

162

Biocompatibility at the Molecular Catherine Klapperich  

E-print Network

#12;#12;#12;#12;#12;What is "Biocompatibility?" · Susceptibility of an implanted material to corrosion Polymer Ceramic #12;biomaterial biomaterial Cells synthesize ECM components, which compete for surface dimensional structures · More than one cell type · Multifunctional #12;Human Skin · Largest organ of the human

163

Preparation of small bio-compatible microspheres  

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

164

Characterization of modified calcium-silicate cements exposed to acidic environment  

SciTech Connect

Portland cement which is used as a binder in concrete in the construction industry has been developed into a biomaterial. It is marketed as mineral trioxide aggregate and is used in dentistry. This material has been reported to be very biocompatible and thus its use has diversified. The extended use of this material has led to developments of newer versions with improved physical properties. The aim of this study was to evaluate the effect of acidic environments found in the oral cavity on fast setting calcium silicate cements with improved physical properties using a combination of techniques. Two fast setting calcium silicate cements (CSA and CFA) and two cement composites (CSAG and CFAG) were assessed by subjecting the materials to lactic acid/sodium lactate buffer gel for a period of 28 days. At weekly intervals the materials were viewed under the tandem scanning confocal microscope (TSM), and scanning electron microscope (SEM). The two prototype cements exhibited changes in their internal chemistry with no changes in surface characteristics. Since the changes observed were mostly sub-surface evaluation of surface characteristics of cement may not be sufficient in the determination of chemical changes occurring. - Research Highlights: {yields} An acidic environment affects modified fast setting calcium silicate-based cements. {yields} No surface changes are observed in acidic environment. {yields} An acidic environment causes sub-surface changes in the material chemistry which are only visible in fractured specimens. {yields} A combination of techniques is necessary in order to evaluate the chemical changes occurring.

Camilleri, Josette, E-mail: josette.camilleri@um.edu.mt

2011-01-15

165

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

PubMed Central

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

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

2010-01-01

166

Recycled rubber in cement composites  

SciTech Connect

Disposal of 200 million waste tires in the US each year has become a major problem. An environmentally sound innovative technology of recycling rubber in cement matrix was examined. Using silane coupling agent the rubber was bonded to the hydrating cement making a lighter composite, which absorbed more energy than ordinary Portland cement. The bonding information was obtained by peel strength analysis. SEM was used to understand the mode of fracture in pure cement paste, cement bonded rubber composite and rubber filled cement paste. It was found that cracks propagate through the rubber particle in rubber bonded cement composite while in unbonded rubber cement mix, the cracks propagate around the interface. The density and shrinkage measurements are also discussed.

Raghavan, D. [Howard Univ., Washington, DC (United States). Dept. of Chemistry; Tratt, K.; Wool, R.P. [Univ. of Illinois, Urbana, IL (United States). Dept. of Material Science and Engineering

1994-12-31

167

Cement Mason's Curriculum. Instructional Units.  

ERIC Educational Resources Information Center

To assist cement mason instructors in providing comprehensive instruction to their students, this curriculum guide treats both the skills and information necessary for cement masons in commercial and industrial construction. Ten sections are included, as follow: related information, covering orientation, safety, the history of cement, and applying…

Hendirx, Laborn J.; Patton, Bob

168

Communication Cement-based thermocouples  

E-print Network

Communication Cement-based thermocouples Sihai Wen, D.D.L. Chung* Composite Materials Research Received 31 May 2000; accepted 4 August 2000 Abstract A cement-based thermocouple in the form of a junction between dissimilar cement pastes and exhibiting thermocouple sensitivity 70 7 mV/°C is provided

Chung, Deborah D.L.

169

Performance Cements Focus on Sustainability  

E-print Network

.5%, reductions of: Raw materials use, 1.6 million tons Energy use, 11.8 trillion BTUs CO2 emissions, 2.7 million the beneficial re-use of byproducts Maximize use of materials with low associated CO2 emissions Blended cements with low associated CO2 emissions Blended cements versus separate components Limestone in cement #12;3 High

170

Development and characterization of an injectable cement of nano calcium-deficient hydroxyapatite/multi(amino acid) copolymer/calcium sulfate hemihydrate for bone repair.  

PubMed

A novel injectable bone cement was developed by integration of nano calcium-deficient hydroxyapatite/multi(amino acid) copolymer (n-CDHA/MAC) and calcium sulfate hemihydrate (CSH; CaSO4 · 1/2H2O). The structure, setting time, and compressive strength of the cement were investigated. The results showed that the cement with a liquid to powder ratio of 0.8 mL/g exhibited good injectability and appropriate setting time and mechanical properties. In vitro cell studies indicated that MC3T3-E1 cells cultured on the n-CDHA/MAC/CSH composite spread well and showed a good proliferation state. The alkaline phosphatase activity of the MC3T3-E1 cells cultured on the n-CDHA/MAC/CSH composite was significantly higher than that of the cells on pure CSH at 4 and 7 days of culture. The n-CDHA/MAC/CSH cement was implanted into critical size defects of the femoral condyle in rabbits to evaluate its biocompatibility and osteogenesis in vivo. Radiological and histological results indicated that introduction of the n-CDHA/MAC into CSH enhanced new bone formation, and the n-CDHA/MAC/CSH cement exhibited good biocompatibility and degradability. In conclusion, the injectable n-CDHA/MAC/CSH composite cement has a significant clinical advantage over pure CSH cement, and may be a promising bone graft substitute for the treatment of bone defects. PMID:24293996

Qi, Xiaotong; Li, Hong; Qiao, Bo; Li, Weichao; Hao, Xinyan; Wu, Jun; Su, Bao; Jiang, Dianming

2013-01-01

171

Development and characterization of an injectable cement of nano calcium-deficient hydroxyapatite/multi(amino acid) copolymer/calcium sulfate hemihydrate for bone repair  

PubMed Central

A novel injectable bone cement was developed by integration of nano calcium-deficient hydroxyapatite/multi(amino acid) copolymer (n-CDHA/MAC) and calcium sulfate hemihydrate (CSH; CaSO4 · 1/2H2O). The structure, setting time, and compressive strength of the cement were investigated. The results showed that the cement with a liquid to powder ratio of 0.8 mL/g exhibited good injectability and appropriate setting time and mechanical properties. In vitro cell studies indicated that MC3T3-E1 cells cultured on the n-CDHA/MAC/CSH composite spread well and showed a good proliferation state. The alkaline phosphatase activity of the MC3T3-E1 cells cultured on the n-CDHA/MAC/CSH composite was significantly higher than that of the cells on pure CSH at 4 and 7 days of culture. The n-CDHA/MAC/CSH cement was implanted into critical size defects of the femoral condyle in rabbits to evaluate its biocompatibility and osteogenesis in vivo. Radiological and histological results indicated that introduction of the n-CDHA/MAC into CSH enhanced new bone formation, and the n-CDHA/MAC/CSH cement exhibited good biocompatibility and degradability. In conclusion, the injectable n-CDHA/MAC/CSH composite cement has a significant clinical advantage over pure CSH cement, and may be a promising bone graft substitute for the treatment of bone defects. PMID:24293996

Qi, Xiaotong; Li, Hong; Qiao, Bo; Li, Weichao; Hao, Xinyan; Wu, Jun; Su, Bao; Jiang, Dianming

2013-01-01

172

Biocompatibility of septal defect closure devices  

PubMed Central

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

Sigler, Matthias

2007-01-01

173

Thermal Shock-resistant Cement  

SciTech Connect

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.

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

2012-02-01

174

Well cementing in permafrost  

SciTech Connect

A process for cementing a string of pipe in the permafrost region of a borehole of a well wherein aqueous drilling fluid actually used in drilling the wellbore in the permafrost region of a wellbore is employed. The drilling fluid contains or is adjusted to contain from about 2 to about 16 volume percent solids. Mixing with the drilling fluid (1) an additive selected from the group consisting of ligno-sulfonate, lignite, tannin, and mixtures thereof, (2) sufficient base to raise the pH of the drilling fluid into the range of from about 9 to about 12, and (3) cementitious material which will harden in from about 30 to about 40 hours at 40/sup 0/F. The resulting mixture is pumped into the permafrost region of a wellbore to be cemented and allowed to harden in the wellbore. There is also provided a process for treating an aqueous drilling fluid after it has been used in drilling the wellbore in permafrost, and a cementitious composition for cementing in a permafrost region of a wellbore.

Wilson, W.N.

1980-01-01

175

Biocompatible, hyaluronic acid modified silicone elastomers.  

PubMed

Although silicones possess many useful properties as biomaterials, their hydrophobicity can be problematic. To a degree, this issue can be addressed by surface modification with hydrophilic polymers such as poly(ethylene glycol), but the resulting structures are usually not conducive to cell growth. In the present work, we describe the synthesis and characterization of covalently linked hyaluronic acid (HA) (35 kDa) to poly(dimethylsiloxane) (PDMS) elastomer surfaces. HA is of interest because of its known biological properties; its presence on a surface was expected to improve the biocompatibility of silicone materials for a wide range of bioapplications. HA was introduced with a coupling agent in two steps from high-density, tosyl-modified, poly(ethylene glycol) tethered silicone surfaces. All materials synthesized were characterized by water contact angle, ATR-FTIR, XPS and (13)C solid state NMR spectroscopy. Biological interactions with these modified silicone surfaces were assessed by examining interactions with fibrinogen as a model protein as well as determining the in vitro response of fibroblast (3T3) and human corneal epithelial cells relative to unmodified poly(dimethylsiloxane) controls. The results suggest that HA modification significantly enhances cell interactions while decreasing protein adsorption and may therefore be effective for improving biocompatibility of PDMS and other materials. PMID:20138660

Alauzun, Johan G; Young, Stuart; D'Souza, Renita; Liu, Lina; Brook, Michael A; Sheardown, Heather D

2010-05-01

176

Biocompatibility of nanoporous alumina membranes for immunoisolation  

PubMed Central

Cellular immunoisolation using semi-permeable barriers has been investigated over the past several decades as a promising treatment approach for diseases such as Parkinson’s, Alzheimer’s, and Type 1 diabetes. Typically, polymeric membranes are used for immunoisolation applications; however, recent advances in technology have led to the development of more robust membranes that are able to more completely meet the requirements for a successful immunoisolation device, including well controlled pore size, chemical and mechanical stability, non-biodegradability, and biocompatibility with both the graft tissue as well as the host. It has been shown previously that nanoporous alumina biocapsules can act effectively as immunoisolation devices, and support the viability and functionality of encapsulated ? cells. The aim of this investigation was to assess the biocompatibility of the material with host tissue. The cytotoxicity of the capsule, as well as its ability to activate complement and inflammation was studied. Further, the effects of PEG-modification on the tissue response to implanted capsules were studied. Our results have shown that the device is non-toxic and does not induce significant complement activation. Further, in vivo work has demonstrated that implantation of these capsules into the peritoneal cavity of rats induces a transient inflammatory response, and that PEG is useful in minimizing the host response to the material. PMID:17335895

La Flamme, Kristen E.; Popat, Ketul C.; Leoni, Lara; Markiewicz, Erica; LaTempa, Thomas J.; Roman, Brian B.; Grimes, Craig A.; Desai, Tejal A.

2011-01-01

177

Biocompatibility of Bacterial Cellulose Based Biomaterials  

PubMed Central

Some bacteria can synthesize cellulose when they are cultivated under adequate conditions. These bacteria produce a mat of cellulose on the top of the culture medium, which is formed by a three-dimensional coherent network of pure cellulose nanofibers. Bacterial cellulose (BC) has been widely used in different fields, such as the paper industry, electronics and tissue engineering due to its remarkable mechanical properties, conformability and porosity. Nanocomposites based on BC have received much attention, because of the possibility of combining the good properties of BC with other materials for specific applications. BC nanocomposites can be processed either in a static or an agitated medium. The fabrication of BC nanocomposites in static media can be carried out while keeping the original mat structure obtained after the synthesis to form the final nanocomposite or by altering the culture media with other components. The present article reviews the issue of biocompatibility of BC and BC nanocomposites. Biomedical aspects, such as surface modification for improving cell adhesion, in vitro and in vivo studies are given along with details concerning the physics of network formation and the changes that occur in the cellulose networks due to the presence of a second phase. The relevance of biocompatibility studies for the development of BC-based materials in bone, skin and cardiovascular tissue engineering is also discussed. PMID:24955750

Torres, Fernando G.; Commeaux, Solene; Troncoso, Omar P.

2012-01-01

178

Biocompatibility of soft-templated mesoporous carbons.  

PubMed

Soft-templated mesoporous carbon is morphologically a non-nano type of carbon. It is a relatively newer variety of biomaterial, which has already demonstrated its successful role in drug delivery applications. To investigate the toxicity and biocompatibility, we introduced three types of mesoporous carbons with varying synthesis conditions and pore textural properties. We compared the Brunauer-Emmett-Teller (BET) surface area and pore width and performed cytotoxicity experiments with HeLa cells, cell viability studies with fibroblast cells and hemocomapatibility studies. Cytotoxicity tests reveal that two of the carbons are not cytotoxic, with cell survival over 90%. The mesoporous carbon with the highest surface area showed slight toxicity (? 70% cell survival) at the highest carbon concentration of 500 ?g/mL. Fibroblast cell viability assays suggested high and constant viability of over 98% after 3 days with no apparent relation with materials property and good visible cell-carbon compatibility. No hemolysis (<1%) was confirmed for all the carbon materials. Protein adsorption experiments with bovine serum albumin (BSA) and fibrinogen revealed a lower protein binding capacity of 0.2-0.6 mg/m(2) and 2-4 mg/m(2) for BSA and fibrinogen, respectively, with lower binding associated with an increase in surface area. The results of this study confirm the biocompatibility of soft-templated mesoporous carbons. PMID:25144129

Gencoglu, Maria F; Spurri, Amanda; Franko, Mitchell; Chen, Jihua; Hensley, Dale K; Heldt, Caryn L; Saha, Dipendu

2014-09-10

179

Polymer reinforcement of cement systems  

Microsoft Academic Search

In the last couple of decades several cement- and concrete-based composites have come into prominence. Of these, cement-polymer composites, like cement-fibre composites, have been recognised as very promising, and considerable research and development on their properties, fabrication methods and application are in progress. Of the three types of concrete materials which incorporate polymers to form composites, polymer impregnated concrete forms

R. Narayan Swamy

1979-01-01

180

Cement penetration after patella venting.  

PubMed

There is a high rate of patellofemoral complications following total knee arthroplasty. Optimization of the cement-bone interface by venting and suction of the tibial plateau has been shown to improve cement penetration. Our study was designed to investigate if venting the patella prior to cementing improved cement penetration. Ten paired cadaver patellae were allocated prior to resurfacing to be vented or non-vented. Bone mineral density (BMD) was measured by DEXA scanning. In vented specimens, a 1.6 mm Kirschner wire was used to breach the anterior cortex at the center. Specimens were resurfaced with standard Profix instrumentation and Versabond bone cement (Smith and Nephew PLC, UK). Cement penetration was assessed from Faxitron and sectioned images by a digital image software package (ImageJ V1.38, NIH, USA). Wilcoxon rank sum test was used to assess the difference in cement penetration between groups. The relationship between BMD and cement penetration was analyzed by Pearson correlation coefficient. There was a strong negative correlation between peak BMD and cement penetration when analyzed independent of experimental grouping (r(2)=-0.812, p=0.004). Wilcoxon rank sum testing demonstrated no significant difference (rank sum statistic W=27, p=0.579) in cement penetration between vented (10.53%+/-4.66; mean+/-std dev) and non-vented patellae (11.51%+/-6.23; mean+/-std dev). Venting the patella using a Kirschner wire does not have a significant effect on the amount of cement penetration achieved in vitro using Profix instrumentation and Versabond cement. PMID:19010682

Jones, Christopher W; Lam, Li-On; Butler, Adam; Wood, David J; Walsh, William R

2009-01-01

181

Natural cement and monumental restoration  

Microsoft Academic Search

Natural cement, called “Roman” cement, was invented at the end of the 19th century and played an important role in the development\\u000a of civil engineering works until the 1860s. More surprisingly, it was also used to restore historic buildings, such as gothic\\u000a cathedrals. This paper deals with the mineralogy and the durability of natural cement in the particular case of

C. Gosselin; V. Verges-Belmin; A. Royer; G. Martinet

2009-01-01

182

Abrasive wear of cemented carbides  

SciTech Connect

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.

Hawk, Jeffrey A.; Wilson, Rick D.

2003-10-01

183

[Allergy to bone cement components].  

PubMed

Intolerance reactions to endoprostheses may lead to allergological diagnostics, which focus mainly on metal allergy. However, bone cement may also contain potential allergens, e.g. acrylates and additives such as benzoyl peroxide (BPO), N,N-dimethyl-p-toluidine, hydroquinone, and antibiotics (particularly gentamicin). In the Munich implant allergy clinic, we found that 28 of 113 patients (24.8%) with cemented prostheses had contact allergies to bone cement components, mostly to gentamicin (16.8%) and BPO (8.0%). The clinical significance of test results cannot always be shown, but we still recommend including bone cement components in the allergological diagnostics of suspected hypersensitivity reactions to arthroplasty. PMID:18227996

Thomas, P; Schuh, A; Eben, R; Thomsen, M

2008-02-01

184

Polymeric additives to enhance the functional properties of calcium phosphate cements  

PubMed Central

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

Perez, Roman A; Kim, Hae-Won

2012-01-01

185

Jet blown PTFE for control of biocompatibility  

NASA Astrophysics Data System (ADS)

The development of fully hemocompatible cardiovascular biomaterials will have a major impact on the practice of modern medicine. Current artificial surfaces, unlike native vascular surfaces, are not able to control clot and thrombus formation. Protein interactions are an important component in hemocompatibility and can result in decreased patency due to thrombus formation or surface passivation which can improve endothelization. It is believed that controlling these properties, specifically the nanometer sizes of the fibers on the material's surface, will allow for better control of biological responses. The biocompatibility of Teflon, a widely used polymer for vascular grafts, would be improved with nanostructured control of surface features. Due to the difficultly in processing polytetrafluoroethylene (PTFE), it has not been possible to create nanofibrous PTFE surfaces. The novel technique of Jet Blowing allows for the formation of nanostructured PTFE (nPTFE). A systematic investigation into controlling polymer properties by varying the processing conditions of temperature, pressure, and gas used in the Jet Blowing allows for an increased understanding of the effects of plasticization on the material's properties. This fundamental understanding of the material science behind the Jet Blowing process has enabled control of the micro and nanoscale structure of nPTFE. While protein adsorption, a key component of biocompatibility, has been widely studied, it is not fully understood. Major problems in the field of biomaterials include a lack of standard protocols to measure biocompatibility, and inconstant literature on protein adsorption. A reproducible protocol for measuring protein adsorption onto superhydrophobic surfaces (ePTFE and nPTFE) has been developed. Both degassing of PBS buffer solutions and evacuation of the air around the expanded PTFE (ePTFE) prior to contact with protein solutions are essential. Protein adsorption experiments show a four-fold difference in the measure of proteins adsorbed using radiometry (I-125 labeled human serum albumin (HSA)) and electrophoresis (unlabeled HSA). This provides evidence that the standard method of radiolabeled protein for measuring adsorption does not fully account for changes to the HSA molecules due to labeling. The differences between measured protein values can be attributed to the radiolabel affecting the HSA hydrophobicity resulting in a change in the protein's interactions with the hydrophobic surface. Additionally, our work has provided repeatable results showing that the amount of protein adsorbed onto the polymer surface, after washing, accounted for only 65% of the amount of protein that was removed from solution based on depletion analysis. This implies that measurement of the amount of strongly bound protein on the material significantly underestimates the actual amount of protein adsorbing into the surface region of the material interface. HSA adsorption isotherms demonstrate an increase in protein adsorption capacity on the nPTFE surface compared to adsorption on the same surface area of ePTFE. Preliminary cell work shows that the nPTFE surfaces had a larger number of cells growing on the surface of the material when compared to ePTFE surfaces. The research also shows that while most endothelial cells were not viable on the ePTFE surface after 96 hours, they remained alive on the nPTFE surface during that same time period. Surface functionalization using ammonia plasma has been performed. X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of amine groups on the nPTFE surface. The amine groups can be used to couple polypeptides onto the PTFE surface in the future. The selection of different peptides will allow for selective control of cell adhesion. This research shows that nPTFE has potential for improved biocompatibility over standard ePTFE, based on increased protein adsorption capacity, increased viability of endothelial cells, and the ability to plasma modify the PTFE surface.

Leibner, Evan Scott

186

Titanium nanostructural surface processing for improved biocompatibility  

SciTech Connect

X-ray photoelectron spectroscopy, grazing incident x-ray diffraction, transmission electron microscopy, and scanning electron microscopy were conducted to evaluate the effect of titanium hydride on the formation of nanoporous TiO{sub 2} on Ti during anodization. Nano-titanium-hydride was formed cathodically before anodizing and served as a sacrificial nanoprecipitate during anodization. Surface oxidation occurred and a multinanoporous structure formed after cathodic pretreatments followed by anodization treatment. The sacrificial nanoprecipitate is directly dissolved and the Ti transformed to nanoporous TiO{sub 2} by anodization. The formation of sacrificial nanoprecipitates by cathodic pretreatment and of the multinanostructure by anodization is believed to improve biocompatibility, thereby promoting osseointegration.

Cheng, H.-C.; Lee, S.-Y.; Chen, C.-C.; Shyng, Y.-C.; Ou, K.-L. [School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China)and Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China) and Department of Emergency Medicine, Mackay Memorial Hospital, Taipei 110, Taiwan (China); Division of Oral and Maxillofacial Surgery, Kaohsiung Military General Hospital, Kaohsiung 807, Taiwan (China); Graduate Institute of Oral Sciences, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China)

2006-10-23

187

Antimicrobial biocompatible bioscaffolds for orthopaedic implants.  

PubMed

Nationally, nearly 1.5 million patients in the USA suffer from ailments requiring bone grafts and hip and other joint replacements. Infections following internal fixation in orthopaedic trauma can cause osteomyelitis in 22-66% of cases and, if uncontrolled, the mortality rate can be as high as 2%. We characterize a procedure for the synthesis of antimicrobial and biocompatible poly-l-lactic acid (PLLA) and poly-ethyleneglycol (PEG) bioscaffolds designed to degrade and absorb at a controlled rate. The bioscaffold architecture aims to provide a suitable substrate for the controlled release of silver nanoparticles (SNPs) to reduce bacterial growth and to aid the proliferation of human adipose-derived stem cells (hASCs) for tissue-engineering applications. The fabricated bioscaffolds were characterized by scanning transmission microscope (SEM) and it showed that the addition of tncreasing concentrations of SNPs results in the formation of dendritic porous channels perpendicular to the axis of precipitation. The antimicrobial properties of these porous bioscaffolds were tested according to a modified ISO 22196 standard across varying concentrations of biomass-mediated SNPs to determine an efficacious antimicrobial concentration. The bioscaffolds reduced the Staphylococcus aureus and Escherichia coli viable colony-forming units by 98.85% and 99.9%, respectively, at an antimicrobial SNPs concentration of 2000?ppm. Human ASCs were seeded on bioscaffolds and cultured in vitro for 20?days to study the effect of SNPs concentration on the viability of cells. SEM analysis and the metabolic activity-based fluorescent dye, AlamarBlue®, demonstrated the growth of cells on the efficacious antimicrobial bioscaffolds. The biocompatibility of in vitro leached silver, quantified by inductively coupled plasma optical emission spectroscopy (ICP-OES), proved non-cytotoxic when tested against hASCs, as evaluated by MTT assay. PMID:22700366

Qureshi, Ammar T; Terrell, Lekeith; Monroe, W Todd; Dasa, Vinod; Janes, Marlene E; Gimble, Jeffrey M; Hayes, Daniel J

2014-05-01

188

Artificial caries formation around fluoride-releasing restorations in roots.  

PubMed

Secondary caries is one of the most important factors leading to replacement of dental restorations. This investigation assessed the capacity of fluoride-releasing restorative materials to resist caries in vitro when used in roots. Class 5 cavities were prepared in the buccal and lingual surfaces of 30 extracted premolars. The six materials used were: glass-ionomer cement (Fuji), glass-ionomer cement with silver particles added (Ketac-silver), fluoride-containing composite resin (Tetric), composite resin (Silux plus), fluoride-containing amalgam (Fluor-Alloy) and high-copper amalgam (Dispersalloy). After 5 weeks in an acid gel for caries-like lesion formation, the teeth were sectioned longitudinally and examined with polarized light. The results showed that repair with glass-ionomer materials of a carious lesion may be of great importance in the prevention of secondary caries around the restorations in roots. PMID:9846901

Dionysopoulos, P; Kotsanos, N; Papadogiannis, Y; Konstantinidis, A

1998-11-01

189

Overview of Stabilizing Ligands for Biocompatible Quantum Dot Nanocrystals  

PubMed Central

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

Zhang, Yanjie; Clapp, Aaron

2011-01-01

190

The effect of pressure changes during simulated diving on the pull out strength of glass fiber posts  

PubMed Central

Background: Scuba diving is one of the fastest growing sports in the world. The objective of this study was to evaluate the effect of pressure variations to which divers are exposed on the pull out strength of glass fiber post luted with different cements. Materials and Methods: In this in vitro study, 120 extracted, single-rooted lower premolars were endodontically treated. They were randomly divided into six groups and restored using the glass fiber post (Ivoclar Vivadent AG) and the following luting agents: Zinc phosphate, conventional glass ionomer, resin reinforced glass ionomer, resin cement with etch-and-rinse adhesive, resin cement with self-etching adhesive, and self-adhesive resin cement. Each group was randomly divided into two equal subgroups, one as a control, and the other to be used experimentally. After 7 days of storage, experimental groups were pressure cycled. The force required to dislodge each post was recorded in Newton (N) on Universal testing machine (Star Testing System) at a crosshead speed of 1 mm/min. Data were statistically analyzed using the ANOVA and Student's t-test (P < 0.001). Results: The pull out strength of posts cemented with zinc phosphate and conventional glass ionomer in pressure cycle group was significantly less than their control group. Although, no significant difference was found between pressure cycle and control group using resin reinforced glass ionomer cement and resin cements. Conclusion: Dentist should consider using resin reinforced glass ionomer or resin cement, for the cementation of glass fiber post, for the patients such as divers, who are likely to be exposed to pressure cycling. PMID:24379861

Gulve, Meenal Nitin; Gulve, Nitin Dilip

2013-01-01

191

[Bone cements based on polymethylmethacrylate].  

PubMed

Bone cements based on polymethylmethacrylate (PMMA) remain an important material for anchorage of artificial joints. Polymers based on PMMA originally developed for dental surgery have been successfully used in bone surgery for more than 40 years. At first sight the cold-curing PMMA bone cement seems to be a rather simple material consisting of a powder and a liquid. But in fact it is a complex material fulfilling various functions at its application site after the implantation. Its properties vary according to the composition of its basic elements. They already play a decisive role for the working behavior during mixing of both components. The differences in the working behavior considerably affect the cementing technique and the accurate application in vivo. These influence the mechanical performance of the cured cement mantle and the long-term results of the implantation. Standardized test methods are used to characterize bone cements,whereas the clinical relevance of the test methods has to be evaluated critically.Additionally,PMMA bone cements act as a drug delivery system as a local carrier of antibiotics. This paper gives a review of the composition and properties of PMMA bone cements and their influence on practical application. PMID:12557085

Breusch, S J; Kühn, K-D

2003-01-01

192

Crown and bridge cements: clinical applications.  

PubMed

Cement selection can be confusing because factors such as substrate, the type of restoration, and patient needs must be considered. Some substrates require additional treatment before cementation. This article describes the most commonly used traditional crown and bridge cements (GI and RMGI) used for metal and metal-ceramic restorations, and resin cements used for all-ceramic restorations. Advantages, disadvantages, indications, and contraindications of cements have been reviewed. Recommended uses of cements for metal, ceramic, and laboratory composite restorations have been presented. General guidelines for surface treatment ot silica- and zirconia-based restorations when using resin cements have been discussed. PMID:23350265

Bunek, Sabiha S; Powers, John M

2012-12-01

193

Characterization of Biocompatible Parylene-C Coatings for BIOMEMS Applications  

E-print Network

a biocompatible coating. Further, improvements in our everyday life can already be felt from existing Bio for adapting MEMS to meet demands for biological applications. The immense popularity of BioMEMS lies

194

Polyurethane Shape-Memory Polymers Demonstrate Functional Biocompatibility  

E-print Network

Polyurethane Shape-Memory Polymers Demonstrate Functional Biocompatibility In Vitro Maricel-vitro cytotoxicity of these resins to be comparable to commercial medical grade polyurethanes.[7,16] The Mitsubishi

Simon, Scott I.

195

Vectorization of copper complexes via biocompatible and biodegradable PLGA nanoparticles  

NASA Astrophysics Data System (ADS)

A double emulsion-solvent diffusion approach with fully biocompatible materials was used to encapsulate copper complexes within biodegradable nanoparticles, for which the release kinetics profiles have highlighted their potential use for a prolonged circulating administration.

Courant, T.; Roullin, V. G.; Cadiou, C.; Delavoie, F.; Molinari, M.; Andry, M. C.; Gafa, V.; Chuburu, F.

2010-04-01

196

Characterization of a novel calcium phosphate/sulphate bone cement.  

PubMed

Apatitic cements have shown excellent biocompatibility and adequate mechanical properties but have slow resorption in the human body. To assure that new bone tissue grows into the bone defect, a certain porosity is necessary although hard to achieve in injectable cements with suitable mechanical properties. An attempt was made by mixing alpha-tricalcium phosphate (alpha-TCP), calcium sulphate hemihydrate (CSH) and an aqueous solution containing 2.5 wt% of Na(2)HPO(4). The aim was to obtain a material containing two phases: a) one apatitic phase (calcium-deficient hydroxyapatite; CDHA) and b) one resorbable phase (calcium sulphate dihydrate; CSD). alpha-TCP and CSH mixtures were produced at relative intervals of 20 wt%. The liquid-to-powder (L/P) ratio to obtain a paste was 0.32 mLg(-1). The highest compressive strength (34 MPa) was obtained for the pure alpha-TCP sample. The strength was, in a first approximation, directly correlated to the weight proportions of the powders. X-ray diffraction analysis showed that the relative intensity for CDHA increased linearly, and the one for CSD decreased exponentially, when the amount of alpha-TCP increased. Thus, CSH ceased to transform to CSD when the amount of alpha-TCP increased. Observations in environmental scanning electron microscopy confirmed the X-ray diffraction results. CSH-crystals (100 microm) were embedded in the HA-matrix permitting gradual porosity in the material when resorbed. PMID:12115450

Nilsson, M; Fernández, E; Sarda, S; Lidgren, L; Planell, J A

2002-09-15

197

Fabrication and Biocompatibility of Electrospun Silk Biocomposites  

PubMed Central

Silk fibroin has attracted great interest in tissue engineering because of its outstanding biocompatibility, biodegradability and minimal inflammatory reaction. In this study, two kinds of biocomposites based on regenerated silk fibroin are fabricated by electrospinning and post-treatment processes, respectively. Firstly, regenerated silk fibroin/tetramethoxysilane (TMOS) hybrid nanofibers with high hydrophilicity are prepared, which is superior for fibroblast attachment. The electrospinning process causes adjacent fibers to ‘weld’ at contact points, which can be proved by scanning electron microscope (SEM). The water contact angle of silk/tetramethoxysilane (TMOS) composites shows a sharper decrease than pure regenerated silk fibroin nanofiber, which has a great effect on the early stage of cell attachment behavior. Secondly, a novel tissue engineering scaffold material based on electrospun silk fibroin/nano-hydroxyapatite (nHA) biocomposites is prepared by means of an effective calcium and phosphate (Ca–P) alternate soaking method. nHA is successfully produced on regenerated silk fibroin nanofiber within several min without any pre-treatments. The osteoblastic activities of this novel nanofibrous biocomposites are also investigated by employing osteoblastic-like MC3T3-E1 cell line. The cell functionality such as alkaline phosphatase (ALP) activity is ameliorated on mineralized silk nanofibers. All these results indicate that this silk/nHA biocomposite scaffold material may be a promising biomaterial for bone tissue engineering. PMID:24957869

Wei, Kai; Kim, Byoung-Suhk; Kim, Ick-Soo

2011-01-01

198

Microbubbles as Biocompatible Porogens for Hydrogel Scaffolds  

PubMed Central

In this study, we explored the application of lipid-shelled, gas-filled microbubbles as a method for creating on-demand microporous hydrogels for cartilage tissue engineering. The technique allowed for homogenous distribution of cells and micropores within the scaffold, increasing the absorption coefficient of large solutes (70 kDa dextran) over controls in a concentration-dependent manner. The stability of the gas-phase of the microbubbles depended on several factors, including the initial size distribution of the microbubble suspension, as well as the temperature and pressure during culture. Application of pressure cycles provided controlled release of the gas phase to generate fluid-filled micropores with remnant lipid. The resulting microporous agarose scaffolds were biocompatible, leading to a 2-fold increase in engineered cartilage properties (EY=492 ± 42 kPa for bubble group vs. 249 ± 49 kPa for bubble-free control group) over a 42-day culture period. Our results suggest that microbubbles offer a simple and robust method of modulating mass transfer in cell-seeded hydrogels through mild pressurization, and the methodology may be expanded in the future to include focused ultrasound for improved spatio-temporal control. PMID:22868194

Lima, Eric G.; Durney, Krista M.; Sirsi, Shashank R.; Nover, Adam B.; Ateshian, Gerard A.; Borden, Mark A.; Hung, Clark T

2013-01-01

199

There is no such thing as a biocompatible material.  

PubMed

This Leading Opinion Paper discusses a very important matter concerning the use of a single word in biomaterials science. This might be considered as being solely concerned with semantics, but it has implications for the scientific rationale for biomaterials selection and the understanding of their performance. That word is the adjective 'biocompatible', which is often used to characterize a material property. It is argued here that biocompatibility is a perfectly acceptable term, but that it subsumes a variety of mechanisms of interaction between biomaterials and tissues or tissue components and can only be considered in the context of the characteristics of both the material and the biological host within which it placed. De facto it is a property of a system and not of a material. It follows that there can be no such thing as a biocompatible material. It is further argued that in those situations where it is considered important, or necessary, to use a descriptor of biocompatibility, as in a scientific paper, a regulatory submission or in a legal argument, the phrase 'intrinsically biocompatible system' would be the most appropriate. The rationale for this linguistic restraint is that far too often it has been assumed that some materials are 'universally biocompatible' on the basis of acceptable clinical performance in one situation, only for entirely unacceptable performance to ensue in quite different clinical circumstances. PMID:25263686

Williams, David F

2014-12-01

200

21 CFR 888.3027 - Polymethylmethacrylate (PMMA) bone cement.  

Code of Federal Regulations, 2010 CFR

...false Polymethylmethacrylate (PMMA) bone cement. 888.3027 Section 888.3027...3027 Polymethylmethacrylate (PMMA) bone cement. (a) Identification. Polymethylmethacrylate (PMMA) bone cement is a device intended to...

2010-04-01

201

21 CFR 888.3027 - Polymethylmethacrylate (PMMA) bone cement.  

Code of Federal Regulations, 2013 CFR

...false Polymethylmethacrylate (PMMA) bone cement. 888.3027 Section 888.3027...3027 Polymethylmethacrylate (PMMA) bone cement. (a) Identification. Polymethylmethacrylate (PMMA) bone cement is a device intended to...

2013-04-01

202

21 CFR 888.3027 - Polymethylmethacrylate (PMMA) bone cement.  

...false Polymethylmethacrylate (PMMA) bone cement. 888.3027 Section 888.3027...3027 Polymethylmethacrylate (PMMA) bone cement. (a) Identification. Polymethylmethacrylate (PMMA) bone cement is a device intended to...

2014-04-01

203

21 CFR 888.3027 - Polymethylmethacrylate (PMMA) bone cement.  

Code of Federal Regulations, 2012 CFR

...false Polymethylmethacrylate (PMMA) bone cement. 888.3027 Section 888.3027...3027 Polymethylmethacrylate (PMMA) bone cement. (a) Identification. Polymethylmethacrylate (PMMA) bone cement is a device intended to...

2012-04-01

204

21 CFR 888.3027 - Polymethylmethacrylate (PMMA) bone cement.  

Code of Federal Regulations, 2011 CFR

...false Polymethylmethacrylate (PMMA) bone cement. 888.3027 Section 888.3027...3027 Polymethylmethacrylate (PMMA) bone cement. (a) Identification. Polymethylmethacrylate (PMMA) bone cement is a device intended to...

2011-04-01

205

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

PubMed

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

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

2014-01-01

206

Portland cement-blast furnace slag blends in oilwell cementing applications  

SciTech Connect

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.

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

1995-12-31

207

Development of high-performance blended cements  

NASA Astrophysics Data System (ADS)

This thesis presents the development of high-performance blended cements from industrial by-products. To overcome the low-early strength of blended cements, several chemicals were studied as the activators for cement hydration. Sodium sulfate was discovered as the best activator. The blending proportions were optimized by Taguchi experimental design. The optimized blended cements containing up to 80% fly ash performed better than Type I cement in strength development and durability. Maintaining a constant cement content, concrete produced from the optimized blended cements had equal or higher strength and higher durability than that produced from Type I cement alone. The key for the activation mechanism was the reaction between added SO4 2- and Ca2+ dissolved from cement hydration products.

Wu, Zichao

2000-10-01

208

Change in Surface Roughness of Esthetic Restorative Materials after Exposure to Different Immersion Regimes in a Cola Drink  

PubMed Central

Context. An in vitro study carried out to evaluate and compare the effect of Cola drink on surface roughness of esthetic restorative materials. Purpose. To compare the effect of different immersion regimes in a Cola drink on surface roughness of esthetic restorative materials. Method. Two hundred samples were grouped into 4 equal groups of 50 samples each: Group I: conventional glass ionomer, Group II: resin modified glass ionomer, Group III: polyacid-modified resin composite, Group IV: Composite resin. Each group was further subdivided into 5 subgroups of 10 samples each. Subgroup A (Control Subgroup). Samples were kept immersed in artificial saliva. Subgroup B. Samples were immersed in Cola drink once a day. Subgroup C. Samples were immersed in Cola drink, 3 times a day. Subgroup D. Samples were immersed in Cola drink 5 times a day. Subgroup E. Samples were immersed in Cola drink 10 times a day. Each immersion lasted 5 minutes. The immersion protocol was repeated for 7 days. Results. Maximum surface roughness was seen in Group I conventional glass ionomer cement, followed by Group II resin modified glass ionomer, Group III polyacid modified resin composite, and Group IV composite resin samples. Conclusion. Resistance to change in surface roughness is more in resin based restorative materials as compared to glass ionomer based materials. PMID:25006464

Bajwa, Navroop Kaur; Pathak, Anuradha

2014-01-01

209

New low-cost permafrost cementing system  

SciTech Connect

Extensive research has resulted in the development and subsequent field application of a new extended cement system for use in permafrost cementing projects. The use of this extended system instead of more expensive specialized cement systems leds to a reduction in overall permafrost cementing costs. This paper reviews the design requirements for permafrost cementing. It also provides laboratory data and reviews the methods which have met those requirements. Results of actual field application of the newly designed cement system and comparison with another specialized extended system are also presented. 6 refs.

Benge, O.G.; Jones, R.R.; Dresher, T.D.; Dolan, R.T.

1982-01-01

210

An estimate of the prevalence of biocompatible and habitable planets.  

PubMed

A Monte Carlo computer model of extra-solar planetary formation and evolution, which includes the planetary geochemical carbon cycle, is presented. The results of a run of one million galactic disc stars are shown where the aim was to assess the possible abundance of both biocompatible and habitable planets. (Biocompatible planets are defined as worlds where the long-term presence of surface liquid water provides environmental conditions suitable for the origin and evolution of life. Habitable planets are those worlds with more specifically Earthlike conditions). The model gives an estimate of 1 biocompatible planet per 39 stars, with the subset of habitable planets being much rarer at 1 such planet per 413 stars. The nearest biocompatible planet may thus lie approximately 14 LY distant and the nearest habitable planet approximately 31 LY away. If planets form in multiple star systems then the above planet/star ratios may be more than doubled. By applying the results to stars in the solar neighbourhood, it is possible to identify 28 stars at distances of < 22 LY with a non-zero probability of possessing a biocompatible planet. PMID:11539465

Fogg, M J

1992-01-01

211

Electron probe microanalysis of ion exchange of selected elements between dentine and adhesive restorative materials  

Microsoft Academic Search

Background: There have been numerous attempts to demonstrate the phenomenon of ion exchange between auto cure glass ionomer cements (GICs) and dentine. The purpose of this study was to employ an electron probe microanalysis (EPMA) technique to examine the interchange of elements between non-demineralized dentine and two types of restorative material, auto cure GICs and a resin composite. Methods: Restorations

GM Knight; JM McIntyre; GG Craig

2007-01-01

212

Collages en odontologie  

Microsoft Academic Search

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.

O. Guastalla; S. Viennot; Y. Allard

2005-01-01

213

The effect of dental restorative materials on dental biofilm.  

PubMed

To investigate the arrangement of biofilms formed in vivo, volunteers wore splints with slabs of six different dental materials inserted to collect smooth surface plaque. After 5 d of undisturbed plaque accumulation, the specimens were vital stained and analyzed by the confocal laser scanning microscopy (CLSM) to evaluate the percentage of vital biofilm microflora (VF percentage). Further parameters were the area of the specimens covered by plaque (surface coating; SC, %) and the height of the biofilms (BH, pm). The metals amalgam and gold, the compomer, as well as the glass-ionomer cement harboured an almost entirely dead biofilm (VF <8%). Resin composite led to vitality values between 4 and 21%, while a very thin biofilm on ceramic revealed the highest vitality values (34-86%). SC varied from 6% on glass-ionomer cement to 100% on amalgam. BH reached its highest value on amalgam and gold of 17 and 11 microm, respectively, while heights of between 1 and 6 microm were found on the ceramic, resin composite, compomer and the glass-ionomer cement. Within their limits, the present findings indicate that amalgam, gold, compomer and glass-ionomer cement exert an influence against the adhering biofilm. No general relationship could be established between the different parameters VF percentage, SC percentage and BH (microm). PMID:11878760

Auschill, Thorsten Mathias; Arweiler, Nicole Birgit; Brecx, Michel; Reich, Elmar; Sculean, Anton; Netuschil, Lutz

2002-02-01

214

A MODIFIED PMMA CEMENT (SUB-CEMENT) FOR ACCELERATED FATIGUE TESTING OF CEMENTED IMPLANT CONSTRUCTS USING CADAVERIC BONE  

PubMed Central

Pre-clinical screening of cemented implant systems could be improved by modeling the longer-term response of the implant/cement/bone construct to cyclic loading. We formulated bone cement with degraded fatigue fracture properties (Sub-cement) such that long-term fatigue could be simulated in short-term cadaver tests. Sub-cement was made by adding a chain-transfer agent to standard polymethylmethacrylate (PMMA) cement. This reduced the molecular weight of the inter-bead matrix without changing reaction-rate or handling characteristics. Static mechanical properties were approximately equivalent to normal cement. Over a physiologically reasonable range of stress intensity factor, fatigue crack propagation rates for sub-cement were higher by a factor of 25 ± 19. When tested in a simplified 2 1/2D physical model of a stem-cement-bone system, crack growth from the stem was accelerated by a factor of 100. Sub-cement accelerated both crack initiation and growth rate. Sub-cement is now being evaluated in full stem/cement/femur models. PMID:18774136

Race, Amos; Miller, Mark A.; Mann, Kenneth A.

2008-01-01

215

Kinetics of Cement Strength Development Using Different Types of Cement and Aggregates  

Microsoft Academic Search

The object of the present study is the kinetics of cement strength development using different cement and aggregate types. The model that has been developed uses the following data: (1) Composition of cement. (2) Mineral composition of clinker. (3) Cement fineness. (4) Early, standard and long-term strength data. (5) Aggregates nature. The parameters of the model are constituted by: (1)

TSAMATSOULIS DIMITRIS

216

Synthesis of Portland cement and calcium sulfoaluminate-belite cement for sustainable development and performance  

Microsoft Academic Search

Portland cement concrete, the most widely used manufactured material in the world, is made primarily from water, mineral aggregates, and portland cement. The production of portland cement is energy intensive, accounting for 2% of primary energy consumption and 5% of industrial energy consumption globally. Moreover, portland cement manufacturing contributes significantly to greenhouse gases and accounts for 5% of the global

Irvin Allen Chen

2009-01-01

217

Biocompatibility correlation of polymeric materials using human osteosarcoma cells  

NASA Astrophysics Data System (ADS)

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.

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

218

Preparation of a biocompatible magnetic film from an aqueous ferrofluid  

NASA Astrophysics Data System (ADS)

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.

Albornoz, Cecilia; Jacobo, Silvia E.

2006-10-01

219

Biocompatibility of Pristine Graphene Monolayers, Nanosheets and Thin Films  

E-print Network

There is an increasing interest to develop nanoscale biocompatible graphene structures due to their desirable physicochemical properties, unlimited application opportunities and scalable production. Here we report the preparation, characterization and biocompatibility assessment of novel graphene flakes and their enabled thin films suitable for a wide range of biomedical and electronic applications. Graphene flakes were synthesized by a chemical vapour deposition method or a liquid-phase exfoliation procedure and then thin films were prepared by transferring graphene onto glass coverslips. Raman spectroscopy and transmission electron microscopy confirmed a predominantly monolayer and a high crystalline quality formation of graphene. The biocompatibility assessment of graphene thin films and graphene flakes was performed using cultured human lung epithelial cell line A549 employing a multimodal approach incorporating automated imaging, high content screening, real-time impedance sensing in combination with bio...

Conroy, Jennifer; Smith, Ronan J; Rezvani, Ehsan; Duesberg, Georg S; Coleman, Jonathan N; Volkov, Yuri

2014-01-01

220

The quantification of biocompatibility: toward a new definition  

NASA Astrophysics Data System (ADS)

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.

Ratner, Buddy

2008-03-01

221

Effects of Biocompatible versus Standard Fluid on Peritoneal Dialysis Outcomes  

PubMed Central

The clinical benefits of using “biocompatible” neutral pH solutions containing low levels of glucose degradation products for peritoneal dialysis compared with standard solutions are uncertain. In this multicenter, open-label, parallel-group, randomized controlled trial, we randomly assigned 185 incident adult peritoneal dialysis patients with residual renal function to use either biocompatible or conventional solution for 2 years. The primary outcome measure was slope of renal function decline. Secondary outcome measures comprised time to anuria, fluid volume status, peritonitis-free survival, technique survival, patient survival, and adverse events. We did not detect a statistically significant difference in the rate of decline of renal function between the two groups as measured by the slopes of GFR: ?0.22 and ?0.28 ml/min per 1.73 m2 per month (P=0.17) in the first year in the biocompatible and conventional groups, respectively, and, ?0.09 and ?0.10 ml/min per 1.73 m2 per month (P=0.9) in the second year. The biocompatible group exhibited significantly longer times to anuria (P=0.009) and to the first peritonitis episode (P=0.01). This group also had fewer patients develop peritonitis (30% versus 49%) and had lower rates of peritonitis (0.30 versus 0.49 episodes per year, P=0.01). In conclusion, this trial does not support a role for biocompatible fluid in slowing the rate of GFR decline, but it does suggest that biocompatible fluid may delay the onset of anuria and reduce the incidence of peritonitis compared with conventional fluid in peritoneal dialysis. PMID:22440906

Brown, Fiona G.; Clarke, Margaret; Boudville, Neil; Elias, Tony J.; Foo, Marjorie W.Y.; Jones, Bernard; Kulkarni, Hemant; Langham, Robyn; Ranganathan, Dwarakanathan; Schollum, John; Suranyi, Michael; Tan, Seng H.; Voss, David

2012-01-01

222

76 FR 24519 - Gray Portland Cement and Cement Clinker From Japan; Institution of a Five-Year Review Concerning...  

Federal Register 2010, 2011, 2012, 2013

...Portland Cement and Cement Clinker From Japan; Institution of a Five-Year Review Concerning...Portland Cement and Cement Clinker From Japan AGENCY: United States International Trade...portland cement and cement clinker from Japan would be likely to lead to...

2011-05-02

223

Neutron Scattering Studies of Cement  

NASA Astrophysics Data System (ADS)

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.

Allen, Andrew

2010-03-01

224

Phase equilibria of hydrated Portland cement  

Microsoft Academic Search

A model is described for predicting the equilibrium phase assemblage in hydrated Portland cement and for calculating the relative contents and composition of phases present in the assemblage, from the chemical composition of the cement and the water\\/cement ratio. The method is also used to calculate the content of capillary pores using the best available data for the densities for

Erik P. Nielsen; Duncan Herfort; Mette R. Geiker

2005-01-01

225

ADVANCED CEMENTS FOR GEOTHERMAL WELLS  

SciTech Connect

Using the conventional well cements consisting of the calcium silicate hydrates (CaO-SiO{sub 2}-H{sub 2}O system) and calcium aluminum silicate hydrates (CaO-Al{sub 2}O{sub 3}-SiO{sub 2}-H{sub 2}O system) for the integrity of geothermal wells, the serious concern confronting the cementing industries was their poor performance in mechanically supporting the metallic well casing pipes and in mitigating the pipe's corrosion in very harsh geothermal reservoirs. These difficulties are particularly acute in two geological regions: One is the deep hot downhole area ({approx} 1700 m depth at temperatures of {approx} 320 C) that contains hyper saline water with high concentrations of CO{sub 2} (> 40,000 ppm) in conjunction with {approx} 100 ppm H{sub 2}S at a mild acid of pH {approx} 5.0; the other is the upper well region between the well's surface and {approx} 1000 m depth at temperatures up to 200 C. The specific environment of the latter region is characterized by highly concentrated H{sub 2}SO{sub 4} (pH < 1.5) brine containing at least 5000 ppm CO{sub 2}. When these conventional cements are emplaced in these harsh environments, their major shortcoming is their susceptibility to reactions with hot CO{sub 2} and H{sub 2}SO4, thereby causing their deterioration brought about by CO{sub 2}-catalyzed carbonation and acid-initiated erosion. Such degradation not only reduced rapidly the strength of cements, lowering the mechanical support of casing pipes, but also increased the extent of permeability of the brine through the cement layer, promoting the rate of the pipe's corrosion. Severely carbonated and acid eroded cements often impaired the integrity of a well in less than one year; in the worst cases, casings have collapsed within three months, leading to the need for costly and time-consuming repairs or redrilling operations. These were the reasons why the geothermal well drilling and cementing industries were concerned about using conventional well cements, and further their deterioration was a major impediment in expediting the development of geothermal energy resources.

SUGAMA,T.

2007-01-01

226

Preparation, characterization, release kinetics, and in vitro cytotoxicity of calcium silicate cement as a risedronate delivery system.  

PubMed

Injectable bone cements have been well characterized and studied in non-load bearing bone fixation and bone screw augmentation applications. Current calcium phosphate cement or poly(methyl methacrylate) cement have drawbacks like low mechanical strength and in situ exothermic properties. This leads especially in patients with osteoporosis to worsening contact between implant and bone and can finally lead to implant failure. To improve these properties, a calcium silicate cement (CSC) was prepared, which additionally contained the bisphosphonate risedronate (RA) to promote osteoblast function. Cement setting rate and compressive strength were measured and found to be reduced by RA above 0.5 wt%. X-ray diffraction, Rietveld refinement analysis, scanning electron microscopy, and porosity measurements by gas sorption revealed that RA reduces calcium silicate hydrate gel formation and changes the cement's microstructure. Cumulative release profiles of RA from CSC up to 6 months into phosphate buffer solution were analyzed by high-performance liquid chromatography, and the results were compared with theoretical release curves obtained from the Higuchi equation. Fourier transform infrared spectra measurements and drug release studies indicate that calcium-RA formed within the cement, from which the drug can be slowly released over time. An investigation of the cytotoxicity of the RA-CSC systems upon osteoblast-like cells showed no toxic effects of concentrations up to 2%. The delivery of RA from within a CSC might thus be a valuable and biocompatible new approach to locally deliver RA and to reconstruct and/or repair osteoporosis-related bone fractures. PMID:23946228

Gong, Tianxing; Wang, Zhiqin; Zhang, Yubiao; Sun, Changshan; Yang, Quanzu; Troczynski, Tom; Häfeli, Urs O

2014-07-01

227

One-step continuous synthesis of biocompatible gold nanorods for optical coherence tomography  

E-print Network

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 ...

Sebastián, Víctor

228

How to avoid myths of squeeze cementing  

SciTech Connect

This article describes a method of hydraulic fracturing using cement. Squeeze cementing is usually accompanied by elevated pressure caused by pumping into a crack, channel, or other severe restriction to high velocity flow. It is recommended that the total pressure inside the well bore at any depth should be about 500-1,000 psi higher than the reservoir pressure of any zone exposed to the cement, but lower than formation fracturing pressure of any exposed zone. The objective is to keep the cement and all well fluids static and in place until the cement sets and reaches at least 500 psi CS.

Crenshaw, P.L.

1985-04-23

229

Process for cementing geothermal wells  

DOEpatents

A pumpable slurry of coal-filled furfuryl alcohol, furfural, and/or a low molecular weight mono- or copolymer thereof containing, preferably, a catalytic amount of a soluble acid catalyst is used to cement a casing in a geothermal well.

Eilers, Louis H. (Inola, OK)

1985-01-01

230

Performance and biocompatibility of extremely tough alginate/polyacrylamide hydrogels  

E-print Network

as minimal swelling for up to 50 days of soaking in culture conditions. Mouse mesenchymal stem cells exposed National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20982 the biocompatibility and maintenance of mechanical properties of these hydrogels in cell culture and in vivo conditions

Suo, Zhigang

231

Biocompatibility and biofouling of MEMS drug delivery devices  

Microsoft Academic Search

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.

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

2003-01-01

232

Development of cost-effective biocompatible packaging for microelectronic devices  

Microsoft Academic Search

A cost-effective, miniaturized and biocompatible packaging method for medical devices is proposed, resulting in a small, soft and comfortable implantable package. Towards this end, the barrier materials and fabrication process for the individual die encapsulation are largely explored. We demonstrate that various common clean room materials are good candidates for preventing metal leaching into body. In accelerated tests at higher

Karen Qian; Karl Malachowski; Paolo Fiorini; Dimitrios Velenis; Maaike Op de Beeck; Chris Van Hoof

2011-01-01

233

Acoustofluidics 12: Biocompatibility and cell viability in microfluidic acoustic resonators  

E-print Network

Wiklund* Received 24th February 2012, Accepted 4th April 2012 DOI: 10.1039/c2lc40201g Manipulation of biological cells by acoustic radiation forces is often motivated by its improved biocompatibility relative, it is important to define safety guidelines for the design and operation of the utilized devices. This tutorial

234

Proteoglycans and glycosaminoglycans improve toughness of biocompatible double network hydrogels.  

PubMed

Based on the molecular stent concept, a series of tough double-network hydrogels (St-DN gels) made from the components of proteoglycan aggregates - chondroitin sulfate proteoglycans (1), chondroitin sulfate (2), and sodium hyaluronate (3) - are successfully developed in combination with a neutral biocompatible polymer. This work demonstrates a promising method to create biopolymer-based tough hydrogels for biomedical applications. PMID:24431128

Zhao, Yu; Nakajima, Tasuku; Yang, Jing Jing; Kurokawa, Takayuki; Liu, Jian; Lu, Jishun; Mizumoto, Shuji; Sugahara, Kazuyuki; Kitamura, Nobuto; Yasuda, Kazunori; Daniels, A U D; Gong, Jian Ping

2014-01-22

235

Biomaterials 26 (2005) 35113519 Fabrication and biocompatibility of polypyrrole implants  

E-print Network

Biomaterials 26 (2005) 3511­3519 Fabrication and biocompatibility of polypyrrole implants suitable Center for Learing and Memory, Massachusetts Institute of Technology, Cambridge, MA 02142, USA c Caritas scaffolds, electrodes, and devices. Stand-alone polymer implants also provide the additional advantages

Sur, Mriganka

236

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

PubMed Central

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

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

2009-01-01

237

Finite element analysis of the effect of cementing concepts on implant stability and cement fatigue failure  

PubMed Central

Background and purpose Two contradictory cementing techniques (using an undersized stem versus a canal-filling stem) can both lead to excellent survival rates, a phenomenon known as the “French paradox”. Furthermore, previous studies have indicated that the type of bone supporting the cement mantle may affect implant survival. To further evaluate the mechanical consequences of variations in cementing technique, we studied the effect of implant size and type of bone supporting the cement mantle on the mechanical performance of cemented total hip arthroplasty, using finite element analysis. Methods In a generic 2-dimensional plane-strain finite element model of a transverse section of a cemented total hip arthroplasty with a Charnley-Kerboull stem, we varied implant size and type of bone supporting the cement mantle. The models were subjected to 2 × 106 cycles of an alternating loading pattern of torque and a transverse load. During this loading history, we simulated cement fatigue crack formation and tracked rotational stability of the implant. Results Canal-filling stems produced fewer cement cracks and less rotation than undersized stems. Cement mantles surrounded by trabecular bone produced more cement cracks and implant rotation than cement mantles surrounded by cortical bone. Interpretation Our investigation provides a possible explanation for the good clinical results obtained with canal-filling Charnley-Kerboull implants. Our findings also indicate that inferior mechanical properties are obtained with these implants if the cement is supported by trabecular bone, which may be minimized by an optimal cementing technique. PMID:19421913

van Aken, Jantien; Scheerlinck, Thierry; Verdonschot, Nico

2009-01-01

238

Identification of organic eluates from four polymer-based dental filling materials.  

PubMed

Elution from polymer-based dental filling materials may have a potential impact on the biocompatibility of the materials. Since information from the manufacturers about ingredients in the materials often is incomplete, analyses of eluates from the materials are necessary for a better knowledge about possible harmful compounds. The aim of this study was to identify organic eluates from polymerized samples of two composites, one compomer and one resin-reinforced glass ionomer cement. Samples were immersed in ethanol or Ringer's solution. Organic leachables were analyzed by gas chromatography-mass spectrometry. Identification was confirmed with reference substances, if available. Among components detected were monomers, co-monomers, initiators, stabilizers, decomposition products and contaminants. Thirty-two substances were identified and 17 were confirmed with reference substances. From elution in Ringer's we identified 13 eluates from Tetric Ceram, 10 from Z250, 21 from Dyract and six from Fuji II LC; HEMA, HC and CQ were found in all samples. From elution in ethanol 12 eluates from Tetric Ceram, 18 eluates from Z250, 19 from Dyract and 10 from Fuji II LC were identified. The diversity of eluates from the four materials under study is demonstrated. Owing to variation between the materials, the biocompatibility including the allergenic potential may be different. PMID:12786959

Michelsen, Vibeke Barman; Lygre, Henning; Skålevik, Rita; Tveit, Anne Bjørg; Solheim, Einar

2003-06-01

239

Synthesis of Portland cement and calcium sulfoaluminate-belite cement for sustainable development and performance  

NASA Astrophysics Data System (ADS)

Portland cement concrete, the most widely used manufactured material in the world, is made primarily from water, mineral aggregates, and portland cement. The production of portland cement is energy intensive, accounting for 2% of primary energy consumption and 5% of industrial energy consumption globally. Moreover, portland cement manufacturing contributes significantly to greenhouse gases and accounts for 5% of the global CO2 emissions resulting from human activity. The primary objective of this research was to explore methods of reducing the environmental impact of cement production while maintaining or improving current performance standards. Two approaches were taken, (1) incorporation of waste materials in portland cement synthesis, and (2) optimization of an alternative environmental friendly binder, calcium sulfoaluminate-belite cement. These approaches can lead to less energy consumption, less emission of CO2, and more reuse of industrial waste materials for cement manufacturing. In the portland cement part of the research, portland cement clinkers conforming to the compositional specifications in ASTM C 150 for Type I cement were successfully synthesized from reagent-grade chemicals with 0% to 40% fly ash and 0% to 60% slag incorporation (with 10% intervals), 72.5% limestone with 27.5% fly ash, and 65% limestone with 35% slag. The synthesized portland cements had similar early-age hydration behavior to commercial portland cement. However, waste materials significantly affected cement phase formation. The C3S--C2S ratio decreased with increasing amounts of waste materials incorporated. These differences could have implications on proportioning of raw materials for cement production when using waste materials. In the calcium sulfoaluminate-belite cement part of the research, three calcium sulfoaluminate-belite cement clinkers with a range of phase compositions were successfully synthesized from reagent-grade chemicals. The synthesized calcium sulfoaluminate-belite cement that contained medium C4A3 S¯ and C2S contents showed good dimensional stability, sulfate resistance, and compressive strength development and was considered the optimum phase composition for calcium sulfoaluminate-belite cement in terms of comparable performance characteristics to portland cement. Furthermore, two calcium sulfoaluminate-belite cement clinkers were successfully synthesized from natural and waste materials such as limestone, bauxite, flue gas desulfurization sludge, Class C fly ash, and fluidized bed ash proportioned to the optimum calcium sulfoaluminate-belite cement synthesized from reagent-grade chemicals. Waste materials composed 30% and 41% of the raw ingredients. The two calcium sulfoaluminate-belite cements synthesized from natural and waste materials showed good dimensional stability, sulfate resistance, and compressive strength development, comparable to commercial portland cement.

Chen, Irvin Allen

240

Reinforced Portland cement porous scaffolds for load-bearing bone tissue engineering applications.  

PubMed

Modified Portland cement porous scaffolds with suitable characteristics for load-bearing bone tissue engineering applications were manufactured by combining the particulate leaching and foaming methods. Non-crosslinked polydimethylsiloxane was evaluated as a potential reinforcing material. The scaffolds presented average porosities between 70 and 80% with mean pore sizes ranging from 300 ?m up to 5.0 mm. Non-reinforced scaffolds presented compressive strengths and elastic modulus values of 2.6 and 245 MPa, respectively, whereas reinforced scaffolds exhibited 4.2 and 443 MPa, respectively, an increase of ?62 and 80%. Portland cement scaffolds supported human osteoblast-like cell adhesion, spreading, and propagation (t = 1-28 days). Cell metabolism and alkaline phosphatase activity were found to be enhanced at longer culture intervals (t ? 14 days). These results suggest the possibility of obtaining strong and biocompatible scaffolds for bone repair applications from inexpensive, yet technologically advanced materials such as Portland cement. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 501-507, 2012. PMID:22121151

Higuita-Castro, Natalia; Gallego-Perez, Daniel; Pelaez-Vargas, Alejandro; García Quiroz, Felipe; Posada, Olga M; López, Luis E; Sarassa, Carlos A; Agudelo-Florez, Piedad; Monteiro, Fernando J; Litsky, Alan S; Hansford, Derek J

2012-02-01

241

Research of magnesium phosphosilicate cement  

NASA Astrophysics Data System (ADS)

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.)

Ding, Zhu

242

Successful Cementing of Shallow Steamflood wells in California  

Microsoft Academic Search

Successful cementing of shallow casing strings (150 to 400 ft) for steamflood operations in Kern County, CA, has been difficult to achieve. Lost-circulation problems accompanied by cement fallback are common. Ultrasonic cement evaluation logs commonly show the cement sheath to be severely cut with gas (air) and show numerous cases of large gaps in the cement column. Extensive remedial work

K. J. Goodwin; D. G. Calvert; R. L. Root; V. S. Henderson

1992-01-01

243

NON-PORTLAND CEMENT ACTIVATION OF BLAST FURNACE SLAG  

Microsoft Academic Search

The purpose of this project was to produce a “greener” cement from granulated ground blast furnace slag (GGBS) using non-Portland cement activation. By eventually developing “greener” cement, the ultimate goal of this research project would be to reduce the amount of Portland cement used in concrete, therefore reducing the amount of carbon dioxide emitted into the atmosphere during cement production.

Anne Elizabeth Oberlink

2010-01-01

244

The density of cement phases  

SciTech Connect

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.

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

245

Bagasse-reinforced cement composites  

Microsoft Academic Search

Bagasse is abundantly available in many countries as a by-product from sugar mills and is being mostly used as fuel or disposed of by incineration. An attempt has been made to convert this byproduct into useful eco-friendly cement-bonded composites, which can be used for various internal and external applications in buildings. The investigations include optimization of parameters such as bagasse

L. K. Aggarwal

1995-01-01

246

Effects of cement particle size distribution on performance properties of Portland cement-based materials  

SciTech Connect

The original size, spatial distribution, and composition of Portland cement particles have a large influence on hydration kinetics, microstructure development, and ultimate properties of cement-based materials. In this paper, the effects of cement particle size distribution on a variety of performance properties are explored via computer simulation and a few experimental studies. Properties examined include setting time, heat release, capillary porosity percolation, diffusivity, chemical shrinkage, autogenous shrinkage, internal relative humidity evolution, and interfacial transition zone microstructure. The effects of flocculation and dispersion of the cement particles in the starting microstructures on resultant properties are also briefly evaluated. The computer simulations are conducted using two cement particle size distributions that bound those commonly in use today and three different water-to-cement ratios: 0.5, 0.3, and 0.246. For lower water-to-cement ratio systems, the use of coarser cements may offer equivalent or superior performance, as well as reducing production costs for the manufacturer.

Bentz, D.P.; Garboczi, E.J.; Haecker, C.J.; Jensen, O.M.

1999-10-01

247

Highly biocompatible zwitterionic phospholipids coated upconversion nanoparticles for efficient bioimaging.  

PubMed

The potential of upconversion nanoparticles (UCNPs) in various biomedical applications, including immunoassays, biomedical imaging, and molecular sensing, requires their surface derivatized to be hydrophilic and biocompatible. Here, a new family of compact zwitterionic ligand systems composed with functional phospholipids was designed and used for the surface modification of UCNPs. The zwitterionic UCNPs are hydrophilic, compact, and easily functionalized. It was proved that zwitterionic phospholipids could provide UCNPs with not only extended pH and salt stability but also little nonspecific interactions to positively and negatively charged proteins, low nonspecific adhesion in live-cell imaging process. Most notably, the efficient in vivo tumor imaging performance and long blood circulation half-life suggests the excellent biocompatibility for in vivo imaging of the zwitterionic UCNPs. PMID:25075628

Yao, Chi; Wang, Peiyuan; Zhou, Lei; Wang, Rui; Li, Xiaomin; Zhao, Dongyuan; Zhang, Fan

2014-10-01

248

Method for making a bio-compatible scaffold  

DOEpatents

A method for forming a three-dimensional, biocompatible, porous scaffold structure using a solid freeform fabrication technique (referred to herein as robocasting) that can be used as a medical implant into a living organism, such as a human or other mammal. Imaging technology and analysis is first used to determine the three-dimensional design required for the medical implant, such as a bone implant or graft, fashioned as a three-dimensional, biocompatible scaffold structure. The robocasting technique is used to either directly produce the three-dimensional, porous scaffold structure or to produce an over-sized three-dimensional, porous scaffold lattice which can be machined to produce the designed three-dimensional, porous scaffold structure for implantation.

Cesarano, III, Joseph (Albuquerque, NM); Stuecker, John N. (Albuquerque, NM); Dellinger, Jennifer G. (Champaigne, IL); Jamison, Russell D. (Urbana, IL)

2006-01-31

249

Cellular Uptake and Biocompatibility of Bismuth Ferrite Harmonic Advanced Nanoparticles  

E-print Network

Bismuth Ferrite (BFO) nanoparticles (BFO-NP) display interesting optical (nonlinear response) and magnetic properties which make them amenable for bio-oriented applications as intra- and extra membrane contrast agents. Due to the relatively recent availability of this material in well dispersed nanometric form, its biocompatibility was not known to date. In this study, we present a thorough assessment of the effects of in vitro exposure of human adenocarcinoma (A549), lung squamous carcinoma (NCI-H520), and acute monocytic leukemia (THP-1) cell lines to uncoated and poly(ethylene glycol)-coated BFO-NP in the form of cytotoxicity, haemolytic response and biocompatibility. Our results support the attractiveness of the functional-BFO towards biomedical applications focused on advanced diagnostic imaging.

Staedler, Davide; Magouroux, Thibaud; Rogov, Andrii; Maguire, Ciaran Manus; Mohamed, Bashir M; Schwung, Sebastian; Rytz, Daniel; Jüstel, Thomas; Hwu, Stéphanie; Mugnier, Yannick; Dantec, Ronan Le; Volkov, Yuri; Gerber-Lemaire, Sandrine; Prina-Melloc, Adriele; Bonacina, Luigi; Wolf, Jean-Pierre

2014-01-01

250

BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES  

SciTech Connect

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.

Farquar, G; Leif, R

2009-07-15

251

The leachability of heavy metals in hardened fly ash cement and cement-solidified fly ash  

Microsoft Academic Search

The effect of mix proportion, leachant pH, curing age, carbonation and specimen making method etc. on the leaching of heavy metals and Cr(VI) in fly ash cement mortars and cement-solidified fly ashes has been investigated. In addition, a method for reducing the leaching of Cr(VI) from cement-solidified fly ashes is proposed. The results mainly indicate that: (1) either Portland cement

Qijun Yu; S. Nagataki; Jinmei Lin; T. Saeki; M. Hisada

2005-01-01

252

Cement industry: sustainability, challenges and perspectives  

Microsoft Academic Search

Cement-based materials, such as concrete and mortars, are used in extremely large amounts. For instance, in 2009 concrete\\u000a production was superior to 10 billion tons. Cement plays an important role in terms of economic and social relevance since\\u000a it is fundamental to build and improve infrastructure. On the other hand, this industry is also a heavy polluter. Cement production\\u000a releases

F. A. Rodrigues; I. Joekes

2011-01-01

253

Biocompatibility of Candidate Materials for the Realization of Medical Microdevices  

Microsoft Academic Search

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

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

2006-01-01

254

[Membrane biocompatibility in dialysis: the role of absorption].  

PubMed

Membrane biocompatibility is a concept that have gained clinical relevance. How to define a "biocompatible membrane" in hemodialysis is still object of discussion. Intermediate biochemical reactions, measured in the blood are more relevant than clinical events to document membrane's quality. In the absence of prospective studies, it is not possible to document that the constant use of a dialysis membrane governs risk of death in the hemodialyzed patient. Nevertheless, some clinical criteria are relevant, such as hemocompatibility, i.e. clotting of the extracorporeal circuit and heparin consumption, hypersensitivity reactions, denutrition associated with the "microinflammatory" stress induced by the hemodialysis session, occurrence of beta 2 microglobulin-derived amyloidosis. Synthetic membranes are credited of higher biocompatibility than cellulosic membranes. In general, they are highly permeable to peptides and proteins of the middle molecular range that contain some uremic toxins. In addition to be "highly permeable", allowing convective transfert, some synthetic membranes (polymethylmetacrylate, polyacrylonitrile, polyamide) bind proteins. Protein adsorption into synthetic membrane results from electrical charges distribution both at the surface and in the bulk of the membrane. Ionic interactions are the main contribution to protein adsorption, but rheological conditions, surface rugosity, and porosity or gel consistency play also a role. Consequently, some membranes can bind cytokines and oxygen species, other bind endotoxins. Recently, it has been demonstrated that heparin coating was possible with the AN69-ST membrane, resulting in improved hemocompatibility and significant lessening of heparin requirements during the sessions. It appears that adsorption characteristics govern biocompatibility. For clinical practice, a classification of various membranes according to these properties must be taken into account. PMID:14650747

Chanard, J

2003-01-01

255

In vitro biocompatibility of equal channel angular processed (ECAP) titanium  

Microsoft Academic Search

This work attempts to understand the in vitro biocompatibility of ultrafine grained titanium prepared by the ECAP route. The results obtained from the mouse fibroblast cell line 3T3 showed a better cell adherence and cell proliferation on ECAP titanium specimen compared to the coarse grain Grade-2 Ti and Ti6Al4V alloy. This could be attributed to the increased surface energy and

Taik Nam Kim; A. Balakrishnan; B. C. Lee; W. S. Kim; K. Smetana; J. K. Park; B. B. Panigrahi

2007-01-01

256

Removal of heavy metals from solution using biocompatible polymers  

Microsoft Academic Search

Well characterised, hydrophobic, poly(vinylidene fluoride) and poly(sulfone) membranes, a physisorbed amphiphillic surfactant as an affi nity linker with covalently attached bio-specific ligands to demonstrate heavy metal ion binding and re-use is reported. Central to this technology are the easy to manufacture membranes and a biocompatible Pluronic™ surfactant that serves multiple functions, where it acts not only as an affi nity

Selvan Govender; W. Przybylowicz; Pieter Swart

2009-01-01

257

New tubular bioabsorbable knitted airway stent: Biocompatibility and mechanical strength  

Microsoft Academic Search

Objective: This study examines the biocompatibility and suitability of a new tubular bioabsorbable knitted stent made of poly-L-lactic acid in normal rabbit airways and examines the mechanical strength of this stent in vitro. Methods: A tubular knitted airway stent (group B, n = 15) made of poly-L-lactic acid wire was implanted operatively in New Zealand White rabbits intratracheally; silicone stents

Yukihito Saito; Kenichirou Minami; Masashi Kobayashi; Yoshihisa Nakao; Hideyasu Omiya; Hiroji Imamura; Noriko Sakaida; Akiharu Okamura

2002-01-01

258

Effect of surface treatment on the biocompatibility of microbial polyhydroxyalkanoates  

Microsoft Academic Search

The biocompatibility of microbial polyesters polyhydroxybutyrate (PHB) and poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx) were evaluated in vitro. The mouse fibroblast cell line L929 was inoculated on films made of PHB, PHBHHx and their blends, polylactic acid (PLA) as control. It was found that the growth of the cells L929 was poor on PHB and PLA films. The viable cell number ranged from 8.8×102

Xianshuang Yang; Kai Zhao; Guo-Qiang Chen

2002-01-01

259

Effects of cement particle size distribution on performance properties of Portland cement-based materials  

Microsoft Academic Search

The original size, spatial distribution, and composition of Portland cement particles have a large influence on hydration kinetics, microstructure development, and ultimate properties of cement-based materials. In this paper, the effects of cement particle size distribution on a variety of performance properties are explored via computer simulation and a few experimental studies. Properties examined include setting time, heat release, capillary

Dale P. Bentz; Edward J. Garboczi; Claus J. Haecker; Ole M. Jensen

1999-01-01

260

General hydration model for portland cement and blast furnace slag cement  

Microsoft Academic Search

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

L. Taerwe

1995-01-01

261

EFFECT OF PORTLAND CEMENT ON STRENGTH DEVELOPMENT OF PHOSPHOANHYDRITE-POZZOLANA CEMENT  

Microsoft Academic Search

The paper is a part of the research on a complex alternative technology of apatite phosphogypsum (PG) obtained during the production of phosphoric acid from Kola apatite, on rare earth concentrate and phosphoanhydrite cement with the recovery of phosphate compounds. The effect of Portland cement on mechanical properties of phosphoanhydrite-pozzolana cement has been determined. The samples of binder were prepared

Andrzej JAROSIÑSKI

1997-01-01

262

Biocompatible two-layer tantalum/titania-polymer hybrid coating.  

PubMed

Using a two-step procedure, radiopaque and biocompatible coatings were obtained, consisting of a tantalum layer deposited by sputtering technique and of an upper organic-inorganic hybrid layer synthesized via sol-gel. As shown by radiographic images, tantalum confers to plastic substrates good X-ray visibility, adjustable via control of deposition time, but its adhesion to the substrate is poor and manipulation easily damages the metal layer. Polymer-titania hybrid coatings, synthesized using poly-?-caprolactone (PCL) or carboxy-terminated polydimethylsiloxane (PDMS) as organic precursors, were applied on the metal layer as biocompatible protective coatings. Biocompatibility is demonstrated by cytotoxicity tests conducted using vascular wall resident-mesenchymal stem cells (VW-MSCs). Both coatings show very good adhesion to the substrate, showing no sign of detachment upon large substrate deformations. Under such conditions, SEM observations show that the PCL-containing hybrid forms cracks, whereas the PDMS-based hybrid does not crack, suggesting possible applications of the latter material as a protective layer of sputtered tantalum radiopaque markers for flexible medical devices. PMID:20831278

Cortecchia, Elisa; Pacilli, Annalisa; Pasquinelli, Gianandrea; Scandola, Mariastella

2010-09-13

263

A biodegradable and biocompatible gecko-inspired tissue adhesive  

PubMed Central

There is a significant medical need for tough biodegradable polymer adhesives that can adapt to or recover from various mechanical deformations while remaining strongly attached to the underlying tissue. We approached this problem by using a polymer poly(glycerol-co-sebacate acrylate) and modifying the surface to mimic the nanotopography of gecko feet, which allows attachment to vertical surfaces. Translation of existing gecko-inspired adhesives for medical applications is complex, as multiple parameters must be optimized, including: biocompatibility, biodegradation, strong adhesive tissue bonding, as well as compliance and conformability to tissue surfaces. Ideally these adhesives would also have the ability to deliver drugs or growth factors to promote healing. As a first demonstration, we have created a gecko-inspired tissue adhesive from a biocompatible and biodegradable elastomer combined with a thin tissue-reactive biocompatible surface coating. Tissue adhesion was optimized by varying dimensions of the nanoscale pillars, including the ratio of tip diameter to pitch and the ratio of tip diameter to base diameter. Coating these nanomolded pillars of biodegradable elastomers with a thin layer of oxidized dextran significantly increased the interfacial adhesion strength on porcine intestine tissue in vitro and in the rat abdominal subfascial in vivo environment. This gecko-inspired medical adhesive may have potential applications for sealing wounds and for replacement or augmentation of sutures or staples. PMID:18287082

Mahdavi, Alborz; Ferreira, Lino; Sundback, Cathryn; Nichol, Jason W.; Chan, Edwin P.; Carter, David J. D.; Bettinger, Chris J.; Patanavanich, Siamrut; Chignozha, Loice; Ben-Joseph, Eli; Galakatos, Alex; Pryor, Howard; Pomerantseva, Irina; Masiakos, Peter T.; Faquin, William; Zumbuehl, Andreas; Hong, Seungpyo; Borenstein, Jeffrey; Vacanti, Joseph; Langer, Robert; Karp, Jeffrey M.

2008-01-01

264

Biocompatibility of Chitosan Carriers with Application in Drug Delivery  

PubMed Central

Chitosan is one of the most used polysaccharides in the design of drug delivery strategies for administration of either biomacromolecules or low molecular weight drugs. For these purposes, it is frequently used as matrix forming material in both nano and micron-sized particles. In addition to its interesting physicochemical and biopharmaceutical properties, which include high mucoadhesion and a great capacity to produce drug delivery systems, ensuring the biocompatibility of the drug delivery vehicles is a highly relevant issue. Nevertheless, this subject is not addressed as frequently as desired and even though the application of chitosan carriers has been widely explored, the demonstration of systems biocompatibility is still in its infancy. In this review, addressing the biocompatibility of chitosan carriers with application in drug delivery is discussed and the methods used in vitro and in vivo, exploring the effect of different variables, are described. We further provide a discussion on the pros and cons of used methodologies, as well as on the difficulties arising from the absence of standardization of procedures. PMID:24955636

Rodrigues, Susana; Dionisio, Marita; Remunan Lopez, Carmen; Grenha, Ana

2012-01-01

265

Biomechanical and biocompatibility characteristics of electrospun polymeric tracheal scaffolds.  

PubMed

The development of tracheal scaffolds fabricated based on electrospinning technique by applying different ratios of polyethylene terephthalate (PET) and polyurethane (PU) is introduced here. Prior to clinical implantation, evaluations of biomechanical and morphological properties, as well as biocompatibility and cell adhesion verifications are required and extensively performed on each scaffold type. However, the need for bioreactors and large cell numbers may delay the verification process during the early assessment phase. Hence, we investigated the feasibility of performing biocompatibility verification using static instead of dynamic culture. We performed bioreactor seeding on 3-dimensional (3-D) tracheal scaffolds (PET/PU and PET) and correlated the quantitative and qualitative results with 2-dimensional (2-D) sheets seeded under static conditions. We found that an 8-fold reduction for 2-D static seeding density can essentially provide validation on the qualitative and quantitative evaluations for 3-D scaffolds. In vitro studies revealed that there was notably better cell attachment on PET sheets/scaffolds than with the polyblend. However, the in vivo outcomes of cell seeded PET/PU and PET scaffolds in an orthotopic transplantation model in rodents were similar. They showed that both the scaffold types satisfied biocompatibility requirements and integrated well with the adjacent tissue without any observation of necrosis within 30 days of implantation. PMID:24703872

Ajalloueian, Fatemeh; Lim, Mei Ling; Lemon, Greg; Haag, Johannes C; Gustafsson, Ylva; Sjöqvist, Sebastian; Beltrán-Rodríguez, Antonio; Del Gaudio, Costantino; Baiguera, Silvia; Bianco, Alessandra; Jungebluth, Philipp; Macchiarini, Paolo

2014-07-01

266

Biocompatible pillararene-assembly-based carriers for dual bioimaging.  

PubMed

Present research provides a successful example to use biocompatible pillararene-based assemblies for delivering mixed dyes in dual bioimaging. A series of tadpole-like and bola amphiphilic pillararenes 1-4 were synthesized by selectively employing water-soluble ethylene glycols and hydrophobic alkyl units as the starting materials. In comparison with their monomers, these amphiphilic pillararenes not only show improved biocompatibility to cells but also could form homogeneous supramolecular self-assemblies. Interestingly, different types of amphiphilic pillararene-based assemblies exhibit various performances on the delivery of dyes with different aqueous solubility. All assemblies can deliver water-soluble rhodamine B to cells, while only tadpole-like amphiphilic pillararene-based assemblies performed better on delivering hydrophobic fluorescein isothiocyanate for imaging. In addition, pillararene derivatives 1, 3, and 4 could complex with a viologen guest, further forming stable assemblies for bioimaging. In such cases, the assembly formed from the complex of tadpole-like amphiphile pillararene 1 with the viologen guest performed better in delivering mixed dyes. Finally, an anticancer drug, doxorubicin, was successfully delivered to cells by using the pillararene-based assemblies. The current research has determined the capacities of pillararene-based assemblies to deliver different dyes for bioimaging and paves the way for using these biocompatible carriers toward combined cancer therapy. PMID:23927086

Zhang, Huacheng; Ma, Xing; Nguyen, Kim Truc; Zhao, Yanli

2013-09-24

267

A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys  

PubMed Central

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

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

2009-01-01

268

Supply chain management in the cement industry .  

E-print Network

??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… (more)

Agudelo, Isabel

2009-01-01

269

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

PubMed

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

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

2014-06-01

270

A green chemistry approach for synthesizing biocompatible gold nanoparticles.  

PubMed

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

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

2014-01-01

271

A green chemistry approach for synthesizing biocompatible gold nanoparticles  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

272

Liquid antibiotics in bone cement  

PubMed Central

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

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

2014-01-01

273

Stem compatibility for cement-in-cement femoral revision: an in vitro study.  

PubMed

Cement-in-cement femoral component revision is a useful and commonly practised technique. Onerous and hazardous re-shaping of the original cement mantle is required if the new stem does not seat easily. Furthermore, without removing the entirety of the original cement mantle, the freedom to alter anteversion or leg length is difficult to predict preoperatively. We present data from in vitro experiments testing the compatibility of the top cemented stems according to UK registry figures (NJR 2013). This data augments preoperative planning by indicating which revision stems require minimal or no cement reshaping when being inserted into another stem's mantle. We also present the maximum shortening and anteversion that can be achieved without reshaping the original cement mantle. PMID:25044270

Berstock, James R; Torrie, Peter A G; Smith, James R A; Webb, Jason C; Baker, Richard P

2014-01-01

274

Antibacterial Activity of Restorative Dental Biomaterials in vitro  

Microsoft Academic Search

This study investigated the antibacterial effects against Streptococcus mutans of a fine-hybrid resin composite (FH-RC; Tetric ceram), an ion-releasing resin composite (Ariston pHc), a self-curing glass ionomer cement (SC-GIC; Ketac-Molar), a resin-modified GIC (RM-GIC; Photac-Fil), and a zinc oxide eugenol cement (ZOE; IRM). In a novel assay, bacterial suspensions were placed into narrow 20-?l conical cavities within the materials. After

Clemens Boeckh; Eliane Schumacher; Andreas Podbielski; Bernd Haller

2002-01-01

275

Fracture model for cemented aggregates  

A mechanisms-based fracture model applicable to a broad class of cemented aggregates and, among them, plastic-bonded explosive (PBX) composites, is presented. The model is calibrated for PBX 9502 using the available experimental data under uniaxial compression and tension gathered at various strain rates and temperatures. We show that the model correctly captures inelastic stress-strain responses prior to the load peak and it predicts the post-critical macro-fracture processes, which result from the growth and coalescence of micro-cracks. In our approach, the fracture zone is embedded into elastic matrix and effectively weakens the material's strength along the plane of the dominant fracture.

Zubelewicz, Aleksander; Thompson, Darla G.; Ostoja-Starzewski, Martin; Ionita, Axinte; Shunk, Devin; Lewis, Matthew W.; Lawson, Joe C.; Kale, Sohan; Koric, Seid

2013-01-01

276

CO 2 emissions from Polish cement industry  

Microsoft Academic Search

The cement industry is one of the most significant sources of anthropogenic emissions of CO2. It is connected with the specific character of the production processes, during which great quantities of CO2 are produced. Basic actions to reduce CO2 emissions recommended by the European Union's, Reference Document on Best Available Techniques in the Cement and Lime Manufacturing Industries, include: reduction

Jan Deja; Alicja Uliasz-Bochenczyk; Eugeniusz Mokrzycki

2010-01-01

277

Acrylic bone cement: current concept review.  

PubMed

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

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

2013-08-01

278

MECHANICAL BEHAVIOUR OF CEMENTED PASTE BACKFILL  

Microsoft Academic Search

Cemented paste backfill is a method increasingly used by modern mines throughout the world due to increasingly stringent environmental regulations on sulfur -rich tailings. This paper studies the mechanical behavior of cemented paste backf ill with mid term (up to 91 days) and long term (more than 91 days) curing times. Two Canadian sulfur mine tailings samples were used for

Tikou BELEM; Mostafa BENZAAZOUA; Bruno BUSSIÈRE

279

Developme nt strategies for foamed cement paste  

Microsoft Academic Search

For several decades numerous research projects dealt with foamed concret e. Although foamed cement-bound materials have very useful properties, for example low density and low thermal conductivity, they are not often used as construction material, because predefined properties are difficult to attain accu- rately. Therefore the intention of this research work is the unerring production of cement-bound foams. Based on

J. U. Pott

2002-01-01

280

"Physio-Mechanical Properties of a New Zinc-Reinforced Glass Ionomer Restorative Material" "Sarah Al-Angari*1  

E-print Network

student, Department of Restorative Dentistry, Division of Dental Biomaterials,Indiana University School, Department of Restorative Dentistry, Division of Dental Biomaterials, Indiana University School of Dentistry.Norman Cook; Associate Professor, Department of Restorative Dentistry, Division of Operative Dentistry

Zhou, Yaoqi

281

Bond strength between composite resin and resin modified glass ionomer using different adhesive systems and curing techniques  

PubMed Central

Aim: To evaluate bond strength between RMGI and composite using different adhesive systems and curing techniques. Materials and Methods: Sixty prepared samples of RMGI were randomly divided into six groups according to adhesive systems (total-etch, two-step self-etch and all-in-one) and curing techniques (co-curing and pre-curing). In co-curing technique, the adhesive systems were applied on uncured RMGI samples and co-cured together. In the pre-curing technique, before application of adhesive systems, the RMGI samples were cured. Composite layers were applied and shear bond strength was measured. Two samples of each group were evaluated by SEM. Failure mode was determined by streomicroscope. Results: Both curing methods and adhesive systems had significant effect on bond strength (P-value < 0.05). There was an interaction between two factors (P-value <0.05). Both self-etch adhesives had significantly higher shear bond strength than the total-etch adhesive (P-value <0.05). The co-curing technique improved the bond strength in self-etch adhesives, but decreased the bond strength in total-etch adhesive (P-value<0.05). Conclusion: The application of self-etch adhesive systems and co-curing technique can improve the bond strength between the RMGI and composite. PMID:24778512

Boruziniat, Alireza; Gharaei, Samineh

2014-01-01

282

Hydrothermal cement/metal interfaces  

SciTech Connect

The authors investigated the adherence of two cementitious materials, calcium phosphate cement (CPC) and silica flour-filled class G cement (CGC), to metal substrates, such as cold-rolled steel (CRS), stainless steel (SS), electroplated zinc-coated steel (EZS), and zinc phosphate-coated steel (ZPS) after autoclaving at 200 C. In CPC/metal joints, the {gamma}-AlOOH phase, which segregated from the hydroxyapatite phase of the CPC matrix, was preferentially precipitated on the CRS and SS surfaces and also mixed with the reaction products formed at the interfaces between CPC and EZS or ZPS. Precipitation of {gamma}-AlOOH caused the formation of a weak boundary layer at the interfacial transition zones, thereby resulting in a low shear-bond strength. Although CGC accelerated the rate of corrosion of CRS and SS surfaces, the growth of Fe{sub 2}O{sub 3} clusters, formed as the corrosion products of metals at interfaces, aided the anchoring effect of xonotlite crystals as the major phase of CGC matrix, thereby conferring a high shear-bond strength. The EZS and ZPS surfaces were susceptible to alkali dissolution caused by the attack of the high-pH interstitial fluid of CGC pastes to the Zn and zinc phosphate coatings. Thus, the bond strengths of the CGC/EZS and /ZPS joints were lower than those of the joints made with CRS and SS.

Sugama, Toshifumi [Brookhaven National Lab., Upton, NY (United States); Baldwin, S. [Worcester Polytechnic Inst., MA (United States). Dept. of Chemistry

1996-01-01

283

Science and technology of biocompatible thin films for implantable biomedical devices.  

SciTech Connect

This presentation focuses on reviewing research to develop two critical biocompatible film technologies to enable implantable biomedical devices, namely: (1) development of bioinert/biocompatible coatings for encapsulation of Si chips implantable in the human body (e.g., retinal prosthesis implantable in the human eye) - the coating involves a novel ultrananocrystalline diamond (UNCD) film or hybrid biocompatible oxide/UNCD layered films; and (2) development of biocompatible films with high-dielectric constant and microfabrication process to produce energy storage super-capacitors embedded in the microchip to achieve full miniaturization for implantation into the human body.

Li, W.; Kabius, B.; Auciello, O.; Materials Science Division

2010-01-01

284

Improved workability of injectable calcium sulfate bone cement by regulation of self-setting properties.  

PubMed

Calcium sulfate hemihydrate (CSH) powder as an injectable bone cement was prepared by hydrothermal synthesis of calcium sulfate dihydrate (CSD). The prepared materials showed X-ray diffraction peaks corresponding to the CSH structure without any secondary phases, implying complete conversion from CSD phase to CSH phase. Thermogravimetric (TG) analyses showed the crystal water content of CSH was about 6.0% (wt.), which is near to the theoretic crystal water value of CSH. From scanning electron microscopy (SEM) micrographs, sheet crystal structure of CSD was observed to transform into rod-like crystal structure of CSH. Most interesting and important of all, CSD as setting accelerator was also introduced into CSH powder to regulate self-setting properties of injectable CSH paste, and thus the self-setting time of CSH paste can be regulated from near 30 min to less than 5 min by adding various amounts of setting accelerator. Because CSD is not only the reactant of preparing CSH but also the final solidified product of CSH, the setting accelerator has no significant effect on the other properties of materials, such as mechanical properties. In vitro biocompatibility and in vivo histology studies have demonstrated that the materials have good biocompatibility and good efficacy in bone regeneration. All these will further improve the workability of CSH in clinic applications. PMID:23827541

Chen, Zonggang; Liu, Huanye; Liu, Xi; Lian, Xiaojie; Guo, Zhongwu; Jiang, Hong-Jiang; Cui, Fu-Zhai

2013-04-01

285

Ultrasound-assisted fabrication of a biocompatible magnetic hydroxyapatite.  

PubMed

This work describes the fabrication and characterization of a biocompatible magnetic hydroxyapatite (HA) using an ultrasound-assisted co-precipitation method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) were used to characterize the structure and chemical composition of the produced samples. The M-H loops of synthesized materials were traced using a vibrating sample magnetometer (VSM) and the biocompatibility was evaluated by cell culture and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Furthermore, in vivo histopathological examinations were used to evaluate the potential toxicological effects of Fe?O?-HA composites on kidney of SD rats injected intraperitoneally with Fe?O?-HA particles. The results showed that magnetic iron oxide particles first replace OH ions of HA, which are parallel to the c axis, and then enter the HA crystal lattice which produces changes in the crystal surface of HA. Chemical bond interaction was observed between PO?³? groups of HA and iron ions of Fe?O?. The saturation magnetization (MS ) of Fe?O?-HA composites was 46.36 emu/g obtained from VSM data. Cell culture and MTT assays indicated that HA could affect the growth and proliferation of HEK-293 cells. This Fe?O?-HA composite produced no negative effects on cell morphology, viability, and proliferation and exhibited remarkable biocompatibility. Moreover, no inflammatory cell infiltration was observed in kidney histopathology slices. Therefore, this study succeeds to develop a Fe?O?-HA composite as a prospective biomagnetic material for future applications. PMID:24339231

Zhou, Gang; Song, Wei; Hou, Yongzhao; Li, Qing; Deng, Xuliang; Fan, Yubo

2014-10-01

286

Development, Characterizations and Biocompatibility Evaluations of Intravitreal Lipid Implants  

PubMed Central

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

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

2014-01-01

287

Biocompatibility and Surface Studies of Microwave CVD Diamond Films  

NASA Astrophysics Data System (ADS)

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.

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

2002-03-01

288

Green chemistry approach for the synthesis of biocompatible graphene  

PubMed Central

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

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

2013-01-01

289

Softec HD hydrophilic acrylic intraocular lens: biocompatibility and precision  

PubMed Central

Intraocular lens development is driven by higher patient expectations for ideal visual outcomes. The recently US Food and Drug Administration-approved Softec HD™ lens is an aspheric, hydrophilic acrylic intraocular lens (IOL). The hydrophilic design of the lens is optimized to address dysphotopsia while maintaining biocompatibility, optical clarity, resistance to damage, and resistance to biocontamination. Aspheric lenses decrease postoperative spherical aberration. The addition of the Softec lens provides clinicians with another option for IOL placement; however, randomized comparative studies of this lens to others already on the market remain to be completed. PMID:21311658

Espandar, Ladan; Sikder, Shameema; Moshirfar, Majid

2011-01-01

290

Softec HD hydrophilic acrylic intraocular lens: biocompatibility and precision.  

PubMed

Intraocular lens development is driven by higher patient expectations for ideal visual outcomes. The recently US Food and Drug Administration-approved Softec HD(™) lens is an aspheric, hydrophilic acrylic intraocular lens (IOL). The hydrophilic design of the lens is optimized to address dysphotopsia while maintaining biocompatibility, optical clarity, resistance to damage, and resistance to biocontamination. Aspheric lenses decrease postoperative spherical aberration. The addition of the Softec lens provides clinicians with another option for IOL placement; however, randomized comparative studies of this lens to others already on the market remain to be completed. PMID:21311658

Espandar, Ladan; Sikder, Shameema; Moshirfar, Majid

2011-01-01

291

Biodegradable Xylitol-Based Elastomers: In Vivo Behavior and Biocompatibility  

PubMed Central

Biodegradable elastomers based on polycondensation reactions of xylitol with sebacic acid, referred to as poly(xylitol sebacate) (PXS) elastomers have recently been developed. Herein, we describe the in vivo behavior of PXS elastomers. Four PXS elastomers were synthesized, characterized and compared to poly(L-lactic-co-glycolic acid) (PLGA). PXS elastomers displayed a high level of structural integrity and form stability during degradation. The in vivo half-life ranged from approximately 3 to 52 weeks. PXS elastomers exhibited increased biocompatibility compared to PLGA implants. PMID:20540093

Bruggeman, Joost P.; Bettinger, Christopher J.; Langer, Robert

2010-01-01

292

3D structuring of biocompatible and biodegradable polymers via stereolithography.  

PubMed

The production of user-defined 3D microstructures from biocompatible and biodegradable materials via free-form fabrication is an important step to create off-the-shelf technologies to be used as tissue engineering scaffolds. One method of achieving this is the microstereolithography of block copolymers, allowing high resolution microstructuring of materials with tuneable physical properties. A versatile protocol for the production and photofunctionalisation of pre-polymers for microstereolithography is presented along with a discussion of the possible microstereolithography set-ups and previous work in the field. PMID:21042980

Gill, Andrew A; Claeyssens, Frederik

2011-01-01

293

Cement-in-cement acetabular revision with a constrained tripolar component.  

PubMed

Dislocation of a total hip replacement (THR) is common following total hip arthroplasty (THA). When nonoperative management fails to maintain reduction, revision surgery is considered. The use of constrained acetabular liners has been extensively described. Complete removal of the old cement mantle during revision THA can be challenging and is associated with significant complications. Cement-in-cement revision is an established technique. However, the available clinical and experimental studies focus on femoral stem revision. The purpose of this study was to present a case of cement-in-cement acetabular revision with a constrained component for recurrent dislocations and to investigate the current best evidence for this technique. This article describes the case of a 74-year-old woman who underwent revision of a Charnley THR for recurrent low-energy dislocations. A tripolar constrained acetabular component was cemented over the primary cement mantle following removal of the original liner by reaming, roughening the surface, and thoroughly irrigating and drying the primary cement. Clinical and radiological results were good, with the Oxford Hip Score improving from 11 preoperatively to 24 at 6 months postoperatively. The good short-term results of this case and the current clinical and biomechanical data encourage the use of the cement-in-cement technique for acetabular revision. Careful irrigation, drying, and roughening of the primary surface are necessary. PMID:22310415

Leonidou, Andreas; Pagkalos, Joseph; Luscombe, Jonathan

2012-02-01

294

Assessment of Natural Radioactivity Levels of Cements and Cement Composites in the Slovak Republic  

PubMed Central

The radionuclide activities of 226Ra, 232Th and 40K and radiological parameters (radium equivalent activity, gamma and alpha indices, the absorbed gamma dose rate and external and internal hazard indices) of cements and cement composites commonly used in the Slovak Republic have been studied in this paper. The cement samples of 8 types of cements from Slovak cement plants and five types of composites made from cement type CEM I were analyzed in the experiment. The radionuclide activities in the cements ranged from 8.58–19.1 Bq·kg?1, 9.78–26.3 Bq·kg?1 and 156.5–489.4 Bq·kg?1 for 226Ra, 232Th and 40K, respectively. The radiological parameters in cement samples were calculated as follows: mean radium equivalent activity Raeq = 67.87 Bq·kg?1, gamma index I? = 0.256, alpha index I? = 0.067, the absorbed gamma dose rate D = 60.76 nGy·h?1, external hazard index Hex = 0.182 and internal hazard index Hin was 0.218. The radionuclide activity in composites ranged from 6.84–10.8 Bq·kg?1 for 226Ra, 13.1–20.5 Bq·kg?1 for 232Th and 250.4–494.4 Bq·kg?1 for 40K. The calculated radiological parameters of cements were lower than calculated radiological parameters of cement composites. PMID:24351739

Estokova, Adriana; Palascakova, Lenka

2013-01-01

295

In vitro cyclic testing of the Exeter stem after cement within cement revision.  

PubMed

Cement-within-cement (C-C) revision arthroplasty minimizes the complications associated with removal of secure polymethylmethacrylate. Failure at the interfacial region between new and old cement mantles remains a theoretical concern. This article assesses the cyclic fatigue properties of bilaminar cement mantles after C-C revision in vitro with the Exeter stem. Seven Exeter stems were cemented into Sawbone femurs and removed, and new undersized stems were cemented into the preserved mantle. The new constructs were loaded for 1,000,000 cycles at body temperature. Cement mantles were inspected postcycling. In no case was there delamination or failure of the cement mantle. The findings support the hypothesis that use of a thin revision cement mantle in conjunction with a polished double-tapered stem is not detrimental to the overall success of the implant. In the presence of a secure cement-bone interface in suitable patients, we recommend C-C revision techniques using double-tapered polished femoral stems. PMID:18534400

Wilson, Lance Jon; Bell, Cameron Gordon Roodveldt; Weinrauch, Patrick; Crawford, Ross

2009-08-01

296

Assessment of natural radioactivity levels of cements and cement composites in the Slovak Republic.  

PubMed

The radionuclide activities of 226Ra, 232Th and 40K and radiological parameters (radium equivalent activity, gamma and alpha indices, the absorbed gamma dose rate and external and internal hazard indices) of cements and cement composites commonly used in the Slovak Republic have been studied in this paper. The cement samples of 8 types of cements from Slovak cement plants and five types of composites made from cement type CEM I were analyzed in the experiment. The radionuclide activities in the cements ranged from 8.58-19.1 Bq·kg(-1), 9.78-26.3 Bq·kg(-1) and 156.5-489.4 Bq·kg(-1) for 226Ra, 232Th and 40K, respectively. The radiological parameters in cement samples were calculated as follows: mean radium equivalent activity Ra(eq) = 67.87 Bq·kg(-1), gamma index I? = 0.256, alpha index I? = 0.067, the absorbed gamma dose rate D = 60.76 nGy·h(-1), external hazard index H(ex) = 0.182 and internal hazard index H(in) was 0.218. The radionuclide activity in composites ranged from 6.84-10.8 Bq·kg(-1) for 226Ra, 13.1-20.5 Bq·kg(-1) for 232Th and 250.4-494.4 Bq·kg(-1) for 40K. The calculated radiological parameters of cements were lower than calculated radiological parameters of cement composites. PMID:24351739

Eštoková, Adriana; Palaš?áková, Lenka

2013-12-01

297

Computer simulation of the diffusivity of cement-based materials  

Microsoft Academic Search

A digital image-based model of the microstructure of cement paste, coupled with exact transport algorithms, is used to study the diffusivity of Portland cement paste. The principal variables considered are water:cement ratio, degree of cement hydration and capillary porosity. Computational methods are described and diffusivity results are presented, which are found to agree with the available experimental measurements within experimental

E. J. Garboczi; D. P. Bentz

1992-01-01

298

CONSTRUCTION-GRADE CEMENT PRODUCTION FROM CONTAMINATED SEDIMENTS USING  

E-print Network

1 CONSTRUCTION-GRADE CEMENT PRODUCTION FROM CONTAMINATED SEDIMENTS USING CEMENT-LOCKTM TECHNOLOGY A developed the Cement-LockTM Technology a versatile, cost-effective, and environmentally friendly manufacturing technology for producing construction-grade cements from a wide variety of contaminated waste

Brookhaven National Laboratory

299

Micromechanical Modeling of Filament Wound Cement-Based Composites  

E-print Network

Micromechanical Modeling of Filament Wound Cement-Based Composites B. Mobasher, M.ASCE1 Abstract. The micromechanical model simulates the mechanical response of a multilayer cement-based composite laminate under: Micromechanics; Cements; Composite materials. Introduction Response of cement-based composites to load

Mobasher, Barzin

300

The effect of foam polystyrene granules on cement composite properties  

Microsoft Academic Search

Crumbled recycled foam polystyrene waste as well as spherical large and fine blown polystyrene waste is used to produce the filler for a light thermo-insulating composite, the matrix of which is light foam cement. For better cohesion, fillers are hydrophilizated with foam cement surfactant solution.Polystyrene granules and foam cement concrete interaction schemes are discussed. The investigation of foam cement concrete

A. Laukaitis; R. Žurauskas

2005-01-01

301

Correlating cement characteristics with rheology of paste  

SciTech Connect

The influence of cement characteristics such as cement fineness and clinker composition on the 'flow resistance' measured as the area under the shear stress-shear rate flow curve has been investigated. Three different types of plasticizers namely naphthalene sulphonate-formaldehyde condensate, polyether grafted polyacrylate, and lignosulphonate have been tested in this context on 6 different cements. The flow resistance correlated well with the cement characteristic (Blaine.{l_brace}d.cC{sub 3}A + [1 - d].C{sub 3}S{r_brace}) where the factor d represents relative reactivity of cubic C{sub 3}A and C{sub 3}S while cC{sub 3}A and C{sub 3}S represent the content of these minerals. It was found to be either a linear or exponential function of the combined cement characteristic depending on plasticizer type and dosage. The correlation was valid for a mix of pure cement and cement with fly ash, limestone filler (4%), as well as pastes with constant silica fume dosage, when the mineral contents were determined by Rietveld analysis of X-ray diffractograms.

Vikan, H. [SINTEF Building and Infrastructure, Concrete, 7465 Trondheim (Norway)], E-mail: hedda.vikan@sintef.no; Justnes, H. [SINTEF Building and Infrastructure, Concrete, 7465 Trondheim (Norway); Winnefeld, F.; Figi, R. [EMPA Swiss Federal Laboratories of Materials Testing and Research, 8600 Duebendorf (Switzerland)

2007-11-15

302

Premixed calcium silicate cement for endodontic applications  

PubMed Central

Calcium silicate-based materials (also called MTA) are increasingly being used in endodontic applications. However, the handling properties of MTA are not optimal when it comes to injectability and cohesion. Premixing the cements using glycerol avoids these issues. However, there is a lack of data on the effect of common cement variables on important properties of premixed cements for endodontic applications. In this study, the effects of liquid-to-powder ratio, amount of radiopacifier and amount of calcium sulfate (added to control the setting time) were screened using a statistical model. In the second part of the study, the liquid-to-powder ratio was optimized for cements containing three different amounts of radiopacifier. Finally, the effect of using glycerol rather than water was evaluated in terms of radiopacity. The setting time was found to increase with the amount of radiopacifier when the liquid-to-powder ratio was fixed. This was likely due to the higher density of the radiopacifier in comparison to the calcium silicate, which gave a higher liquid-to-powder ratio in terms of volume. Using glycerol rather than water to mix the cements led to a decrease in radiopacity of the cement. In conclusion, we were able to produce premixed calcium silicate cements with acceptable properties for use in endodontic applications. PMID:23507729

Persson, Cecilia; Engqvist, Hakan

2011-01-01

303

[The coherence between 3 evaluation methods of biocompatibility].  

PubMed

Three successive series of tests (the primary including cytocompatibility tests and the secondary in vivo and usage tests) can be used to evaluate the biocompatibility of dental materials. The products are only submitted to secondary tests in case of satisfactory results obtained with primary tests. A coherence between the results of primary and secondary tests is necessary before performing in vivo tests. The aim of this paper is to study the coherence between two primary tests and a secondary test. The biocompatibility of Sealite and a pulp canal sealer was studied 4 and 12 weeks after mixing, according to two primary models (cell culture on agarose and a toxicity study of the extraction products) and a secondary model (intrabony implantation in the rabbit). The two primary tests gave different results for Sealite and the pulp canal sealer. Only the agarose cell culture and the intrabony implantation in the rabbit have given similar statistical results. The biological evaluation of biomaterials should begin with a study of the mechanism of action of the cytotoxic products using several in vitro tests. These latter are unable to predict the behaviour of a biomaterial in an in vivo test. PMID:1339089

Camps, J; Salomon, J P; Pertot, W J; Dejou, J

1992-12-01

304

Polymeric barrier membranes for device packaging, diffusive control and biocompatibility  

NASA Astrophysics Data System (ADS)

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.

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

2008-11-01

305

Biocompatible Coating of Encapsulated Cells Using Ionotropic Gelation  

PubMed Central

The technique of immunoisolated transplantation has seen in the last twenty years improvements in biocompatibility, long term stability and methods for avoidance of fibrosis in alginate capsules. However, two major problems are not yet solved: living cellular material that is not centered in the capsule is not properly protected from the hosts’ immune system and the total transplant volume needs to be reduced. To solve these problems, we present a method for applying fully biocompatible alginate multilayers to a barium-alginate core without the use of polycations. We report on the factors that influence layer formation and stability and can therefore provide data for full adjustability of the additional layer. Although known for yeast and plant cells, this technique has not previously been demonstrated with mammalian cells or ultra-high viscous alginates. Viability of murine insulinoma cells was investigated by live-dead staining and live cell imaging, for murine Langerhans’ islets viability and insulin secretion have been measured. No hampering effects of the second alginate layer were found. This multi-layer technique therefore has great potential for clinical and in vitro use and is likely to be central in alginate matrix based immunoisolated cell therapy. PMID:24039964

Ehrhart, Friederike; Mettler, Esther; Böse, Thomas; Weber, Matthias Max; Vásquez, Julio Alberto; Zimmermann, Heiko

2013-01-01

306

Biocompatibility of orthodontic adhesives in rat subcutaneous tissue  

PubMed Central

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

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

2010-01-01

307

A rheological and microscopical characterization of biocompatible ferrofluids  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

308

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

PubMed

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

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

2014-05-01

309

In vivo biocompatibility of radiation crosslinked acrylamide copolymers  

NASA Astrophysics Data System (ADS)

In vitro swelling and in vivo biocompatibility of radiation crosslinked acrylamide copolymers such as acrylamide/crotonic acid (AAm/CA) and acrylamide/itaconic acid (AAm/IA) were studied. The swelling kinetics of acrylamide copolymers were performed in distilled water, human serum and some simulated physiological fluids such as phosphate buffer, pH 7.4, glycine-HCl buffer, pH 1.1, physiological saline solution, and some swelling and diffusion parameters have been calculated. AAm/CA and AAm/IA hydrogels were subcutaneously implanted in rats for up to 10 weeks and the immediate short- and long-term tissue response to these implants were investigated. Histological analysis indicated that tissue reaction at the implant site progressed from an initial acute inflammatory response. No necrosis, tumorigenesis or infection was observed at the implant site up to 10 weeks. The radiation crosslinked AAm/CA and AAm/IA copolymers were found well tolerated, non-toxic and highly biocompatible. However, AAm/IA copolymer was not found to be compatible biomaterials, because one of the AAm/IA samples was disintegrated into small pieces in the rat.

Sarayd?n, Dursun; Ünver-Sarayd?n, Serpil; Karada?, Erdener; Koptagel, Emel; Güven, Olgun

2004-04-01

310

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

PubMed

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 (t1/2? ?=?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

Imran Ul-Haq, Muhammad; Lai, Benjamin F L; Kizhakkedathu, Jayachandran N

2014-10-01

311

BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES  

SciTech Connect

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.

farquar, G; Leif, R

2008-09-12

312

Coulomb frictional interfaces in modeling cemented total hip replacements: A more realistic model  

Microsoft Academic Search

Loosening of cemented femoral hip stems could be initiated by failure of the cement mantle due to high cement stresses. The goals of this study were to determine if realistic stem-cement interface characteristics could result in high cement stresses when compared to a bonded stem-cement interface and to determine if stem design parameters could be chosen to reduce peak cement

K. A. Mann; D. L. Bartel; T. M. Wright; A. H. Burstein

1995-01-01

313

Influence of cement layer thickness on the adhesive bond strength of polyalkenoate cements.  

PubMed

The fracture toughness and yield stress values of model zinc polycarboxylate and glass polyalkenoate cements have been used to calculate plastic zone sizes. The size of the plastic zone at the crack tip in these materials has been used to predict whether cement layer thickness is likely to influence the adhesive bond strength. In the model zinc polycarboxylate cement studied, the plastic zone size was comparable to the cement layer thickness and had a pronounced influence on the shear bond strengths obtained. In contrast, the plastic zone sizes obtained for the glass polyalkenoate cements were much smaller and the shear bond strengths were found to be much less dependent on cement layer thickness. PMID:1477262

Akinmade, A O; Hill, R G

1992-01-01

314

Phosphate-bonded calcium aluminate cements  

DOEpatents

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.

Sugama, T.

1993-09-21

315

Influence of Cement Particle-Size Distribution on Early Age Autogenous Strains and Stresses in Cement-Based Materials  

Microsoft Academic Search

The influence of cement particle-size distribution on autoge- nous strains and stresses in cement pastes of identical water- to-cement ratios is examined for cement powders of four different finenesses. Experimental measurements include chemical shrinkage, to quantify degree of hydration; internal relative humidity development; autogenous deformation; and eigenstress development, using a novel embedded spherical stress sensor. Because the latter three measurements

Dale P. Bentz; Ole Mejlhede Jensen; Kurt Kielsgaard Hansen; John F. Olesen; Henrik Stang; Claus-Jochen Haecker

2001-01-01

316

Effect of temperature on the hydration of the main clinker phases in portland cements: part ii, blended cements  

Microsoft Academic Search

The hydration of three blended cements, i.e., Portland cement blended with GGBFS, PFA, and volcanic ash, based on two neat cements investigated previously, has been followed at five temperatures ranging from 10°C to 60°C. The cements were cured under water and tested at various time intervals over a period of one year. The hydration products were characterised by means of

J. I. Escalante-Garc??a; J. H. Sharp

1998-01-01

317

Cement mantle defects in total hip arthroplasty: influence of stem size and cementing technique  

Microsoft Academic Search

The cause of isolated osteolysis in the femoral shaft around stem implants in patients with cemented THR has so far not been\\u000a established. A number of factors have been considered such as torsional stability of the femoral stem implant, the time of\\u000a reduction intraoperatively after cementing and iatrogenic and load-induced defects in the cement mantle. The aim of this in

A. Katzer; A. Ince; M. Hahn; M. M. Morlock; W. Steens

2007-01-01

318

Fabrication of biporous low-crystalline apatite based on mannitol dissolution from apatite cement.  

PubMed

Biporous (macro- and microporous) calcium phosphate gains much attention as a bone substitute material because of its large surface area and that it improves cell penetration. In the present study, we evaluated the feasibility of biporous, low-crystalline apatite based on dissolution of mannitol from self-setting apatite cement (Biopex). Mannitol--known as a biocompatible, easily dissolved monosaccharide alcohol--was recrystallized to obtain larger crystals. It was crushed with pestle and mortar, sieved to obtain crystals which passed through a 500-microm mesh but which remained against a 300-microm mesh, and then used as porogen. Although Biopex containing 60 wt% mannitol was not able to be taken out of the mold, addition of mannitol caused no initial setting inhibition to Biopex if the amount was 40 wt% or less. Similarly, transformation to apatitic product was confirmed when the apatite cement was immersed in 0.9% saline kept at 37 degrees C for seven days. The set mass became low-crystalline, biporous apatite with approximately 60% porosity. PMID:17076336

Tajima, Shinya; Kishi, Yuji; Oda, Makoto; Maruta, Michito; Matsuya, Shigeki; Ishikawa, Kunio

2006-09-01

319

Bioactive calcium sulfate/magnesium phosphate cement for bone substitute applications.  

PubMed

A novel calcium sulfate/magnesium phosphate cement (CSMPC) composite was prepared and studied in the present work. The physical properties including the phases, the microstructures, the setting properties and the compressive strengths of the CSMPCs were studied. The bio-performances of the CSMPCs were comprehensively evaluated using in vitro simulated body fluid (SBF) method and in vitro cell culture. The dependence of the physical and chemical properties of the CSMPC on its composition and microstructure was studied in detail. It is found that the CSMPC composites exhibited mediate setting times (6-12 min) compared to the calcium sulfate (CS) and the magnesium phosphate cement (MPC). They showed an encapsulation structure in which the unconverted hexagonal prism CSH particles were embedded in the xerogel-like MPC matrix. The phase compositions and the mechanical properties of the CSMPCs were closely related to the content of MPC and the hardening process. The CSMPCs exhibited excellent bioactivity and good biocompatibility to support the cells to attach and proliferate on the surface. The CSMPC composite has the potential to serve as bone grafts for the bone regeneration. PMID:24411353

Yang, Guangyong; Liu, Jianli; Li, Fan; Pan, Zongyou; Ni, Xiao; Shen, Yue; Xu, Huazi; Huang, Qing

2014-02-01

320

Microstructure, mechanical property, biodegradation behavior, and biocompatibility of biodegradable FeFe2O3 composites  

E-print Network

applications. On the other hand, from the mechanical point of view, the properties of 316L stainless steelMicrostructure, mechanical property, biodegradation behavior, and biocompatibility of biodegradable behaviors, and in vitro biocompatibility of Fe� Fe2O3 composites fabricated by spark plasma sintering were

Zheng, Yufeng

321

Quantitative Evaluation by Glucose Diffusion of Microleakage in Aged Calcium Silicate-Based Open-Sandwich Restorations  

PubMed Central

This study compared the in vitro marginal integrity of open-sandwich restorations based on aged calcium silicate cement versus resin-modified glass ionomer cement. Class II cavities were prepared on 30 extracted human third molars. These teeth were randomly assigned to two groups (n = 10) to compare a new hydraulic calcium silicate cement designed for restorative dentistry (Biodentine, Septodont, Saint Maur des Fossés, France) with a resin-modified glass ionomer cement (Ionolux, Voco, Cuxhaven, Germany) in open-sandwich restorations covered with a light-cured composite. Positive (n = 5) and negative (n = 5) controls were included. The teeth simultaneously underwent thermocycling and mechanocycling using a fatigue cycling machine (1,440 cycles, 5–55°C; 86,400 cycles, 50?N/cm2). The specimens were then stored in phosphate-buffered saline to simulate aging. After 1 year, the teeth were submitted to glucose diffusion, and the resulting data were analyzed with a nonparametric Mann-Whitney test. The Biodentine group and the Ionolux group presented glucose concentrations of 0.074 ± 0.035?g/L and 0.080 ± 0.032?g/L, respectively. No statistically significant differences were detected between the two groups. Therefore, the calcium silicate-based material performs as well as the resin-modified glass ionomer cement in open-sandwich restorations. PMID:22194747

Koubi, S.; Elmerini, H.; Koubi, G.; Tassery, H.; Camps, J.

2012-01-01

322

21 CFR 888.3790 - Wrist joint metal constrained cemented prosthesis.  

Code of Federal Regulations, 2010 CFR

...joint metal constrained cemented prosthesis. 888.3790 Section 888...joint metal constrained cemented prosthesis. (a) Identification. A wrist joint metal constrained cemented prosthesis is a device intended...

2010-04-01

323

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

PubMed Central

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

2014-01-01

324

Effects of pre-cooling and pre-heating procedures on cement polymerization and thermal osteonecrosis in cemented hip replacements  

Microsoft Academic Search

Numerical studies were performed to investigate bone cement polymerization, temperature history and thermal osteonecrosis in cemented hip replacements with finite element methods. In this paper, the effects of pre-cooling and pre-heating of the prosthesis and\\/or the cement prior to implantation were simulated. It was found that the cement polymerization initiated near the bone–cement interface and progressed toward the prosthesis when

Chaodi Li; Steven Schmid; James Mason

2003-01-01

325

Supply chain management in the cement industry  

E-print Network

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 ...

Agudelo, Isabel

2009-01-01

326

PCC (Portland Cement Concrete) Mix Design.  

National Technical Information Service (NTIS)

Properties of portland cement concrete (PCC) mixes, including workability, strength, durability, and abrasion resistance, are discussed along with the specific mix factors that affect each property. The mix design process is then discussed and the effect ...

D. Janssen

1989-01-01

327

Well cement fluid loss additive and method  

SciTech Connect

This patent describes a method of cementing a casing in a wellbore. It comprises pumping a cement slurry into the annulus between the casing and the wellbore, the cement slurry containing from 0.2 to 2.0 percent by weight, based on the weight of cement solids in the slurry, of an additive consisting essentially of from 30 to 80 percent by weight of partially hydrolyzed high molecular weight vinyl acetate polymer, calcium sulfate in an amount equivalent to from 10 to 60 percent by weight of calcium sulfate hemihydrate, up to 5 percent by weight of a cross-linking compound for the polyvinyl acetate, and from 0 to 5 percent by weight of defoamer.

Moran, L.K.; Murray, T.R.

1991-04-23

328

A nanochemomechanical investigation of carbonated cement paste  

E-print Network

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 ...

Vanzo, James (James F.)

2009-01-01

329

Simulation of silica fume blended cement hydration  

Microsoft Academic Search

A model is proposed in this paper to simulate silica fume (SF) blended cement hydration based on the kinetics, stoichiometry\\u000a and physical chemistry of cement hydration and pozzolanic reaction. The pozzolanic reaction degree, volume fraction of hydration\\u000a products, capillary porosity and gel porosity can be obtained from model simulation. By using proper amount of silica fume\\u000a replacement, the microstructure of

J. Yajun; J. H. Cahyadi

2004-01-01

330

Case Study of the California Cement Industry  

SciTech Connect

California is the largest cement producing state in theU.S., accounting for between 10 percent and 15 percent of U.S. cementproduction and cement industry employment. The cement industry inCalifornia consists of 31 sites that consume large amounts of energy,annually: 1,600 GWh of electricity, 22 million therms of natural gas, 2.3million tons of coal, 0.25 tons of coke, and smaller amounts of wastematerials, including tires. The case study summarized in this paperfocused on providing background information, an assessment ofenergy-efficiency opportunities and barriers, and program recommendationsthat can be used by program planners to better target products to thecement industry. The primary approach to this case study involvedwalk-through surveys of customer facilities and in depth interviews withcustomer decision makers and subsequent analysis of collected data. Inaddition, a basic review of the cement production process was developed,and summary cement industry energy and economic data were collected, andanalyzed. The analysis of secondary data provides background informationon the cement industry and identification of potential energy-efficiencyopportunities. The interviews provide some understanding of the customerperspective about implementation of energy-efficiencyprojects.

Coito, Fred; Powell, Frank; Worrell, Ernst; Price, Lynn; Friedmann, Rafael

2005-05-01

331

In vitro and in vivo evaluation of SU-8 biocompatibility  

PubMed Central

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

Nemani, Krishnamurthy V.; Moodie, Karen L.; Brennick, Jeoffry B.; Su, Alison; Gimi, Barjor

2013-01-01

332

Surface functionalized biocompatible magnetic nanospheres for cancer hyperthermia.  

SciTech Connect

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 with maleimide groups, and have saturation magnetization values of 25-40 emu/g. The efficiency of the heating induced by 400-kHz oscillating magnetic fields is compared for two samples with different magnetite loadings. Results show that these nanospheres have the potential to provide an efficient cancer-targeted hyperthermia.

Liu, X.; Novosad, V.; Rozhkova, E. A.; Chen, H.; Yefremenko, V.; Pearson, J.; Torno, M.; Bader, S. D.; Rosengart, A. J.; Univ. Chicago Pritzker School of Medicine

2007-06-01

333

Biocompatibility of defect-related luminescent nanostructured and microstructured hydroxyapatite.  

PubMed

Three defect-related luminescent hydroxyapatite (HAP) particles, S1, S2, and S3, with different morphologies (the samples S1 and S2 are nanorods with diameters of 25 nm and lengths of 30 and 100 nm, respectively; sample S3 is bur-like microspheres with diameters of 5-6 ?m) were synthesized, and their biocompatibility was investigated by MTT, reactive oxygen species (ROS), interleukin-6 (IL-6), comet, and hemolysis assays. The results indicated that all samples were stable in cell culture medium and did not induce the synthesis of proinflammatory cytokine IL-6 or result in hemolysis. It was found that samples S1 and S3 inhibited osteoblast (OB) viability at concentrations of 5, 10, 20, 40, and 80 ?g/mL for 24, 48, and 72 h. Sample S2 had no effect on the viability of OB at all tested concentrations for 24 and 48 h, but the viability of OB was increased at concentrations of 20, 40, and 80 ?g/mL for 72 h. Samples S1 and S3 could increase the level of cellular ROS; sample S2 had no effect on the level of cellular ROS at a concentration of 20 ?g/mL for 48 h. Although samples S1 and S3 induced significant DNA damage, sample S2 could not cause significant DNA damage at a concentration of 20 ?g/mL for 72 h. The results suggest that longer nanorod HAP can show excellent biocompatibility and therefore may find potential applications in biomedical fields. PMID:25312382

Dai, Chunyan; Duan, Jianlei; Zhang, Liang; Jia, Guang; Zhang, Cuimiao; Zhang, Jinchao

2014-12-01

334

Evaluation of the Biocompatibility of Silicone Gel Implants - Histomorphometric Study  

PubMed Central

CONFLICT OF INTEREST: NONE DECLARED Breast implants are medical devices that are used to augment breast size or to reconstruct the breast following mastectomy or to correct a congenital abnormality. Breast implants consist of a silicone outer shell and a filler (most commonly silicone gel or saline). Approximately 5 to 10 million women worldwide have breast implants. Histomorphometric study to evaluate the biological tissue compatibility of silicone implants suitable for plastic surgery and the adverse effects and risks of this material. Thirty Wistar white rats received subcutaneous implants and the revestiment of silicone gel Silimed ®®, and randomized into six groups of five animals each, according to the type of implanted material and the time of sacrifice. Eight areas of 60.11mm2 corresponding to the obtained surgical pieces were analyzed, counting mesenchymal cells, eosinophils, and foreign body giant cells, observing an acceptable biocompatibility in all implants, for subsequent statistical analysis by Tukey test. Silicone gel showed inflammation slightly greater than for other groups, with tissue reactions varying from light to moderate, whose result was the formation of a fibrous capsule around the material, recognized by the organism as a foreign body. Despite frequent local complications and adverse outcomes, this research showed that the silicone and top layer presented an acceptable chronic inflammatory reaction, which did not significantly differ from the control group. In general, it is possible to affirm that silicone gel had acceptable levels of biocompatibility, confirmed the rare presence of foreign body giant cells, and when of the rupture, formed a fibrous capsule around the material, separating the material of the organism. PMID:24039333

Franca, Diurianne Caroline Campos; de Castro, Alvimar Lima; Soubhia, Ana Maria Pires; de Aguiar, Sandra Maria Herondina Coelho Avila; Goiato, Marcelo Coelho

2013-01-01

335

An Octacalcium Phosphate Forming Cement  

PubMed Central

The osteoconductive and possibly osteoinductive characteristics of OCP increased the interest in preparation of bone graft materials that contain OCP in its composition. Calcium phosphate cements (CPCs) were prepared using a mixture of ?-tricalcium phosphate (?-TCP) and dicalcium phosphate anhydrous (DCPA), with ?-TCP / DCPA molar ratio of 1/1 and distilled water or 0.5 mol / L phosphate aqueous solution (pH = 6.1 ± 0.1) as the cement liquid. Hardening time was (30 ± 1) min for the CPC mixed with water and (5 ± 1) min for the CPC mixed with phosphate solution. Diametral tensile strength (DTS), porosity (P), and phase composition (powder x-ray diffraction) were determined after the hardened specimens had been immersed in a physiological-like solution (PLS) for 1 d, 3 d, and 7 d. In CPC specimens prepared with water, calcium hydroxyapatite (HA) was formed and DTS and P were (9.03 ± 0.48) MPa and (37.05 ± 0.20) vol % after 1 d, respectively, and (9.15 ± 0.45) MPa and (37.24 ± 0.63) vol % after 3 d, respectively. In CPC specimens prepared with phosphate solution OCP and HA were formed and DTS and P were (4.38 ± 0.49) MPa and (41.44 ± 1.25) vol % after 1 d, respectively,(4.38 ± 0.29) MPa and (42.52 ± 2.15) vol % after 3 d, respectively, and (4.30 ± 0.60) MPa and (41.38 ± 1.65) vol % after 7 d, respectively. For each group DTS and P did not change with PLS immersion time. DTS was significantly higher and P was significantly lower for CPCs prepared with water. HA formation slightly increased with immersion time from 40 mass % after 1 d to 50 mass % after 3 d in CPCs prepared with water. OCP + HA formation increased with immersion time from 30 mass % after 1 d to 35 mass % after 3 d and to 45 mass % after 7 d in CPCs prepared with 0.5 mol / L phosphate solution. PMID:20976025

Markovic, M.; Chow, L. C.

2010-01-01

336

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

Microsoft Academic Search

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

Maria S. Konsta-Gdoutos; Surendra P. Shah

2003-01-01

337

EVALUATION OF HAZARDOUS WASTE INCINERATION IN CEMENT KILNS AT SAN JUAN CEMENT COMPANY  

EPA Science Inventory

Cement kiln incineration of chlorinated liquid organic wastes was investigated in a 5-month demonstration program at San Juan Cement Company in Puerto Rico. Chlorinated monocarbon compounds (POHC's) were monitored in the waste and emissions, and the fate of added chlorine in ceme...

338

Alternative Fuel for Portland Cement Processing  

SciTech Connect

The production of cement involves a combination of numerous raw materials, strictly monitored system processes, and temperatures on the order of 1500 °C. Immense quantities of fuel are required for the production of cement. Traditionally, energy from fossil fuels was solely relied upon for the production of cement. The overarching project objective is to evaluate the use of alternative fuels to lessen the dependence on non-renewable resources to produce portland cement. The key objective of using alternative fuels is to continue to produce high-quality cement while decreasing the use of non-renewable fuels and minimizing the impact on the environment. Burn characteristics and thermodynamic parameters were evaluated with a laboratory burn simulator under conditions that mimic those in the preheater where the fuels are brought into a cement plant. A drop-tube furnace and visualization method were developed that show potential for evaluating time- and space-resolved temperature distributions for fuel solid particles and liquid droplets undergoing combustion in various combustion atmospheres. Downdraft gasification has been explored as a means to extract chemical energy from poultry litter while limiting the throughput of potentially deleterious components with regards to use in firing a cement kiln. Results have shown that the clinkering is temperature independent, at least within the controllable temperature range. Limestone also had only a slight effect on the fusion when used to coat the pellets. However, limestone addition did display some promise in regards to chlorine capture, as ash analyses showed chlorine concentrations of more than four times greater in the limestone infused ash as compared to raw poultry litter. A reliable and convenient sampling procedure was developed to estimate the combustion quality of broiler litter that is the best compromise between convenience and reliability by means of statistical analysis. Multi-day trial burns were conducted at a full-scale cement plant with alternative fuels to examine their compatibility with the cement production process. Construction and demolition waste, woodchips, and soybean seeds were used as alternative fuels at a full-scale cement production facility. These fuels were co-fired with coal and waste plastics. The alternative fuels used in this trial accounted for 5 to 16 % of the total energy consumed during these burns. The overall performance of the portland cement produced during the various trial burns performed for practical purposes very similar to the cement produced during the control burn. The cement plant was successful in implementing alternative fuels to produce a consistent, high-quality product that increased cement performance while reducing the environmental footprint of the plant. The utilization of construction and demolition waste, woodchips and soybean seeds proved to be viable replacements for traditional fuels. The future use of these fuels depends on local availability, associated costs, and compatibility with a facilityâ??s production process.

Anton K. Schindler; Steve R. Duke; Thomas E. Burch; Edward W. Davis; Ralph H. Zee; David I. Bransby; Carla Hopkins; Rutherford L. Thompson; Jingran Duan; Vignesh Venkatasubramanian; Stephen Giles.

2012-06-30

339

The biocompatibility evaluation of mPEG-PLGA-PLL copolymer and different LA/GA ratio effects for biocompatibility.  

PubMed

Biomaterial poly(lactic-co-glycolic acid) (PLGA), a FDA-approved material for clinical application, showed broad prospects in the past, but gradually can no longer meet present clinical developments and requirements, which we synthesized monomethoxy(polyethylene glycol)-poly(D,L-lactic-co-glycolic acid)-poly(L-lysine) (mPEG-PLGA-PLL) (PEAL) and have had some relevant reports. But studies on biocompatibility and the impacts of LA and GA ratio (LA/GA=60/40, 70/30, and 80/20) in main material have not yet been reported. Hemolysis experiment indicates that the hemolysis rate of PEAL extraction medium is less than 5%. Whole blood clotting time (CT), plasma recalcification time, activated partial thromboplastin time, prothrombin time evaluations, and dynamic CT assay show that the anticoagulant time of PEAL copolymer for blood is longer than that under negative and positive control. Protein adsorption assay indicates that PEAL films adsorb less protein than PLGA films (p<0.01); but comparing with expanded polytetrafluoroethylene, the aforementioned difference is not significant (p>0.05). Complement activation test shows that PEAL surface does not induce complement activation. CCK8 measurement shows that the relative growth rates of Huh7, L02, and L929 cells co-incubated with PEAL nanoparticles (NPs) are more than 90%. PEAL NPs co-incubated with 5% foetal bovine serum or 2% bovine serum albumin, through dynamic light scattering assay, remain stable. Different concentrations of PEAL NPs co-incubated with zebrafish embryos at 6-72?h post fertilization show that comparing with negative control, 10, 100, or 500??M of NPs for embryos development has no significant effects (p>0.05), only 1000 or 2000??M of NPs has some effects (p<0.05). It is concluded that the PEAL copolymer, with excellent biocompatibility, proves to be a high-safety dose as drug carrier and implant candidate in vivo. PMID:24811211

He, Zelai; Wang, Qi; Sun, Ying; Shen, Ming; Zhu, Mingjie; Gu, Malin; Wang, Yi; Duan, Yourong

2014-01-01

340

A New Biocompatible and Antibacterial Phosphate Free Glass-Ceramic for Medical Applications  

PubMed Central

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

Cabal, Belen; Alou, Luis; Cafini, Fabio; Couceiro, Ramiro; Sevillano, David; Esteban-Tejeda, Leticia; Guitian, Francisco; Torrecillas, Ramon; Moya, Jose S.

2014-01-01

341

A New Biocompatible and Antibacterial Phosphate Free Glass-Ceramic for Medical Applications  

NASA Astrophysics Data System (ADS)

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.

Cabal, Belén; Alou, Luís; Cafini, Fabio; Couceiro, Ramiro; Sevillano, David; Esteban-Tejeda, Leticia; Guitián, Francisco; Torrecillas, Ramón; Moya, José S.

2014-06-01

342

New technology improves cement-slurry design  

SciTech Connect

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.

NONE

1997-08-01

343

Reinforcing of Cement Composites by Estabragh Fibres  

NASA Astrophysics Data System (ADS)

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.

Merati, A. A.

2014-04-01

344

A fluoride release-adsorption-release system applied to fluoride-releasing restorative materials.  

PubMed

This investigation compared the initial fluoride release and release following refluoridation of three resin-modified glass-ionomer cements (Photac-Fil Applicap, Vitremer, and Fuji II LC) and a new polyacid-modified resin composite material (Dyract). After daily flouride release was measured for 8 days, specimens were refluoridated in 1,000-ppm solutions of fluoride ion for 10 minutes and fluoride release was measured for 5 days. Two further 5-day refluoridation-release periods were carried out. All materials released fluoride initially. Photac released the most; Dyract released the least. Initial release was greatest over the first few days. All materials released significantly more fluoride for 24 to 48 hours after refluoridation. Less fluoride was released with each successive refluoridation for the three glass-ionomer cements. The release from the Dyract compomer remained at a comparatively constant and significantly lower level following each refluoridation. PMID:9180421

Suljak, J P; Hatibovic-Kofman, S

1996-09-01

345

[Evaluation of cermet fillings in abutment teeth in removable partial prostheses].  

PubMed

The aim of the study was to describe the clinical process of setting the purpose filling on abutment teeth, after finishing the removable partial dentures. The aim was also to investigate the use of cermet glass-ionomer cement for the purpose filling in the abutment teeth for removable partial dentures, as well as to investigate the surface of the purpose filling. For the clinical evaluation of purpose filling slightly modified criteria according to Ryg's were used in 20 patients with different type of edentulousness. Changes occurring on the surface of purpose filling have been experimentally established by the method of scanning electron microscopy on the half-grown third molars in seven patients. It could be concluded that cement glass-ionomer was not the appropriate material for the purpose fillings in abutment teeth for removable partial dentures. PMID:11858021

Saulic, S; Tihacek-Sojic, Lj

2001-01-01

346

Management of mucosal fenestration with external root resorption by multidisciplinary approach.  

PubMed

Mucosal fenestration is a clinical condition in which the overlying gingiva is denuded and the root is exposed to the oral cavity. Invasive cervical resorption is an entirely uncommon entity and its aetiology is poorly understood. This case presents an invasive cervical resorption of maxillary right central incisor with fenestration at the cervical third of the tooth. The resorption area was chemomechanically debrided. It was then restored with Mineral Trioxide Aggregate over which pink glass ionomer cement (GC Fuji VII) was placed. Lateral pedicle flap was used to cover the fenestration. The resorptive defect was restored using tooth coloured restorative resin after removal of the pink glass ionomer cement. Orthodontic treatment was continued for correction of malocclusion. PMID:25301425

Bharti, Ramesh; Chandra, Anil; Tikku, Aseem Prakash; Prasad, Veerendra; Shakya, Vijay Kumar; Singhal, Rameshweri

2014-01-01

347

Corrosion of Aluminium in Composite Cements Anthony Setiadi* and Neil B. Milestone  

E-print Network

A composite cement is a hydraulic cement composed of Portland cement and one or more inorganic materials products have any effects on the cement durability and phases formed in cement. Current work has involvedCorrosion of Aluminium in Composite Cements Anthony Setiadi* and Neil B. Milestone Immobilisation

Sheffield, University of

348

Identification of Concrete Incompatibilities Using Cement Paste Rheology  

E-print Network

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...

Jang, Se Hoon

2010-07-14

349

Morphology of the osteonal cement line in human bone  

SciTech Connect

While current consensus suggests the absence of collagen in osteonal cement lines, the extent of cement line mineralization and the nature of the ground substance within the cement line are unclear. Samples of human radius were examined by using scanning electron microscopy, electron microprobe, and histochemical techniques. X-ray intensities were used to compare the amount of calcium, phosphorus, and sulfur in cement lines with amounts in surrounding lamellar bone. The results indicate that cement lines contain significantly less calcium and phosphorus, but significantly more sulfur, than surrounding bone matrix. The Ca/P ratio of cement lines was significantly greater than that of lamellar bone, suggesting that the mineral in cement lines may not be in the form of mature hydroxyapatite. No selective staining of the cement lines could be demonstrated by using periodic acid-Schiff, Sudan black B, or alcian blue critical electrolyte concentration techniques.

Schaffler, M.B.; Burr, D.B.; Frederickson, R.G.

1987-03-01

350

Cementation of Colloidal Particles on Electrodes in a Galvanic Microreactor  

E-print Network

processing, galvanic corrosion, cementation, reaction products INTRODUCTION Colloidal crystals have the galvanic corrosion of copper microelectrodes embedded in a gold substrate and immersed in an acidicCementation of Colloidal Particles on Electrodes in a Galvanic Microreactor Linda Jan, Christian

Aksay, Ilhan A.

351

Microemulsions for use as spaces in well cementation  

SciTech Connect

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.

Carriay, J.; De Lautrec, J.

1980-09-23

352

Cementation of intermediate gas sands in Central Luconia Province  

SciTech Connect

This paper is a 'case study' of the techniques developed by Sarawak Shell Berhad (SSB) to successfully overcome problems encountered in primary cementing of shallow gas bearing intervals. During a recent gas development project, successful isolation from surface of three separate intermediate gas sands above the main reservoir was achieved by improved cement displacement efficiency and by improved pressure control of the gas sands during cement gellation. This was possible by drilling a smaller hole, minimising hole washouts, using fast setting cement, displacing the cement as fast as possible, reducing the length of cement columns by use of dual stage equipment and by applying backpressure above the cement columns immediately after displacement. The approach used can in principle be applied for the design of any cementation. The specific techniques developed will be applied in future gas developments to be undertaken by SSB, and may find applications with other operators facing similar problems.

Ratcliffe, S.H.

1984-02-01

353

Effect of aluminium phosphate as admixture on oxychloride cement  

Microsoft Academic Search

The effect of admixing of aluminium phosphate on oxychloride cement in the matrix has been investigated. It is shown that\\u000a aluminium phosphate retards the setting process of the cement and improves water-tightness.

M. P. S. Chandrawat; R. N. Yadav

2000-01-01

354

Characterization, physicochemical properties and biocompatibility of La-incorporated apatites.  

PubMed

In this study, the physicochemical properties and biocompatibilities of La-containing apatites were intensively investigated together with their characterizations in terms of composition, structure, valent state and morphology using X-ray diffraction, Fourier-transform infrared spectra, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. The results indicate that the La(3+) ion can be incorporated into the crystal lattice of hydroxyapatite resulting in the production of La-incorporated apatites (La(x)Ca(10-x)(PO(4))(6)(OH)(2+x-2y)O(y square y-x) (x> or =0.5, y<1+x/2) or La(x)Ca(10-x)(PO(4))(6)O(y square y-x) (0.5biocompatibilities of the La-incorporated apatites. In contrast to La-free apatite, La-incorporated apatites possess a series of attractive properties, including higher thermal stability, higher flexural strength, lower dissolution rate, larger alkaline phosphatase activity, preferable osteoblast morphology and comparable cytotoxicity. In particular, the sintered La-incorporated apatite block achieves a maximal flexure strength of 66.69+/-0.98 MPa at 5% La content (confidence coefficient 0.95), increased 320% in comparison with the La-free apatite. The present study suggests that the La-incorporated apatite possesses application potential in developing a new type of bioactive coating material for metal implants and also as a promising La carrier for further exploring the beneficial functions of La in the human body. PMID:19477306

Guo, D G; Wang, A H; Han, Y; Xu, K W

2009-11-01

355

Influence of the activator in an acrylic bone cement on an array of cement properties.  

PubMed

In all but one of the acrylic bone cement brands used in cemented arthroplasties, N,N-dimethyl-4-toluidine (DMPT) serves as the activator of the polymerization reaction. However, many concerns have been raised about this activator, all related to its toxicity. Thus, various workers have assessed a number of alternative activators, with two examples being N,N-dimethylamino-4-benzyl laurate (DMAL) and N,N-dimethylamino-4-benzyl oleate (DMAO). The results of limited characterization of cements that contain DMAL or DMAO have been reported in the literature. The present work is a comprehensive comparison of cements that contain one of these three activators, in which the values of a large array of their properties were determined. These properties range from the setting time and maximum exotherm temperature of the curing cement to the variation of the loss elastic modulus of the cured cement with frequency of the applied indenting force in dynamic nanoindentation tests. The present results, taken in conjunction with those presented in previous reports by the present authors and co-workers on other properties of these cements, indicate that both DMAL and DMPT are suitable alternatives to DMPT. PMID:17133450

Lewis, Gladius; Xu, Jie; Deb, Sanjukta; Lasa, Blanca Vázquez; Román, Julio San

2007-06-01

356

The influence of ultrasound on removal of prefabricated metal post cemented with different resin cements  

PubMed Central

Background: Ultrasonic vibrations are used to remove a cemented post from a root canal requiring endodontic retreatment. Various results have been reported from the studies that evaluated the effect of ultrasonic instruments in removing the posts cemented with resin cements. The aim of this study was to evaluate the effect of ultrasonic energy on the retention of prefabricated metal post cemented with Panavia or Maxcem Elite cements. Materials and Methods: In this in vitro study, forty eight extracted single root premolars were decoronated with a diamond disc leaving a 13 mm long root and endodontically treated. The root canals were obturated by gutta-percha up to 5 mm with vertical condensation method and the 8 mm post-space was prepared to receive a no. 2 long Dentorama post. The roots were placed in an incubator for 48 h in 37°C and 100% humidity. After mounting the teeth in acrylic blocks, posts were cemented in the root canals using Panavia F2.0 in 24 specimens and Maxcem Elite in 24 others. For half of the specimens in each subgroup, an ultrasonic device was applied for 4 min. Universal testing machine was used to measure the force needed to remove the posts with a crosshead speed of 1 mm/min until the post came out of the canal. Kruskal-Wallis test was used for statistical analysis at 5% level of significance. Results: The removal force was not significantly different among the groups (P > 0.05). Conclusion: Ultrasonic energy did not decrease the retention of posts cemented with Panavia or Maxcem Elite cements. Furthermore, it seems that there is no significant difference between removal force of self-etch (Panavia) and the self-etch self-adhesive (Maxcem Elite) resin cements. PMID:24379864

Feiz, Atiyeh; Barekatain, Behnaz; Naseri, Roohollah; Zarezadeh, Hossein; Askari, Navid; Nasiri, Saman

2013-01-01

357

Extension and replacement of aspalt cement with sulphur  

E-print Network

2 Asphalt Cement Selection 3 Physical Properties of Asphalt Cements 4 Roughness (Surface Texture) of Aggregate . 5 Physical Properties of Aggregates 6 Selected Asphalt, Binder and Sulphur Contents for Screening Tests 7 Sulphur and Asphalt... 2 Asphalt Cement Selection 3 Physical Properties of Asphalt Cements 4 Roughness (Surface Texture) of Aggregate . 5 Physical Properties of Aggregates 6 Selected Asphalt, Binder and Sulphur Contents for Screening Tests 7 Sulphur and Asphalt...

Pickett, Daniel Ernest

2012-06-07

358

Compact biocompatible quantum dots via RAFT-mediated synthesis of imidazole-based random copolymer ligand  

E-print Network

We present a new class of polymeric ligands for quantum dot (QD) water solubilization to yield biocompatible and derivatizable QDs with compact size (10?12 nm diameter), high quantum yields (>50%), excellent stability ...

Liu, Wenhao

359

Laser-Deposited Biocompatible Films, and Methods and Apparatuses for Producing Same.  

National Technical Information Service (NTIS)

The present invention provides a method and an apparatus for laser depositing a thin film of biocompatible material of controlled chemical composition and crystalline structure onto a substrate to provide articles which may be used as medical or orthopedi...

C. M. Cotell, D. B. Chrisey, K. S. Grabowski, J. A. Sprague

1991-01-01

360

Mechanical Property and Biocompatibility of PLLA Coated DCPD Composite Scaffolds Nida Tanataweethum1  

E-print Network

of Engineering and Technology; 2 Department of Restorative Dentistry, Indiana University School of Dentistry degradation and excellent biocompatibility. Mentor: Tien-Min G. Chu, Department of Restorative Dentistry, Indiana University School of Dentistry, IUPUI #12;

Zhou, Yaoqi

361

In vitro swelling studies and preliminary biocompatibility evaluation of acrylamide-based hydrogels.  

PubMed

In this in vitro study, the biocompatibility of acrylamide-based hydrogels such as acrylamide/crotonic and acrylamide/itaconic acid, prepared by using gamma-rays, has been investigated against some biochemical parameters of human serum. The swelling kinetics of acrylamide/crotonic and acrylamide/itaconic acid hydrogels are investigated in distilled water and physiological saline solution and some swelling and diffusion parameters have been calculated. For the analysis of biocompatibility, acrylamide/crotonic and acrylamide/itaconic acid hydrogels are incubated in 10 different human sera for 24 h and their biocompatibilities with some biochemical parameters have been investigated. No significant difference in values before and after the test procedures have been found. It is therefore concluded that acrylamide/crotonic and acrylamide/itaconic acid hydrogels are biocompatible. PMID:8962950

Karada?, E; Saraydin, D; Cetinkaya, S; Güven, O

1996-01-01

362

Properties of composite specimens of old and new bone cement.  

PubMed

The most common cause of failure of a total hip replacement is aseptic loosening of an implant. In a number of cases, the cement-bone interface of at least one component is not compromised. In cases of aseptic cup loosening, removal of a well-fixed femoral stem may be undertaken to facilitate exposure of the acetabulum for cup revision, and the surgeon may choose to leave the functional cement-bone interfaces in the femur undisturbed. After cup revision, new cement is pressurized within the old cement mantle and a stem is cemented into this 'old-new cement' composite. Retaining the old cement mantle is an attractive option as it reduces the duration of surgery, minimizes bleeding, and preserves the bone stock. Excellent results have been shown with this technique of 'in-cement femoral revision' using a double-tapered polished stem. While considerable literature is available on the short- and long-term properties of PMMA bone cement, very little is known about the mechanical properties of old-new composite cement specimens where the old cement is more than a few days old. This paper tests the properties of such old-new composite specimens where the 'old' cement is aged between 3.3 and 17.7 years, better reflecting clinical situations. PMID:21381491

Acharya, A; Timperley, A J; Lee, A J C

2011-01-01

363

Baghouse dust used in clinkerization of portland cements  

Microsoft Academic Search

Many industrial materials considered essential for supporting a better quality of life consume large amounts of energy for their production. Ordinary portland cement (OPC) is used widely as a building material, and its manufacture consumes much energy. In India, the cost of energy accounts for >40% of the total cost of cement manufacture. The cost to manufacture cement is expected

N. B. Singh; K. N. Bhattacharjee; A. K. Shukla

1995-01-01

364

Modelling of carbonation of PC and blended cement concrete  

Microsoft Academic Search

Presented herein is a numerical model to predict the carbonation depth of Portland cement (PC) and blended cement concrete under a wide range of environmental conditions. The improved model for hydration of PC and activity of blended cement is proposed and used in this carbonation model. This carbonation model can be used for concrete made of silica fume, fly ash

Sabet Divsholi Bahador; Jong Herman Cahyadi

2009-01-01

365

Binding of chloride and alkalis in Portland cement systems  

Microsoft Academic Search

A thermodynamic model for describing the binding of chloride and alkalis in hydrated Portland cement pastes has been developed. The model is based on the phase rule, which for cement pastes in aggressive marine environment predicts multivariant conditions, even at constant temperature and pressure. The effect of the chloride and alkalis has been quantified by experiments on cement pastes prepared

Erik P. Nielsen; Duncan Herfort; Mette R. Geiker

2005-01-01

366

MODELLING OF Pb RELEASE DURING PORTLAND CEMENT ALTERATION Anne Bnarda  

E-print Network

1 MODELLING OF Pb RELEASE DURING PORTLAND CEMENT ALTERATION Anne Bénarda , Jérôme Roseb , Jean and models the molecular mechanisms of Pb release during Portland cement leaching. Since Pb release about Fe phases in cement, making the interpretation difficult. Can Fe-substituted hydrogranet (C3AH6

Boyer, Edmond

367

Influence of limestone on the hydration of Portland cements  

Microsoft Academic Search

The influence of the presence of limestone on the hydration of Portland cement was investigated. Blending of Portland cement with limestone was found to influence the hydrate assemblage of the hydrated cement. Thermodynamic calculations as well as experimental observations indicated that in the presence of limestone, monocarbonate instead of monosulfate was stable. Thermodynamic modelling showed that the stabilisation of monocarbonate

Barbara Lothenbach; Gwenn Le Saout; Emmanuel Gallucci; Karen Scrivener

2008-01-01

368

Guide to Cement-Based Integrated Pavement Solutions  

E-print Network

Guide to Cement-Based Integrated Pavement Solutions August 2011 #12;Cement-Based Integrated Pavement Solutions Heavy Industrial Airports Highways Country Roads Arterials Commercial Commercial Residential Recreation LAND USE CEMENT-BASED INTEGRATED PAVEMENT SOLUTIONS 1 2 3 4 5 6 7 8

369

Study of composite cement containing burned oil shale  

E-print Network

limestone Silica fume BOS Quarry Crushing Clinkering Cooling Grinding Transport SCMs Common cements BOS aims to characterize the effect of BOS in cement and concrete. To this end, 4 Holcim cements were species. Bound water, ettringite, partly C-S-H Portlandite Carbonated species Concrete samples were

Dalang, Robert C.

370

The cement mantle in the exeter impaction allografting technique  

Microsoft Academic Search

The postoperative radiographs of 35 patients who underwent impaction allografting of the proximal femur were reviewed. Of Gruen zones that could be clearly visualized, 39.9% contained areas where cement was absent. Even when an adequate mantle was present, cement voids were commonly seen. These cement mantle deficiencies were confirmed in a series of cadaveric impaction allografting procedures. They appear to

Eric L. Masterson; Bassam A. Masri; Clive P. Duncan

1997-01-01

371

Control of in vivo mineral bone cement degradation.  

PubMed

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

Kanter, Britta; Geffers, Martha; Ignatius, Anita; Gbureck, Uwe

2014-07-01

372

ELIMINATION OF WATER POLLUTION BY RECYCLING CEMENT PLANT KILN DUST  

EPA Science Inventory

Excessive amounts of alkalies can have deleterious effects upon the process of cement manufacture and the product. Normally much of the alkali present in cement raw materials is volatilized in the cement kiln and condenses on the particles of kiln dust which are carried out of th...

373

Model for the developing microstructure in Portland cement pastes  

Microsoft Academic Search

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

Hamlin M. Jennings; Paul D. Tennis

1994-01-01

374

Stabilization of residual soil with rice husk ash and cement  

Microsoft Academic Search

Stabilization of residual soils is studied by chemically using cement and rice husk ash. Investigation includes the evaluation of such properties of the soil as compaction, strength, and X-ray diffraction. Test results show that both cement and rice husk ash reduce the plasticity of soils. In term of compactability, addition of rice husk ash and cement decreases the maximum dry

E. A. Basha; R. Hashim; H. B. Mahmud; A. S. Muntohar

2005-01-01

375

Durability of pulp fiber-cement composites  

NASA Astrophysics Data System (ADS)

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.

Mohr, Benjamin J.

376

Chloride ingress in cement paste and mortar  

SciTech Connect

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.

Jensen, O.M.; Hansen, P.F.; Coats, A.M.; Glasser, F.P.

1999-09-01

377

Nd:YAG laser in endodontics: filling-material edge bordering on a root channel laser cavity  

NASA Astrophysics Data System (ADS)

For the very first time it is represented a study of filling material edge bordering upon root channel cavity modified with a laser. As a filling material it is used a glass ionomer cement. It is demonstrated that Nd:YAG laser radiation effects on increase of grade of edge bordering on the average of 20 - 30% at temperature rise of no more than 2 - 3 degrees in periodontium area in a period of operation.

Belikov, Andrei V.; Sinelnik, Yuri A.; Moroz, Boris T.; Pavlovskaya, Irina V.

1997-12-01

378

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

Microsoft Academic Search

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

Michel Goldberg

2008-01-01

379

In vitro Caries-inhibitory Properties of a Silver Cermet  

Microsoft Academic Search

Recurrent caries is one of the primary causes of failure of dental restorations. One method for reducing the frequency and severity of this problem is the use of fluoride-releasing restorative materials.The glass-ionomer cements are a type of fluoride-releasing material. They have been used extensively in recent years for a variety of clinical applications. However, in comparison with other restorative materials

E. J. Swift

1989-01-01

380

Piper betle-mediated green synthesis of biocompatible gold nanoparticles  

NASA Astrophysics Data System (ADS)

Here, we report the novel use of the ethonolic leaf extract of Piper betle for gold nanoparticle (AuNP) synthesis. The successful formation of AuNPs was confirmed by UV-visible spectroscopy, and different parameters such as leaf extract concentration (2%), gold salt concentration (0.5 mM), and time (18 s) were optimized. The synthesized AuNPs were characterized with different biophysical techniques such as transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). TEM experiments showed that nanoparticles were of various shapes and sizes ranging from 10 to 35 nm. FT-IR spectroscopy revealed that AuNPs were functionalized with biomolecules that have primary amine group -NH2, carbonyl group, -OH groups, and other stabilizing functional groups. EDX showed the presence of the elements on the surface of the AuNPs. FT-IR and EDX together confirmed the presence of biomolecules bounded on the AuNPs. Cytotoxicity of the AuNPs was tested on HeLa and MCF-7 cancer cell lines, and they were found to be nontoxic, indicating their biocompatibility. Thus, synthesized AuNPs have potential for use in various biomedical applications.

Punuri, Jayasekhar Babu; Sharma, Pragya; Sibyala, Saranya; Tamuli, Ranjan; Bora, Utpal

2012-08-01

381

Biocompatibility Evaluation of Nanosecond Laser Treated Titanium Surfaces  

NASA Astrophysics Data System (ADS)

We developed surface modification technologies for dental implants in this study. The study contributes to shortening the time required for adhesion between alveolar bone and fixtures which consist of dental implants. A Nd:YVO4 nanosecond laser was used to modify the surfaces of commercially pure titanium (CP Ti) disks, and their biocompatibility was evaluated cytocompatibility and bioactivity. First, rows of 200 µm spaced rectilinear laser treatments were performed on surfaces of CP Ti disks. Osteoblasts derived from rat mesenchymal stem cells were then cultured on the treated surfaces. Cytocompatibility on the laser treated area was evaluated by observing adhesion behavior of cells on these surfaces. The results indicated that the micro-order structure formed by the laser treatment promoted adhesion of osteoblasts and that traces of laser treatment without microstucture didn't affect the adhesion. Second, surfaces of CP Ti disks were completely covered by traces of laser treatment, which created complex microstructures of titania whose crystal structure is rutile and anatase. This phenomenon allowed the creation of hydroxyapatite on the surface of the disks in 1.5-times simulated body fluid (1.5SBF) while no hydroxyapatite was observed on conventional polished surfaces in the same conditions. This result indicates that bioactivity was enabled on CP Ti by the laser treatment. From these two results, laser treatment for CP Ti surfaces is an effective method for enhancing adhesion of osteoblasts and promoting bioactivity, which are highly appreciated properties for dental implants.

Honda, Ryo; Mizutani, Masayoshi; Ohmori, Hitoshi; Komotori, Jun

382

Affinity chromatography using biocompatible and reusable biotinylated membranes.  

PubMed

A novel, reusable biotinylated affinity chromatography strategy for the bio-specific binding of bioactive avidin tagged enzymes or polypeptides is reported. Using an avidin coupled peroxidase fusion protein as a test system; non-specific protein shielding and matrix regeneration were also shown. The amphiphilic surfactant Pluronic F108 was used as an affinity linker, by non-covalent binding to membrane chromatographic matrices while the terminal hydroxyl groups of Pluronic were covalently coupled to the biological ligand biotin. Planar nonporous membranes of varying surface chemistry were synthesised to test the matrix dependent affinity binding of biotinylated Pluronic and their respective ability to resist non-specific protein adsorption. Membrane regeneration using sodium dodecyl sulphate (SDS) was capable of displacing both adsorbed proteins and Pluronic. SDS micelles (34 mM) were effective in desorbing membrane bound protein while 5mM SDS removed up to 85% of the bound ligand after 20 h incubation at 20 degrees C. In this study, polyvinylidene membranes had the highest ligand binding capacity of 0.22 mg cm(-2) and specific, competitive affinity binding of avidin-peroxidase was shown in the presence of up to 0.2 mg ml(-1) 'contaminant' proteins. The resultant biocompatible affinity chromatographic system was regenerated and reused with no significant change in performance for up to five cycles. PMID:17875407

Govender, S; Jacobs, E P; Bredenkamp, M W; Swart, P

2007-11-01

383

In vivo biocompatibility of the PLGA microparticles in parotid gland  

PubMed Central

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

Cantin, Mario; Miranda, Patricio; Suazo Galdames, Ivan; Zavando, Daniela; Arenas, Patricia; Velasquez, Luis; Vilos, Cristian

2013-01-01

384

Reinforcement of bacterial cellulose aerogels with biocompatible polymers  

PubMed Central

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

Pircher, N.; Veigel, S.; Aigner, N.; Nedelec, J.M.; Rosenau, T.; Liebner, F.

2014-01-01

385

Biocompatibility of biodegradable semiconducting melanin films for nerve tissue engineering  

PubMed Central

The advancement of tissue engineering is contingent upon the development and implementation of advanced biomaterials. Conductive polymers have demonstrated potential for use as a medium for electrical stimulation, which has shown to be beneficial in many regenerative medicine strategies including neural and cardiac tissue engineering. Melanins are naturally occurring pigments that have previously been shown to exhibit unique electrical properties. This study evaluates the potential use of melanin films as a semiconducting material for tissue engineering applications. Melanin thin films were produced by solution processing and the physical properties were characterized. Films were molecularly smooth with a roughness (Rms) of 0.341 nm and a conductivity of 7.00 ± 1.10 × 10?5 S cm?1 in the hydrated state. In vitro biocompatibility was evaluated by Schwann cell attachment and growth as well as neurite extension in PC12 cells. In vivo histology was evaluated by examining the biomaterial–tissue response of melanin implants placed in close proximity to peripheral nerve tissue. Melanin thin films enhanced Schwann cell growth and neurite extension compared to collagen films in vitro. Melanin films induced an inflammation response that was comparable to silicone implants in vivo. Furthermore, melanin implants were significantly resorbed after 8 weeks. These results suggest that solution-processed melanin thin films have the potential for use as a biodegradable semiconducting biomaterial for use in tissue engineering applications. PMID:19286252

Bettinger, Christopher J.; Bruggeman, Joost P.; Misra, Asish; Borenstein, Jeffrey T.; Langer, Robert

2014-01-01

386

Neuronal cell biocompatibility and adhesion to modified CMOS electrodes.  

PubMed

The use of CMOS (Complementary Metal Oxide Semiconductor) integrated circuits to create electrodes for biosensors, implants and drug-discovery has several potential advantages over passive multi-electrode arrays (MEAs). However, unmodified aluminium CMOS electrodes may corrode in a physiological environment. We have investigated a low-cost electrode design based on the modification of CMOS metallisation to produce a nanoporous alumina electrode as an interface to mammalian neuronal cells and corrosion inhibitor. Using NG108-15 mouse neuroblastoma x rat glioma hybrid cells, results show that porous alumina is biocompatible and that the inter-pore distance (pore pitch) of the alumina has no effect on cell vitality. To establish whether porous alumina and a cell membrane can produce a tight junction required for good electrical coupling between electrode and cell, we devised a novel cell detachment centrifugation assay to assess the long-term adhesion of cells. Results show that porous alumina substrates produced with a large pore pitch of 206 nm present a significantly improved surface compared to the unmodified aluminium control and that small pore-pitches of 17 nm and 69 nm present a less favourable surface for cell adhesion. PMID:19459049

Graham, Anthony H D; Bowen, Chris R; Taylor, John; Robbins, Jon

2009-10-01

387

Green synthesis, characterization and evaluation of biocompatibility of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Although green synthesis of silver nanoparticles (Ag NPs) by various plants and microorganisms has been reported, the potential of plants as biological materials for the synthesis of nanoparticles and their compatibility to biological systems is yet to be fully explored. In this study, we report a simple green method for the synthesis of Ag NPs using garlic clove extract as a reducing and stabilizing agent. In addition to green synthesis, biological response of Ag NPs in human lung epithelial A549 cells was also assessed. Ag NPs were rapidly synthesized using garlic clove extract and the formation of nanoparticles was observed within 30 min. The green synthesized Ag NPs were characterized using UV-vis spectrum, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), X-ray energy-dispersive spectroscopy (EDX) and dynamic light scattering (DLS). Characterization data demonstrated that the particles were crystalline in nature and spherical shaped with an average diameter of 12 nm. Measurements of cell viability, cell membrane integrity and intracellular production of reactive oxygen species have shown that the green synthesized Ag NPs were nontoxic to human lung epithelial A549 cells. This study demonstrated a simple, cost-effective and environmentally benign synthesis of Ag NPs with excellent biocompatibility to human lung epithelial A549 cells. This preliminary in vitro investigation needs to be followed up by future studies with various biological systems.

Ahamed, Maqusood; Majeed Khan, M. A.; Siddiqui, M. K. J.; AlSalhi, Mohamad S.; Alrokayan, Salman A.

2011-04-01

388

Performance and Biocompatibility of Extremely Tough Alginate/Polyacrylamide Hydrogels  

PubMed Central

Although hydrogels now see widespread use in a host of applications, low fracture toughness and brittleness have limited their more broad use. As a recently described interpenetrating network (IPN) of alginate and polyacrylamide demonstrated a fracture toughness of ?9000 J/m2, we sought to explore the biocompatibility and maintenance of mechanical properties of these hydrogels in cell culture and in vivo conditions. These hydrogels can sustain a compressive strain of over 90% with minimal loss of Young's Modulus as well as minimal swelling for up to 50 days of soaking in culture conditions. Mouse mesenchymal stem cells exposed to the IPN gel-conditioned media maintain high viability, and although cells exposed to conditioned media demonstrate slight reductions in proliferation and metabolic activity (WST assay), these effects are abrogated in a dose-dependent manner. Implantation of these IPN hydrogels into subcutaneous tissue of rats for 8 weeks led to mild fibrotic encapsulation and minimal inflammatory response. These results suggest the further exploration of extremely tough alginate/PAAM IPN hydrogels as biomaterials. PMID:23896005

Darnell, Max; Sun, Jeong-Yun; Mehta, Manav; Johnson, Chris; Arany, Praveen; Suo, Zhigang

2013-01-01

389

Laser synthesis of aluminium nanoparticles in biocompatible polymer solutions  

NASA Astrophysics Data System (ADS)

Pulsed laser ablation of Aluminium (Al) in pure water rapidly forms a thin alumina (Al2O3) layer which drastically modifies surface plasmon resonance (SPR) absorption characteristics in deep-UV region. Initially, pure aluminium nanoparticles (NPs) are generated in water without any stabilizers or surfactants at low laser fluence which gradually transform to stable Al-Al2O3 core-shell nanostructure with increasing either residency time or fluence. The role of laser wavelength and fluence on the SPR properties and oxidation characteristics of Al NPs has been investigated in detail. We also present a one-step in situ synthesis of oxide-free stable Al NPs in biocompatible polymer solutions using laser ablation in liquid method. We have used nonionic polymers (PVP, PVA and PEG) and anionic surfactant (SDS) stabilizer to suppress the Al2O3 formation and studied the effect of polymer functional group, polymeric chain length, polymer concentration and anionic surfactant on the incipient embryonic aluminium particles and their sizes. The different functional groups of polymers resulted in different oxidation states of Al. PVP and PVA polymers resulted in pure Al NPs; however, PEG and SDS resulted in alumina-modified Al NPs. The Al nanoparticles capped with PVP, PVA, and PEG show a good correlation between nanoparticle stability and monomeric length of the polymer chain.

Singh, Rina; Soni, R. K.

2014-08-01

390

Towards a Biocompatible, Biodegradable Copolymer Incorporating Electroactive Oligothiophene Units  

PubMed Central

As part of an ongoing effort to develop biocompatible, biodegradable conducting polymers, we report here the synthesis and characterization of a novel copolymer, 5,5"'bishydroxymethyl-3,3"'-dimethyl-2,2':5',2":5",2"'-quaterthiophene-co-adipic acid polyester (QAPE). This system was designed so as to incorporate alternating electroactive quaterthiophene units and biodegradable ester units into one macromolecular framework, while allowing for facile preparation of the polymer via a polycondensation reaction. In agreement with the design expectations, the ester groups were found to be incorporated into the polymer between the quaterthiophene subunits, as inferred from standard chemical and spectroscopic analyses. QAPE exhibited redox activity as detected by cyclic voltammetry and a new red-shifted absorption peak upon doping, providing support for the notion that the quaterthiophene units maintain electroactivity after incorporation into the QAPE polymer framework. The degradation, likely through surface erosion, of this polymer in the presence of cholesterol esterase was confirmed by the detection of a fluorescence signal at wavelengths corresponding to the quaterthiophene subunit and comparisons to appropriate controls. In vitro cytocompatability studies, carried out over 48 h, indicate that the QAPE polymer is nontoxic to Schwann cells. PMID:20046223

Guimard, Nathalie K. E.; Sessler, Jonathan L.; Schmidt, Christine E.

2009-01-01

391

Investigating Cell Adhesion via Parallel Disk Rotational Flow: A Biocompatibility Study  

E-print Network

INVESTIGATING CELL ADHESION VIA PARALLEL DISK ROTATIONAL FLOW: A BIOCOMPATIBILITY STUDY A Thesis by ARACELY ROCHA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 2008 Major Subject: Mechanical Engineering INVESTIGATING CELL ADHESION VIA PARALLEL DISK ROTATIONAL FLOW: A BIOCOMPATIBILITY STUDY A Thesis by ARACELY ROCHA Submitted to the Office...

Rocha, Aracely

2011-08-08

392

A novel fabrication process for out-of-plane microneedle sheets of biocompatible polymer  

Microsoft Academic Search

This paper presents a novel process for fabricating out-of-plane microneedle sheets of biocompatible polymer using in-plane microneedles. This process comprises four steps: (1) fabrication of in-plane microneedles using inclined UV lithography and electroforming, (2) conversion of the in-plane microneedles to an out-of-plane microneedle array, (3) fabrication of a negative PDMS mold and (4) fabrication of out-of-plane microneedle sheets of biocompatible

Manhee Han; Dong-Hun Hyun; Hyoun-Hyang Park; Seung S. Lee; Chang-Hyeon Kim; Changgyou Kim

2007-01-01

393

Effect of CO2 pulsed laser irradiation on improving the biocompatibility of a polyethersulfone film  

NASA Astrophysics Data System (ADS)

In this paper a 200 ns pulsed TEA CO2 laser is used for treatment of polyethersulfone (PES) films surface. The laser induced structures and chemical compositions on the surface upon irradiation are studied. The hydrophilicity and biocompatibility of the irradiated surfaces are examined by contact angle and platelet adhesion measurements, respectively. The optimum number of pulses and fluence for improving the surface biocompatibility are found.

Jelvani, S.; Pazokian, H.; Moradi Farisar, S.

2013-02-01

394

Preparation of the acellular scaffold of the spinal cord and the study of biocompatibility  

Microsoft Academic Search

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

S-Z Guo; X-J Ren; B Wu; T Jiang

2010-01-01

395

Biocompatibility and tolerability of a purely bicarbonate-buffered peritoneal dialysis solution  

Microsoft Academic Search

BACKGROUND: Novel peritoneal dialysis solutions are characterized by a minimal content of glucose degradation products and a neutral pH. Many studies have shown the biocompatibility of neutral lactate-buffered solutions; however, until now, the effect of purely bicarbonate-buffered solutions has not been intensively studied in vivo. METHODS: This study was an open label, prospective, crossover multicenter trial to investigate the biocompatibility

L. Weiss; B. Stegmayr; G. Malmsten; M. Tejde; H. Hadimeri; C. E. Siegert; J. Ahlmen; R. Larsson; B. Ingman; O. Simonsen; H. W. van Hamersvelt; A. C. Johansson; B. Hylander; M. Mayr; P. H. Nilsson; P. O. Andersson; T. De Los Rios

2009-01-01

396

Effect of antibiotic loading on the shear strength at the stem–cement interface (Shear strength of antibiotic loaded cement)  

Microsoft Academic Search

The purpose of this study was to investigate the effects of addition of antibiotics into cement powder on the shear properties\\u000a of the cement–metal interface. The approach involved adding 800 mg of teicoplanin to 40 g bone cement powder in the t-800\\u000a group, 1,600 mg teicoplanin in the t-1,600 group, and no antibiotic in the control group. Industrially prepared bone cement\\u000a containing 500 mg

Onder Kilicoglu; L. Ozgur Koyuncu; V. Emre Ozden; Ergun Bozdag; Emin Sunbuloglu; Onder Yazicioglu

2008-01-01

397

In Vitro Models in Biocompatibility Assessment for Biomedical-Grade Chitosan Derivatives in Wound Management  

PubMed Central

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

Keong, Lim Chin; Halim, Ahmad Sukari

2009-01-01

398

Glass powder blended cement hydration modelling  

NASA Astrophysics Data System (ADS)

The use of waste materials in construction is among the most attractive options to consume these materials without affecting the environment. Glass is among these types of potential waste materials. In this research, waste glass in powder form, i.e. glass powder (GP) is examined for potential use in enhancing the characteristics of concrete on the basis that it is a pozzolanic material. The experimental and the theoretical components of the work are carried out primarily to prove that glass powder belongs to the "family" of the pozzolanic materials. The chemical and physical properties of the hydrated activated glass powder and the hydrated glass powder cement on the microstructure level have been studied experimentally and theoretically. The work presented in this thesis consists of two main phases. The first phase contains experimental investigations of the reaction of glass powder with calcium hydroxide (CH) and water. In addition, it includes experiments that are aimed at determining the consumption of water and CH with time. The reactivity, degree of hydration, and nature of the pore solution of the glass powder-blended cement pastes and the effect of adding different ratios of glass powder on cement hydration is also investigated. The experiments proved that glass powder has a pozzolanic effect on cement hydration; hence it enhances the chemical and physical properties of cement paste. Based on the experimental test results, it is recommended to use a glass powder-to-cement ratio (GP/C) of 10% as an optimum ratio to achieve the best hydration and best properties of the paste. Two different chemical formulas for the produced GP C-S-H gel due to the pure GP and GP-CH pozzolanic reaction hydration are proposed. For the pure GP hydration, the produced GP C-S-H gel has a calcium-to-silica ratio (C/S) of 0.164, water-to-silica ratio (H/S) of 1.3 and sodium/silica ratio (N/S) of 0.18. However, for the GP-CH hydration, the produced GP C-S-H gel has a C/S ratio of 1.17, H/S ratio of 2.5 and N/S ratio of 0.18. In the second phase of this research, theoretical models are built using a modified version of an existing cement hydration modelling code, "CEMHYD3D", to simulate the chemical reaction of the activated glass powder hydration and glass powder in cement. The modified model, which is referred to as the "MOD-model" is further used to predict the types, compositions and quantities of reaction products. Furthermore, the glass powder hydration data, which is obtained experimentally, is incorporated into the MOD-model to determine the effect of adding glass powder to the paste on the process of cement hydration and resulting paste properties. Comparisons between theoretical and experimental results are made to evaluate the developed models. The MOD-model predictions have been validated using the experimental results, and were further used to investigate various properties of the hydrated glass powder cement paste. These properties include, for example, CH content of the paste, porosity, hydration degree of the glass powder and conventional C-S-H and GP CS-H contents. The results show that the MOD-model is capable of accurately simulating the hydration process of glass powder-blended cement paste and can be used to predict various properties of the hydrating paste.

Saeed, Huda

399

Investigation into the stabilization\\/solidification performance of Portland cement through cement clinker phases  

Microsoft Academic Search

This research studied the influence of individual heavy metal on the hydration reactions of major cement clinker phases in order to investigate the performance of cement based stabilization\\/solidification (S\\/S) system. Tricalcium silicate (C3S) and tricalcium aluminate (C3A) had been mixed with individual heavy metal hydroxide including Zn(OH)2, Pb(OH)2 and Cu(OH)2, respectively. The influences of these heavy metal hydroxides on the

X. C. Qiao; C. S. Poon; C. R. Cheeseman

2007-01-01

400

Micro-thermal stress analysis of cement based pavement composite  

SciTech Connect

A four-layer sphere model for microscopic thermal analysis was proposed based upon the structural form of cement based pavement composites. Using temperature induced stresses of pavement structure as the external field, the micro-thermal stresses of two types of cement based pavement composite were calculated. The results showed that, by introducing the low stiffness rubberized asphalt in the interphase of coarse aggregate phase and cement mortar phase of Portland cement concrete, the interfacial thermal stresses could be reduced significantly, thus improving crack resistance of the pavement material under low temperature environment. Factors affecting micro-thermal stress of cement based pavement composite were discussed.

Li, G.; Zhao, Y.; Pang, S.S. [Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Mechanical Engineering; Huang, W. [Southeast Univ., Nanjing (China). Coll. of Transportation

1998-12-31

401

A unique experience with foamed cement  

SciTech Connect

An extensive laboratory program showed that foamed cement was the only technically feasible solution to prepare a floating cement plug for solving severe lost circulation problems in big caverns. The technique had, however, to be adapted to fit well conditions that are relatively unusual in the oil field: the cement slurry should not become diluted and destabilized upon exiting the drill pipe and entering the 60-plus inches wellbore and the huge caves, several feet in radius, both filled with sea water. Moreover, the foam had to remain stable, even when surrounded by large volume of water, until cement setting. Therefore a technique of using protective fluids was devised. In addition, logistics dictated the use of compressed air rather than nitrogen to prepare the foamed slurry. Therefore special gas metering and regulation devices were used for the first time in the oil field in order to automate the process and get a perfect control of the slurry density whatever the slurry mixing and pumping rates. Before field implementation, the metering and regulation device was successfully yard tested, the gas phase being supplied by nitrogen bottles. The successful field implementation with air compressors, together with the protective fluid technique to combat lost circulation in loose coral reef and in highly fractured dolomitic formation, is described.

Piot, B.; Ferriere, R.; Fraboulet, B.

1994-12-31

402

Neutron scattering studies of hydrating cement pastes  

NASA Astrophysics Data System (ADS)

The progress of the hydration reactions of tricalcium silicate (C3S) has been followed using quasielastic neutron scattering (QNS) at an energy resolution of 60 ?eV and a momentum transfer of q=1 Å-1. The degree of reaction in the hydrating cement paste is inferred from the fraction of water that is chemically bound to the cement reaction products and the known stoichiometry of C3S hydration. Three different water-to-cement ratios were studied in this experiment: W/C=0.7, 0.5 and 0.3. The results of an Avrami-model analysis of the first 15 h of the reaction are consistent with three types of C3S-H2O reaction product morphology and growth mechanisms: (i) a plate-type product phase from either phase boundary growth with no nucleation; (ii) diffusion-limited growth with constant nucleation; or (iii) a needle-type product phase with phase boundary growth and constant nucleation. Analysis of the later-time diffusion-limited portion of the reaction provides apparent diffusion constants for the migration of water through the C3S hydration products. These data indicate that the diffusion constants vary approximately exponentially over the range of water-to-cement values studied.

Berliner, R.; Popovici, M.; Herwig, K.; Jennings, H. M.; Thomas, J.

1998-04-01

403

Economic analysis of the European cement industry  

E-print Network

for the scenarios 41 3.4 Additional assumptions for the sensitivity analysis 42 4. The profitability Economic analysis of the European cement industry Marcel Boyer1 and JeanPierre Ponssard2 December 2013 Abstract We present a methodology to assess the profitability of a capital intensive industry

Paris-Sud XI, Université de

404

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 ...

405

Properties of ceramic fiber reinforced cement composites  

Microsoft Academic Search

Mechanical properties and preliminary durability of ceramic fiber reinforced Portland cement composites tested with wet-hot accelerating method were investigated. The results showed that the flexural strength of mortar could be increased obviously by adding ceramic fiber into it, but the effect of the flexural reinforcement was influenced by various factors, including fiber length, fiber content and kinds of matrices; the

Yiping Ma; Beirong Zhu; Muhua Tan

2005-01-01

406

21 CFR 872.3275 - Dental cement.  

Code of Federal Regulations, 2010 CFR

...tooth filling, to affix dental devices such as crowns...tooth to protect the tooth pulp. (2) Classification...to § 872.9. (b) Dental cement other than zinc...tooth filling, to affix dental devices such as crowns...tooth to protect the tooth pulp. (2)...

2010-04-01

407

The Kosmosdale expansion project [cement plant upgrade  

Microsoft Academic Search

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

A. Rowley; D. Babel

2002-01-01

408

Nondestructive evaluation of bone cement and bone cement/metal interface failure.  

PubMed

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

Browne, M; Jeffers, J R T; Saffari, N

2010-02-01

409

Mechanical properties of a cemented porous implant interface  

PubMed Central

Background Revision arthroplasty often requires anchoring of prostheses to poor-quality or deficient bone stock. Recently, newer porous materials have been introduced onto the market as additional, and perhaps better, treatment options for revision arthroplasty. To date, there is no information on how these porous metals interface with bone cement. This is of clinical importance, since these components may require cementing to other prosthesis components and occasionally to bone. Methods We created porous metal and bone cylinders of the same size and geometry and cemented them in a well-established standardized setting. These were then placed under tensile loading and torsional loading until failure was achieved. This permitted comparison of the porous metal/cement interface (group A) with the well-studied bone/cement interface (group B). Results The group A interface was statistically significantly stronger than the group B interface, despite having significantly reduced depth of cement penetration: it showed a larger maximum tensile force (effect size 2.7), superior maximum tensile strength (effect size 2.6), greater maximum torsional force (effect size 2.2), and higher rotational stiffness (effect size 1.5). Interpretation The newer porous implants showed good interface properties when cemented using medium-viscosity bone cement. The axial and rotational mechanical strength of a porous metal/cement interface appeared to be greater than the strength of the standard bone/cement interface. These results indicate that cementing of porous implants can provide great stability in situations where it is needed. PMID:24798109

Beckmann, Nicholas A; Bitsch, Rudi G; Seeger, Joern B; Klotz, Matthias CM; Kretzer, Jan Philippe; Jaeger, Sebastian

2014-01-01

410

Immobilization of radioactive waste by cementation with purified kaolin clay.  

PubMed

A study is undertaken to determine the waste immobilization performance of low-level wastes in cement-clay mixtures. Liquid low-level wastes are precipitated using chemical methods, followed by solidification in drums. Solidification is done using cementation processes. Long-term leaching rates of the radionuclides are used as indicators of immobilization performance of solidified waste forms. In addition to evaluating the effects of kaolin clay on the leaching properties of the cemented waste forms, the effect of addition of kaolin on the strength of the cemented waste form is also investigated. The long term leaching tests show that inclusion of kaolin in cement reduces the leaching rates of the radionuclides significantly. However, clay additions in excess of 15 wt.% causes a significant decrease in the hydrolytic stability of cemented waste form. It is found that the best waste isolation, without causing a loss in the mechanical strength, is obtained when the kaolin content in cement is 5%. PMID:12092756

Osmanlioglu, A Erdal

2002-01-01

411

Biocompatibility evaluation of porous ceria foams for orthopedic tissue engineering.  

PubMed

Ceria ceramics have the unique ability to protect cells from free radical-induced damage, making them materials of interest for biomedical applications. To expand upon the understanding of the potential of ceria as a biomaterial, porous ceria, fabricated via direct foaming, was investigated to assess its biocompatibility and its ability to scavenge free radicals. A mouse osteoblast (7F2) cell line was cultured with the ceria foams to determine the extent of the foams' toxicity. Toxicity assessments indicate that mouse osteoblasts cultured directly on the ceria scaffold for 72 h did not show a significant (p?>?0.05) increase in toxicity, but rather show comparable toxicity to cells cultured on porous 45S5 Bioglass®. The in vitro inflammatory response elicited from porous ceria foams was measured as a function of tumor necrosis factor alpha (TNF-?) secreted from a human monocytic leukemia cell line. Results indicate that the ceria foams do not cause a significant inflammatory response, eliciting a response of 27.1?±?7.1 pg mL(-1) of TNF-? compared to 36.3?±?5.8 pg mL(-1) from cells on Bioglass, and 20.1?±?2.9 pg mL(-1) from untreated cells. Finally, we report cellular toxicity in response to free radicals from tert-butyl hydroperoxide with and without foamed ceria. Our preliminary results show that the foamed ceria is able to decrease the toxic effect of induced oxidative stress. Collectively, this study demonstrates that foamed ceria scaffolds do not activate an inflammatory response, and show potential free radical scavenging ability, thus they have promise as an orthopedic biomaterial. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 8-15, 2015. PMID:24677427

Ball, Jordan P; Mound, Brittnee A; Monsalve, Adam G; Nino, Juan C; Allen, Josephine B

2015-01-01

412

HEMOCOMPATIBILITY AND BIOCOMPATIBILITY OF ANTIBACTERIAL BIOMIMETIC HYBRID FILMS  

PubMed Central

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

Ferrer, M. Carme Coll; Eckmann, Uriel N.; Composto, Russell J.; Eckmann, David M.

2013-01-01

413

Cement augmentation of hip implants in osteoporotic bone: how much cement is needed and where should it go?  

PubMed

Several studies proved the beneficial effect of cement augmentation of proximal femoral nail antirotation (PFNA) blades on implant purchase in osteoporotic bone. We investigated the effect of different localizations and amounts of bone cement. Polyurethane foam specimens were instrumented with a PFNA blade and subsequently augmented with PMMA bone cement. Eight study groups were formed based on localization and amount of cement volume related to the blade. All specimens underwent cyclic loading with physiological orientation of the force vector until construct failure. Foam groups were compared between each other and to a cadaveric control group. The experiments revealed a significant dependency of implant purchase on localization and amount of cement. Biomechanically favorable cement positions were found at the implant tip and at the cranial side. However, none of the tested augmentation patterns performed significantly inferior to the cadaveric benchmark. These findings will allow surgeons to further reduce the amount of injected PMMA, decreasing the risk of cement leakage or cartilage damage. PMID:24259367

Sermon, A; Hofmann-Fliri, L; Richards, R G; Flamaing, J; Windolf, M

2014-03-01

414

Fabrication of porous scaffolds by three-dimensional plotting of a pasty calcium phosphate bone cement under mild conditions.  

PubMed

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

Lode, Anja; Meissner, Katrin; Luo, Yongxiang; Sonntag, Frank; Glorius, Stefan; Nies, Berthold; Vater, Corina; Despang, Florian; Hanke, Thomas; Gelinsky, Michael

2014-09-01

415

Synthesis and characterization of thermoresponsive and biocompatible core–shell microgels based on N-isopropylacrylamide and carboxymethyl chitosan  

Microsoft Academic Search

The objective of the study is to report thermally sensitive and biocompatible capability core–shell microgels. These core–shell microgels composed of a chemically crosslinked poly(N-isopropylmethacrylamide) (PNIPAM) core and a carboxymethyl chitosan (CMCS) shell were designed and synthesized by seed emulsion polymerization in this work. Due to the excellent biocompatible nature of CMCS, these PNIPAM\\/CMCS hybrid microgels have good biocompatibility. The chemical

Sai-bo Chen; Hui Zhong; Li-li Zhang; Yu-feng Wang; Zhi-peng Cheng; Yu-lan Zhu; Cheng Yao

2010-01-01

416

Influence of different transitional restorations on the fracture resistance of premolar teeth.  

PubMed

Controversy exists over the most favorable material and type of restoration to be used to transitionally restore teeth destined to be crowned. This in vitro study uses fracture resistance testing to compare eight different transitional resto