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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.

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

2013-01-01

2

Antibacterial activity of selected glass ionomer cements.  

PubMed

Introduction: The aim of the paper was to determine the antibacterial activity of four glass ionomer cements against bacteria of the genera Streptococcus and Lactobacillus. Material and methods: Four capsulated glass ionomer cements were applied in the study: Fuji Triage (GC), Fuji IX (GC), Ketac Molar (3M Espe) and Ketac Silver (3M Espe). Four standard bacterial strains were used to assess the antibacterial activity of the studied cements: Streptococcus mutans, S. sanguis, S. salivarius and Lactobacillus casei. The antibacterial activity was determined by the agar diffusion method. The bacterial suspension was spread with a cotton swab on TSA plates. For each material six wells (7 mm diameter, 5 mm deep) were made with a cork borer. Each well was then filled with freshly prepared cements. The results were obtained by measuring the bacterial growth inhibition zone after 1, 2, 3 and 7 days. Results: Fuji Triage cement inhibited the growth of all bacterial strains. Fuji IX cement demonstrated the most potent antibacterial activity against S. sanguis. Ketac Molar showed antibacterial activity against S. sanguis and S. salivarius, whereas Ketac Silver was efficient against S. mutans as well. Neither of the Ketac cements inhibited growth of the standard L. casei strain. Discussion: Antibacterial activity of glass ionomer cements has attracted the interest of scientists in recent years. Most authors, including us, carried out experiments using the agar diffusion method and demonstrated antibacterial activity of glass ionomer cements. Different antibacterial activity of glass ionomer cements, observed in our study and studies of other authors, depended on the evaluated cement, bacterial strain and period of evaluation. PMID:24491892

Luczaj-Cepowicz, El?bieta; Marczuk-Kolada, Gra?yna; Zalewska, Anna; Pawi?ska, Ma?gorzata; Leszczy?ska, Katarzyna

2014-01-01

3

Evaluation of Adhesive and Compressive Strength of Glass Ionomer Cements  

Microsoft Academic Search

The aim of the study was to assess, compare and evaluate the adhesive strength and compressive strength of different brands\\u000a of glass ionomer cements to a ceramometal alloy. (A) Glass ionomer cements: GC Fuji II (GC Corporation, Tokyo), Chem Flex\\u000a (Dentsply DeTrey, Germany), Glass ionomer FX (Shofu-11, Japan), MR dental (MR dental suppliers Pvt Ltd, England). (B) Ceramometal\\u000a alloy (Ni–Cr:

Ramashanker; Raghuwar D. Singh; Pooran Chand; Sunit Km. Jurel; Shuchi Tripathi

4

Evaluation of adhesive and compressive strength of glass ionomer cements.  

PubMed

The aim of the study was to assess, compare and evaluate the adhesive strength and compressive strength of different brands of glass ionomer cements to a ceramometal alloy. (A) Glass ionomer cements: GC Fuji II (GC Corporation, Tokyo), Chem Flex (Dentsply DeTrey, Germany), Glass ionomer FX (Shofu-11, Japan), MR dental (MR dental suppliers Pvt Ltd, England). (B) Ceramometal alloy (Ni-Cr: Wiron 99; Bego, Bremen, Germany). (C) Cold cure acrylic resin. (E) Temperature cum humidity control chamber. (F) Instron Universal Testing Machine. Four different types of Glass ionomer cements were used in the study. From each type of the Glass ionomer cements, 15 specimens for each were made to evaluate the compressive strength and adhesive strength, respectively. The 15 specimens were further divided into three subgroups of five specimens. For compressive strength, specimens were tested at 2, 4 and 12 h by using Instron Universal Testing Machine. To evaluate the adhesive strength, specimens were surface treated with diamond bur, silicone carbide bur and sandblasting and tested under Instron Universal Testing Machine. It was concluded from the study that the compressive strength as well as the adhesive bond strength of MR dental glass ionomer cement with a ceramometal alloy was found to be maximum compare to other glass ionomer cements. Sandblasting surface treatment of ceramometal alloy was found to be comparatively more effective for adhesive bond strength between alloy and glass ionomer cement. PMID:23204729

Ramashanker; Singh, Raghuwar D; Chand, Pooran; Jurel, Sunit Km; Tripathi, Shuchi

2011-12-01

5

Amino acid containing glass-ionomer cement for orthopedic applications  

NASA Astrophysics Data System (ADS)

Amino acid containing glass-ionomer cements were synthesized, formulated, and evaluated for orthopedic application. The formulation of different amino acid containing glass-ionomer bone cements was optimized, and conventional and resin-modified glass-ionomer bone cements were compared. Properties of interest included handling characteristics, physical and chemical properties, and mechanical strength of the bone cement. The study was based on the synthesis of different vinyl containing amino acids, different polyelectrolytes containing these amino acid residues, and different resin-modified polyelectrolytes, as well as formulation and evaluation of conventional and resin-modified glass-ionomer bone cements using these polyelectrolytes. Systematic preparation of polyelectrolytes and formulation of glass-ionomer bone cements were essential features of this work, since we anticipated that the mechanical properties of the glass-ionomer bone cements could be strongly affected by the nature of the polyelectrolytes and formulation. Mechanical properties were evaluated in a screw driven mechanical testing machine, and structure-property relationships were determined by scanning electron microscopic (SEM) observation of the fracture surface of the specimens. How the structure of polyelectrolytes, such as different amino acid residues, molecular weight, different modifying resin, and formulation of glass-ionomer bone cement, affected the mechanical properties was also studied.

Wu, Wei

6

The effect of strontium oxide in glass–ionomer cements  

Microsoft Academic Search

The reaction of strontium oxide powder with poly(acrylic acid) has been studied both alone and within glass–ionomer cements. Reaction was found to be slow and the strontium-carboxylate structure was found to be partially covalent in character, as determined by Fourier transform infrared spectroscopy (FTIR). These are similar to the structures formed by calcium in glass–ionomer cements, but are different from

S. Deb; J. W. Nicholson

1999-01-01

7

In vitro enamel remineralization at orthodontic band margins cemented with glass ionomer cement  

Microsoft Academic Search

Demineralization adjacent to orthodontic bands remains a clinical concern. The release of fluoride from glass ionomer cement has been shown to inhibit demineralization. The purpose of this study was to examine the remineralization effects of a glass ionomer cement adjacent to orthodontic bands. Forty extracted molars were painted with an acid-protective varnish, excluding a 2 × 6 mm window on

Kevin James Donly; Shayne Istre; Todd Istre

1995-01-01

8

Adhesive properties of modified glass-ionomer cements.  

PubMed

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

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

1992-01-01

9

Glass-ionomer (Polyalkenoate) cements. Part 1. Development, setting reaction, structure and types.  

PubMed

The unique properties of the glass-ionomer (or polyalkenoate) cement have widened the compass of restorative and preventive dentistry and changed traditional practice methods. Glass-ionomer cements are the reaction product of an aluminosilicate glass and a polyacid, for example poly (acrylic acid). PMID:2518638

Tay, W M; Lynch, E

1989-06-01

10

The bonding of glass-ionomer cements to dental amalgam.  

PubMed

Clinicians are frequently confronted with the problem of ditched amalgam restorations. Materials which develop strong bonds to amalgam and tooth substance appear to be suitable for repair of such restorations and eliminate the need for complete replacement. This study evaluated the bond strengths of three glass-ionomer cements to amalgam made from conventional and high copper alloys. It was found that the bond strength values to amalgam were comparable with those to enamel and significantly higher than those to dentine. All bonds to the high copper amalgam failed in a cohesive mode; for the conventional amalgam, failure was either of the adhesive or cohesive type. PMID:2650727

Aboush, Y E; Jenkins, C B

1989-04-01

11

Wear and microhardness of glass-ionomer cements.  

PubMed

Pin-and-disc wear and Knoop Hardness measurements were made on three commercial glass-ionomer cements having slightly different compositions. The specific objective was to determine whether these cements have potential for use in posterior teeth, and, if not, what modifications in composition and structure would be appropriate to enhance their performance. The specimens were pre-conditioned in air, water, or lactic acid at 37 degrees C for one week prior to being wear-tested. Although differences among the samples were noted, some common trends were observed. From changes in hardness, before and after storage, two opposing trends were observed. One trend involved continued cross-linking and possible dehydration, resulting in a substantial increase in hardness. The other trend involved softening from penetrant liquid absorption and a concomitant decrease in hardness. The wear resistances compared favorably with those for resin-based composites except for the lactic-acid-stored specimens, for which changes in microstructure were revealed by SEM. All specimens were very brittle, and catastrophic failure during wear was frequent. Although our conclusion is that glass-ionomer cements with composition similar to those evaluated here are not acceptable for posterior occlusal application, some compositional changes may enhance their performance in stress-bearing applications. PMID:3476584

McKinney, J E; Antonucci, J M; Rupp, N W

1987-06-01

12

In vitro study of resin-modified glass ionomer cements for cementation of orthodontic bands  

Microsoft Academic Search

The aim of this in vitro study was to investigate different light-cured and chemically cured resin-modified glass ionomer cements used for the cementation of orthodontic bands and to analyze various factors influencing the adhesive strength between enamel, cement and stainless steel.

Saskia M. Liebmann; Paul-Georg Jost-Brinkmann

1999-01-01

13

Solubility of a resin-modified glass ionomer cement.  

PubMed

Thirty standardized discs were fabricated from a resin-modified glass ionomer cement (Vitremer -3M) using three different powder/liquid ratios. All specimens were immediately weighed. Specimens were stored in artificial saliva for thirty days. Twice each day the specimens received a 30-min. artificial caries challenge (pH 4.4) and were returned to artificial saliva. At the end of the thirty-day experimental period, the specimens were dried and weighed again. Duncan's Multiple Range Test indicated that the 145 mg powder/35 mg liquid ratio had significantly less weight loss than the 145 mg powder/105 mg liquid ratio (p < 0.05). The results appear to demonstrate that solubility decreases as the aluminosilicate glass powder increases. PMID:9795733

Quackenbush, B M; Donly, K J; Croll, T P

1998-01-01

14

Adhesion of different brands of glass ionomer cements to a ceramometal alloy  

Microsoft Academic Search

Aims  The aim of the study was to assess, compare and evaluate the adhesive strength and compressive strength of different brands\\u000a of glass ionomer cements to a ceramometal alloy.\\u000a \\u000a \\u000a \\u000a \\u000a Materials  (A) Glass ionomer cements: GC Fuji II - GC Corporation, Tokyo; Chem Flex — Dentsply DeTrey, Germany; Glass ionomer FX — Shofu-11,\\u000a Japan; MR dental — MR Dental Suppliers Pvt. Ltd., England;

Rama Shankar; Arvind Tripathi; Raghuwar D. Singh; Pooran Chand

2010-01-01

15

Effects of polycarboxylate and glass ionomer cements on stainless steel crown retention  

Microsoft Academic Search

Retentive properties of three dental cements were tested using stainless steel crowns Fitted to extracted third molar teeth. No significant difference was Found between the overall mean retentive Forces of the polycarboxylate cement and the two glass ionomer cements. Mechanical retention of the crowns was not a Factor in the overall retentive value.

David P. Noffsinger; Joseph R. Jedrychowski; Angelo A. Caputo

1983-01-01

16

Resin-modified glass ionomer cements for bonding orthodontic retainers.  

PubMed

The aims of this study were to evaluate the shear bond strength (SBS), fracture mode, and wire pull out (WPO) resistance between resin-modified glass ionomer cement (RMGIC) and conventional orthodontic composite used as a lingual retainer adhesive. Forty lower human incisors were randomly divided into two equal groups. To determine the SBS, either Transbond-LR or Fuji Ortho-LC was applied to the lingual surface of the teeth by packing the material into cylindrical plastic matrices with an internal diameter of 2.34 mm and a height of 3 mm (Ultradent) to simulate the lingual retainer bonding area. To test WPO resistance, 20 samples were prepared for each composite where the wire was embedded in the composite material and cured, 20 seconds for Transbond-LR and 40 seconds for Fuji Ortho-LC. The ends of the wire were then drawn up and tensile stress was applied until failure of the resin. A Student's t-test for independent variables was used to compare the SBS and WPO data. Fracture modes were analyzed using Pearson chi-square test. Significance was determined at P < 0.05. The SBS values were 24.7 +/- 9.2 and 10.2 +/- 5.5 MPa and the mean WPO values 19.8 +/- 4.6 and 11.1 +/- 5.7 N for Transbond-LR and Fuji Ortho-LC, respectively. Statistical analysis showed that the SBS and WPO values of Transbond-LR and Fuji Ortho-LC were significantly different (P < 0.001). No significant differences were present among the groups in terms of fracture mode. However, the RMGIC resulted in a significant decrease in SBS and WPO; it produced sufficient SBS values on the etched enamel surfaces, when used as a bonded orthodontic retainer adhesive. PMID:19793779

Baysal, Asli; Uysal, Tancan

2010-06-01

17

Bioactive glass-ionomer cement with potential therapeutic function to dentin capping mineralization.  

PubMed

We have developed a novel bioactive resin-modified glass-ionomer cement system with therapeutic function to dentin capping mineralization. In the system, the newly synthesized star-shape poly(acrylic acid) was formulated with water, Fuji II LC filler, and bioactive glass S53P4 to form resin-modified glass-ionomer cement. Compressive strength (CS) was used as a screening tool for evaluation. The commercial glass-ionomer cement Fuji II LC was used as a control. All the specimens were conditioned in simulated body fluid (SBF) at 37 degrees C prior to testing. The effect of aging in SBF on CS and microhardness of the cements was investigated. Scanning electron microscopy was used to examine the in vitro dentin surface changes caused by the incorporation of bioactive glass. The results show that the system not only provided strengths comparable to original commercial Fuji II LC cement but also allowed the cement to help mineralize the dentin in the presence of SBF. It appears that this bioactive glass-ionomer cement system has direct therapeutic impact on dental restorations that require root surface fillings. PMID:18821992

Xie, Dong; Zhao, Jun; Weng, Yiming; Park, Jong-Gu; Jiang, Hui; Platt, Jeffrey A

2008-10-01

18

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

2014-05-23

19

Dispersive surface properties of glass-ionomer cements determined by inverse gas chromatography  

NASA Astrophysics Data System (ADS)

The surface properties of several glass-ionomer cements (GIC), restorative dental materials, (GC-Fuji, Chemadent G-J, Ketac Fil and Ketac Molar) were investigated for the first time by means of inverse gas chromatography. This method enables characterization of surface activity in dispersive (non-polar) and acid-base interactions. The ability of the surface of glass-ionomers to participate in dispersive interactions was expressed by the use of the dispersive component of surface free energy ?sd. This parameter was determined with satisfactory precision, meaning that the values of ?sd can be further used in the discussion of the influence of the type of GIC, its preparation and the storage time on the surface properties. The greatest capacity for dispersive interactions was revealed by Ketac Molar and the lowest by GC-Fuji. Dispersive interactions in the surface activity of glass-ionomers increased with increasing storage time after cement preparation.

Andrzejewska, E.; Voelkel, A.; Andrzejewski, M.; Limanowska-Shaw, H.

2005-05-01

20

Bone-like apatite layer formation on the new resin-modified glass-ionomer cement  

Microsoft Academic Search

In this study, the apatite-forming ability of the new resin-modified glass-ionomer cement was evaluated by soaking the cement\\u000a in the simulated body fluid. The Fourier Transform Infrared (FTIR) spectrometer and X-Ray Diffraction (XRD) patterns of the\\u000a soaked cement pointed to the creation of poorly crystalline carbonated apatite. It was found that the releasing of calcium\\u000a ions from the soaked cement

Jhamak Nourmohammadi; S. K. Sadrnezhaad; A. Behnam Ghader

2008-01-01

21

Benefits and drawbacks of zinc in glass ionomer bone cements.  

PubMed

Glass polyalkenoate (ionomer) cements (GPCs) based on poly(acrylic acid) and fluoro-alumino-silicate glasses are successfully used in a variety of orthopaedic and dental applications; however, they release small amounts of aluminium, which is a neurotoxin and inhibits bone mineralization in vivo. Therefore there has been significant interest in developing aluminium-free glasses containing zinc for forming GPCs because zinc can play a similar structural role in the glass, allowing for glass degradation and subsequent cement setting, and is reported to have beneficial effects on bone formation. We created zinc-containing GPCs and characterized their mechanical properties and biocompatibility. Zinc-containing cements showed adhesion to bone close to 1 MPa, which was significantly greater than that of zinc-free cements (<0.05 MPa) and other currently approved biological adhesives. However, zinc-containing cements produced significantly lower metabolic activity in mouse osteoblasts exposed to cell culture medium conditioned with the cements than controls. Results show that although low levels of zinc may be beneficial to cells, zinc concentrations of 400 µM Zn(2+) or more resulted in cell death. In summary, we demonstrate that while zinc-containing GPCs possess excellent mechanical properties, they fail basic biocompatibility tests, produce an acute cytotoxic response in vitro, which may preclude their use in vivo. PMID:21680957

Brauer, Delia S; Gentleman, Eileen; Farrar, David F; Stevens, Molly M; Hill, Robert G

2011-08-01

22

Influence of the Retention of Antiseptic Solution Dyes on the Translucence of Glass-Ionomer Cements  

Microsoft Academic Search

Due to the great importance that antiseptic solutions have on the control and prevention of oral diseases and their influence on the translucence of esthetic restorative materials, the present study evaluated the effect of antiseptic solutions on the translucence of two glass-ionomer cements, Vidrion R and Chelon Fil, at eight time periods. Four antiseptic solutions were used: Listerine, Malvona, Flogoral

Alma Blásida; Elizaur CATIRSE

23

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

PubMed Central

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

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

2014-01-01

24

A novel furanone-modified antibacterial dental glass ionomer cement.  

PubMed

A novel furanone derivative and a polyacid constructed from it were synthesized, characterized and formulated into experimental high strength cements. The compressive strength (CS) and Streptococcus mutans viability were used to evaluate the mechanical strength and antibacterial activity of the cements. The effect of human saliva and aging were investigated. The antibacterial activity against Lactobacillus sp. and cytotoxicity to human pulp cells were also evaluated. The results show that all the formulated furanone-containing cements showed antibacterial activity, with an initial reduction in CS. The effect of the furanone derivative loading was significant. Increasing loading enhanced the antibacterial activity but reduced the initial CS of the formed cements. The derivative showed antibacterial activity against both S. mutans and Lactobacillus sp. Human saliva did not affect the antibacterial activity of the cement. The cytotoxicity study with human dental pulp cells shows that the furanone-modified cement was biocompatible. A 30 day aging study indicated that the cements may have long-lasting antibacterial activity. Within the limitations of this study it appears that the experimental cement could be a clinically attractive dental restorative due to its high mechanical strength and antibacterial function. PMID:22554887

Weng, Yiming; Howard, Leah; Chong, Voon Joe; Sun, Jun; Gregory, Richard L; Xie, Dong

2012-08-01

25

Diametral tensile strength and water sorption of glass-ionomer cements used in Atraumatic Restorative Treatment.  

PubMed

The purposes of this study were to evaluate the diametral tensile strength and the water sorption of restorative (Fuji IX and Ketac Molar) and resin-modified glass-ionomer luting cements (ProTec Cem, Fuji Plus and Vitremer) mixed at both manufacturer and increased powder: liquid ratio, for their use in the Atraumatic Restorative Treatment. A conventional restorative glass-ionomer (Ketac Fil) was used as control. Specimens (6.0 mm in diameter x 3.0 mm in height) were prepared and stored (1 hour, 1 day and 1 week) for a diametral tensile strength test. Data were subjected to two-way ANOVA and Tukey tests (p<0.05). For the water sorption test, specimens of 15.0 mm in diameter x 0.5 mm in height were prepared and transfered to desiccators until a constant mass was obtained. Then the specimens were immersed in deionized water for 7 days, weighed and reconditioned to a constant mass in desiccators. Data were subjected to one-way ANOVA and Tukey tests (p<0.05). Five specimens of each studied material and consistency were prepared for each test. The resin-modified glass-ionomer cements showed significantly higher strength than the conventional materials. Except for ProTec Cem, the diametral tensile strength of the resin-modified materials significantly increased from luting to restorative consistency. Except for ProTec Cem, the water sorption of the resin-modified glass ionomers was higher than the others. The water sorption of resin-modified materials at restorative consistency was significantly lower than at luting consistency. Resin-modified glass-ionomer luting cements mixed at increased powder: liquid ratio showed better properties than at luting consistency. PMID:21409320

Cefaly, Daniela Francisca Gigo; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; Francisconi, Paulo Afonso Silveira; Navarro, Maria Fidela de Lima

2003-06-01

26

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.

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

2014-01-01

27

A three-year clinical trial using a glass ionomer cement for the bonding of orthodontic brackets.  

PubMed

Recent clinical studies measuring orthodontic bracket failure, when using glass ionomer cement as an adhesive, have reported a wide range of percentages of bracket failure. The present study recorded bracket failure over a 3-year period, longer than had been previously measured. Seventeen participants were randomly assigned to one of two treatment groups, either using glass ionomer cement or composite resin for bonding. In each group, brackets were bonded to incisors, canines, and premolars. Bracket failure was measured over the duration of comprehensive orthodontic treatment for all participants. Brackets bonded with the glass ionomer cement were more likely to fail (log-rank test; P < or = 0.022). This difference was clinically significant. At the present time, the disadvantage of extra bracket failures appears to outweigh potential advantages when considering glass ionomer cement for the routine bonding of orthodontic brackets. PMID:8863967

Miller, J R; Mancl, L; Arbuckle, G; Baldwin, J; Phillips, R W

1996-01-01

28

The glass polyphosphonate cement: a novel glass-ionomer cement based on poly(vinyl phosphonic acid).  

PubMed

This paper outlines research which aimed to develop a new type of Glass-ionomer cement, the glass polyphosphonate cement. The glass polyalkenoate cement, a form of Glass-ionomer cement, is now widely used in dentistry and is based on the reaction between an ion-leachable aluminosilicate glass and an aqueous solution of poly(acrylic acid) or its copolymers. The new cements described in this paper employ a novel polymer, poly(vinyl phosphonic acid), PVPA, as the acidic component. This is a much stronger acid than those used in the glass polyalkenoate cement, and various means must be employed to moderate the reaction in order to obtain a viable cement. These cements show a number of important differences in performance in comparison with PAA-based systems and these differences are discussed in the paper. PMID:10149147

Ellis, J; Anstice, M; Wilson, A D

1991-01-01

29

Effects of incorporation of HA/ZrO(2) into glass ionomer cement (GIC).  

PubMed

Glass ionomer cements (GICs) are a class of bioactive cements that bond directly to bone. In this paper, a new bioactive hydroxyapatite (HA)/zirconia (ZrO(2))-filled GIC composite was developed to improve the biocompatibility and bioactivity of the GICs with the surrounding bone and connective tissues. Nano-sized HA/30 wt% ZrO(2) powders were heat treated at 700 degrees Celsius and 800 degrees Celsius for 3 h to elucidate the influence of the crystallinity of composite powders on the performance of HA/ZrO(2)-GICs. The effects of different volume percentages of HA/ZrO(2) powders (4, 12, 28 and 40 vol%) substituted within GICs were investigated based on their microhardness, compressive strength and diametral tensile strength. The HA/ZrO(2)-GICs composite was soaked in distilled water for 1 day and 1 week before subjecting the samples to mechanical testing. Results showed that the glass and HA/ZrO(2) particles were distributed uniformly in the GIC matrix. The substitution of highly crystalline HA/ZrO(2) improved the mechanical properties of the HA/ZrO(2)-GICs due to the slow resorption rate for highly crystalline powders in distilled water. The mechanical properties of HA/ZrO(2)-GICs increased with increasing soak time due to the continuous formation of aluminium salt bridges, which improved the final strength of the cements. The compositions 4 and 12 vol% HA/ZrO(2)-GICs exhibited superior mechanical properties than the original GICs. The mechanical properties of HA/ZrO(2)-GICs were found to be much better than those of HA-GICs because ZrO(2) has the attributes of high strength, high modulus, and is significantly harder than glass and HA particles. Furthermore, ZrO(2) does not dissolve with increasing soaking time. PMID:15350775

Gu, Y W; Yap, A U J; Cheang, P; Khor, K A

2005-03-01

30

Microtensile bond strengths of glass ionomer (polyalkenoate) cements to dentine using four conditioners  

Microsoft Academic Search

Objectives: The purpose of this study was to measure the microtensile bond strengths of three glass ionomer cements to dentine (Photac-Fil Quick; Fuji II LC; Fuji IX GP) using four different conditioners (Ketac Conditioner; Dentin Conditioner; Cavity Conditioner; and an experimental conditioner, K-930).Methods: Superficial occlusal dentine of extracted human third molars was exposed, finished with wet 600-grit silicon carbide paper,

M Tanumiharja; M. F Burrow; M. J Tyas

2000-01-01

31

Dissolution behavior and fluoride release from new glass composition used in glass ionomer cements  

Microsoft Academic Search

The degradability in an acidic environment and the release of different ions, such as Na+, Ca2+, Al3+ and F? from a calcium fluoro-aluminosilicate glass (used in glass ionomer cements) during different exposure times at 37°C has been the object of this study. The formation of a leached layer on the surface of the glass has proved to be an important

Jhamak Nourmohammadi; Reza Salarian; Mehran Solati-Hashjin; Fatollah Moztarzadeh

2007-01-01

32

Fourier Transform Infrared Spectroscopic Study of the Role of Tartaric Acid in Glass-ionomer Dental Cements  

Microsoft Academic Search

(+) - Tartaric acid is incorporated into glass-ionomer dental cements to control the setting characteristics. FTIR has been used to examine the cements as they set, and has confirmed previous results that (+)-tartaric acid reacts more readily with the glass than does poly(acrylic acid), thereby delaying the setting of the cement. Subsequently, ions released by the glass become available for

J. W. Nicholson; P. J. Brookman; O. M. Lacy; A. D. Wilson

1988-01-01

33

In vivo study of pulp reaction to glass ionomer cements and dentin adhesives.  

PubMed

The aim of this study was to evaluate histopathologically the pulp tissue response of the researched materials 7 and 30 days after their application. The reaction of pulp tissue has been examined on first upper molars in 24 Wistar rats, following the previously set parameters. For that purpose, 48 class V cavities were prepared with a high-speed handpiece using a diamond burr under copious water-cooling. The cavities were divided into four groups. In the cavities from the first group we applied Fuji Lining LC, and in the secound group cavities we applied Fuji IX as a base. In the third and fourth group cavities we applied Prime and Bond and G Bong as a base. All the cavities were restored with liquid light cured composite. Seven days after the application, 3 rats from each group were killed and the restored teeth were extracted and immersed in a fixative solution, Osteomol. After removing the Osteomol, the specimens were processed according to histological procedures. The histological evaluation was made using a light microscope connected to a video camera. Thirty days after the application of the dental materials we re-did the procedure with the other restored teeth. For Fuji Lining LC and Fuji IX most of the specimens exhibited no pulpal response or slight inflammatory reaction associated with slight tissue disorganization during a seven-day period. A slight to moderate inflammatory pulpal response occurred in the specimens restored with G Bond, while Prime and Bond exhibited the strongest toxic effect on the pulp tissue. After 30 days the pulp tissue in all groups recovered and displayed a normal appearance. Key wards: Biocompatibility, dentin adhesives, glass ionomer cements, pulpal respon-se. PMID:22983105

Rendjova, V; Gjorgoski, I; Ristoski, T; Apostolska, S

2012-07-01

34

Etching conditions for resin-modified glass ionomer cement for orthodontic brackets.  

PubMed

This study reports the tensile bond strength of orthodontic eyelets (RMO, Inc, Denver, Colo) bonded to human extracted teeth with a resin-modified glass ionomer cement (RMGIC) (Fuji Ortho LC, GC America, Alsip, Ill) and various acid etchants (Etch-37 and All-Etch, Bisco, Schaumburg, Ill; Ultra Etch, 3M Unitek, St Paul, Minn) for enamel preparation before bonding. The enamel etch conditions were as follows: 37% phosphoric acid with silica; 37% phosphoric acid, silica-free; 10% phosphoric acid, silica-free; 10% polyacrylic acid; and unetched enamel. Bond strength was measured by pulling in tension on the eyelet with a 0.018-in steel wire perpendicular to the enamel surface with a testing machine (Instron model 1125, Canton, Mass) at a speed of 2 mm/min. A light-cured resin cement (Transbond XT, 3M Unitek, Monrovia, Calif) applied to enamel etched with 37% phosphoric acid containing silica served as a control. Each group included 30 specimens. The Weibull distribution (m) was used for statistical analysis with a 90% CI. The different etchants used with RMGIC did not affect tensile bond strength. The resin cement group had the highest tensile strength. Significantly lower bond strengths were observed when glass ionomer cement was used to bond orthodontic attachments to nonetched teeth. However, unlike resin cement, RMGIC can bond effectively to etched teeth in a moist environment without an additional bonding agent. PMID:12045770

Valente, Rudolfo M; De Rijk, Waldemar G; Drummond, James L; Evans, Carla A

2002-05-01

35

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

36

A study of glass-ionomer cement and its interface with enamel and dentin using a low-temperature, high-resolution scanning electron microscopic technique.  

PubMed

This report describes a method of immobilizing the water contained in glass-ionomer cement and dental hard tissues and stabilizing the delicate organic component of dentin. With this method, the intact interface between glass-ionomer and dental hard tissues can be observed under scanning electron microscope with few of the artifacts that are caused by the desiccation associated with conventional scanning electron microscopic studies. There was a distinct zone of interaction between the glass-ionomer cement and enamel and dentin. Under severe thermal stress, glass-ionomer cement failed cohesively, leaving an intact interface with enamel and dentin. Machine-mixed glass-ionomer cements displayed a high level of porosity. Some glass particles were separated from the matrix, and there was evidence that some are dislodged from the matrix during specimen preparation. PMID:10332357

Ngo, H; Mount, G J; Peters, M C

1997-01-01

37

Wear and microhardness of a silver-sintered glass-ionomer cement.  

PubMed

Knoop Hardness and pin-and-disc-wear measurements were made on a commercial silver-sintered glass-ionomer cement. The objective was to determine whether the incorporation of a bonded-metal-to-glass filler would enhance durability as determined by the above measurements. As with the previous work on conventional (non-metalized) glass-ionomer cements, the specimens were preconditioned at 37 degrees C in air, water, 0.02 mol/L lactic acid (pH 2.67), and heptane. The influence of these media on the microhardness of the silver-sintered material was about the same as that on the conventional materials. Storing in air produced dehydration, which increased the hardness considerably. Heptane storage increased the hardness less, but this increase is attributed to continued curing during storage. After storage in water, the hardness was essentially unchanged; the influence of increased cure is believed to be offset by softening or plasticization from water uptake. Lactic acid produced a decrease in hardness from chemical dissolution as seen from the SEM observations. In most cases, in particular for the air-stored specimens, the wear resistance was enhanced markedly over that of the conventional materials evaluated previously. The exception was the lactic acid-stored specimens for which little, or no, improvement was observed during early periods of wear. The incorporation of silver appeared to provide lubrication, thus reducing wear. However, catastrophic failure from brittle fracture was still a problem, but its occurrence was less frequent. PMID:2966819

McKinney, J E; Antonucci, J M; Rupp, N W

1988-05-01

38

In vitro wear of Ionofil Molar AC quick glass-ionomer cement.  

PubMed

Aim: The aim of this study was to evaluate the three-body wear-resistance of one type of restorative glass-ionomer cement (GIC). Materials and Methods: Specimen including conventional GIC (Ionofil Molar AC Quick: IMACQ), hybrid ionomer (Fuji II LC), and composite resin (Heliomolar) were tested in a wearing machine. In this machine, a 6?kg load was applied via pressable chromium-cobalt bar at 5,000, 10,000, 20,000, 40,000, 80,000, 120,000 cycles. Specimen weight was measured by an electronical weight balance before and after each cycle. Data were analyzed using one-way analysis of variance (ANOVA) followed by a t-test, and a paired t-test at P?0.05. Results: The highest weight loss has been found in Fuji II LC, then in GIC IMACQ and the least wear rate has been reported in heliomolar composite in all cycles except 120,000 cycles. In 120,000 cycles, the highest weight loss was seen in GIC IMACQ, then Fuji II LC, and finally heliomolar composite. There was a statistically significant difference in weight loss between GIC IMACQ and heliomolar composite (P=0/001). Conclusion: The wear rate of GIC IMACQ was between those of heliomolar composite and Fuji II LC glass ionomer in all cycles except 120,000 cycles. The most important advantage of this new-generation glass ionomer is its good manipulability and also high wear-resistance compared to the hybrid ionomer. Therefore, it is suggested that it can be used as restorative material in class I restorations in primary teeth. PMID:22406725

Abesi, Farida; Safarcherati, Hengameh; Sadati, Javad; Kheirollahi, Hossein

2011-01-01

39

[An in-vitro study on improving the bonding strength of steel bands with the use of glass ionomer cements].  

PubMed

An in-vitro investigation was carried out with the aim of improving bond strength at the glass-ionomer cement/stainless steel interface, thus reducing loosening rates. In bovine incisors it had previously been shown that the week point is the glass-ionomer cement/stainless steel, rather than the enamel/glass-ionomer cement interface. In a simple, standardized experimental set-up permitting reproducible measurements, the semi-flexible and irregularly shaped orthodontic bands were replaced by solid stainless steel cylinders made of the same alloy, and both shear and tensile bond strength were measured. Using this set-up, five different types of surface preparation were compared in terms of their bond strength. The highest bond strength was found to be associated with a steel surface sandblasted with coarse aluminium oxide. In further experiments, the devices provided by the manufacturer for dosing powder and liquid were found to be quite inaccurate. This is particularly unfortunate, since the bonding properties of the glass-ionomer cement investigated proved to vary significantly with small variations in the powder:liquid ratio. To reduce the rate of loosening of orthodontic bands, the cement should be mixed at refrigerator temperature, using capsules filled by the manufacturer with the optimal dosages, and then used with bands previously sandblasted with coarse aluminium oxide powder. PMID:8375785

Jost-Brinkmann, P G; Miethke, R R; Appenzeller, A H

1993-08-01

40

Characterization of the kinetic behavior of resin modified Glass-ionomer cements by DSC, TMA and ultrasonic wave propagation  

Microsoft Academic Search

In this study the isothermal kinetic behavior of two resin modified glass ionomer cements (RMGIC) and a dental composite have been compared by differential scanning calorimetry (DSC) and thermo-mechanical analysis (TMA). The simultaneous evolution of the multiple reactions occurring in RMGIC has been analyzed not only by DSC and TMA but also by ultrasonic wave propagation using the pulse-echo technique.

F. Micelli; A. Maffezzoli; R. Terzi; V. A. M. Luprano

2001-01-01

41

Sealing ability of mineral trioxide aggregate, glass ionomer cement and composite resin when repairing large furcal perforations  

Microsoft Academic Search

Objective To evaluate the sealing ability of different repair materials and the pathway of bacterial penetration after closure of large pulp chamber floor perforations. Materials and methods Perforations were made in the furcation area of extracted human molars and sealed with either mineral trioxide aggregate (MTA), glass ionomer cement or resin composite. The bacterial leakage method was used with Enterococcus

M. Kleivmyr; E. Bruzell; D. Ørstavik; G. Lodiene

2011-01-01

42

Powder-liquid ratio and properties of two restorative glass ionomer cements.  

PubMed

Changes in the powder-liquid ratio of glass ionomer cements may affect some of its physical properties and acid erosion. The aim of this study was to evaluate the physical properties and acid erosion of two conventional restorative glass ionomer cements against ISO 9917-1:2007 standards after changing the powder-liquid ratio to an adequate consistency for luting indirect restorations. The methodology of ISO Specification 9917-1:2007 was applied to the powder-liquid ratio indicated by the manufacturer and to a modified ratio. Two restorative glass ionomer cements, ChemFil (Ch) (Dentsply) and lonofil Plus (IP) (Voco), were used to evaluate film thickness, compressive strength, net setting time and acid erosion. Thickness was measured three times with a digital micrometer (Digimatic Mitutoyo Corporation). Sample size was five for each cement or condition. Compressive strength (Instron 1011, crosshead speed of 1 mm/min) was evaluated after 24 h immersion in water at 37 degreesC. Sample size was five for each cement or condition. Setting time was evaluated for Ch and IP at 37 degreesC. Sample size was three for each cement or condition. Specimen moulds (30 x 30 x 5 mm) with a central perforation of 5 mm in diameter and 2 mm depth were usedfor acid erosion tests. Erosion depth was measured with a micrometer gauge with a precision of 0. 001 mm, before and after 24-hour immersion in a lactic acid-sodium lactate solution with pH 2.74 at 370C. Sample size wasfivefor each condition. Student's t test was performed with a level of significance ofp< O.05 for each material and condition tested. Arithmetic mean (Standard Deviation). Powder-liquid ratio according to manufacturers: film thickness (in pm): Ch 220 (40), IP: 382 (5); compressive strength (in MPa) at 24 hs: Ch 166.3 (16,6), IP: 100 (10); net setting time (in min.) at 370C: Ch 3.44 (0.3), IP: 5.26 (0.1) ; depth of acid erosion (in mm): Ch 0.15 (0.02), IP: 0.17 (0.02). Modified powder-liquid ratio: film thickness (in pm): Ch 23(1), IP:24(1); compressive strength at 24 hs (in MPa): Ch: 69.3 (14.6), IP: 46.5 (7.4); net setting time (in min.) at 370C: Ch 5.72 (0.1) and IP 9.38 (0.1); depth of acid erosion (in mm): Ch 0.22 (0.02). Data were not recorded for IP because the sample disintegrated in the solution. Student's t test was performed for both materials and conditions with a level of significance of p< 0.05. The difference between each condition tested was statistically significant (p<0.01). While changes in the powder-liquid ratio of a restorative glass ionomer cement can result in some of its properties having values that are not far from those required for luting cements according to ISO specifications, it did not meet the requirements for acid erosion. PMID:22165320

Zahra, Vivian N; Kohen, Sergio G; Macchi, Ricardo L

2011-01-01

43

The effect of maturation on in-vitro erosion of glass-ionomer and other dental cements.  

PubMed

The clinical durability of restorations made using water-based materials depends upon the type of material used. Current specification tests cannot predict durability, possibly because these are carried out on samples matured for 24 hours whereas longer maturation times may be more relevant. The lactic acid jet test was selected as a test method, being believed capable of ranking materials in the same order of erosion resistance in vitro as found in vivo. The powder/liquid interaction (glass or zinc oxide with polymeric or phosphoric acid) was investigated by selecting glass-ionomer, zinc polycarboxylate, silicate and zinc phosphate cements, with emphasis placed on glass ionomers. Two test times, 24 hours and 2 months, were chosen, with eight samples for each material tested at each time. All glass ionomers showed a significant reduction in erosion rate with time; two zinc polycarboxylates also showed some reduction but not to a significant degree. The silicate and zinc phosphate cements increased in erosion rate but not significantly. It was concluded that materials using polymeric acids had erosion rates which reduced with time, significantly so for glass ionomers. This might explain their longevity over silicate cements. PMID:1467010

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

44

Effect of glass-ionomer cement on the progression of proximal caries.  

PubMed

Although effective preventive strategies exist for pit and fissure caries, prevention of proximal caries remains a significant challenge. This split-mouth study was designed to investigate the effect of glass-ionomer cement (GIC) on the progression of initial proximal caries in posterior teeth, testing the hypothesis that local application of fluoride-releasing GIC would reduce this progression. GIC was applied to 41 pairs of posterior teeth after elastic band separation in 7- to 19-year-old individuals. Follow-up bitewing radiographs were taken at 6 and 12 months. Differences in ? mean lesion depth at 6 and 12 months between test and control groups were significant (p < 0.05, p < 0.000). Lesions treated with GIC were more likely to remain in or regress to the outer half of enamel (OR = 6.3; 95%CI, 1.3-30.9). GIC provides an effective approach to the clinical management of incipient proximal caries. PMID:20858776

Trairatvorakul, C; Itsaraviriyakul, S; Wiboonchan, W

2011-01-01

45

FTIR investigation of polymerisation and polyacid neutralisation kinetics in resin-modified glass-ionomer dental cements  

Microsoft Academic Search

A new diamond ATR FTIR method has been developed to quantify the processes occurring in the resin-modified glass-ionomer cement (RMGIC), Fuji II LC (Improved), at 1mm depth from the cement\\/water interface. With Fuji II LC (Improved) various changes in the spectra due to 90% monomer polymerisation were observed within 1min after 20s exposure to a dental light. Following polymerisation further

A. M. Young

2002-01-01

46

Effects of N-vinylpyrrolidone (NVP) containing polyelectrolytes on surface properties of conventional glass-ionomer cements (GIC)  

Microsoft Academic Search

It has been found that polyacids containing an N-vinylpyrrolidinone (NVP) comonomer produces a glass inomer cement with improved mechanical and handling properties. The objective of this study was to investigate the effect of NVP modified polyelectrolytes on the surface properties and shear bond strength to dentin of glass ionomer cements.Poly(acrylic acid (AA)-co-itaconic acid (IA)-co-N-vinylpyrrolidone) was synthesized by free radical polymerization.

Alireza Moshaverinia; Nima Roohpour; Sahar Ansari; Maryam Moshaverinia; Scott Schricker; Jawwad A. Darr; Ihtesham U. Rehman

2009-01-01

47

Effect of Hygroscopic Expansion on the Push-Out Resistance of Glass Ionomer-Based Cements Used for the Luting of Glass Fiber Posts  

Microsoft Academic Search

This study examined the contribution of hygroscopic expansion of glass-ionomer (GIC) and resin modified glass-ionomer (RMGIC) luting cements to the push-out resistance of fiber posts. Glass fiber posts were luted to post spaces using different cements. Experimental specimens were stored in water, while control specimens were desiccated and stored in mineral oil to eliminate water from intraradicular dentinal tubules and\\/or

Álvaro H. Cury; Cecilia Goracci; Maria Fidela de Lima Navarro; Ricardo M. Carvalho; Fernanda T. Sadek; Franklin R. Tay; Marco Ferrari

2006-01-01

48

An in vitro study to assess the setting and surface crazing of conventional glass ionomer cement when layered over partially set mineral trioxide aggregate.  

PubMed

The aim of our study was to assess the setting time and surface crazing of glass ionomer cement when layered over partially set mineral trioxide aggregate (MTA). To assess setting time, 40 hollow, cylindrical stainless steel molds were taken and equally divided into 4 groups. In groups I, II, and III glass ionomer cement was layered over partially setting MTA at 45 minutes, 4 hours, and 3 days, respectively. Group IV was used as a control. An additional 50 specimens were prepared for assessment of surface crazing. Twenty specimens (groups I and II) were prepared to study normal and desiccated patterns of conventional glass ionomer cement, respectively. Thirty specimens (groups III, IV, and V) were prepared by layering glass ionomer cement over partially set MTA at various time intervals. All the specimens were stained with red ink and analyzed for craze lines by light microscopy. From our study, it was observed that there was no statistical difference in setting time of glass ionomer cement when layered over partially set MTA in comparison to that of the control group. No craze lines were observed in those specimens (groups III, IV, and V) when viewed under staining and light microscopy. It could be concluded that conventional glass ionomer cement might be layered over partially set MTA after 45 minutes and could be used for single visit procedures. PMID:18358902

Ballal, Suma; Venkateshbabu, Nagendrababu; Nandini, Suresh; Kandaswamy, Deivanayagam

2008-04-01

49

Factors that influence the setting characteristics of encapsulated glass ionomer cements.  

PubMed

The slow rate of the setting reaction of glass ionomer cements (GICs) is one of the problems associated with their clinical use. The manufacturers of these materials suggest that increasing the mixing time will increase the rate of reaction and it was the purpose of this study to investigate the limits of this relationship. The method used to monitor the setting reaction with Differential Thermal Analysis (DTA). The results obtained using DTA were compared with those obtained using the ISO penetrometer method as defined in the ISO standard for water-based cements, ISO 9917:1991E. It was shown that increasing the mixing time of cements did not significantly reduce the setting time (P > 0.05). Under the conditions of the study it was only possible to measure a working time for the Chemfil II (and then only if it was mixed for less than 12 s). Storing the capsules at 4 degrees C did enable a working time to be measured using the DTA for all the materials, however these storage conditions also produced a significant increase in the setting time which would be undesirable to the clinician. The penetrometer method underestimated the duration of the setting reaction by up to 32% compared with the DTA method. However it was a quick and reproducible method of measuring setting time and as such may still be an appropriate method for use in the ISO standards. PMID:8027462

Kilpatrick, N M; McCabe, J F; Murray, J J

1994-06-01

50

Effects of nanocrystalline calcium deficient hydroxyapatite incorporation in glass ionomer cements.  

PubMed

Glass ionomer cements (GICs) are clinically attractive filling materials often employed in the field of dentistry as restorative and luting materials. The present work aims to formulate bioactive nanocrystalline calcium deficient hydroxyapatite (nCDHA)-GIC composite cements with improved mechanical and resorption properties of the set cement than GICs. The nCDHA was synthesized via an accelerated microwave process and characterized by X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) methods. The synthesized nCDHA was mixed with GIC in different compositions (5, 10 and 15 wt%) maintaining the powder to liquid ratio. Cylinders of dimensions 8 mm height and 4 mm diameter were formed using a Teflon mold following a conventional cement forming technique. The XRD and FT-IR of the cylinders showed increased intensity and characteristic bands of CDHA with increase in nCDHA content. The surface cracks and the elemental composition of the set cements were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Decreased surface hardness was observed for composite cements with increase in nCDHA addition. The cement cylinders were tested for ionic release in Millipore water (pH=7) via inductive coupled plasma (ICP) spectroscopy and in demineralization solution of pH=5 to find out the weight loss in an acidic environment at 37 °C performed periodically for 5 weeks. The ionic release percentage, weight loss and compressive strength were observed to increase with an increase in nCDHA addition. PMID:22340686

Goenka, Sumit; Balu, Rajkamal; Sampath Kumar, T S

2012-03-01

51

Effect of ultrasound on the setting characteristics of glass ionomer cements studied by Fourier Transform Infrared Spectroscopy  

Microsoft Academic Search

Objective To investigate the effect of ultrasound (US) application, US staring time and US duration on the setting of glass ionomer\\u000a cement (GIC) by using Attenuated Total Reflectance Fourier Transform Infrared (ATR\\/FTIR) spectrometer. Methods Two conventional GICs, Fuji IX Fast and Ketac Molar were studied. US application was started at 30 s or 40 s after mixing\\u000a and was applied

A. Talal; K. E. Tanner; R. Billington; G. J. Pearson

2009-01-01

52

The effect of ultrasound on the uptake of fluoride by glass ionomer cements.  

PubMed

Ultrasound has been shown to improve the set of glass ionomer cements (GICs) and also other cement properties. In particular, the release of fluoride is enhanced. These cements also can take up fluoride ion from liquids. The aim of this study is to investigate the effect of ultrasound on this cement property. Two commercial dental restorative GICs were used together with a modified commercial material and an experimental material based on a F-free glass. All three commercial materials came in capsules which were mixed as makers directed, the experimental material was mixed as in previous papers. Mixed cement was placed polyethylene moulds to create 3 × 2 mm thick discs. These were either allowed to standard set for 6 min or set with ultrasound for 55 s. 18 samples were made for each material/set. Three samples were placed in 4 ml of 0.2% NaF solution for 24 h at 37°C. The cylinders were removed and the F concentration of the solutions measured by ISE using TISAB decomplexant. F uptake was determined by difference from the original NaF concentration. The two conventional GICs showed reductions of 17.4 and 8.5% for ultrasound compared to standard set whereas the modified material increased by 32.3% and the experimental one by 20.6%. It is suggested that the effect of ultrasound may increase the surface area of the residual glass particles in the GIC which would increase F uptake. In GICs where considerable F ion is released into the cement matrix by the enhanced reaction caused by ultrasound this may be sufficient to reverse the former effect producing the reduced uptake observed. PMID:21221738

Shahid, S; Billington, R W; Hill, R G

2011-02-01

53

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.

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

2013-01-01

54

Review Paper: Role of Aluminum in Glass-ionomer Dental Cements and its Biological Effects  

Microsoft Academic Search

The role of aluminum in glass-ionomers and resin-modified glass-ionomers for dentistry is reviewed. Aluminum is included in the glass component of these materials in the form of Al2O3 to confer basicity on the glass and enable the glass to take part in the acid—base setting reactions. Results of studies of these reactions by FTIR and magic-angle spinning (MAS)-NMR spectroscopy are

John W. Nicholson; Beata Czarnecka

2009-01-01

55

The effect of heating and ultrasound on the shear bond strength of glass ionomer cement.  

PubMed

The aim of this study was to compare the influence of externally applied "command set" methods (heat, ultrasound) on shear bond strength to enamel of several glass ionomer cements (GIC). The vestibular surfaces of 180 extracted premolars were wet ground until a flat enamel surface was created, and divided into three groups. Three restorative GICs (Fuji IX GP Fast, Fuji Triage, Ionofil Molar AC) were cured in three ways: standard (SC), ultrasonic excitation (UC) and by an external heat source (HC). In each group, teeth were conditioned in two ways: 30 with 10% polyacrylic acid and 30 without conditioning. The GIC were used to fill teflon molds (3 x 4 mm). The samples were loaded in a Universal testing machine (Lrx Material Testing Machine) at a 1 mm/min crosshead speed. Results showed that heat cured Fuji IX on conditioning enamel had significantly greater shear bond strength (13.3 MPa) than all other tested groups (8.6-10.8 MPa) (p < 0.001). The mean shear bond strength in GIC with SC and without enamel conditioning was 3.6-5 MPa and had significantly lower bond strength. Heating of GIC increase bond strength, improves the properties of GIC restoration and can be recommended for use as a "command set" method. PMID:23390826

Gorseta, Kristina; Skrinjari?, Tomislav; Glavina, Domagoj

2012-12-01

56

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

57

Effectiveness of surface protection of resin modified glass ionomer cements evaluated spectrophotometrically.  

PubMed

The effectiveness of four surface protectors for resin-modified glass ionomer cements was evaluated by spectrophotometrically determining dye uptake. Ninety specimens, 3.0 mm in diameter and 1.0 mm in height, were made with Photac-Fil, Fuji II LC and Vitremer and divided into six groups for each material. Positive and negative controls were not protected while experimental specimens were protected with proprietary glaze, nail varnish, flowable resin and glaze. The discs were immersed in 0.1% methylene blue solution for 10 minutes after mixing, except for those negative control specimens that were immersed in deionized-water. After 24 hours, the specimens were washed and the protectors trimmed with Sof-Lex discs. The specimens were then removed from the matrixes and individually placed in 1.5 mL of 65% nitric acid for five hours. The absorbance was determined spectrophotometrically at 590 nm. Dye uptake was expressed in microgram dye/specimen. The data were analyzed by two-way ANOVA and Tukey-Kramer tests. All surface protectors tested were effective. For Fuji II LC and Vitremer no differences were observed among tested protections. For Photac-Fil, nail varnish showed better performance than the proprietary glaze. PMID:11504441

Cefaly, D F; Seabra, B G; Tapety, C M; Taga, E M; Valera, F; Navarro, M F

2001-01-01

58

Water sorption of resin-modified glass-ionomer cements photoactivated with LED.  

PubMed

The Light Emitting Diodes (LED) technology has been used to photoactivate composite resins and there is a great number of published studies in this area. However, there are no studies regarding resin-modified glass-ionomer cements (RMGIC), which also need photoactivation. Therefore, the aim of this study was to evaluate water sorption of two RMGIC photoactivated with LED and to compare this property to that obtained with a halogen light curing unit. A resin composite was used as control. Five specimens of 15.0 mm in diameter x 1.0 mm in height were prepared for each combination of material (Fuji II LC Improved, Vitremer, and Filtek Z250) and curing unit (Radii and Optilight Plus) and transferred to desiccators until a constant mass was obtained. Then the specimens were immersed into deionized water for 7 days, weighed and reconditioned to a constant mass in desiccators. Water sorption was calculated based on weight and volume of specimens. The data were analyzed by two-way ANOVA and Tukey test (p < 0.05). Specimens photocured with LED presented significantly more water sorption than those photocured with halogen light. The RMGIC absorbed statistically significant more water than the resin composite. The type of light curing unit affected water sorption characteristics of the RMGIC. PMID:17242796

Cefaly, Daniela Francisca Gigo; Wang, Linda; de Mello, Liliam Lucia Carrara Paes; dos Santos, Janaína Lima; dos Santos, Jean Rodrigo; Lauris, José Roberto Pereira

2006-01-01

59

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.

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

2013-01-01

60

Biaxial flexural strength of high-viscosity glass-ionomer cements heat-cured with an LED lamp during setting.  

PubMed

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/cm(2) for 30?s while setting (Group 2), and heated with LED lamp of 1400?mW/cm(2) 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/cm(2) 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

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

2013-01-01

61

Development of a novel aluminum-free glass ionomer cement based on magnesium/strontium-silicate glasses.  

PubMed

The effects of strontium substitution for magnesium in a novel aluminum-free multicomponent glass composition for glass ionomer cements (GICs) were investigated. A series of glass compositions were prepared based on SiO2-P2O5-CaO-ZnO-MgO(1-X)-SrOX-CaF2 (X=0, 0.25, 0.5 and 0.75). The mechanical properties of GICs prepared were characterized by compressive strength, flexural strength, flexural modules, and microhardness. Cell proliferation was evaluated indirectly by CCK-8 assay using various dilutions of the cement and rat mesenchyme stem cells. Incorporation of strontium instead of magnesium in the glasses has a significant influence on setting time of the cements and the properties. All mechanical properties of the GICs with SrO substitution at X=0.25 were significantly increased, then gradually decreased with further increase of the amount of strontium substitution in the glass. The GIC at X=0.25, also, showed an improved cell viability at low doses of the cement extracts in comparison with other groups or control without extracts. The results of this study demonstrate that the glass compositions with strontium substitution at low levels can be successfully used to prepare aluminum-free glass ionomer cements for repair and regeneration of hard tissues. PMID:25063167

Kim, Dong-Ae; Abo-Mosallam, Hany A; Lee, Hye-Young; Kim, Gyu-Ri; Kim, Hae-Won; Lee, Hae-Hyoung

2014-09-01

62

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

PubMed

The objective of this study is to investigate the effects of application of ultrasound on the physical properties of a novel NVC (N-vinylcaprolactam)-containing conventional glass-ionomer cement (GIC). Experimental GIC (EXP) samples were made from the acrylic 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. Specimens were mixed and fabricated at room temperature and were conditioned in distilled water at 37°C for 1 day up to 4 week. Ultrasound (US) was applied 20 s after mixing by placing the dental scaler tip on the top of the cement and applying light hand pressure to ensure the tip remained in contact with cement without causing any deformation. Vickers hardness was determined using a microhardness tester. The working and setting times were determined using a Gillmore needle. Water sorption was also investigated. Commercial Fuji IX was used as control for comparison (CON). The data obtained for the EXP GIC set through conventional set (CS) and ultrasonically set (US) were compared with the CON group, using one-way ANOVA and the Tukey multiple range test at ? = 0.05. Not only ultrasonic (US) application accelerated the curing process of both EXP cement and CON group but also improved the surface hardness of all the specimens. US set samples showed significantly lower water sorption values (P < 0.05) due to improved acid-base reaction within the GIC matrix and accelerated maturation process. According to the statistical analysis of data, significant increase was observed in the surface hardness properties of CS and US specimens both in EXP samples and the CON groups. It was concluded that it is possible to command set GICs by the application of ultrasound, leading to GICs with enhanced physical and handling properties. US application might be a potential way to broaden the clinical applications of conventional GICs in restorative dentistry for procedures such as class V cavity restorations. PMID:21769626

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

2011-09-01

63

Discolouration of glass-ionomer cement at different fluoride concentration levels.  

PubMed

Background: Although application of professionally applied Acidulated Phosphate fluoride (APF) gel is effective in prevention of dental caries, APF-induced discolouration and/or surface degradation of dental restorations has been reported. However, no publication has reported a dose-response effect of APF gel on Glass Ionomer Cement (GIC) restorations in vivo and/or human teeth. Therefore, this study aimed to examine the discolouration effect of APF gel at various concentration levels on GIC restorations of human teeth in vitro. Materials and Methods: Seventy extracted human teeth were used. Each was restored with GIC and then topically applied with a different dilution of APF gel. Change of shade and/or colour of restorations was assessed by a trained examiner. Results: GIC discolouration was detected on 4 (5.71%) and 23 specimens (32.86%) after the first and the second APF applications, respectively. The discolouration rate increased with APF gel concentration on the second application (?(2)=38.314, df=1, p<0.001) but not the first ( ?(2) =2.352, df=1, p=0.125). Discolouration of GIC restorations was more likely to form under application of a higher concentration of APF gel (OR=1.099, 95%CI=1.052, 1.148), a higher concentration of fluoride (OR=1.001, 95%CI=1.000, 1.001) and/or a lower pH value (OR=0.002, 95%CI=0.000, 0.039). Conclusions: Discolouration of GIC was associated with concentration and frequency of APF gel application in extracted natural human teeth in vitro. Increasing discolouration rates were related to increased fluoride concentration and increasing acidity of APF gel. Further investigation is indicated. PMID:24984633

Wang, Eric; Huang, Boyen

2014-06-01

64

Effect of Marginal Sealant on Shear Bond Strength of Glass Ionomer Cement: Used as A Luting Agent  

PubMed Central

Background: Moisture sensitivity and dissolution has been a known drawback of glass ionomer cement (GIC). When used as a luting agent for cementation of casted indirect restoration, the exposed cement at the margins is often a primary factor for marginal leakage and consequent failure of the restoration. The following in vitro study was planned to evaluate the effect of a marginal sealant on GIC used as luting agent. Materials and Methods: Sixty healthy extracted premolars were selected and prepared to receive metal-ceramic prosthesis. The prepared restorations were cemented using GIC and were divided randomly into two groups. The specimens in Group A were directly immersed in artificial saliva solution without any protection at the margins, while the exposed cement for Group B specimens was protected using a marginal sealant before immersing it in the artificial saliva solution. The specimens were tested after 24 h using a crown pull test on the universal testing machine to measure the shear bond strength of the cement. Result: The specimens in Group B showed statistically significant difference from the specimens in Group A with the mean shear bond strength of 6.60 Mpa and 5.32 respectively. Conclusion: Protection of GIC exposed at the margins of indirect cast restorations with a marginal sealant can significantly increase the longevity of the prosthesis by reducing the marginal leakage and perlocation of fluids. How to cite the article: Nazirkar G, Singh S, Badgujar M, Gaikwad B, Bhanushali S, Nalawade S. Effect of marginal sealant on shear bond strength of glass ionomer cement: Used as a luting agent. J Int Oral Health 2014;6(3):65-9

Nazirkar, Girish; Singh, Shailendra; Badgujar, Mayura; Gaikwad, Bhushan; Bhanushali, Shilpa; Nalawade, Sumit

2014-01-01

65

Degree of conversion and hardness of two different systems of the Vitrebond™ glass ionomer cement light cured with blue LED.  

PubMed

This study investigated the physicochemical properties of the new formulation of the glass ionomer cements through hardness test and degree of conversion by infrared spectroscopy (FTIR). Forty specimens (n = 40) were made in a metallic mold (4 mm diameter x 2 mm thickness) with two resin-modified glass ionomer cements, Vitrebond™ and Vitrebond™ Plus (3M/ ESPE). Each specimen was light cured with blue LED with power density of 500 mW/cm(2) during 30 s. Immediately after light curing, 24h, 48h and 7 days the hardness and degree of conversion was determined. The Vickers hardness was performed by the MMT-3 microhardness tester using load of 50 gm force for 30 seconds. For degree of conversion, the specimens were pulverized, pressed with KBr and analyzed with FT-IR (Nexus 470). The statistical analysis of the data by ANOVA showed that the Vitrebond™ and Vitrebond™ Plus were no difference significant between the same storage times (p > 0.05). For degree of conversion, the Vitrebond™ and Vitrebond™ Plus were statistically different in all storage times after light curing. The Vitrebond™ showed higher values than Vitrebond™ Plus (p < 0.05). The performance of Vitrebond™ had greater results for degree of conversion than Vitrebond™ Plus. The correlation between hardness and degree of conversion was no evidence in this study. PMID:23811653

Calixto, Luiz Rafael; Tonetto, Mateus Rodrigues; Pinto, Shelon Cristina Souza; Barros, Erico Damasceno; Borges, Alvaro Henrique; Lima, Fabricio Viana Pereira; de Andrade, Marcelo Ferrarezi; Bandéca, Matheus Coelho

2013-01-01

66

Removal of amalgam, glass-ionomer cement and compomer restorations: changes in cavity dimensions and duration of the procedure.  

PubMed

This study investigated changes in the dimensions of Class II cavities following the removal of amalgam, glass ionomer and compomer restorations. In 30 extracted caries-free human molars, preparation for 60 mesio-occlusal and occluso-distal cavities (two cavities per tooth) occurred. With a CEREC 3 laser triangulation sensor and software-based construction analysis, the dimensions of the cavities at seven defined sites were measured. The cavities were randomized into four groups. Group 1 was restored with Ketac-Fil glass-ionomer cement, Group 2 with amalgam and Group 3 with Compoglass F compomer. In Group 4, Compoglass F was used in combination with photochromic Tetric Flow Chroma as a cavity liner. The completed restorations were then removed using 2x magnification and the cavities were once again controlled using the laser system. The duration of the removal procedure was also recorded. Changes in cavity dimensions (depth, height and width) following removal of the restorations were significantly smaller in Groups 1 and 2. Groups 3 and 4 were characterized by a significant overextension of the cavities compared to Groups 1 and 2 in all three dimensions. Group 4, with Tetric Flow Chroma as a cavity liner, showed better results than Group 3, but this improvement was not statistically significant. The duration of the removal procedure was significantly shorter in Group 2 than in the other groups. PMID:12413228

Szep, Susanne; Baum, C; Alamouti, C; Schmidt, D; Gerhardt, T; Heidemann, D

2002-01-01

67

In vitro investigation of aluminum and fluoride release from compomers, conventional and resin-modified glass-ionomer cements: a standardized approach.  

PubMed

The amount of fluoride release from dental cements necessary for an anticariogenic effect is not established: moreover, the possible toxic effects due to high fluoride and aluminum release are not well known and the results are still controversial. The aim of our study was to evaluate fluoride (F) and aluminum (Al) release from dental cements using a 'standardized approach' according to the end-use of the materials, i.e. biocompatibility testing. Two polyacid-modified resin composites of recent application, commonly called compomers (Dyract and Dyract Cem), were compared with two conventional acid-based (Fuji I, Ketac-Cem) and two resin-modified (Vitremer, Vitrebond) glass-ionomer cements (GICs). All types of cement are used in dentistry and are commercially available. Extracts of the cements into minimum essential medium, after setting over a 1-h (group A) and 1-week (group B) period, were performed. The extraction conditions were rigorously standardized. Mean values +/- standard deviation of F- and Al-levels in such extracts were measured and were expressed as microg g(-1) (micrograms of ions per gram of cement). A great difference in the amount of ion release, both F and Al, was shown among the tested materials. The GICs, as well as Ketac-Cem, released more F and Al than the compomers. All of the materials released the greatest proportion of ions when the extraction was performed in the first hour after mixing (group A). Al- and F-values showed a highly significant positive correlation, independently from the curing time. We conclude that the biological assessment of dental cements can be performed only if a pre-evaluation of the leachables is obtained by applying a standardized protocol which allows a useful comparison between the different materials. PMID:10841280

Savarino, L; Cervellati, M; Stea, S; Cavedagna, D; Donati, M E; Pizzoferrato, A; Visentin, M

2000-01-01

68

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

69

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.  

PubMed

Retention of fixed partial dentures is mostly dependent upon the bond between metal and cement as well as cement and tooth structure. However, most of the time clinical failure of bond has been observed at metal and cement interface. The treatment of metal surface, prior to luting, plays a crucial role in bonding cement with the metal. This study is conducted to evaluate and compare the effect of different surface preparations on the bond strength of resin-modified glass ionomer cement with nickel-chromium metal ceramic alloy. Fifty caries-free extracted molar teeth were made flat until the dentin of the occlusal surface was exposed. After fabrication of the wax patterns and subsequent castings, the castings were subjected to porcelain firing cycles. The nickel-chromium metal ceramic alloy discs were also divided into five groups and subjected to various surface treatments: (1) Unsandblasted (U), (2) sandblasted (S), (3) sandblasted and treated with 10% aqueous solution of KMnO4 (SK), (4) unsandblasted and roughened with diamond abrasive points (UD) and (5) unsandblasted and roughened with diamond abrasive points and treated with 10% aqueous solution of KMnO(4) (UDK). After surface treatments, the castings were cemented using Fuji PLUS encapsulated resin-modified glass ionomer cement. The obtained values of all the groups were subjected to statistical analysis for Tensile and Shear bond strength. Different surface treatments of the metal affects the bond strength values of resin-modified glass ionomer cement when used as luting agent. PMID:22379300

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

2011-03-01

70

Effect of time on the diametral tensile strength of resin-modified restorative glass ionomer cements and compomer.  

PubMed

The aim of this study was to analyze the diametral tensile strengths of three resin-modified restorative glass ionomer cements--Vitremer, Fuji II LC and Photac Fil and one compomer--Dyract. They were tested at 1 hour, 1 day and 1 week. Kratos testing machine was used to load the specimens at a cross-head speed of 0.5 mm/min. The data were analyzed by two-way ANOVA and Tukey's test that showed statistically significant differences among the materials. The tested materials presented an increase in strength from 1 hour to 1 week and were as follows for each material respectively: Vitremer (19.22-27.29), Fuji II LC (23.91-28.67), Photac Fil (19.35-22.86), Dyract (28.83-46.95). Dyract presented the highest strengths. PMID:11696919

Cefaly, D F; Valarelli, F P; Seabra, B G; Mondelli, R F; Navarro, M F

2001-01-01

71

The use of laser-induced breakdown spectroscopy for the determination of fluorine concentration in glass ionomer cement  

NASA Astrophysics Data System (ADS)

The influence of He atmosphere and gate width in laser-induced breakdown spectroscopy (LIBS) determination of fluorine concentration was investigated in detail. The measurements were realized on two double pulse LIBS devices featuring different parameters. Calibration curves, describing the relationship between the fluorine concentration and the corresponding intensity of the LIBS signal, were constructed for both LIBS devices, with and without He flow, respectively. Detection limits achieved were in the range 1.18-0.47 wt.%. The best LOD value was obtained in He atmosphere. The LIBS measurement of fluorine content is influenced by different gate widths and the atmosphere in the working chamber. The proposed method was successfully applied to the determination of fluorine concentration in glass ionomer cements.

Kratochvíl, T.; Pouzar, M.; Novotný, K.; Havránek, V.; ?ernohorský, T.; Zvolská, M.

2013-10-01

72

Cytotoxicity evaluation of a new fast set highly viscous conventional glass ionomer cement with L929 fibroblast cell line  

PubMed Central

Aim: This study aims to evaluate the cytotoxicity of a new fast set highly viscous conventional glass ionomer cement (GIC) with L929 fibroblasts. Materials and Methods: The cement capsule was mixed and introduced into a paraffin wax mould. After setting, the cement was incubated in Dulbecco's Modified Eagle's Medium. Six replicates of the material extract were added to the culture medium in 96-well plates. L929 mouse fibroblast cells were added into the wells and then incubated for 48 h. Dimethylthiazol diphenyltetrazolium bromide test was performed for cytotoxicity evaluation. Results: The results showed that this GIC brand did not yield a half-maximal inhibitory concentration value, IC50, as the cell viability was above 50% at all concentrations. Cell viability over 90% was observed at the concentrations of 3.125 and 1.5625 mg/ml. Maximum concentration of the material showed cell viability of 59.4%. Conclusions: This new fast set highly viscous conventional GIC showed low cytotoxicity to mouse fibroblast cells, and it can be suggested as a substitute for dental cements exhibiting a long setting time.

Ahmed, Hany Mohamed Aly; Omar, Nor Shamsuria; Luddin, Norhayati; Saini, Rajan; Saini, Deepti

2011-01-01

73

Effect of acid and laser etching on shear bond strength of conventional and resin-modified glass-ionomer cements to composite resin.  

PubMed

Success in sandwich technique procedures can be achieved through an acceptable bond between the materials. The aim of this study was to compare the effect of 35% phosphoric acid and Er,Cr:YSGG laser on shear bond strength of conventional glass-ionomer cement (GIC) and resin-modified glass-ionomer cement (RMGIC) to composite resin in sandwich technique. Sixty-six specimens were prepared from each type of glass-ionomer cements and divided into three treatment groups as follows: without pretreatment, acid etching by 35% phosphoric acid for 15 s, and 1-W Er,Cr:YSGG laser treatment for 15 s with a 600-?m-diameter tip aligned perpendicular to the target area at a distance of 1 mm from the surface. Energy density of laser irradiation was 17.7 J/cm(2). Two specimens in each group were prepared for evaluation under a scanning electron microscope (SEM) after surface treatment and the remainder underwent bonding procedure with a bonding agent and composite resin. Then the shear bond strength was measured at a crosshead speed of 0.5 mm/min. Two-factor analysis of variance and post-hoc Tukey test showed that the cement type, surface treatment method, and the interaction of these two factors significantly affect the shear bond strength between glass-ionomer cements and composite resin (p < 0.05). Surface treatment with phosphoric acid or Er,Cr:YSGG laser increased the shear bond strength of GIC to composite resin; however, in RMGIC only laser etching resulted in significantly higher bond strength. These findings were supported by SEM results. The fracture mode was evaluated under a stereomicroscope at ×20. PMID:21234634

Navimipour, Elmira Jafari; Oskoee, Siavash Savadi; Oskoee, Parnian Alizadeh; Bahari, Mahmoud; Rikhtegaran, Sahand; Ghojazadeh, Morteza

2012-03-01

74

Effect of different light curing systems on the shear bond strength of resin-modified glass ionomer cement and polyacid-modified composite resin  

Microsoft Academic Search

The aim of this study was to determine in vitro shear bond strength of resin-modified glass ionomer cement (RMGIC) and polyacid-modified composite resin (PMCR) polymerized with conventional halogen light curing unit (LCU) or light emitting diode (LED). Twenty-four mandibular molar teeth were used. Enamel was removed from buccal and lingual surfaces of the teeth to expose superficial dentin. Teeth were

Oya Bala; Hacer Deniz Arisu; Bagdagul Helvacioglu Kivanc; Sara Samur

75

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

76

In vitro antibacterial effects of glass-ionomer cement containing ethanolic extract of propolis on Streptococcus mutans  

PubMed Central

Objective: The aim of this study was to evaluate the antibacterial property of glass-ionomer cement (GIC) containing propolis against Streptococcus mutans and its effect on the in vitro S. mutans biofilm formation. Methods: Ethanolic extract of propolis (EEP) was prepared at two concentrations as 25 and 50%. Three different experimental GIC disks were prepared using pure liquid and liquid solutions diluted with 25 and 50 percent of EEP concentrations. Minimum inhibitory concentration (MIC) of EEP on the growth of S. mutans ATCC 25175 was determined by using agar dilution method. Agar diffusion test and an in vitro S. mutans biofilm assay for GIC disks with and without EEP were performed. Results: MIC values of Turkish propolis for S. mutans ATCC 25175 was found as 25 ?g/mL. Experimental GICs containing propolis exhibited inhibition zones and their dry biofilm weights were less than the pure GIC. The bacterial density was lower in the GIC containing 50% EEP. Conclusions: A distinct antibacterial and antibiofilm efficacy of propolis containing GIC on S. mutans has been observed. Although further research is needed to show clinical results, antibacterial GIC containing propolis would be a promising material for restoration.

Topcuoglu, Nursen; Ozan, Fatih; Ozyurt, Mustafa; Kulekci, Guven

2012-01-01

77

Comparison of conventional and resin-modified glass-ionomer luting cements in the retention of post-crowns by fatigue loading.  

PubMed

Fatigue testing may be used for in vitro evaluation of luting cements, allowing comparison of materials under controlled conditions. It is recognized that glass-ionomer cements are materials which are susceptible to microcracking, even during curing prior to load application, and their failure can be related to crack propagation. The aim of this study was to compare the retention of post-crowns cemented with conventional and resin-modified glass-ionomer cements, the latter having significantly greater fracture toughness, under cyclic loads which are representative of physiological service. A custom-designed fatigue machine was used for three tests each comprising 18 specimens in a modified randomized complete block programme. Correlation of load amplitude to endurance was low, as expected from static test experience, but cement comparison was made through Kaplan-Meier survival and cumulative hazard functions. Differences in the performance of the cements were indicated, but were not statistically significant in this study, although analysis by Cox's proportional hazards model indicated that significance may be gained by a larger study. PMID:9687122

Mitchell, C A; Orr, J F

1998-06-01

78

Effect of novel chitosan-fluoroaluminosilicate resin modified glass ionomer cement supplemented with translationally controlled tumor protein on pulp cells.  

PubMed

Dental materials that can promote cell proliferation and function is required for regenerative pulp therapy. Resin modified glass ionomer cement (RMGIC), a broadly used liner or restorative material, can cause apoptosis to pulp cells mainly due to HEMA (2-hydroxyethyl methacrylate), the released residual monomer. Recent studies found that chitosan and albumin could promote release of protein in GIC while translationally controlled tumor protein (TCTP) has an anti-apoptotic activity against HEMA. The aim of this study was to examine the effect of chitosan and albumin modified RMGIC (Exp-RMGIC) supplemented with TCTP on pulp cell viability and mineralization. Exp-RMGIC+TCTP was composed of RMGIC powder incorporated with 15 % of chitosan, 5 % albumin and supplemented with TCTP mixed with the same liquid components of RMGIC. The effect of each specimen on pulp cells was examined using the Transwell plate. From the MTT assay, Exp-RMGIC+TCTP had the highest percentages of viable cells (P < 0.05) at both 24 and 74 h. Flow cytometry revealed that, after 24 h, Exp-RMGIC+TCTP gave the lowest percentages of apoptotic cells compared to other groups. There was no difference in alkaline phosphatase (ALP) activity among different formula of the specimens, while cells cultured in media with TCTP had higher ALP activity. Von Kossa staining revealed that RMGIC+TCTP, and Exp-RMGIC+TCTP had higher percentages of calcium deposit area compared to those without TCTP. It was concluded that Exp-RMGIC supplemented with TCTP had less cytotoxicity than RMGIC and can protect cells from apoptosis better than RMGIC supplemented with TCTP. PMID:24398913

Wanachottrakul, Nattaporn; Chotigeat, Wilaiwan; Kedjarune-Leggat, Ureporn

2014-04-01

79

Shear bond strength of resin-modified glass ionomer cements to Er:YAG laser-treated tooth structure.  

PubMed

This study evaluated the effect of Er:YAG laser irradiation of enamel and dentin on the shear bond strength of resin-modified glass ionomer cements (RMGIC). Twenty molars were selected and the roots removed. The crowns were bisected, embedded in polyester resin and ground to plane the enamel or expose the dentin. The bonding site was delimited, and samples were randomly assigned according to the cavity preparation device: I--Er.YAG laser (350mJ/2Hz); II--Carbide bur (control group). They were subdivided according to the restorative material employed: A) Fuji II LC (GC); B) Vitremer (3M). Samples were then fixed to a metallic device where ionomer cylinders were prepared. Sequentially, the molars were stored for 24 hours and subjected to a shear bond strength test (50Kgf at 0.5 mm/minute). Means in MPa were: Enamel--IA) 4.77 (+/- 1.12); IB) 4.36 (+/- 1.50); IIA) 7.70 (+/- 1.53); IIB) 7.34 (+/- 1.52) and Dentin--IA) 3.13 (+/- 1.15); IB) 2.67 (+/- 0.74); IIA) 6.38 (+/- 1.44); IIB) 5.58 (+/-2.09). Data were submitted to statistical analysis by ANOVA. Adhesion for enamel was more efficient than for dentin (p < 0.01). The cavities prepared with a conventional bur (control group) presented higher bond strength values than those recorded for Er:YAG laser (p < 0.01). No significant differences were observed between the restorative materials. Based on these results, it was concluded that Er:YAG laser adversely affected the shear bond strength of RMGIC for both enamel and dentin. PMID:16827024

de Souza-Gabriel, Aline Evangelista; do Amaral, Flávia Lucisano Botelho; Pécora, Jesus Djalma; Palma-Dibb, Regina Guenka; Corona, Silmara Aparecida Milori

2006-01-01

80

The effect of ytterbium fluoride and barium sulphate nanoparticles on the reactivity and strength of a glass-ionomer cement  

Microsoft Academic Search

ObjectivesWhile clinical advantages of glass-ionomers include fluoride release and radiopacity, disadvantages include low strength, slow initial setting times and opacity. The addition of nanoparticles, in particular those containing fluoride and cross-linkable ions, may mitigate the disadvantages while further improving the advantages. This investigation evaluated the effects of the addition of ytterbium fluoride (YbF3) and barium sulphate (BaSO4) on the strength

Leon H. Prentice; Martin J. Tyas; Michael F. Burrow

2006-01-01

81

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

82

Shear bond strength evaluation of resin composite bonded to glass-ionomer cement using self-etching bonding agents with different pH: In vitro study  

PubMed Central

Aim: To evaluate the bonding ability of composite to unset glass-ionomer cement (GIC) using different self-etching bonding systems. Materials and Methods: One hundred samples of composite bonded to unset GIC were prepared and were divided into four groups. In Group A, composite was bonded to unset GIC employing a strong (pH 1) self-etch primer was used. In Group B, intermediary strong (pH 1.4) self-etch primer was employed. In Group C and D, mild (pH 2) and (pH 2.2) self-etch primer was employed. Shear bond strength analysis was performed at a cross-head speed of 0.5 mm/min. Results: Statistical analysis performed with one way analysis of variance and Tukey's test showed that the bond strength of composite to unset GIC was significantly higher for the mild self-etch primer group. In addition, energy dispersive x-ray (EDX) analysis was used to determine the composition of various structural phases identified by FE-SEM along the GIC-bonding agent interfaces. Conclusion: Hence this present study concludes that clinically the use of mild self-etching bonding agent over unset GIC has improved bond strength compared to the use of strong and intermediate self-etching bonding agent.

Kandaswamy, Deivanayagam; Rajan, Karunamoorthy Jeyavel; Venkateshbabu, Nagendrababu; Porkodi, Ilango

2012-01-01

83

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.

Kemoli, Arthur M

2014-01-01

84

In vitro evaluation of the marginal microleakage of amalgam restorations associated with dentin adhesive, glass ionomer cement and cavity varnish by means of different evaluation methods.  

PubMed

This in vitro study evaluated the marginal microleakage of amalgam restorations associated with the cavity varnish Copalite - Cooley & Cooley (GI-CP), dentin adhesive OptiBond Solo - Kerr (GII-OS) and the glass ionomer cement Vitremer - 3M (GIII-VT). Forty-five premolars were employed, which were submitted to independent class II preparations at the mesial and distal aspects comprising the marginal ridges and were restored with Dispersalloy - Dentsply. Afterwards, the teeth were thermocycled and stored in 0.5% basic fuchsine for 24 hours. The evaluations were conducted on a light microscope with 150x magnification and on the Sigma Scan software with employment of a single line and segmented lines. Data analysis allowed to establish that none of the materials was able to eliminate the marginal microleakage, having the GI - CP presented greater and statistically significant values in relation to the other groups in all evaluation methods (p<0.05). The lowest values were displayed by the GIII-VT, yet with no statistically significant difference when compared to GII-OS, except for the evaluation at the Sigma Scan in single line. The three evaluation methods showed a strong positive relationship to each other. PMID:20944873

Hoshi, Adriano Tomio; Silva, Salete Moura Bonifácio da; Pavarini, Aymar

2005-03-01

85

Microleakage in restorations with glass ionomer liners after thermocycling.  

PubMed

The purpose of this study was to compare microleakage around two types of restorations lined with polyalkenoate (glass ionomer) cements after thermocycling. Preparations were made in 48 molars to a diameter and depth of 2.0 mm. Half of the preparations were lined with glass ionomer, and the remainder were not lined. Dental amalgam or glass ionomer restorative material was placed and the amalgams were left unburnished and unpolished. Selected restorations were thermocycled 625 times between 4 degrees C and 50 degrees C. Teeth were immersed in 0.5 per cent methylene blue solution, sectioned and visually scored for microleakage at X 100 magnification. Data analysis indicated significant differences in microleakage because of: thermocycling (chi 2 = 103.38, d.f. = 19,2P less than 0.0004); presence of glass ionomer liners (chi 2 = 53.28, d.f. = 19,2P less than 0.0001); and type of restorative material (chi 2 = 103.44,d.f. = 19,2P less than 0.0004). The use of a glass ionomer liner significantly reduced microleakage in both amalgam and glass ionomer restorations when subjected to thermocycling. PMID:2347987

Arcoria, C J; Vitasek, B A; DeWald, J P; Wagner, M J

1990-04-01

86

Glass-ionomer dental restorative: part I: a structural study.  

PubMed

A structural study of glass-ionomer cement (GIC) dental restoratives has been completed. Transmission electron microscopy, selected area electron diffraction, and X-ray diffraction studies indicate domain-like microstructure in a new experimental material, whereas a featureless amorphous gel-like microstructure exists in the conventional GIC. Nuclear magnetic resonance studies were also conducted. The new experimental GIC contains domains of (i) bonelike material (apatite), (ii) mesoporous material and (iii) other framework structures (aluminium phosphate in the high cristobalite structure), with its setting chemistry a restructuring of the aluminosilicate glass around the template of poly(acrylic acid). Conventional glass-ionomer cement may set by a similar but slower process. Leaching properties of glass-ionomer cements are also explained. PMID:15348734

Milne, K A; Calos, N J; O'Donnell, J H; Kennard, C H; Vega, S; Marks, D

1997-06-01

87

Effect of Ascorbic Acid on Shear Bond Strength of Orthodontic Brackets Bonded with Resin-modified Glass-ionomer Cement to Bleached Teeth  

PubMed Central

Background and aims Bleaching can considerably reduce shear bond strength (SBS) of orthodontic brackets bonded with composite adhesives. Application of antioxidants is a method to reverse the negative effect of bleaching on composite-to-enamel bond. However, the efficacy of antioxidants in increasing the SBS of brackets bonded using resin-modified glass-ionomer cement (RMGIC) has not been studied, which was the aim of this study. Materials and methods Fifty freshly extracted human maxillary first premolars were bleached with 35% hydrogen peroxide (Pola Office Bleaching, SDI). Sodium ascorbate 10% was applied to the experimental specimens (n=25). All the specimens were etched with 37% phosphoric acid (Ivoclar/Vivadent) and bonded using RMGIC (Fuji Ortho LC, GC). The specimens were subjected to incubation (37°C, 24h) and thermocycling (1000 cycles, 5-55°C, dwell time = 1 min). The SBS was measured at 0.5 mm/min debonding crosshead speed. The adhesive remnant index (ARI) was scored under ×10 magni-fication. Data were analyzed using Mann-Whitney U test, one- and independent-samples t-test, and Fisher’sexact test (?=0.05). Results The mean SBS of experimental and control groups were 11.97 ± 4.49 and 7.7 ± 3.19 MPa, respectively. The dif-ference was statistically significant (P=0.000 by t-test). SBS of both control (P=0.014) and experimental (P=0.000) groups were significantly higher than the minimum acceptable SBS of 6 MPa, according to one-sample t-test. Conclusion Application of ascorbic acid can guarantee a strong bond when RMGIC is to be used. However, RMGIC might tolerate the negative effect of bleaching with minimum SA treatments (or perhaps without treatments), which de-serves further studies.

Khosravanifard, Behnam; Rakhshan, Vahid; Araghi, Solmaz; Parhiz, Hadi

2012-01-01

88

A comparative evaluation of the retention of metallic brackets bonded with resin-modified glass ionomer cement under different enamel preparations: A pilot study  

PubMed Central

Introduction: For orthodontists, the ideal bonding material should be less moisture-sensitive and should release fluoride, thereby reducing unfavorable iatrogenic decalcification. Resin-Modified Glass Ionomer Cements (RMGICs), due to their ability to bond in the presence of saliva and blood can be a very good bonding agent for orthodontic attachments especially in the areas of mouth, which are difficult to access. Moreover, their fluoride releasing property makes them an ideal bonding agent for patients with poor oral hygiene. However, their immediate bond strength is said to be too low to immediately ligate the initial wire, which could increase the total number of appointments. The effect of sandblasting and the use of sodium hypochlorite (NaOCL) on the immediate bond failure of RMGIC clinically have not been reported in the literature until the date. This investigation intended to assess the effect of sandblasting (of the bracket base and enamel) and NaOCL on the rate of bond failure (with immediate ligation at 30 min) of Fuji Ortho LC and its comparison with that of conventional light cured composite resin over a period of 1 year. Materials and Methods: 400 sample teeth were further divided into 4 groups of 100 each and bonded as follows: (1) Group 1: Normal metallic brackets bonded with Fuji Ortho LC. (2) Group 2: Sandblasted bracket base and enamel surface, brackets bonded with Fuji Ortho LC. (3) Group 3: Deproteinized enamel surface using sodium hypochlorite and brackets bonded with Fuji Ortho LC. (4) Group 4: Normal metallic bracket bonded with Transbond XT after etching enamel with 37% phosphoric acid. This group served as control group. Results and Conclusion: Results showed that sandblasting the bracket base and enamel, can significantly reduce the bond failure rate of RMGIC.

Sharma, Padmaja; Valiathan, Ashima; Arora, Ankit; Agarwal, Sachin

2013-01-01

89

An evaluation of accelerated Portland cement as a restorative material  

Microsoft Academic Search

Biocompatibility of two variants of accelerated Portland cement (APC) were investigated in vitro by observing the cytomorphology of SaOS-2 osteosarcoma cells in the presence of test materials and the effect of these materials on the expression of markers of bone remodelling. Glass ionomer cement (GIC), mineral trioxide aggregate (MTA) and unmodified Portland cement (RC) were used for comparison. A direct

D. Abdullah; T. R. Pitt Ford; S. Papaioannou; J. Nicholson; F. McDonald

2002-01-01

90

Reinforcement of conventional glass-ionomer restorative material with short glass fibers.  

PubMed

This study investigated the strengthening effect of glass fibers when added to conventional glass-ionomer restorative material. Glass fibers were incorporated into glass-ionomer powder in 3 wt% and 5 wt%. The fibers used had 1 mm length and 10 microm thickness. These criteria of fiber length, diameter, and concentration represent a new approach for reinforcing conventional glass-ionomer [Medifill, conventional restorative glass-ionomer]. The mechanical properties tested were diametral tensile strength, hardness, flexural strength, flexural modulus and fracture toughness after 24-h and 7-days of storage in deionized water. Glass short fibers were mixed thoroughly into the glass-ionomer powder before mixing with the cement liquid. Samples of specific dimensions were prepared for each time interval and fiber loading according to the manufacturer's instructions and international standards. Hardness was measured using a micro-hardness tester at 100 gram applied load for 15 s. The other mechanical properties were measured using a Lloyd universal testing machine. The results showed increased diametral tensile strength, flexural strength, flexural modulus, and fracture toughness by the addition of glass fibers. There was an appreciable increase of the tested mechanical properties of glass-ionomer restorative material as a result of increasing fiber loading and water storage for 1 week. It was concluded that conventional glass-ionomer can be reinforced by the addition of short glass fibers. PMID:19627810

Hammouda, Ibrahim M

2009-01-01

91

Dental composites/glass ionomers: the materials.  

PubMed

Most commercial dental composites contain liquid dimethacrylate monomers (including BIS-GMA or variations of it) and silica-containing compositions as inorganic reinforcing filler particles coated with methacrylate-functional silane coupling agents to bond the resin to the filler. They also contain initiators, accelerators, photo-initiators, photosensitizers, polymerization inhibitors, and UV absorbers. Durability is a major problem with posterior composites. The typical life-span of posterior composites is from three to 10 years, with large fillings usually fewer than five years. Polymerization shrinkage and inadequate adhesion to cavity walls are remaining problems. Some pulp irritation can occur if deep restorations are not placed over a protective film. Some have advocated the use of glass-ionomer cement as a lining under resin composite restorations in dentin. The concept of glass-ionomer cements (GICs) was introduced to the dental profession in the early 1970's. Current GICs may contain poly(acrylic acid) or a copolymer. Higher-molecular-weight copolymers may also be used to improve the physical properties of some GICs. Stronger and less-brittle hybrid materials have been produced by the addition of water-soluble compatible polymers to form light-curing GIC formulations. The ion-leachable aluminosilicate glass powder, in an aqueous solution of a polymer or copolymer of acrylic acid, is attacked by the hydrated protons of the acid, causing the release of aluminum and calcium ions. Salt bridges are formed, and a gel matrix surrounds the unreacted glass particles. The matrix is adhesive to mineralized tissues. Provisions must be made for maintenance of the water balance of restorations for the first 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1292462

Bowen, R L; Marjenhoff, W A

1992-09-01

92

Influence of ultrasound, with and without water spray cooling, on removal of posts cemented with resin or glass ionomer cements: An in-vitro study  

PubMed Central

Aims/objectives: To evaluate in vitro the ultrasonic vibration efficacy with and without water spray cooling on the reduction of the amount of force necessary to dislodge the cast posts cemented with resin cement and to compare it with those cemented with GIC Type I luting cement. Materials and Methods: Sixty samples were divided into six groups: groups 1, 2, 3, posts cemented with GIC; groups 4, 5, 6, posts cemented with resin; groups 1 and 4 (controls), no ultrasound; groups 2 and 5, ultrasound without water spray; and groups 3 and 6, ultrasound with water spray. Instron testing machine was used to dislodge the posts from the root canals and the data was statistically analyzed. Results: Ultrasound with water spray (group 3) among the GIC groups reduced the traction force necessary to extract posts by 53.33% whereas ultrasound without water spray (group 5) among the resin groups reduced by 59.5% compared to control. Conclusion: Ultrasound with water is more effective in removing posts cemented with GIC because of the ultrasonic energy being transferred to the post. Ultasonics without water is more effective in removing posts fixed with resin cement probably by the indirect action of heat production.

Adarsha, M S; Lata, D A

2010-01-01

93

Materials for restoration of primary teeth: I. Conventional materials and early glass ionomers.  

PubMed

This paper demonstrates how the treatment of primary dentition may present the clinician with increased difficulties compared with the preparation and placement of restorations in adult dentition. Established dental materials (dental amalgam and conventional glass ionomer cements) and less well established alternative materials (copper cements) are reviewed. The use of amalgam to restore primary dentition is the subject of concern amongst the dental profession in terms of lack of adhesion and potential toxicity concerns, while the low tensile strength of traditional glass ionomer cements make them less suitable for the restoration of primary dentition. PMID:11862849

Fleming, G J; Burke, F J; Watson, D J; Owen, F J

2001-12-01

94

Tunnel restorations using glass ionomer or glass cermet: in vitro marginal ridge fracture and microleakage.  

PubMed

The purpose of this in vitro study was to compare the marginal ridge fracture resistance and microleakage following restorations of partial tunnel preparations using glass ionomer and glass cermet cements. Sixty eight sound premolars were selected for this study and were divided randomly into six groups. A standardized partial tunnel preparation was done on all the teeth except specimens belonging to Group I. The partial tunnel preparations of Groups III & V were restored with glass ionomer and that of Groups IV & VI were restored with glass cermet. The teeth belonging to Groups I, II, III & IV were subjected to marginal ridge fracture resistance testing. The teeth of Groups V & VI were tested for microleakage after immersing them in 5% methylene blue solution for 4 hours. The results indicated that the teeth restored with glass cermet were marginally better than that with glass ionomer in terms of marginal ridge fracture resistance. Both the materials failed to reinforce the marginal ridge to the level of an intact tooth. The microleakage which occurred around both the materials were statistically insignificant, but on comparison glass ionomer showed better results. Hence, glass ionomer is preferred as a restorative material for partial tunnel preparations because of additional inherent advantages like superior esthetics and fluoride leachability. PMID:9161212

Shetty, R; Munshi, A K

1996-01-01

95

In vivo biocompatibility versus degree of conversion of resin-reinforced cements in different time periods.  

PubMed

This study focused on test the null hypothesis that there is no difference between the degree of conversion and biocompatibility of different resin reinforced glass ionomer cements (RRGICs). Forty-eight male Wistar rats were used, distributed into four groups (n?=?12), as follows: Group C (Control, polyethylene), Group FOB (Fuji Ortho Band), Group UBL (Ultra band Lok), and Group MCG (Multicure Glass), in subcutaneous tissue. The events of edema, necrosis, granulation tissue, multinuclear giant cells, young fibroblasts, and collagen formation were analyzed at 7, 15, and 30 days. The degree of conversion was evaluated by the Fourier method. Biocompatibility and degree of conversion were assessed using the Kruskal-Wallis and Dunn tests, and ANOVA and Tukey's test, respectively (P?

Lacerda-Santos, Rogério; De Farias, Maria Isabel Serpa Simões; De Carvalho, Fabiola Galbiatti; Pithon, Matheus Melo; Alves, Pollianna Muniz; Tanaka, Orlando Motohiro; Guênes, Gymenna Maria Tenório

2014-05-01

96

Acid base surface properties of glass-ionomers determined by IGC  

NASA Astrophysics Data System (ADS)

SummaryThe surface properties of several glass-ionomer restorative dental materials (GC Fuji, Chemadent G-J, Ketac Fil and Ketac Molar) were investigated by means of inverse gas chromatography. The capacity of the surface of glass-ionomers to undergo specific interactions was expressed using the specific component of free energy ? Gs as well as the parameters KA and KD to describe the ability of the cement to act both as an electron acceptor and an electron donor, respectively. The character of the examined surface was expressed with the use of the SC parameter. All these parameters were determined with a high degree of precision. It was found that the surface of glass-ionomer cements had a well-marked acidic character. The ability of the cement surface to take part in specific interactions differed with the various types of commercial products. The surface activity of the glass-ionomers investigated changed with the storage time (up to 6 months) indicating an on-going setting reaction.

Voelkel, A.; Andrzejewska, E.; Limanowska-Shaw, H.; Andrzejewski, M.

2005-05-01

97

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.

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

2013-01-01

98

Fuji III vs. Fuji VII glass ionomer sealants--a clinical study.  

PubMed

Glass ionomer cements possess several properties that support their consideration in a wide variety of clinical applications including Pit and fissure sealants. The aim of this study was to compare and evaluate Fuji III and Fuji VII glass ionomer sealants in terms of retention, caries incidence and salivary fluoride release between two groups of children aged 6 and-8 years respectively. One hundred and ten first permanent molars were sealed and the clinical evaluation showed no incidence of caries. There was partial or complete retention of the sealant in 80% of the treated teeth in both groups at the one-year evaluation. Irrespective of the sealant used, the pattern of fluoride release remained consistent, with an initial high fluoride release followed by low prolonged leakage before returning to baseline value at the end of one year. PMID:19093648

Kamala, B K; Hegde, Amitha M

2008-01-01

99

Comparative evaluation of microleakage in conventional glass ionomer cements and triclosan incorporated glass ionomer cements  

PubMed Central

Aim and Objective: The aim of the following study is to comparatively evaluate the microleakage of triclosan incorporated GIC with conventional restorative GIC. Materials and Methods: Triclosan in powder form was added to conventional GIC to formulate a concentration of 2.5%. Class five cavities were prepared in non-carious extracted molars and were respectively restored with conventional restorative GIC and triclosan incorporated GIC. Samples were kept in 10% methylene blue dye. Ground sections were obtained and were observed under a binocular microscope for dye penetration. Result: No significant difference was found in the microleakage of two groups. Conclusion: Triclosan incorporated GIC can be considered as an alternative to GIC with enhanced antibacterial property.

Somani, Rani; Jaidka, Shipra; Jawa, Deepti; Mishra, Shreya

2014-01-01

100

An ex vivo study to evaluate the remineralizing and antimicrobial efficacy of silver diamine fluoride and glass ionomer cement type VII for their proposed use as indirect pulp capping materials - Part I  

PubMed Central

Aim: Indirect pulp capping (IPC) preserves the pulp vitality by disinfecting and remineralizing remaining carious dentin. In the present study, glass ionomer (GC, FUJI VII) and silver diamine fluoride (SDF) were tested and compared to calcium hydroxide for their antimicrobial efficacy and remineralizing potential. Materials and Methods: Dentin disks prepared from 45 freshly extracted first premolars were divided into three groups (n = 15). Each disk was cut into two equal parts, in which one half formed the control. Thirty dentin samples were used for ion estimation and the other 15 for microhardness testing. Atomic absorption spectrophotometry, colorimetric and potentiometric titration analyses were performed for calcium, phosphate and fluoride ion detection, respectively. The antimicrobial efficacy was analyzed using pure culture of Streptococcus mutans and mixed flora. Results: Increase in the levels of calcium and phosphate ions was the highest in calcium hydroxide group. Both SDF and GC VII groups showed significant increase in fluoride ion levels. Samples treated with GC VII showed maximum increase in micro hardness. The highest zone of bacterial inhibition was found with SDF group. Conclusions: This in vitro study documented the remineralizing, re-hardening and antimicrobial efficacy of both SDF and GC VII and hence can act as effective IPC materials.

Gupta, A; Sinha, N; Logani, A; Shah, N

2011-01-01

101

Biocompatibility of retrograde root filling materials: a review.  

PubMed

The aim of a retrograde filling material is to fill the apical canal space and to obtain a hermetic seal between the periodontium and the root canal system. Several materials have been suggested for root-end filling including: amalgam, gutta-percha, zinc oxide-eugenol cements, glass ionomer cement, gold foil pellets, Cavit, composite resin and mineral trioxide aggregate (MTA). Super-ethoxy benzoic acid and MTA are the most suitable materials and provide better results in apicoectomy procedures than other filling materials. Unfortunately, the ideal material for this purpose has yet to be found. This article is a review of the biocompatibility of retrograde filling materials. PMID:18352901

Bodrumlu, Emre

2008-04-01

102

Physicomechanical properties of a zinc-reinforced glass ionomer restorative material.  

PubMed

We compared a zinc-reinforced glass ionomer restorative material (ChemFil Rock) with three commercially available glass ionomer cements (GICs), namely, Fuji IX GP Extra, Ketac Molar Quick Aplicap, and EQUIA Fil, with respect to fracture toughness, microhardness, roughness, and abrasive wear. Fracture toughness (KIC) was tested according to ISO 13586 (n = 10). Hardness, roughness, and abrasive wear were also tested (n = 9). Data were analyzed using the Wilcoxon rank-sum test with adjustment for multiple comparisons (? = 0.05). As compared with the other GICs ChemFil Rock exhibited a greater increase in surface roughness (P < 0.05) and lower microhardness (P < 0.01). The wear resistance of ChemFil Rock was comparable to that of the other GICs (P > 0.05). ChemFil Rock had significantly lower fracture toughness as compared with EQUIA Fil (P = 0.01) and significantly higher fracture toughness as compared with the other GICs (P < 0.02). In conclusion, as compared with the three other commercially available GICs, ChemFil Rock had intermediate fracture toughness, the lowest microhardness, and the greatest change in surface roughness. PMID:24739702

Al-Angari, Sarah S; Hara, Anderson T; Chu, Tien-Min; Platt, Jeffrey; Eckert, George; Cook, N Blaine

2014-01-01

103

Resin-modified glass ionomer restorations in primary molars: a comparison of three in vitro procedures.  

PubMed

In recent years, interest in the use of glass ionomer cements as a restorative material has been increased. The aim of this in vitro study was to evaluate the microleakage of a glass ionomer restorative material (Vitremer TM) in Class V cavities of primary molars using three different application procedures. The experimental material consisted of 24 freshly extracted human primary molars in which a standardized class V cavities were prepared and restored with Vitremer utilizing three different application procedures (Vitremer with conditioner, with conditioner and primer or with primer). Teeth were covered with green stick compound and nail polish except approximately 1 mm from the class V cavities margins. Later, teeth were immersed in 5% methylene blue for 4 hours, rinsed with water and embedded in acrylic resin. The marginal microleakage was assessed according to the degree of dye penetration of the occlusal and cervical margins. The results showed no significant difference between the three different application procedures. However, the occlusal margin microleakage was significantly higher than the cervical margin (P = 0.0079). It was concluded that using different application procedures of Vitremer, including the recommendations of the manufacturer does not affect microleakage of class V cavities in primary molars. PMID:9161211

al-Obaidi, F F; Salama, F S

1996-01-01

104

Marginal ridge fracture resistance, microleakage and pulpal response to glass ionomer/glass cermet partial tunnel restorations.  

PubMed

Sixty sound premolars which were to be extracted for orthodontic treatment purposes were restored either with glass ionomer cement or glass cermet cements after partial tunnel preparation, and prior to the extraction after a time interval of 30 and 60 days respectively. The teeth were then subjected to marginal ridge fracture resistance, microleakage study using dye penetration and histological evaluation of the pulpal response to these materials. Both the materials exhibited increase in marginal ridge fracture resistance at 60 days, with minimal degree of microleakage and were biologically compatible with the dental pulp. PMID:9484134

Prabhu, N T; Munshi, A K; Shetty, T R

1997-01-01

105

A comparative evaluation of dental luting cements by fracture toughness tests and fractography.  

PubMed

In recent years there has been a shift from traditional methods of investigating dental materials to a fracture mechanics approach. Fracture toughness (KIC) is an intrinsic material property which can be considered to be a measure of a material's resistance to crack propagation. Glass-ionomer cements are biocompatible and bioactive dental restorative materials, but they suffer from poor fracture toughness and are extremely susceptible to dehydration. The main objective of this study was to evaluate the fracture toughness of three types of commercially available dental cements (polyacid-modified composite resin, resin-modified and conventional glass ionomer) using a short-rod chevron-notch test and to investigate and interpret the results by means of fractography using scanning electron microscopy. Ten specimens of each cement were fabricated according to manufacturers' instructions, coated in varnish, and stored at ambient laboratory humidity, 100 per cent relative humidity, or in water at 37 degrees C for 7 days prior to preparation for testing. Results indicated that significant differences existed between each group of materials and that the fracture toughness ranged from 0.27 to 0.72 MN/m3/2. It was concluded that the resin-modified glass-ionomer cement demonstrated the highest resistance to crack propagation. Fractographs clearly showed areas of stable and unstable crack growth along the fractured surfaces for the three materials examined. PMID:11323987

Ryan, A K; Orr, J F; Mitchell, C A

2001-01-01

106

Biocompatibility of a new pulp capping cement  

PubMed Central

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

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

2014-01-01

107

The use of glass ionomer in special needs patients.  

PubMed

Placement of restorations for patients who are physically or intellectually disabled or mentally ill can pose considerable difficulties for the general practitioner. Access to the oral environment is often limited and patient tolerance and concentration may be reduced to rather brief periods of time. Oral hygiene routines may be less than ideal leading to a high caries rate. Enamel surfaces which do not normally become carious can develop broad but shallow lesions with a poorly defined outline. Selection of the most suitable restorative material will be important, with longevity of the restoration as the prime consideration. Other factors such as access, isolation of the lesion and patient co-operation must also be taken into account. Also, forces acting on restorative materials may be less than usual due to poor occlusion, teeth opposing dentures or being completely unopposed. Restoration by indirect techniques will often not be possible so the choice will be limited to the three plastic restorative materials normally used in restorative dentistry: amalgam, resin composite and glass ionomer. As a result of clinical experience it is suggested that glass ionomer will often be the material of choice. This paper describes five years experience with the resin-modified glass ionomers in an institutional practice which is limited to patients with special needs. Clinical significance Placement of restorations, with a reasonable expectation of longevity, can pose considerable problems for the patient with special needs. Resin-modified glass ionomer is a useful alternative material and has been placed with a high degree of success over a period of five years. PMID:10687236

Gryst, M E; Mount, G J

1999-12-01

108

Synthesis and application of novel multi-arm poly(carboxylic acid)s for glass-ionomer restoratives.  

PubMed

We have developed a novel glass-ionomer cement system composed of multi-arm poly(acrylic acid-co-itaconic acid)s. These polyacids were synthesized via a chain-transfer polymerization reaction using newly synthesized multi-arm chain-transfer agents. The cements formulated with the multi-arm polyacids showed significantly lower viscosities in water as compared to those formulated with the linear polyacids. Due to the lower viscosities, the MW of the polyacids can be significantly increased for enhanced mechanical strengths, while keeping the ease of mixing and handling. The experimental cements showed significantly improved compressive strengths as compared to Fuji II after aged in water for 3 months. PMID:19033326

Xie, Dong; Zhao, Jun; Weng, Yiming

2010-01-01

109

N-vinylpyrrolidone modified glass-ionomer resins for improved dental restoratives  

NASA Astrophysics Data System (ADS)

The studies described in this dissertation focus on improvement of mechanical properties of current glass-ionomer cements. Thermal properties and microstructures of the cements were correlated with their mechanical strengths. The first study evaluated mechanical properties of selected commercial glass-ionomer cements and examined their microstructures. The results showed that resin-modified glass-ionomer cements (RM GICs) exhibited much higher flexural (FS) and diametral tensile strengths (DTS), compared to conventional GICs (C GICs). In addition, they exhibited comparable compressive strength (CS), relatively low microhardness and less wear resistance than C GICs. The C GICs exhibited brittle behavior, whereas the RM GICs underwent substantial plastic deformation in compression. The mechanical properties of the GICs were closely related to their microstructures. Factors such as the density of the microstructure, the integrity of the interface between the glass particles and polymer matrix, particle size and the number and size of voids have important roles in determining the mechanical properties. The second study evaluated thermal properties of these GICs. The results showed that the RM GICs exhibited higher thermal transition temperatures than those of the C GICs, thermal expansion coefficients of these cements were close to those of human teeth, and the indentation creep of the RM GICs were higher than the C GICs. The third study explored and evaluated the effect of a water-soluble monomer, N-vinylpyrrolidone (NVP), on the performance of current C GICs, indicating a significant improvement in both mechanical and working properties. The fourth study demonstrated the process of determining the optimal molar ratio of the NVP-containing copolymers, using design of experiment. The results showed that the optimal molar ratio for these copolymers was 7:1:3 for poly(acrylic acid-co-itaconic acid-co-N-vinylpyrrolidone), based on the FS test. The molar ratio of 8:2:1 (AA:IA:NVP) was considered as the best molar ratio for these copolymers, based on the DTS and CS tests. The fifth study formulated the NVP-containing RM GICs using a statistical design of experiment. The results indicated that the best graft ratio for 2-isocyanatoethyl methacrylate (IEM) in this system was 15% of the terpolymer by a molar ratio. The optimal formulation was found to be at the weight ratio of 55:15:30 (RM NVP-containing terpolymer: 2-hydroxyethyl methacrylate (HEMA): Hsb2O). Stress-strain curves showed that a relatively high amount of water in the formulation led to higher elastic modulus and proportional limit and lower malleability, whereas a relatively high amount of HEMA gave the opposite results. The sixth study evaluated the NVP modified GICs (NVPM GICs) with the best molar ratios and optimal formulations in the mechanical, thermal and working properties. The results showed that the effect of molecular weight on mechanical properties of the NVPM GICs were evident. Different glass powders exhibited different effects on properties of the NVPM GICs, due to different compositions, size and affinity. Powder/liquid ratios had significant effects on the mechanical properties of NVPM GICs, especially on FS. P/W ratios are only beneficial to the NVPM GICs mixed with the Fuji II glass powders. The NVPM GICs showed a higher WT than the models, due to water retention of the NVP ring. Thermal expansion coefficients for the NVPM GICs were close to those for the natural tooth. Mismatch between the glass powders used and the polymer matrix was a big concern in this study and should be solved in the future.

Xie, Dong

110

Early erosion of dental cements.  

PubMed

The disintegration in water of various unset glass ionomer cements, a polycarboxylate and a zinc phosphate cement was measured gravimetrically after exposure of the cements to a constant water jet. The test gave reproducible results with significant variations between the various types and brands of cements. For zinc phosphate and polycarboxylate cements, no weight loss was observed in the period from 4 to 8 min after commencement of mixing. All the glass ionomer cements showed a significant loss of weight at 4 min and a somewhat reduced weight loss at 6 min after start of mixing. Two cements, a filling and a luting material, showed reduced weight when exposed to a water jet even 8 min after start of mixing. The early erosion as recorded in the present study conforms with the setting of the glass ionomer cements. PMID:6597538

Oilo, G

1984-12-01

111

The effect of saliva on surface hardness and water sorption of glass–ionomers and “compomers”  

Microsoft Academic Search

A study is reported in which commercial dental materials (glass–ionomers, resin-modified glass–ionomer and polyacid-modified composite resins) in the form of discs of dimensions 6 mm diameter×1 mm thickness were prepared and exposed to natural salivas (parotid and unstimulated whole), artificial saliva and water for up to 1 year. Surface hardness was measured at various time intervals, and water sorption characteristics

M. Aliping-McKenzie; R. W. A. Linden; J. W. Nicholson

2003-01-01

112

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

113

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

114

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

115

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

PubMed Central

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

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

2014-01-01

116

The biocompatibility of porous vs non-porous bone cements: a new methodological approach.  

PubMed

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

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

2014-01-01

117

Microleakage of resin-modified glass ionomer restorations with selective enamel etching.  

PubMed

SUMMARY Aim : Bonding of resin-modified glass ionomers to enamel is an important quality, especially when saliva contamination is inevitable. This study evaluated if microleakage of a resin-modified glass ionomer improves with selective enamel etching, with or without saliva contamination. Methods : Class V cavities with the occlusal margin in enamel and the gingival margin on the root were prepared in extracted human permanent teeth and filled with a resin-modified glass ionomer using an acidic primer according to the manufacturer's recommendation or with an additional selective enamel etching step. Preparations were contaminated with saliva before primer application or before restoration placement (n=10). Restored teeth were thermocycled between 5°C and 55°C for 1000 cycles, stained with basic fuchsin, and sectioned. Microleakage distance was measured and analyzed with analysis of variance followed by Duncan post hoc test at a significance level of 0.05. Results : Enamel microleakage was highest when saliva contamination occurred before the placement of resin-modified glass ionomer. Microleakage distances were significantly reduced in the selective etching groups regardless of saliva contamination. However, selective etching of enamel increased microleakage in cementum. The increase in cementum leakage was significantly higher when saliva contamination occurred before restoration placement. Conclusion : Selective etching reduces enamel microleakage of a resin-modified glass ionomer even with saliva contamination, but it may increase microleakage at the cementum. The severity of microleakage is affected by the timing of saliva contamination. PMID:24967989

Ludlow, Sw; Farmer, Sn; Donaldson, Me; Tantbirojn, D; Versluis, A

2014-01-01

118

Effect of Vital Bleaching on Disintegration Tendency of Glass Ionomer Restorations  

PubMed Central

Introduction: This study was designed to assess the effect of two bleaching agents on the disintegration tendency of three types of glass ionomers. Materials and Methods: A total of 90 specimens were prepared by using a split Teflon ring with an internal diameter of 5 mm and a thickness of 2 mm. The tested materials were applied and bleached according to manufacturer’s instructions. Dissolution measurements were made by calculating weight loss through different periods of the test; (one week, one month and three months) and they were analyzed by using one-way analysis of variance (ANOVA), followed by Tukey’s post-hoc test. Results: All glass ionomer materials exhibited a degree of dissolution. Opalescence Xtra increased the dissolution of Photac Fil and F2000 significantly, while Opalescence Quick had no effect on dissolution of glass ionomer restoratives. Conclusion: Bleaching effect on dissolution of glass ionomers is material and time dependant. Care should be taken by clinicians When bleaching teeth that are restored by glass ionomer, because this dissolution may affect the physical properties of these restorations.

Baroudi, Kusai; Mahmoud, Rasha Said; Tarakji, Bassel; Altamimi, Mohammed Alsakran

2014-01-01

119

Effect of vital bleaching on disintegration tendency of glass ionomer restorations.  

PubMed

Introduction: This study was designed to assess the effect of two bleaching agents on the disintegration tendency of three types of glass ionomers. Materials and Methods: A total of 90 specimens were prepared by using a split Teflon ring with an internal diameter of 5 mm and a thickness of 2 mm. The tested materials were applied and bleached according to manufacturer's instructions. Dissolution measurements were made by calculating weight loss through different periods of the test; (one week, one month and three months) and they were analyzed by using one-way analysis of variance (ANOVA), followed by Tukey's post-hoc test. Results: All glass ionomer materials exhibited a degree of dissolution. Opalescence Xtra increased the dissolution of Photac Fil and F2000 significantly, while Opalescence Quick had no effect on dissolution of glass ionomer restoratives. Conclusion: Bleaching effect on dissolution of glass ionomers is material and time dependant. Care should be taken by clinicians When bleaching teeth that are restored by glass ionomer, because this dissolution may affect the physical properties of these restorations. PMID:24701538

Baroudi, Kusai; Mahmoud, Rasha Said; Tarakji, Bassel; Altamimi, Mohammed Alsakran

2014-02-01

120

A comparison of a hybrid light-cured glass-ionomer base and liner vs. a light-cured resin tooth fragment attachment  

Microsoft Academic Search

parable strengths when fragments were meshed to- gether and luted by resin, with or without mechani- cal tooth preparations. More recently, reports involving successful fragment reattachment with glass ionomer have appeared. 5 Glass ionomer is recom- mended in many situations because of its dentin-bond- ing, fluoride-releasing, and decreased microleakage properties. 6 Bond strengths of tooth fragments reattached by glass ionomer

Jeffrey A. Dean; Anthony L. Minutilio; B. Keith Moore

1998-01-01

121

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.

Krishnan, Vidya; Lakshmi, T.

2013-01-01

122

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

PubMed Central

Brushite (dicalcium phosphate dihydrate, DCPD) cement, owing to its high solubility in physiological condition and ability to guide new bone formation, is widely used to treat bone defects. In the present study, we have evaluated the effects of poly ethylene glycol (PEG) addition on the setting time, compressive strength and in vitro biocompatibility of brushite cement. The brushite cements were prepared by mixing ?-tricalcium phosphate [?-TCP, Ca3(PO4)2] and monocalcium phosphate monohydrate [MCPM, Ca(H2PO4)2. H2O]. PEG was introduced at 2.0 and 5.0 wt% with the liquid. Introduction of PEG resulted in marginal increase in both initial and final setting time; however, significantly affected the compressive strength. Effects of PEG incorporation on in vitro biocompatibility of brushite cements were studied by using human fetal osteoblast cells (hFOB) cells. Field emission scanning electron microscope (FESEM) images and immunohistochemical analysis indicated that pure and PEG incorporated brushite cement facilitates cell adhesion, proliferation and differentiation. Fewer cells expressed vinculin protein with increased PEG content in the cement. Cell proliferation was found to decrease with increased PEG concentration while the cell differentiation increased with PEG content. Our results provide a better understanding of in vitro biocompatibility of PEG added brushite cements that can be used to customize the cement compositions based on application need.

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

2012-01-01

123

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

PubMed

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

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

2012-12-01

124

Biocompatibility of a new radiopaque iodine-containing acrylic bone cement.  

PubMed

Radiopacity in the vast majority of the commercially available acrylic bone cements that are used clinically is provided by particles of either BaSO(4) or ZrO(2). Literature reports have shown these agents to have a detrimental effect on some mechanical properties of the cements as well as on its biological response. We, therefore, have developed a new type of bone cement, for which radiopacity results from the presence of an iodine-containing methacrylic copolymer. The focus of the present work was the comparison of the biocompatibility of this new cement and a commercially available cement that contains barium sulfate. In vitro experiments show that both cements are cytocompatible materials, for which no toxic leachables are found. Implantation of the cements in a rabbit for three months resulted in the occasional presence of a thin fibrous tissue at the cement-bone interface, which is common for acrylic bone cements. Consideration of all the results led to the conclusion that the new cement is as biocompatible as the BaSO(4)-containing one. PMID:16850468

van Hooy-Corstjens, Catharina S J; Bulstra, Sjoerd K; Knetsch, Menno L W; Geusens, Piet; Kuijer, Roel; Koole, Leo H

2007-02-01

125

Dentin Surface Treatment and Bond Strength of Glass Ionomers. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

This study evaluated the effect of dentin surface treatment on shear bond strengths of two visible light activated glass ionomer restorative materials to dentin. Cylinders of Fuji II LC and VariGlass VLC were bonded to dentin surfaces that were untreated,...

D. G. Charlton C. W. Haveman

1994-01-01

126

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.

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

2012-01-01

127

A clinical comparison of glass ionomer, resin-modified glass ionomer and resin composite restorations in the treatment of cervical caries in xerostomic head and neck radiation patients.  

PubMed

Controversy exists as to whether there is less secondary caries at the margins of glass ionomer restorations compared with other materials that do not release fluoride. This study examined the incidence of secondary caries for three types of restorative materials in Class V restorations in xerostomic patients. The study group consisted of 45 high caries-risk adult patients who had undergone head and neck irradiation for the treatment of cancer. All were substantially xerostomic and in need of at least three restorations in the same arch. Every patient received a restoration with each of the test materials, a conventional glass ionomer (GI), a resin modified glass ionomer (RMGI) and a resin composite (C). Patients were instructed in the daily use of a neutral pH sodium fluoride gel in custom trays. Recall appointments were made at 6, 12, 18 and 24 months, and the restorations were examined for material loss, marginal integrity and recurrent caries at the restoration margin. Fluoride compliance was determined at each recall period and recorded as the percentage of recommended use during that interval. Patients were categorized at the end of the study as fluoride non-users if their average compliance was 50% or less. Those with greater than 50% compliance were categorized as fluoride users. In the latter group, no recurrent caries was found for any of the restorations, whereas a material-dependent incidence of recurrent caries was found in the fluoride non-user group. None of the GI, one RMGI and eight C restorations failed due to recurrent caries. For the fluoride non-user patients, Fishers exact test (p=0.05) showed no statistical difference between GI and RMGI but statistical differences were found among those materials and resin composite at each recall period. Recurrent caries reductions for GI and RMGI relative to C were greater than 80% in xerostomic patients not using topical fluoride supplementation. PMID:12216559

McComb, D; Erickson, R L; Maxymiw, W G; Wood, R E

2002-01-01

128

Biocompatibility and resorption of a brushite calcium phosphate cement  

Microsoft Academic Search

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

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

2005-01-01

129

Durability of cermet ionomer cement conditioned in different media.  

PubMed

The glass ionomer cement has exhibited significant adhesion to hard tooth structures, and good cariostatic properties. The sintering of the silver alloy powder and glass ionomer cement "cermet cement" has provided additional improvement in the physical properties of the restorative material. These were flexural resistance, wear resistance, increased radio-opacity, hardness and porosity. The improvement in the physical properties of the cermet glass cements has provided an extension in their clinical use as core build up, lining for inlays, amalgam and composite restoratives, fissure filling, restoration of primary teeth, class II tunnel preparation, treatment of root caries and repair of defective metal margins in crown and inlays. PMID:1343996

el-Din, I M

1992-01-01

130

Failure of resin-modified glass-ionomers subjected to shear loading  

Microsoft Academic Search

The mechanism of bond failure of resin-modified glass-ionomers is unknown. This study examined the failure on shear loading at the dentine interface of these materials. Twenty-five teeth (embedded in acrylic blocks) were sectioned longitudinally to expose a flat dentine surface. Cylinders of materials were made by injecting into a tube placed on the dentine of each section surface. The materials

S. K. Sidhu; M. Sherriff; T. F. Watson

1999-01-01

131

Clinical performance of reinforced glass ionomer restorations placed in UK dental practices  

Microsoft Academic Search

Aim To retrospectively evaluate the performance of reinforced glass ionomer restorations placed in load-bearing surfaces of posterior teeth in three UK general dental practices.Methods Inclusion criteria for the participating practitioners were that they would be able to find, in their regularly attending patients' mouths, a minimum of 30 Fuji IX restorations placed in load-bearing cavities in posterior teeth. The three

C. Siddons; S. Phipps; J. Bardha; R. J. Crisp; B. Dopheide; F. J. T. Burke

2007-01-01

132

In vitro biocompatibility of chitosan/hyaluronic acid-containing calcium phosphate bone cements.  

PubMed

The need for bone repair has increased as the population ages. In this research, calcium phosphate cements, with and without chitosan (CS) and hyaluronic acid (HA), were synthesized. The composition and morphological properties of cements were evaluated by X-ray diffraction and scanning electron microscopy. The acellular in vitro bioactivity revealed that different apatite morphologies were formed on the surfaces of cements after soaking in simulated body fluid. The in vitro osteoblastic cell biocompatibility of in situ forming cements was evaluated and compared with those of conventional calcium phosphate cements (CPCs). The viability and growth rate of the cells were similar for all CPCs, but better alkaline phosphatase activity was observed for CPC with CS and HA. Calcium phosphate cements supported attachment of osteoblastic cells on their surfaces. Spindle-shaped osteoblasts with developed cytoplasmic membrane were found on the surfaces of cement samples after 7 days of culture. These results reveal the potential of the CPC-CS/HA composites to be used in bone tissue engineering. PMID:24399509

Hesaraki, Saeed; Nezafati, Nader

2014-08-01

133

The bactericidal and biocompatible characteristics of reinforced calcium phosphate cements.  

PubMed

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

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

2012-08-01

134

New acrylic bone cements conjugated to vitamin E: curing parameters, properties, and biocompatibility.  

PubMed

Acrylic bone cement formulations with antioxidant character were prepared by incorporation of a methacrylic monomer derived from vitamin E (MVE). Increasing concentrations of this monomer provided decreasing peak temperature values, ranging from 62 to 36 degrees C, and increasing setting time with values between 17 and 25 min. Mechanical properties were evaluated by compression and tension tests. Compressive strength of the new formulations were superior to 70 MPa in all cases. The cement containing 25 wt % MVE, however, showed a significant decrease in tensile properties. Biocompatibility of the new formulations was studied in vitro. The analysis of the effect of leachables from cements into the media showed continued cell proliferation and cell viability with a significant increase for the cement containing 15 wt % MVE. This formulation also showed a significant increase in cellular proliferation over a period of 7 days as indicated by the Alamar Blue test. The cells were able to differentiate and express phenotypical markers in presence of all materials. A significant increase in alkaline phosphatase activity was observed on the cements prepared in presence of 15-25 wt % MVE compared with PMMA. Morphological assessment showed that the human osteoblast (HOB) cells were able to adhere, retain their morphology, and proliferate on all the cements. PMID:12209951

Méndez, J A; Aguilar, M R; Abraham, G A; Vázquez, B; Dalby, M; Di Silvio, L; San Román, J

2002-11-01

135

Human pulp cells response to Portland cement in vitro.  

PubMed

The aim of this study was to investigate the cellular effects of Portland cement on cultured human pulp cells. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, no cytotoxicity was observed in the Portland cement group in comparison with the negative control group, whereas the glass ionomer cement, intermediate restorative material, and Dycal groups showed a survival rate of less than 40% at 12 hours. Scanning electron microscopy revealed that human pulp cells attached to the Portland cement were flat and had numerous cytoplasmic extensions. In the groups in which other materials were used, a few rounded cells were observed on the material but no living cells were observed. The expression of both osteonectin and dentin sialophosphoprotein mRNAs was induced in the Portland cement-treated group. These results suggest that Portland cement is biocompatible, allows the expression of mineralization-related genes on cultured human pulp cells, and has the potential to be used as a proper pulp-capping material. PMID:17258637

Min, Kyung-San; Kim, Hyun-Il; Park, Hyo-Jin; Pi, Sung-Hee; Hong, Chan-Ui; Kim, Eun-Cheol

2007-02-01

136

ART restorations and glass ionomer sealants in Zimbabwe: survival after 3 years.  

PubMed

Atraumatic restorative treatment (ART) consists of removing demineralised tooth tissues with hand instruments only, restoring the prepared cavity and sealing the adjacent pits and fissures with an adhesive filling material. This relatively painless, no-handpiece, minimal intervention approach to controlling dental caries is described. ART was applied in an oral health care programme in Zimbabwe that was carried out amongst secondary school students from 1994 to 1997. A new glass ionomer (Fuji IX) was used as the restorative and sealant material. Sealants were placed in high caries risk students using the 'press-finger' technique. A total of 297 one-surface ART restorations and 95 glass ionomer sealants were placed in 142 and 66 students, respectively. After 3 years, the lost-to-follow-up percentages for one-surface ART restorations and glass ionomer sealants were 30.6% and 30.5%, respectively. Actuarial (life table) analysis resulted in 3-year survival rates of one-surface ART restorations of 88.3% (95% CI: 92.4%-84.2%), ranging from 94.3% to 65.4% per operator. A total of 28 ART restorations placed in 25 students failed. Reasons for failure related to the material and the operator (11 restorations or 5.3% each), and to caries adjacent to the restoration (one restoration or 0.5%). Reasons for failure were not recorded for five restorations (2.3%). Sealants were placed on surfaces diagnosed as early enamel lesions. After 3 years, 71.4% (95% CI: 81.7%-61.1%) of the fully and partially retained sealants survived with a range of 100% to 55.6% per operator. Of the sealed surfaces 96.3% (95% CI: 100%-92.2%) survived 3 years without developing caries. Experienced operators placed better ART restorations than inexperienced operators. This study has demonstrated that ART with a glass ionomer restorative material and sealants provided high quality preventive and restorative dental care to this student population. ART has become one of the treatment modalities available to oral health workers in managing dental caries. PMID:9870536

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

1998-12-01

137

Dependence of in vitro biocompatibility of ionomeric cements on ion release  

Microsoft Academic Search

The in vitro biocompatibility of a group of ionomeric cements (ICs) was evaluated with respect to their ion release properties. These ICs were made from a defined series of glasses with the general formula 1.5SiO2·0.5P2O5·Al2O3·(1.0-Z)CaO·0.75CaF2 where Z was the mole fraction (ranging from 0–0.1) of an alkali metal oxide, either sodium or potassium or a mixture of both. For these

A. J. Devlin; P. V. Hatton; I. M. Brook

1998-01-01

138

Adhesion of Polycarboxylate-based Dental Cements to Enamel: An in vivo Study  

Microsoft Academic Search

The bond strength of two polycarboxylate and two glass ionomer cements to enamel in vivo has been measured by a tensile test method. The four cements were used to cement small stainless steel cylinders onto the facial surfaces of 11 and 21. The cylinders were removed by a tensile force applied by a handpiece containing a semi-conductor sensory unit.The results

T. Jemt; P. A. Stålblad; G. Øilo

1986-01-01

139

Effect of home-use fluoride gels on glass ionomer and composite restorations.  

PubMed

The effect of home-use topical fluorides on the surface integrity of two glass ionomers and a composite was studied using SEM. Class V cavities prepared in extracted teeth were restored with two commercial glass ionomers and a composite. Teeth were randomly divided into groups and each group treated for 24 h with one of the following fluoride gels: acidulated phosphate fluoride (pH5), stannous fluoride (pH4.5), sodium fluoride (pH7), and a non-proprietary sodium fluoride (pH5.8). Surface degradation of the restorations was studied using SEM, rated according to specific criteria, and statistically analyzed by the Wilcoxon test (Rank Sums). It was found that the APF and the non-proprietary gel had a significant effect on both Gl matrix and particles and on the composite particles (p < 0.01). The neutral sodium fluoride had no significant effect on the materials (p > 0.01). PMID:8299874

el-Badrawy, W A; McComb, D; Wood, R E

1993-01-01

140

Radiopacity Evaluation of Contemporary Luting Cements by Digitization of Images  

PubMed Central

Objective. The aim of this study was to evaluate the radiopacity of two conventional cements (Zinc Cement and Ketac Cem Easymix), one resin-modified glass ionomer cement (RelyX Luting 2) and six resin cements (Multilink, Bistite II DC, RelyX ARC, Fill Magic Dual Cement, Enforce and Panavia F) by digitization of images. Methods. Five disc-shaped specimens (10 × 1.0?mm) were made for each material, according to ISO 4049. After setting of the cements, radiographs were made using occlusal films and a graduated aluminum stepwedge varying from 1.0 to 16?mm in thickness. The radiographs were digitized, and the radiopacity of the cements was compared with the aluminum stepwedge using the software VIXWIN-2000. Data (mmAl) were submitted to one-way ANOVA and Tukey's test (? = 0.05). Results. The Zinc Cement was the most radiopaque material tested (P < 0.05). The resin cements presented higher radiopacity (P < 0.05) than the conventional (Ketac Cem Easymix) or resin-modified glass ionomer (RelyX Luting 2) cements, except for the Fill Magic Dual Cement and Enforce. The Multilink presented the highest radiopacity (P < 0.05) among the resin cements. Conclusion. The glass ionomer-based cements (Ketac Cem Easymix and RelyX Luting 2) and the resin cements (Fill Magic Dual Cement and Enforce) showed lower radiopacity values than the minimum recommended by the ISO standard.

Reis, Jose Mauricio dos Santos Nunes; Jorge, Erica Gouveia; Ribeiro, Joao Gustavo Rabelo; Pinelli, Ligia Antunes Pereira; Abi-Rached, Filipe de Oliveira; Tanomaru-Filho, Mario

2012-01-01

141

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

PubMed

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

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

2013-01-01

142

Fluoride release of glass ionomer restorations after bleaching with two different bleaching materials  

PubMed Central

Objective: This study was designed to evaluate the effect of two bleaching agents on the fluoride release of three types of glass ionomer materials. Materials and Methods: A total of 90 specimens of the tested materials (Ketac Fil, Photac Fil and F2000) were prepared by a split Teflon ring with an internal diameter of 5 mm and thickness of 2 mm. The tested materials were applied and bleached according to manufacturer instructions. Fluoride release measurements were made by using specific ion electrode. Results: Results revealed that bleaching with opalescence Xtra caused little increase in fluoride release from Ketac Fil and Photac Fil but has no effect on F2000. However, Opalescence Quick had no significant effect on the three tested materials. Conclusions: Bleaching effect on fluoride release is material dependent and time has a significant role on fluoride release.

Baroudi, Kusai; Mahmoud, Rasha Said; Tarakji, Bassel

2013-01-01

143

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

NASA Astrophysics Data System (ADS)

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

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

144

Evaluation of surface roughness and hardness of different glass ionomer cements  

PubMed Central

Objectives: The aim of this study was to evaluate surface roughness and hardness of a nanofiller GIC, a resin-modified GIC, three conventional GICs, and a silver-reinforced GIC. Methods: For each material, 11 spcecimens were prepared and then stored in distilled water at 37 °C for 24 h. The surface roughness of 5 specimens was measured using a surface profilometer before polishing and after polishing with coarse, medium, fine, superfine aluminum oxide abrasive Sof-Lex discs respectively. The hardness of the upper surfaces of the remaining 6 specimens was measured with a Vickers microhardness measuring instrument. Results: All tested GICs showed lower surface roughness values after the polishing procedure. Surface finish of nanofiller GIC was smoother than the other tested GICs after polishing. This was followed by resin-modified GIC, Fuji II LC; then silver-reinforced GIC, Argion Molar, conventional GICs, Aqua Ionofil Plus, Fuji IX, and Ionofil Molar, respectively. The result of the hardness test indicated that the microhardness value of silver-reinforced GIC was greater than that of the other GICs. When the hardness values of all tested GICs were compared, the differences between materials (except Aqua Ionofil Plus with Ionofil Molar and Ketac N100 with Fuji II LC (P>.05)) were found statistically significant (P<.05). Conclusions: According to the results of this study, it can be concluded that the differences in the composition of GICs may affect their surface roughness and hardness.

Bala, Oya; Arisu, Hacer Deniz; Yikilgan, Ihsan; Arslan, Seda; Gullu, Abdulkadir

2012-01-01

145

The influence of resin coating on the shear punch strength of a high strength auto-cure glass ionomer  

Microsoft Academic Search

Objectives. The aim of this study is to examine the influence of early water contact on the shear punch strength of a modern, high strength, auto-cure glass ionomer (Fuji IX GP).Methods. Specimens, 8.0mm in diameter and approximately 1.25mm thick, were prepared in metal washers, and allowed to remain covered by polyester strips for 7min, to ensure completion of the initial

Jakob Leirskar; Håkon Nordbø; Graham J Mount; Hien Ngo

2003-01-01

146

Healing patterns after subgingival placement of a resin-modified glass-ionomer restoration: a histometric study in dogs.  

PubMed

The aim of this study was to evaluate, clinically and histometrically, the effects of subgingival placement of a resin-modified glass-ionomer restoration during flap surgery. Nine dogs were included in this study. The mandibular canines were randomly assigned to receive either a transgingival resin-modified glass-ionomer restoration (test group) or no restoration (control group). The apical margins of the restorations in the test group and a reference notch on those in the control group were placed at the level of the bone crest. Clinical parameters were recorded 7 days before sacrifice. The dogs were sacrificed after 107 days, and undecalcified sections were obtained for histologic evaluation. Clinically, both groups presented significant clinical attachment loss and an increase in probing depth, but differences between groups were not statistically significant (P > .05). Histologically, a significant difference between groups was observed for length of epithelium (test, 4.05 ± 0.57 mm; control, 3.36 ± 0.63 mm; P = .01). The test group showed more bone resorption (2.02 ± 1.47 mm) when compared with the control group (0.74 ± 0.37 mm) (P = .048). It can be concluded that even with the claimed favorable properties of resin-modified glass ionomer, the presence of the restoration within the biologic width causes increased migration of the apical epithelium and bone resorption. PMID:23998164

Santamaria, Mauro Pedrine; Suaid, Fabricia Ferreira; Carvalho, Marcelo Diniz; Nociti, Francisco Humberto; Casati, Marcio Zaffalon; Sallum, Antonio Wilson; Sallum, Enilson Antonio

2013-01-01

147

SEM observations of the reactions of the components of a light-activated glass polyalkenoate (ionomer) cement on bovine dentine  

Microsoft Academic Search

Objectives: Glass ionomer cements are used in clinical dentistry as lining, luting and restorative materials. The precise nature of their bonding mechanism to dentine is unclear. This study is an SEM examination of the effect of the liquid contained in Vitrebond cement (3M Co., MN) on the surface of bovine dentine, with respect to delays in photocuring and washing off

K. C. Titley; D. C. Smith; R. Chernecky

1996-01-01

148

Evaluating dentin surface treatments for resin-modified glass ionomer restorative materials.  

PubMed

This in vitro study evaluated the effect of six surface treatments on the shear bond strength of three resin-modified glass ionomers (RMGIs) to dentin. Occlusal surfaces of caries-free third molars were reduced to expose only dentin. Surface treatments were smear layer intact (negative control), Cavity Conditioner, EDTA, Ketac Primer, Self Conditioner, and etching with 35% phosphoric acid followed by the application of Optibond Solo Plus. Filtek Z250 composite resin bonded with Optibond Solo Plus served as a positive control. Conditioning agents were used according to the manufacturers' instructions. After surface treatments, Fuji II LC, Riva LC, Ketac Nano, and Filtek Z250 were placed in copper-band matrices 5 mm in diameter and 2 mm in height and were light-cured for 20 seconds. Specimens were stored in 100% humidity for 24 hours, after which they were placed in deionized water for 24 hours at 37°C. They were then tested under shear forces in an Instron Universal Testing Machine at a crosshead speed of 0.5 mm/min. A two-way analysis of variance and Tukey honestly significant difference statistical analyses (p<0.05) indicated significant interaction between RMGIs and conditioning agents. Acid etching followed by Optibond Solo Plus provided highest bond strengths for all three RMGIs, which were not statistically different from the positive control. PMID:23088188

Imbery, T A; Namboodiri, A; Duncan, A; Amos, R; Best, A M; Moon, P C

2013-01-01

149

Bond strength of resin-modified glass ionomer restorative materials using a no-rinse conditioner.  

PubMed

A paste-paste resin-modified glass ionomer (RMGI) restorative material has been introduced recently with a new conditioner that requires no rinsing. The purpose of this study was to compare the shear bond strength of an encapsulated RMGI (Fuji II LC) and a new paste-paste RMGI (Fuji Filling LC) to dentin conditioned with 20% polyacrylic acid (Cavity Conditioner), a new no-rinse conditioner (Self Conditioner,), or no conditioner. Mounted human third molars were flattened and the dentin surface was conditioned. The RMGI restorative materials were mixed and incrementally inserted into a mold and photocured. The specimens were loaded until failure in a universal testing machine after 24 hours of storage in distilled water. Fuji II LC had significantly greater bond strength to dentin than Fuji Filling LC. The use of Cavity Conditioner or Self Conditioner resulted in bond strengths that were not significantly different from each other; however, both produced greater bond strengths than those in the non-conditioned groups. PMID:23220322

Suihkonen, Rian W; Vandewalle, Kraig S; Dossett, Jon M

2012-01-01

150

Physicochemical properties and in vitro biocompatibility of a hydraulic calcium silicate/tricalcium aluminate cement for endodontic use.  

PubMed

This study sought to prepare a calcium silicate cement (CSC) with varying additions of tricalcium aluminate (Ca(3)Al(2)O(6), C(3)A), and to find an optimal amount of C(3)A by evaluating the effect of C(3)A on the physicochemical and in vitro biological properties of the CS/C(3)A cement. The results indicated that the addition of C(3)A into CSC reduced the setting time and improved the compressive strength especially at the early stage of setting. However, the 15% C(3)A was too much for the CS/C(3)A system and did harm to its strength development. Furthermore, the CS/C(3)A cement was bioactive and biocompatible in vitro, and had a stimulatory effect on the cell growth, when the content of C(3)A was 5 or 10%. When compared with the commercially available Dycal(®), the CS/C(3)A cement was notably more compatible with the human dental pulp cells. Therefore, the CS/C(3)A cement with 5-10% C(3)A produced the best compromise between setting and in vitro biological properties, and may be a promising candidate for endodontic use. PMID:22576986

Liu, Weining; Peng, Weiwei; Zhu, Yaqin; Chang, Jiang

2012-07-01

151

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

PubMed

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

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

2014-06-01

152

The uptake and release of fluoride by ion-leaching cements after exposure to toothpaste  

Microsoft Academic Search

Objectives: The cariostatic action associated with the glass-ionomer cement (GIC) is usually attributed to its sustained release of fluoride. However the ability of the GIC to act as a fluoride reservoir, taking it up from an external source (e.g. toothpaste, mouthwash) and subsequently releasing it over time, may also be a contributory factor. This study investigated the reservoir effect of

M Rothwell; H. M Anstice; G. J Pearson

1998-01-01

153

Clinical evaluation of the retention and wear of a light-cured pit and fissure glass ionomer sealant.  

PubMed

The purpose of this study was to evaluate the 12-month retention and wear of an experimental light-cured glass ionomer for pit and fissure sealing. A total of 25 patients 7-14 years-old were selected from the Pediatric Dentistry Clinic at the University of Texas Health Science Center at San Antonio. The patients resided in areas without fluoridated water. Each tooth was isolated with cotton rolls, dried with oil-free compressed air and GC Dentin Conditioner applied with a small disposable brush to the pits and fissures for 20 seconds. The teeth were rinsed with water and gently air dried using an air/water syringe. The teeth were not desiccated. GC experimental glass ionomer for pit and fissures was used. The powder/liquid ratio was dispensed at 1.4 gm/1.0 gm (one level spoonful of powder to one drop of liquid). The powder was mixed for 15-20 seconds. An explorer was used to apply the mixed sealant to the tooth and teased into all pits and fissures. The sealant was then cured for 20 seconds. Occlusion was corrected after the sealant was light-cured. Immediately, a color slide and a vinyl polysiloxane impressions were taken. The impressions were poured in epoxy resin. Color slides, impressions and epoxy models were also made at 3, 6, 9 and 12-month recalls. A total of 95 sealants were placed and follow-up for 12 months. The results showed that with the clinical visual inspection all sealants were present at 3 and 6 months postoperatively. At 12 months, only 20% of the sealants were clinically evident.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7547485

Aranda, M; Garcia-Godoy, F

1995-01-01

154

Influence of the temperature on the cement disintegration in cement-retained implant restorations.  

PubMed

The aim of this study was to estimate the average disintegration temperature of three dental cements used for the cementation of the implant-supported prostheses. One hundred and twenty metal frameworks were fabricated and cemented on the prosthetic abutments with different dental cements. After heat treatment in the dental furnace, the samples were set for the separation to test the integration of the cement. Results have shown that resin-modified glass-ionomer cement (RGIC) exhibited the lowest disintegration temperature (p<0.05), but there was no difference between zinc phosphate cement (ZPC) and dual cure resin cement (RC) (p>0.05). Average separation temperatures: RGIC - 306 ± 23 °C, RC - 363 ± 71 °C, it could not be calculated for the ZPC due to the eight unseparated specimens. Within the limitations of the study, it could be concluded that RGIC cement disintegrates at the lowest temperature and ZPC is not prone to break down after exposure to temperature. PMID:23455980

Linkevicius, Tomas; Vindasiute, Egle; Puisys, Algirdas; Linkeviciene, Laura; Svediene, Olga

2012-01-01

155

Marginal ridge strength of tunnel-prepared teeth restored with various adhesive filling materials 1 1 This paper was originally submitted to Advanced Cement Based Materials on 2 February 1998. The paper was received at the Editorial Office of Cement and Concrete Research on 2 November 1998 and accepted in final form on 22 December 1998  

Microsoft Academic Search

This study evaluated the load required to fracture the marginal ridge of tunnel-filled teeth restored with various adhesive filling materials. Five test groups, each consisting of 20 extracted maxillary premolars, were filled with either composite resin or a conventional, a cermet, or two brands of resin-modified glass ionomer (polyalkenoat) cements. The tunnels were prepared with the occlusal access placed in

Gunhild Vesterhus Strand; Anne Bjørg Tveit; Nils Roar Gjerdet

1999-01-01

156

Connective tissue graft and resin glass ionomer for the treatment of gingival recession associated with noncarious cervical lesions: a case series.  

PubMed

This article describes the treatment of gingival recession associated with noncarious cervical lesions by a connective tissue graft in combination with a resin-modified glass-ionomer restoration (CTG + R). Eleven patients showing the association of recession and lesions were selected and treated by CTG + R. Bleeding on probing, probing depth, relative gingival recession, clinical attachment level, noncarious cervical lesion height, and dentin sensitivity were measured. The treatment provided statistically significant gains in clinical attachment level and shallow probing depths. The percentage of cervical lesion height covered was 74.0% ± 22.90%. It can be concluded that the presence of resin-modified glass-ionomer filling did not interfere with coverage achieved by the connective tissue graft. PMID:21845238

Santamaría, Mauro Pedrine; Ambrosano, Glaucia Maria Bovi; Casati, Marcio Zaffalon; Nociti, Francisco Humberto; Sallum, Antônio Wilson; Sallum, Enilson Antônio

2011-01-01

157

Three-Year Survival of One-Surface ART Restorations and Glass-Ionomer Sealants in a School Oral Health Programme in Zimbabwe  

Microsoft Academic Search

An oral health care programme in secondary schools using the atraumatic restorative treatment (ART) approach for dental caries was started in 1993. Glass ionomer (restorative type II, 1) was used as the restorative and sealant material. Sealants were placed using the ‘press-finger’ technique. Results after 3 years revealed a survival percentage for one-surface ART restorations of 85.3 (95% CL: 89.7–80.9%),

J. E. Frencken; F. Makoni; W. D. Sithole; E. Hackenitz

1998-01-01

158

Effects of conventional and high-intensity light-curing on enamel shear bond strength of composite resin and resin-modified glass-ionomer  

Microsoft Academic Search

The purpose of this study was to evaluate the shear bond strengths of a composite resin (Transbond XT; 3M\\/Unitek, Monrovia, Calif) and a resin-modified glass ionomer (Fuji Ortho LC; GC America Inc, Alsip, Ill) cured with 2 different light-curing units: a conventional visible light unit (Ortholux XT; 3M Dental Products, St Paul, Minn) and a xenon arc light unit (Plasma

Maria Francesca Sfondrini; Vittorio Cacciafesta; Angela Pistorio; Giuseppe Sfondrini

2001-01-01

159

Morphological Changes Of The Root Surface And Fracture Resistance After Treatment Of Root Fracture By CO2 Laser And Glass Ionomer Or Mineral Trioxide Aggregates  

NASA Astrophysics Data System (ADS)

This in vitro study evaluates the morphological changes of the root surface and fracture resistance after treatment of root cracks by CO2 laser and glass Ionomer or mineral trioxide aggregates (MTA). Fifty freshly extracted human maxillary central incisor teeth with similar dimension were selected. Crowns were sectioned at the cemento-enamel junction, and the lengths of the roots were adjusted to 13 mm. A longitudinal groove with a dimension of 1×5 mm2 and a depth of 1.5 mm was prepared by a high speed fissure bur on the labial surface of the root. The roots were divided into 5 groups: the 10 root grooves in group 1 were remained unfilled and were used as a control group. The 10 root grooves in group 2 were filled with glass Ionomer, 10 root grooves in group 3 were filled with MTA, the 10 root grooves in group 4 were filled with glass Ionomer and irradiated by CO2 laser and the 10 root grooves in group 5 were filled with MTA and irradiated with CO2 laser. Scanning electron microscopy was performed for two samples in each group. Tests for fracture strength were performed using a universal testing machine and a round tip of a diameter of 4 mm. The force was applied vertically with a constant speed of 1 mm min 1. For each root, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically with ANOVA and Turkey's Honestly Significant Difference (HSD) tests. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight Chemical bond between the cementum and glass Ionomer and melted masses and globular like structure between cementum and MTA. The mean fracture resistance was the maximum fracture resistance in group 5 (810.8 N). Glass Ionomer and MTA with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture. CO2 laser increase the resistance of the teeth to fracture.

Badr, Y. A.; Abd El-Gawad, L. M.; Ghaith, M. E.

2009-09-01

160

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

SciTech Connect

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

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

1988-06-01

161

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.

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

2013-01-01

162

The effect of pre-warming and delayed irradiation on marginal integrity of a resin-modified glass-ionomer.  

PubMed

Recent studies have indicated that the acid-base reactions and polymerization of resin-modified glass-ionomers (RMGIs) compete with and inhibit each other; however, external energy can also influence the properties of RMGIs. This in vitro study evaluated the effect of pre-warming and/or delayed light irradiation on marginal integrity of RMGIs in cervical restorations. Standard Class V cavities were prepared on the buccal aspects of 60 human maxillary premolars. Each cavity was treated with a cavity conditioner for 10 seconds, rinsed, and gently air-dried. An RMGI was applied to the prepared cavities as dictated by the study protocol. Group 1 samples were treated per manufacturers' instructions. Group 2 samples were photocured after a delay of 2 minutes. For samples in Group 3, the encapsulated material was pre-warmed (at 40° C) for 90 seconds; for Group 4 samples, capsules were pre-warmed and photocuring was delayed for 2.4 minutes. Microleakage scores were determined using dye penetration technique; Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis (? = 0.05). The enamel groups exhibited statistically significant differences (P = 0.036), while the dentin groups did not (P = 0.122); however, in both cases, Group 2 demonstrated the highest marginal integrity. Based on the results of this study, pre-warming could jeopardize the marginal integrity of RMGIs in cervical restorations, while delaying the curing process might improve it (particularly for enamel). PMID:23220316

Khoroushi, Maryam; Mansoori-Karvandi, Tayebeh; Hadi, Saeed

2012-01-01

163

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

164

In vivo Cariostatic Effect of Resin Modified Glass lonomer Cement and Amalgam on Dentine  

Microsoft Academic Search

Fluoride-releasing materials have been reported to be bactericidal in vitro. This may be of benefit to modern dentistry, which is directed to the preservation of tooth tissue during restorative treatment. Little is known about in vivo effects. The aim is to investigate the influence of a resin-modified glass ionomer cement (RM-GIC) on carious dentine that remains under restorations, compared to

C. M. Kreulen; J. J. Soet; K. L. Weerheijm; W. E. van Amerongen

1997-01-01

165

Practical clinical considerations of luting cements: A review  

PubMed Central

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

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

2014-01-01

166

Practical clinical considerations of luting cements: A review.  

PubMed

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

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

2014-02-01

167

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

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

2014-03-01

168

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.

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

2014-01-01

169

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.

Kumar, R Vinod; Shruthi, CS

2012-01-01

170

Three-year survival of one-surface ART restorations and glass-ionomer sealants in a school oral health programme in Zimbabwe.  

PubMed

An oral health care programme in secondary schools using the atraumatic restorative treatment (ART) approach for dental caries was started in 1993. Glass ionomer (restorative type II, 1) was used as the restorative and sealant material. Sealants were placed using the 'press-finger' technique. Results after 3 years revealed a survival percentage for one-surface ART restorations of 85.3 (95% CL: 89.7-80.9%), which ranged from 96.1 to 69.3% per operator. Failures were related to 'unacceptable marginal defects' (8.1%), 'falling out' (6.1%) and 'excessive wear' (2.5%). Of the 33 failed one-surface ART restorations, 17 were material-related, 7 had caries and no information was available for 9 restorations. Sealants were placed only on surfaces diagnosed as early enamel lesions and on some small dentinal lesions. After 3 years, 50.1% (95% CL: 55.1-45.1%) of the fully and partially retained sealants survived with a range of 68.5-25.9% per operator. Regardless of the low rate of retention, the sealed surfaces had a 4 times lower chance of developing caries than unsealed surfaces with early enamel lesions over the 3-year period. The retention of sealants and the survival of one-surface ART restorations were influenced by an operator effect. The mean treatment time for one-surface ART restorations without chairside assistance was 22.1 min (range per operator of 19.8-23.6 min), whilst the mean time for placing sealants was 9.3 min (range per operator of 8.2-10.8 min). It is concluded that the ART approach and the use of glass-ionomer sealants have made preventive and restorative dental care available for this student population and further that ART seems to be appropriate for population groups currently not receiving preventive and restorative dental care. PMID:9544860

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

1998-01-01

171

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

172

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

PubMed Central

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

Reza, Fazal; Lim, Siau Peng

2012-01-01

173

Radiographic appearance of commonly used cements in implant dentistry.  

PubMed

Cement-retained restorations allow for a conventional fixed partial denture approach to restoring dental implants. However, inadequate removal of excess cement at the time of cementation may introduce a severe complication: cement-induced peri-implantitis. Radiopaque cements are more easily detected on radiographs and should improve the recognition of extravasated cement at the time of insertion. The purpose of this study was to evaluate the radiopacity of commercially available cements in vitro. Eighteen different cements commonly used for luting restorations to implants were tested at both 0.5- and 1.0-mm thicknesses. The cements examined were zinc oxide eugenol, zinc oxide, zinc polycarboxylate, zinc phosphate, resin-reinforced glass ionomer, urethane resin, resin, and composite resin. Two samples of each cement thickness underwent standardized radiography next to an aluminum step wedge as a reference. The mean grayscale value of each of the nine 1-mm steps in the step wedge were used as reference values and compared to each of the cement samples. Temp Bond Clear (resin), IMProv (urethane resin), Premier Implant Cement (resin), and Temrex NE (resin) were not radiographically detectable at either sample thickness. Cements containing zinc were the most detectable upon radiographic analysis. There are significant differences in the radiopacity of many commonly used cements. Since cementinduced peri-implantitis can lead to late implant failure, cements that can be visualized radiographically may reduce the incidence of this problem. PMID:23342348

Pette, Gregory A; Ganeles, Jeffrey; Norkin, Frederic J

2013-01-01

174

Comparison of Tissue Reaction of Pulp Chamber Perforations in Dogs' Teeth Treated with MTA, Light Cured Glass Ionomer and Amalgam  

Microsoft Academic Search

Statement of Problem: Perforations are significant complications that can occur during root canal therapy and may result in the destruction of adjacent periodontal tissues. An ideal material for repairing a perforation should be biocompatible and have a high sealing ability. Purpose: The aim of this study was to compare histologic tissue responses of experimentally induced pulp chamber perforations in dogs'

K. Ashofteh-Yazdi; M. Masoodi; N. Shokouhinejad

175

Comparison of the Shear Bond Strength of Resin Modified Glass Ionomer to Enamel in Bur-Prepared or Lased Teeth (Er:YAG)  

PubMed Central

Objective: The purpose of this study was to evaluate the effect of Er:YAG laser on the shear bond strength of resin modified glass ionomer (RMGI) to enamel. Materials and Methods: Twenty extracted caries-free human premolars were selected. The teeth were embedded in acrylic resin. The buccal surfaces of each sample were ground to plane enamel with carbonated disc. The teeth were randomly divided in two groups. In the first group, the surfaces were treated by Er:YAG laser (350mJ/10Hz). The second group was prepared by carbide bur. Fuji IX RMGI was adhered to surfaces of the samples in both groups in rod shape. The shear bond strength of samples was measured by a universal testing machine. The results of the two groups were analyzed by T- test. Results: The means and standard deviations of shear bond strength of the laser-treated group and the bur-treated group were 6.75 ± 1.99 and 4.41 ± 1.62 Mpa, respectively. There is significant difference in the shear bond strength of RMGI between the two groups (P-value=0.01). Conclusion: The laser group showed better results. Er:YAG laser can be an alternative technology in restorative dentistry.

Jafari, Ahmad; Shahabi, Sima; Chiniforush, Nasim; Shariat, Ali

2013-01-01

176

Effects of uncontrolled outdoor storage on the polymerization, manipulation, and appearance of visible light-cured composite resin and resin-modified glass ionomer materials.  

PubMed

Four light-cured composite resins (Z100, Heliomolar RO, Herculite XRV, and Prisma APH) and two resin-modified glass ionomer restorative materials (Fuji II LC and VariGlas VLC) were placed in an uncooled, unheated outdoor storage shed for 12 months. Maximum and minimum ambient temperatures were recorded every 24 hours. Each month, samples were polymerized with a visible light source and alterations in polymerization were assessed using a scratch test. Problems with manipulation or changes in appearance were also monitored. Samples stored outdoors were compared to control samples maintained at room temperature [68-74 degrees F (20-23.3 degrees C)]. Results showed that polymerization of all materials tested was apparently unaffected to any significant clinical degree by outdoor storage at temperatures ranging from 20 to 112 degrees F (-6.6-44.4 degrees C) over 12 months. Eight months into the study, the VariGlas VLC liquid had separated into a viscous gel and watery component. None of the other remaining materials demonstrated any changes in manipulation or appearance. All materials tested except VariGlas VLC appear suitable for use during military deployment or field training exercises under similar environmental conditions. PMID:8855062

Fallo, G J; Wakefield, C W; Czerw, R J

1996-05-01

177

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

178

Dentin-cement Interfacial Interaction  

PubMed Central

The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the “mineral infiltration zone”, where the alkaline caustic effect of the calcium silicate cement’s hydration products degrades the collagenous component of the interfacial dentin. This degradation leads to the formation of a porous structure which facilitates the permeation of high concentrations of Ca2+, OH-, and CO32- ions, leading to increased mineralization in this region. Comparison of the dentin-restorative interfaces shows that there is a dentin-mineral infiltration with the Biodentine, whereas polyacrylic and tartaric acids and their salts characterize the penetration of the GIC. A new type of interfacial interaction, “the mineral infiltration zone”, is suggested for these calcium-silicate-based cements.

Atmeh, A.R.; Chong, E.Z.; Richard, G.; Festy, F.; Watson, T.F.

2012-01-01

179

Brushing abrasion of luting cements under neutral and acidic conditions.  

PubMed

Four resin based materials (Compolute Aplicap, ESPE; Variolink Ultra, Vivadent; C&B Metabond, Parkell and Panavia 21, Kuraray), two carboxylate cements (Poly-F Plus, Dentsply DeTrey and Durelon Maxicap, ESPE), two glass-ionomer cements (Fuji I, GC and Ketac-Cem Aplicap, ESPE), one resin-modified glass ionomer cement (Vitremer, 3M) one polyacid-modified resin composite (Dyract Cem, Dentsply DeTrey) and one zinc phosphate cement (Harvard, Richter & Hoffmann) were investigated according to their brushing resistance after storage in neutral and acidic buffer solutions. For this purpose 24 cylindrical acrylic molds were each filled with the materials. After hardening, the samples were stored for seven days in 100% relative humidity and at 37 degrees C. Subsequently, they were ground flat and polished. Then each specimen was covered with an adhesive tape leaving a 4 mm wide window on the cement surface. Twelve samples of each material were stored for 24 hours in a buffer solution with a pH of 6.8. The remaining 12 samples were placed in a buffer with a pH of 3.0. All specimens were then subjected to a three media brushing abrasion (2,000 strokes) in an automatic brushing machine. Storage and brushing were performed three times. After 6,000 brushing strokes per specimen, the tape was removed. Brushing abrasion was measured with a computerized laser profilometer and statistically analyzed with ANOVA and Tukey's Standardized Range Test (p < or = 0.05). The highest brushing abrasion was found for the two carboxylate cements. The lowest brushing abrasion was found for one resin based material, Compolute Aplicap. With the exception of three resin-based materials, a lower pH led to a higher brushing abrasion. PMID:11203860

Buchalla, W; Attin, T; Hellwig, E

2000-01-01

180

Clinical evaluation of giomer- and resin-modified glass ionomer cement in class V noncarious cervical lesions: An in vivo study  

PubMed Central

Objectives: To evaluate and compare the clinical performance of Giomer (Beautifil II) and RMGIC (Fuji II LC) in noncarious cervical lesions. Materials and Methods: Thirty-two subjects with one or two pairs of noncarious cervical lesions were included in the study. Each pair of lesion was restored with either giomer or RMGIC assigned randomly. Clinical evaluation of restorations was done using USPHS criteria. Data was formulated in a predesigned format and subjected to statistical analysis using the chi square test. Results: Statistically significant difference was found between RMGIC and Giomer with respect to surface roughness with P value <0.001. Conclusion: Giomer showed superior surface finish compared to RMGIC. Both Giomer and RMGIC showed equal retention ability.

Jyothi, KN; Annapurna, S; Kumar, Anil S; Venugopal, P; Jayashankara, CM

2011-01-01

181

Zirconia: cementation of prosthetic restorations. Literature review  

PubMed Central

SUMMARY Aim of the work Aim of the work was to execute a review of the international literature about the cementation of zirconia restorations, analyzing the properties of the cements most commonly used in clinical activities. Materials and methods It was performed, through PubMed, a bibliographic search on the international literature of the last 10 years using the following limits: studies in English, in vitro studies, randomized clinical trial, reviews, meta-analysis, guide-lines. Were excluded from the search: descriptive studies, case reports, discussion articles, opinion’s leader. Results From studies results that common surface treatments (silanization, acid etching) are ineffective on zirconia because it has an inert surface without glassy component (on which this surface treatments act primarily), instead the sandblasting at 1atm with aluminium oxide (Al2O3) results significantly effective for the resulting roughening that increase the surface energy and the wettability of the material. Furthermore it has been shown that zinc phosphate-based cements, Bis-GMA-based and glass-ionomer cements can’t guarantee a stable long-term adhesion, instead resin cements containing phosphate monomer 10-methacryloyloxyidecyl-dihyidrogenphosphate (MDP) have shown higher adhesion and stability values than the other cements. In particular, it has seen that bond strength of zirconia copings on dentin, using MDP-based cement, is about 6,9MPa; this value is comparable to that obtained with gold copings cementation. Conclusions Analyzed studies have led to the following conclusions: sandblasting with aluminium oxide (Al2O3) is the best surface treatment to improve adhesion between resin cements and zirconia; resin cements containing phosphate ester monomers 10-methacryloyloxyidecyl-dihyidrogenphosphate (MDP) have shown in the studies an higher bond strength and stability after ageing treatment; the best procedure for cementing zirconia restorations results the combination of sandblasting with aluminium oxide (Al2O3) at 50?m and MDP-based cements.

GARGARI, M.; GLORIA, F.; NAPOLI, E.; PUJIA, A.M.

2011-01-01

182

Development of a new temporary luting agent consisting of PEMA and eugenol--residue ratio and bond strength of luting cements for abutment materials.  

PubMed

PEMA- and eugenol-based trial agents (PE 1.0, PE 1.6) possessed the requisite dental engineering properties that satisfied the requirements for temporary luting agents. To assess their clinical applicability, this study examined the following properties after the trial agents were removed: their residue ratios on the abutment surface and the bond strengths of resin-modified glass ionomer cement and resin cement for the abutment materials. The residue ratio of PE 1.0 on the abutment material after temporary restoration removal was lower than those of comparable temporary luting agents (polycarboxylate cement type, zinc oxide-eugenol cement type), and no residue was recognized for PE 1.6. On bond strength, those of the resin-modified glass ionomer cement and resin cement for the resin core and bovine dentin surface after the removal of trial agents tended to be the same or increase in comparison to commercial temporary luting agents. In conclusion, results of this study suggested that the trial agents were suitable for clinical use. PMID:19662723

Okada, Hidetoshi; Ishida, Yoshinori; Noguchi, Hiroshi; Ryukata, Ichiro; Nagayama, Katsuya

2009-05-01

183

Diagnosis and management of cemental tear: a case report.  

PubMed

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

Gupta, Hitesh; Puri, Abhinhay; Kumar, Saru

2014-01-01

184

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

185

Evaluation of pH at the Bacteria-Dental Cement Interface  

PubMed Central

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.

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

2011-01-01

186

Evaluation of mechanical properties of five cements for orthodontic band cementation.  

PubMed

The aim of this in vitro study was to compare the flexural, compressive and diametral tensile strengths of five cements used in orthodontics for band cementation. Twelve specimens of each cement were tested: 1 - GC Fuji Ortho Band (FJ), GC America Inc.; 2 - Meron (MR), Voco; 3 - Multi-Cure Glass Ionomer Band Cement (MC), 3M Unitek; 4 - Band-Lok (BL), Reliance Orthodontic Products; and 5 - Ketac Cem (KC), 3M ESPE. The results (mean) for diametral tensile strength were: 10.51 MPa (FJ), 9.60 MPa (MR), 20.04 MPa (MC), 42.80 MPa (BL), and 4.08 MPa (KC). The results for compressive strength were (in the same order): 64.50 MPa, 77.71 MPa, 94.21 MPa, 193.88 MPa, and 81.93 MPa. The results for flexural strength were (in the same order): 20.72 MPa, 25.84 MPa, 53.41 MPa, 137.41 MPa, and 20.50 MPa. The statistical analysis was performed by two-way ANOVA and Tukey tests with p-value £ 0.05. In terms of diametral tensile strength, BL showed the highest strength statistically, and MC, the second highest. In terms of compressive tensile strength, BL showed the highest strength statistically, and FJ did not attain the minimum recommended strength. In terms of flexural tensile strength, BL cement was superior to MC, and MR, FJ and KC were equivalent and inferior to BL and MC. PMID:23459769

Aguiar, Diego Andrei; Ritter, Daltro Enéas; Rocha, Roberto; Locks, Arno; Borgatto, Adriano Ferreti

2013-01-01

187

Microleakage along glass-fibre posts cemented with three different materials after cyclic loading: a pilot study.  

PubMed

The purpose of this in vitro study was to evaluate microleakage along glass-fibre posts cemented with three different cements after cyclic loading. After post-space preparation, fifty obturated root canals were randomly divided into three experimental groups and two control groups. In group 1, Glassix posts were cemented using Harvard cement, in group 2, Fuji PLUS cement was used and in group 3, Variolink II was used for post cementation. The specimens were artificially aged by loading in a special testing machine. Coronal leakage was evaluated using a fluid transport system. Posts cemented with Variolink II, showed significantly higher failure rate after loading, compared to group 1 and 2 (p = 0.009). Comparing microleakage in samples that have not failed, specimens cemented with Variolink II showed significantly less fluid transport than specimens cemented with zinc phosphate and glass ionomer cements (p = 0.04 and p = 0.006, respectively). Variolink II cement exibited significantly less fluid movement compared with Harvard and Fuji PLUS cement. PMID:23940985

Barbi?, Marija Rogi?; Segovi?, Sanja; Baraba, Anja; Ribari?, Sonja Pezelj; Katunari?, Marina; Ani?, Ivica

2013-06-01

188

Finite element analysis of stresses in fixed prosthesis and cement layer using a three-dimensional model  

PubMed Central

Context: To understand the effect of masticatory and parafunctional forces on the integrity of the prosthesis and the underlying cement layer. Aims: The purpose of this study was to evaluate the stress pattern in the cement layer and the fixed prosthesis, on subjecting a three-dimensional finite element model to simulated occlusal loading. Materials and Methods: Three-dimensional finite element model was simulated to replace missing mandibular first molar with second premolar and second molar as abutments. The model was subjected to a range of occlusal loads (20, 30, 40 MPa) in two different directions – vertical and 30° to the vertical. The cements (zinc phosphate, polycarboxylate, glass ionomer, and composite) were modeled with two cement thicknesses – 25 and 100 ?m. Stresses were determined in certain reference points in fixed prosthesis and the cement layer. Statistical Analysis Used: The stress values are mathematic calculations without variance; hence, statistical analysis is not routinely required. Results: Stress levels were calculated according to Von Mises criteria for each node. Maximum stresses were recorded at the occlusal surface, axio-gingival corners, followed by axial wall. The stresses were greater with lateral load and with 100-?m cement thickness. Results revealed higher stresses for zinc phosphate cement, followed by composites. Conclusions: The thinner cement interfaces favor the success of the prosthesis. The stresses in the prosthesis suggest rounding of axio-gingival corners and a well-established finish line as important factors in maintaining the integrity of the prosthesis.

Sangeetha, Arunachalam; Padmanabhan, Thallam Veeravalli; Subramaniam, R.; Ramkumar, Vivekanandan

2012-01-01

189

One year clinical performance and post-operative sensitivity of a bioactive dental luting cement--a prospective clinical study.  

PubMed

A one-year clinical study was performed on the efficacy of a bioactive dental cement (Ceramir C&B) with calcium aluminate and glass ionomer components. The study was performed on 38 crown and bridge abutments in 17 patients. Preparation parameters were recorded, as well as working-times, setting-times, and other handling characteristics. Baseline data were also recorded for gingival inflammation (GI) and pre-cementation sensitivity. Post-cementation parameters included sensitivity, gingival tissue reactions, marginal integrity and discolorations. All patients were seen for recall examinations at 30 days, and 6 months. For sixteen patients one-year recall data were collected on retention and subjective sensitivity. Fifteen subjects were available for one year clinical examinations. Three independent examiners found the working and setting time of the cement to be well within expected limits and that cement removal was easy. Four patients reported low-grades of immediate post-cementation sensitivity, however, this disappeared after an occlusal adjustment or without intervention within one month. At 12 months no retentive failures were recorded and no subjective sensitivity reported. All crowns were rated in the "Excellent" quality category for marginal integrity. Both GI-scores and scores for tooth sensitivity decreased during the course of the study. One year recall data yielded no incidence of secondary caries and no visible marginal discoloration. The new cement was thus found to perform favorably as a luting agent for permanent cementation. PMID:20162930

Jefferies, S R; Pameijer, C H; Appleby, D; Boston, D; Lööf, J; Glantz, P O

2009-01-01

190

A study of cements formed by aqueous lactic acid and aluminosilicate glass.  

PubMed

A study is reported of the formation of cements from aqueous lactic acid and aluminosilicate glass of the type used in dental glass-ionomer cements. These cements were found to set quickly, and were shown by infrared spectroscopy to have undergone a neutralization reaction to yield mainly calcium lactate. They were very soluble in water at 1 h, but became progressively less so over time; when matured for 6 h before being placed in water, they had become almost insoluble. No spectroscopic differences could be detected between the cements at 1 h or 6 h, indicating that insolubilization arises from a reaction that does not alter the part of the infrared spectrum examined. This suggested that a wholly inorganic reaction between the ion-depleted glass fragments is responsible for the formation of the insoluble structure. After 24 h, the cements were found to have compressive strengths in the range 9-35 MPa, the actual value varying with concentration of lactic acid used to form the cement, and there was no statistically significant increase in strength for the strongest of these after one month. PMID:15348618

Nicholson, John W; Tawfik, Hamsa; Czarnecka, Beata

2002-04-01

191

Genotoxic and cytotoxic effects of different types of dental cement on normal cultured human lymphocytes.  

PubMed

In this study we have investigated the genotoxic and cytotoxic effects of eluates derived from different types of commercially available dental cements, including glass ionomer cements (GICs) (Ketac Cem/3M ESPE and GC Fuji I/GC Corp), resin-modified glass ionomer cements (RM-GICs) (RelyX Luting/3M ESPE and Vitrebond/3M ESPE) and dual-cure resin cements (RCs) (Variolink II/ Ivoclar-Vivadent and Panavia F 2.0/Kuraray) on normal cultured human lymphocytes. Lymphocyte primary cultures obtained from blood samples of three healthy donors were exposed to serial dilutions of eluates derived from specimens of each material tested. Metaphases were induced with phytohaemagglutinin, collected after 72h treatment by use of colchicine and stained according to the fluorescence plus giemsa (FPG) procedure. Preparations were scored for sister chromatid exchange (SCE) and chromosomal aberrations (CAs), while the proliferation rate index (PRI) was also calculated. Our results show that eluates derived from the RM-GICs and RCs caused severe genotoxic effects by significantly increasing the frequencies of SCEs and CAs in cultures of peripheral blood lymphocytes and by decreasing the relevant PRI values in a dose-dependent manner, whereas the two GICs caused only minor cytogenetic effects. Eluates of the two RM-GICs (Vitrebond and RelyX) were also very cytotoxic, as the first serial dilutions of both materials caused a complete mitotic arrest in lymphocyte cultures. Overall, the degree of genotoxicity and cytotoxicity caused by dental cements decreased as follows: Viterbond>Rely X>Panavia F 2.0>Variolink II>Ketac Cem=GC Fuji I. These results indicate that different types of dental cement differ extensively in their genotoxic and cytotoxic potential and their ability to affect chromosomal integrity, cell-cycle progression, DNA replication and repair. Although these results cannot be directly extrapolated to the clinical situation, the potential occurrence of adverse effects caused by the RM-GICs and RCs tested in this study should be considered when making a clinical decision about dental cements. PMID:19028600

Bakopoulou, A; Mourelatos, D; Tsiftsoglou, A S; Giassin, N P; Mioglou, E; Garefis, P

2009-01-31

192

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

193

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

PubMed

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

Villat, Cyril; Grosgogeat, Brigitte; Seux, Dominique; Farge, Pierre

2013-11-01

194

Correlation between margin fit and microleakage in complete crowns cemented with three luting agents.  

PubMed

Microleakage can be related to margin misfit. Also, traditional microleakage techniques are time-consuming. This study evaluated the existence of correlation between in vitro margin fit and a new microleakage technique for complete crowns cemented with 3 different luting agents. Thirty human premolars were prepared for full-coverage crowns with a convergence angle of 6 degrees, chamfer margin of 1.2 mm circumferentially, and occlusal reduction of 1.5 mm. Ni-Cr cast crowns were cemented with either zinc phosphate (ZP) (S.S. White), resin-modified glass-ionomer (RMGI) (Rely X Luting Cement) or a resin-based luting agent (RC) (Enforce). Margin fit (seating discrepancy and margin gap) was evaluated according to criteria in the literature under microscope with 0.001 mm accuracy. After thermal cycling, crowns were longitudinally sectioned and microleakage scores at tooth-cement interface were obtained and recorded at x100 magnification. Margin fit parameters were compared with the one-way ANOVA test and microleakage scores with Kruskal-Wallis and Dunn's tests (alpha=0.05). Correlation between margin fit and microleakage was analyzed with the Spearman's test (alpha=0.05). Seating discrepancy and marginal gap values ranged from 81.82 microm to 137.22 microm (p=0.117), and from 75.42 microm to 78.49 microm (p=0.940), respectively. Marginal microleakage scores were ZP=3.02, RMGI=0.35 and RC=0.12 (p<0.001), with no differences between RMGI and RC scores. The correlation coefficient values ranged from -0.27 to 0.30 (p>0.05). Conclusion: Margin fit parameters and microleakage showed no strong correlations; cast crowns cemented with RMGI and RC had lower microleakage scores than ZP cement. PMID:19089292

Rossetti, Paulo Henrique Orlato; do Valle, Accacio Lins; de Carvalho, Ricardo Marins; De Goes, Mario Fernando; Pegoraro, Luiz Fernando

2008-01-01

195

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

196

Adhesion of conventional and simplified resin-based luting cements to superficial and deep dentin.  

PubMed

This study evaluated the bond strengths of conventional (chemically and dual-polymerized) and simplified resin-based luting cements with their corresponding adhesives to superficial dentin (SD) and deep dentin (DD). Recently extracted third molars (N = 70, n = 10 per group) were obtained and prepared for testing procedures. After using their corresponding etchants, primers, and/or adhesive systems, the conventional and simplified cements (Variolink II [group A, conventional], Bifix QM [group B, conventional], Panavia F2.0 [group C, conventional], Multilink Automix [group D, simplified], Superbond C&B [group E, conventional], Clearfil Esthetic Cement [group F, simplified], Ketac-Fil [group G, conventional]) were adhered incrementally onto the dentin surfaces using polyethylene molds (inner diameter 3.5 mm, height 5 mm) and polymerized accordingly. Resin-modified glass-ionomer cement (RMGIC) acted as the control material. Shear bond strengths (1 mm/min) were determined after 500 times of thermocycling. Kruskal-Wallis and Mann-Whitney tests were used to analyze the data (? = 0.05). Bond strength (MPa) results were significantly affected by the cement types and their corresponding adhesive systems (p ? 0.05). The shear bond strengths (MPa ± SD) for groups A-G were 14.6 ± 3.8, 18.9 ± 3.9, 5.5 ± 4.5, 3.1 ± 3.6, 1.1 ± 2.5, 15.5 ± 2.6, 7 ± 4.3 and 7.1 ± 5.8, 15.1 ± 7.8, 8.4 ± 7.3, 7.5 ± 7.3, 4.9 ± 5.1, 12.5 ± 2.1, 6 ± 2.6 for SD and DD, respectively. The level of dentin depth did not decrease the bond strength significantly (p > 0.05) for all cements, except for Variolink II (p < 0.05). On the SD, bond strength of resin cements with "etch-and-rinse" adhesive systems (Variolink II, Bifix QM, Super-Bond C&B) showed similar results being higher than those of the simplified ones. Simplified cements and RMGIC as control material showed inferior adhesion to superficial and deep dentin compared to conventional resin cements tested. PMID:21833482

Özcan, Mutlu; Mese, Ayse

2012-08-01

197

Biocompatibility of Titanium  

NASA Astrophysics Data System (ADS)

Titanium is the material of choice for orthopaedic applications because of its known biocompatibility. In order to enhance osteogenic properties of the Ti implants, it is necessary to understand the origin of its biocompatibility. We addresses the origin of Ti biocompatibility through (1) theoretical modeling, (2) the precise determination of Ti surface chemistry by X-ray photoelectron spectroscopy (XPS), (3) and the study of fibronectin adsorption as a function of Ti (near) surface chemistry by Enzyme-linked immunosorbent assay (ELISA). We compare the protein adsorption on Ti with the native oxide layer and the one coated by TiO2 in anatase phase using ion beam assisted deposition (IBAD). We show that the thin native sub-stoichiometric titanium oxide layer is crucial for biocompatibility of Ti surface. This is due to the enhancement of the non-specific adsorption of proteins which mediate cell adhesion. Improving the surface oxide quality, i.e. fabricating stoichiometric TiO2 (using IBAD) as well as nanoengineering the surface topology that matches its dimensions to that of adhesive proteins, is crucial for increased protein adsorption and, as a result, further increases biocompatibility of Ti implant materials.

Namavar, Fereydoon; Sabirianov, Renat; Marton, Denes; Rubinstein, Alexander; Garvin, Kevin

2012-02-01

198

Asphalt cement  

MedlinePLUS

... petroleum material that hardens when it cools. Asphalt cement poisoning occurs when someone swallows asphalt. This is ... Road paving materials Roofing materials Tile cements Note: This list may not include all uses of asphalt.

199

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

200

Cement disease.  

PubMed

Does "cement disease" exist? The bony environment surrounding a loosened cemented prosthesis is an abnormal pathologic condition which, if left unattended, will progress to a total failure of the joint including an inhibition of function and immobilizing pain. That biomaterial properties of the cement used for fixation also contribute to the pathologic state separates this disease from other modes of loosening. This leads inevitably to the conclusion that "cement disease" does exist. Methyl methacrylate has revolutionized the treatment of severe joint dysfunction. There can be no doubt that improving surgical technique, cement handling, and the cement itself will continue to improve the results and reduce the incidence of failure due to loosening. Cement is undoubtedly satisfactory for elderly patients with low activity levels and relatively short life expectancies. However, because of the inherent biologic and biomechanical properties of methyl methacrylate, it is unlikely that it can be rendered satisfactory in the long run for the young, the active, or the overweight patient, for whom alternatives are currently being sought. In such cases, the elimination of "cement disease" can only occur with the elimination of cement. Alternatives include the search for other grouting materials and the development of prostheses with satisfactory surfaces for either press-fit or biologic ingrowth. PMID:3315375

Jones, L C; Hungerford, D S

1987-12-01

201

A comparison of the shear bond strength and failure mode to metals of unsupported and supported luting cement specimens.  

PubMed

Purpose: To compare the mean shear bond strength (SBS) and failure mode of a resin-modified glass-ionomer luting cement (RM-GIC) to five different metals using unsupported and supported cement specimens with different placement of the shear load. Materials and Methods: A RM-GIC was bonded to five metals using "unsupported" and "supported" techniques at a SBS-specimen diameter of 2.36 mm. The bond was stressed to failure using shear knife and wire loop debonding protocols. For the shear knife method, the distance of the shear force from the interface was 0 mm or 0.3 mm. Failure analysis was assessed by stereomicroscope and SEM. Results: Two-way ANOVA and post-hoc Tukey's test revealed a significant difference between the unsupported and supported mean SBS. The SBS of supported specimens, where the shear force was applied to the mold that enclosed the specimens, were in most cases statistically significantly higher (p < 0.05) than specimens that were not supported. The mean bond strengths of RM-GIC ranged from 4.5 ± 2.3 MPa to 27.4 ± 3.7 MPa. Analysis of the failure mode showed significant differences (p < 0.001) for the test methods except for adhesion to gold-based metal. The adhesive failure mode was between 91% and 97% for supported specimens and between 47% and 63% for unsupported specimens. Conclusion: Within the limits of this study, supported specimens exhibited higher mean SBS than unsupported specimens. The method of debonding had a significant effect on the mean SBS for RM-GIC bonded to metal. Mold-supported specimens had a higher incidence of adhesive failure than unsupported cement specimens. PMID:24479119

Cheetham, Joshua J; Palamara, Joseph E; Tyas, Martin J; Burrow, Michael F

2014-06-01

202

Ionomeric cement--a bone glue for device fixation.  

PubMed

Ionocap, an ionomeric cement, is a new bone replacement material. Its generic name is polymaleinate ionomer, and it is an inert standardized biomaterial which is offered in a two component system. Since 1988 the ionomeric cement has been evaluated clinically in different situations. Its unique properties of biocompatibility, biostability and permanent adherence to bone make this new material very useful in head and neck surgery. PMID:8205982

Rüdel, C; Zöllner, W

1994-03-01

203

Cementing apparatus  

SciTech Connect

For use in cementing a casing string within a well bore, an assembly is described comprising: a float collar including an outer body connectable as part of the casing string and an inner body having a bore there through having upper and lower ends and a valve member in the bore to permit flow downwardly and prevent flow upwardly there through, a cement plug including a body having a bore there through and upper and lower ends with a frangible diaphragm there across and lips there about flexibly engagable with the casing string to permit the plug to be prepared downwardly onto the float collar, the upper end of the bore of the float collar having threads thereon and the lower end of the body of the cement plug having threads there about for limited make-up with the threads in the bore of the float collar in response to rotation of the cement plug in one direction, and a wiper plug comprising a body having lips there about flexibly engagable with the casing string to permit the wiper plug to be pumped downwardly onto the cement plug, the upper end of the bore of the cement plug having threads thereon and the lower end of the bore of the body of the wiper plug having threads there about for limited make-up with the threads in the bore of the cement plug in response to rotation of the wiper plug in said one direction, and the inner body of the float collar and the bodies of the cement and wiper plugs being of a drillable material.

Coone, M.G.; Cole, F.

1993-08-10

204

Investigating calcium polyphosphate addition to a conventional calcium phosphate cement for bone-interfacing applications  

Microsoft Academic Search

Calcium phosphate cements (CPCs) are of great interest in bone regeneration applications because of their biocompatibility and osteoconductivity, and as delivery vehicles for therapeutics; however, delivery applications have been limited by adverse interactions between therapeutics and the cement setting reaction. Amorphous calcium polyphosphate (CPP) yields a biodegradable material with a demonstrated drug delivery capacity following appropriate processing. The incorporation of

Jennifer Lynn Krausher

2010-01-01

205

Transition element contained partial-stabilized cement (PSC) as a dental retrograde-filling material  

Microsoft Academic Search

A modified silicate cement has previously been developed as a dental retrograde filling; it has great sealing ability, good biocompatibility, and anti-bacterial properties. However, its clinical application is limited by a long setting time and poor handling property. In the present study, the setting time has been shortened by raising the preparation temperature of the cement and adding transition elements

Feng-Huei Lin; Wen-Hsi Wang; Chun-Pin Lin

2003-01-01

206

Cement invasion  

SciTech Connect

Damage from cement and cement filtrate has been a much discussed subject since set-through-and-perforate completions were first used. Historically, much of the discussion was similar to that for rotary drilling and drilling mud - it would be nice to prevent all damage, but in the real world, some damage must be tolerated to allow the operator to reap the benefits of cementing. The principal perceived formation damage due to cement invasion is seen by the operator as reducing production. The pure idealist requires full potential production under all alternatives, and would to complete all oil and gas wells free of any formation damage. The more practical idealist holds that damage would result in lower production with the completion method he prefers should be prevented. The pragmatic operator compares the cost of preventing damage to the cost of correcting the damage. Even an extremely high damage ratio is academic if the planned stimulation treatment eliminates the influence the cement invasion might have on production. Formations with permeability high enough to yield economical production without some sort of stimulation or cleanup treatment are unlikely to be subject to significant cement filtrate damage.

Sutton, D.L.

1988-09-01

207

Tooth Abfraction Lesions  

MedlinePLUS

... Choices include a composite material or glass ionomer cement . A tooth with abfraction lesions may be more ... need treatment. For others, filling the areas with cement or composite solves the problem. Additional Info American ...

208

Biocompatibility of dental amalgams.  

PubMed

Objective. The purpose of this review paper is to review the literature regarding the toxicology of mercury from dental amalgam and evaluate current statements on dental amalgam. Materials and Methods. Two key-words "dental amalgam" and "toxicity" were used to search publications on dental amalgam biocompatibility published in peer-reviewed journals written in English. Manual search was also conducted. The most recent declarations and statements were evaluated using information available on the internet. Case reports were excluded from the study. Results. The literature show that mercury released from dental amalgam restorations does not contribute to systemic disease or systemic toxicological effects. No significant effects on the immune system have been demonstrated with the amounts of mercury released from dental amalgam restorations. Only very rarely have there been reported allergic reactions to mercury from amalgam restorations. No evidence supports a relationship between mercury released from dental amalgam and neurological diseases. Almost all of the declarations accessed by the internet stated by official organizations concluded that current data are not sufficient to relate various complaints and mercury release from dental amalgam. Conclusions. Available scientific data do not justify the discontinuation of amalgam use from dental practice or replacement with alternative restorative dental materials. PMID:22145006

Uçar, Yurdanur; Brantley, William A

2011-01-01

209

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

210

Lunar cement  

NASA Astrophysics Data System (ADS)

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.

211

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

212

Sculpting with Cement.  

ERIC Educational Resources Information Center

Cement offers many creative possibilities for school art programs. Instructions are given for sculpting with fiber-cement and sand-cement, as well as for finishing processes and the addition of color. Safety is stressed. (IS)

Olson, Lynn

1983-01-01

213

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.

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

2010-01-01

214

Biocompatibility studies on silicone rubber  

Microsoft Academic Search

Medical grade silicone rubber has been developed for use as a material for the fabrication of medical implant devices. It has high performance, strength, elongation and very resistant to flaws and crack propagation with an excellent fatigue flex life. The toxicological\\/biocompatibility studies such as systemic toxicity, intracutaneous irritation, haemolysis, intramuscular implantation, rabbit pyrogen, LAL, sterility and safety tests was carried

P. V. Mohanan; K. Rathinam

1995-01-01

215

Bone cement/layered double hydroxide nanocomposites as potential biomaterials for joint implant.  

PubMed

Poly(methyl methacrylate)-based bone cement and layered double hydroxide (LDH) nanocomposites have been used as a grouting material for total joint arthroplasty. Few weight percentage of nanoLDH was uniformly dispersed in the bone cement matrix to have adequate interaction with matrix polymer. Mechanical strength, stiffness, toughness, and fatigue resistance of the nanocomposites are found to be higher than that of pure bone cement. Nanocomposites are thermally stable as compared to pristine bone cement. Direct mixing of the nanoLDH without any organic solvent makes these nanocomposites biocompatible. Biocompatibility was evaluated and compared with that of commercial bone cement by measuring hydrophilic nature, hemolysis assay, thrombosis assay, and deposition of apatite in simulated body fluid immersion. Finally, the viability of human osteoblast cells on the above developed nanocomposites was testified for actual biocompatibility. The experiment showed better cell growth in nanocomposites as compared to pure bone cement. Thus, these nanocomposites are found to be better grouting material than bone cement. PMID:22733710

Kapusetti, Govinda; Misra, Nira; Singh, Vakil; Kushwaha, R K; Maiti, Pralay

2012-12-01

216

Stretchable biocompatible electronics by embedding electrical circuitry in biocompatible elastomers.  

PubMed

Stretchable and curvilinear electronics has been used recently for the fabrication of micro systems interacting with the human body. The applications range from different kinds of implantable sensors inside the body to conformable electrodes and artificial skins. One of the key parameters in biocompatible stretchable electronics is the fabrication of reliable electrical interconnects. Although very recent literature has reported on the reliability of stretchable interconnects by cyclic loading, work still needs to be done on the integration of electrical circuitry composed of rigid components and stretchable interconnects in a biological environment. In this work, the feasibility of a developed technology to fabricate simple electrical circuits with meander shaped stretchable interconnects is presented. Stretchable interconnects are 200 nm thin Au layer supported with polyimide (PI). A stretchable array of light emitting diodes (LEDs) is embedded in biocompatible elastomer using this technology platform and it features a 50% total elongation. PMID:23367298

Jahanshahi, Amir; Salvo, Pietro; Vanfleteren, Jan

2012-01-01

217

Water absorption characteristics and cytotoxic and biological evaluation of bone cements formulated with a novel activator.  

PubMed

A novel activator, N,N,Dimethylamino 4-benzyl laurate (DML) was used in the curing of acrylic bone cements, based on poly(methylmethacrylate). The water absorption characteristics were studied, and the behavior was found to be similar to commercial bone cements. The net amount of solubles were also in the same range as obtained for commercial cements cured with conventional activators. Biocompatibility tests were conducted on the neat activator (DML) and cured cements. The present study indicated that there were no toxic effects; furthermore, osteoblast-like cells were seen to proliferate and differentiate more readily on DML containing cements. The analysis of the effect of leachables from cements into the media showed continued cell proliferation and cell viability. PMID:10490688

Deb, S; Silvio, L D; Vazquez, B; San Roman, J

1999-01-01

218

Downhole cementing tool assembly  

SciTech Connect

A cementing apparatus for use in cementing a casing string in a well bore is described comprising: (a) a float collar incorporated in the casing string, the float collar including a passage extending therethrough; (b) a cementing plug having a cylindrical body including an axial passage extending therethrough, the cementing plug body further including closure means extending across the axial passage; (c) a wiper plug having a cylindrical body including wiper means extending about the wiper plug body for wiping the casing as the wiper plug is advanced through the casing; (d) cooperative interlocking means located on the float collar, the cementing plug and the wiper plug for locking the cementing plug and the wiper plug to the float collar in a nonrotatable position; and (e) wherein the cementing plug and the wiper plug including frangible internal cutters embedded in the cementing plug and the wiper plug.

Wardlaw, L.J.; Young, J.A.

1987-12-08

219

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

220

Do cement nanotubes exist?  

PubMed

Using atomistic simulations, this work indicates that cement nanotubes can exist. The chemically compatible nanotubes are constructed from the two main minerals in ordinary Portland cement pastes, namely calcium hydroxide and a calcium silicate hydrate called tobermorite. These results show that such nanotubes are stable and have outstanding mechanical properties, unique characteristics that make them ideally suitable for nanoscale reinforcements of cements. PMID:22589176

Manzano, H; Enyashin, A N; Dolado, J S; Ayuela, A; Frenzel, J; Seifert, G

2012-06-26

221

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

222

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, comparison studies of the three cement systems examined several properties: tensile strength, Young's modulus, and shear bond. Testing to determine the effect of temperature cycling on the shear bond properties of the cement systems was also conducted. In addition, the stress-strain behavior of the cement types was studied. This report discusses a software program that is being developed to help design ULHS cements and foamed cements.

Fred Sabins

2002-04-29

223

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

224

Polycrystalline Silicon: a Biocompatibility Assay  

NASA Astrophysics Data System (ADS)

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

Pecheva, E.; Laquerriere, P.; Bouthors, Sylvie; Fingarova, D.; Pramatarova, L.; Hikov, T.; Dimova-Malinovska, D.; Montgomery, P.

2010-01-01

225

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

226

Enhanced Biocompatibility of Porous Nitinol  

NASA Astrophysics Data System (ADS)

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.

Munroe, Norman; Pulletikurthi, Chandan; Haider, Waseem

2009-08-01

227

Enhanced Biocompatibility of Porous Nitinol.  

PubMed

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

2009-08-01

228

Ex vivo human trabecular bone model for biocompatibility evaluation of calcium phosphate composites modified with spray dried biodegradable microspheres.  

PubMed

Our aim was to study the suitability of the ex-vivo human trabecular bone bioreactor ZetOS to test the biocompatibility of calcium phosphate bone cement composites modified with spray dried, drug loaded microspheres. We hypothesized, that this bone bioreactor could be a promising alternative to in vivo assessment of biocompatibility in living human bone over a defined time period. Composites consisting of tetracycline loaded poly(lactic-co-glycolic acid) microspheres and calcium phosphate bone cement, were inserted into in vitro cultured human femora head trabecular bone and incubated over 30 days at 37°C in the incubation system. Different biocompatibility parameters, such as lactate dehydrogenase activity, alkaline phosphatase release and the expression of relevant cytokines, IL-1?, IL-6, and TNF-?, were measured in the incubation medium. No significant differences in alkaline phosphatase, osteocalcin, and lactate dehydrogenase activity were measured compared to control samples. Tetracycline was released from the microspheres, delivered and incorporated into newly formed bone. In this study we demonstrated that ex vivo biocompatibility testing using human trabecular bone in a bioreactor is a potential alternative to animal experiments since bone metabolism is still maintained in a physiological environment ex vivo. PMID:23568426

Schnieders, Julia; Gbureck, Uwe; Germershaus, Oliver; Kratz, Marita; Jones, David B; Kissel, Thomas

2013-10-01

229

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

230

Downhole cementing tool assembly  

SciTech Connect

This patent describes a cementing apparatus for use in cementing a casing string in a well bore. It comprises a float collar incorporated in the casing string, the float collar including a passage extending therethrough; a cementing plug having a cylindrical body including an axial passage extending therethrough, the cementing plug body further including closure means extending across the axial passage; a wiper plug having a cylindrical body including wiper means extending about the wiper plug body for wiping the casing as the wiper plug is advanced through the casing; and cooperative interlocking means located on the float collar, the cementing plug and the wiper plug for locking the cementing plug and the wiper plug to the float collar in a nonrotatable position.

Wardlaw, L.J.; Young, J.A.

1991-08-06

231

Biomechanical parameters of the BP-enriched bone cement.  

PubMed

Bisphosphonates (BPs) are well-known substances with very efficient antiresorptive properties. Their beneficial actions are useful not only in achieving better bone mineral density but also in improving bone microarchitecture, strength and, consequently, its quality. Surgical cement, being a polymer composite, is required to be highly biocompatible and biotolerant. The goal of the presented study was to assess whether the enrichment of cement with pamidronate has changed its biomechanical properties. We compared the biomechanical parameters of clean bone cement and BP-enriched bone cement, which were both used formerly in our rat models. Biomechanical properties of BP-enriched bone cement are defined by two basic terms: stress and strain, which are caused by the influence of external force. In the investigatory process of the bone's biomechanical parameters, the compressive test and the three-point flexural tests were used. During the three-point flexural investigation, the sample was supported at both ends and loaded in the middle, resulting in a flexure. After a specific range of flexure, the sample was fractured. In obtained results, there were no significant differences in the values of the stress determined at the point of maximal load and the energy stored in the samples for proportional stress-strain limit (elastic region). There were also no significant differences in the density of the samples. The study shows that the enrichment of bisphosphonates causes yielding of the bone cement material. In the presented data, we conclude that use of pamidronate implanted in bone cement did not have a detrimental effect on its biomechanical properties. Therefore, the obtained results encouraged us to perform further in vivo experiments which assess the biomechanical properties of bones implanted with BP-enriched bone cement. PMID:23670846

Matuszewski, Lukasz; Olchowik, Gra?yna; Mazurkiewicz, Tomasz; Kowalczyk, Bart?omiej; Zdrojewska, Agata; Matuszewska, Anna; Ciszewski, Andrzej; Gospodarek, Ma?gorzata; Morawik, Iwona

2014-05-01

232

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. DOE joined the Materials Management Service (MMS)-sponsored joint industry project ''Long-Term Integrity of Deepwater Cement under Stress/Compaction Conditions.'' Results of the project contained in two progress reports are also presented in this report.

Fred Sabins

2003-01-31

233

How polysulfone dialysis membranes containing polyvinylpyrrolidone achieve excellent biocompatibility?  

Microsoft Academic Search

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

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

2004-01-01

234

SURFACE CHEMISTRY INFLUENCE IMPLANT BIOCOMPATIBILITY  

PubMed Central

Implantable medical devices are increasingly important in the practice of modern medicine. Unfortunately, almost all medical devices suffer to a different extent from adverse reactions, including inflammation, fibrosis, thrombosis and infection. To improve the safety and function of many types of medical implants, a major need exists for development of materials that evoked desired tissue responses. Because implant-associated protein adsorption and conformational changes thereafter have been shown to promote immune reactions, rigorous research efforts have been emphasized on the engineering of surface property (physical and chemical characteristics) to reduce protein adsorption and cell interactions and subsequently improve implant biocompatibility. This brief review is aimed to summarize the past efforts and our recent knowledge about the influence of surface functionality on protein:cell:biomaterial interactions. It is our belief that detailed understandings of bioactivity of surface functionality provide an easy, economic, and specific approach for the future rational design of implantable medical devices with desired tissue reactivity and, hopefully, wound healing capability.

Thevenot, Paul; Hu, Wenjing; Tang, Liping

2011-01-01

235

Preclinical evaluation of strontium-containing bioactive bone cement.  

PubMed

Strontium (Sr) has become more attractive for orthopaedic applications as they can simultaneously stimulate bone formation and prevent bone loss. A Sr-containing bioactive bone cement (Sr-BC) has been designed to fix osteoporotic bone fracture. Sr is a trace element, so the safety of containing Sr is concerned when Sr-BC is implanted in human body. The preclinical assessment of biocompatibility of Sr-BC was conducted according to ISO 10993 standards. MTT assay showed that this bioactive bone cement was non-toxic to mouse fibroblasts, and it met the basic requirement for the orthopaedic implant. The three independent genetic toxicity studies including Ames, chromosome aberration and bone marrow micronucleus assays demonstrated absence of genotoxic components in Sr-BC, which reassured the safety concerns of this novel bone cement. The muscle implantation results in present study were also encouraging. The acute inflammation around the cement was observed at 1 week post-implantation; however, no significant difference was observed between control and Sr-BC groups. These responses may be attributed to the presence of the foreign body, but the tissue healed after 12 weeks implantation. In summary, the above preclinical results provide additional assurance for the safety of this implant. Sr-BC can be used as a potential alternative to the traditional bone cement. PMID:24094231

Li, Zhaoyang; Yuan, Ning; Lam, Raymond Wing Moon; Cui, Zhenduo; Yang, Xianjin; Lu, William Weijia

2013-12-01

236

Strength of cemented grains  

NASA Astrophysics Data System (ADS)

We conducted compaction tests (isotropic drained loading) on randomly packed glass beads that were a) uncemented and b) cemented by epoxy at their contacts. In the latter case, the volume of the epoxy accounted for 10 percent of the pore space. Intensive crushing of grains was observed in the first case at about 50 MPa. In the second case, the cemented grains stayed intact, the failure being localized within the epoxy. Therefore, even small amounts of cement at contacts prevent the failure of grains. Theoretically, this effect follows from our theory of cemented granular materials: stress concentration is high at the contacts of uncemented grains, whereas even small amounts of relatively soft cement result in a more uniform stress distribution over a larger contact area.

Yin, Hezhu; Dvorkin, Jack

1994-05-01

237

Cement-based electronics  

NASA Astrophysics Data System (ADS)

The term Intelligent Highway is usually intended to mean external systems that are added to pre-existing highways. However, the ability to construct basic passive electronic elements is demonstrated employing electrically dissimilar Portland cement pastes. These electronic elements include resistors, rectifying pn-junctions, piezoelectric and piezoresistive sensors, and thermocouple junctions. It may therefore be possible to build intelligence into the highway itself utilizing cement-based electronic devices. As compared to semiconductor-based electronic components, those derived from cement have minimal materials and processing costs, do not require clean rooms, and are mechanically more rugged. Results and characterizations are presented for resistive elements and rectifying pn-junctions derived from admixtures of stainless steel fiber (n-type) and carbon fiber (p-type) in Portland cement. These elements are then combined to produce a monolithic cement-based digital logic 2-input AND gate.

Konesky, Gregory A.

238

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

239

Large strains in cemented granular aggregates: Elastic-plastic cement  

Microsoft Academic Search

We describe large-strain behavior of cemented geomaterials by modeling the deformation of a random pack of identical cemented spheres. In this model we assume that the grains are elastic but that the intergranular cement becomes partly plastic as local stresses meet a plasticity condition. This plasticity condition for a thin elastic-plastic cement layer is derived based on the von Mises

Jack Dvorkin

1996-01-01

240

Premixed macroporous calcium phosphate cement scaffold.  

PubMed

Calcium phosphate cement (CPC) sets in situ to form resorbable hydroxyapatite and is promising for orthopaedic applications. However, it requires on-site powder-liquid mixing during surgery, which prolongs surgical time and raises concerns of inhomogeneous mixing. The objective of this study was to develop a premixed CPC scaffold with macropores suitable for tissue ingrowth. To avoid the on-site powder-liquid mixing, the CPC paste was mixed in advance and did not set in storage; it set only after placement in a physiological solution. Using 30% and 40% mass fractions of mannitol porogen, the premixed CPC scaffold with fibers had flexural strength (mean +/- sd; n = 5) of (3.9 +/- 1.4) MPa and (1.8 +/- 0.8) MPa, respectively. The scaffold porosity reached (68.6 +/- 0.7)% and (74.7 +/- 1.2)%, respectively. Osteoblast cells colonized in the surface macropores of the scaffold and attached to the hydroxyapatite crystals. Cell viability values for the premixed CPC scaffold was not significantly different from that of a conventional non-premixed CPC known to be biocompatible (P > 0.1). In conclusion, using fast-dissolving porogen and slow-dissolving fibers, a premixed macroporous CPC scaffold was developed with strength approaching the reported strengths of sintered porous hydroxyapatite implants and cancellous bone, and non-cytotoxicity similar to a biocompatible non-premixed CPC. PMID:17277972

Xu, Hockin H K; Carey, Lisa E; Simon, Carl G

2007-07-01

241

In vivo biocompatibility of bacterial cellulose.  

PubMed

The biocompatibility of a scaffold for tissue engineered constructs is essential for the outcome. Bacterial cellulose (BC) consists of completely pure cellulose nanofibrils synthesized by Acetobacter xylinum. BC has high mechanical strength and can be shaped into three-dimensional structures. Cellulose-based materials induce negligible foreign body and inflammatory responses and are considered as biocompatible. The in vivo biocompatibility of BC has never been evaluated systematically. Thus, in the development of tissue engineered constructs with a BC scaffold, it is necessary to evaluate the in vivo biocompatibility. BC was implanted subcutaneously in rats for 1, 4, and 12 weeks. The implants were evaluated in aspects of chronic inflammation, foreign body responses, cell ingrowth, and angiogenesis, using histology, immunohistochemistry, and electron microscopy. There were no macroscopic signs of inflammation around the implants. There were no microscopic signs of inflammation either (i.e., a high number of small cells around the implants or the blood vessels). No fibrotic capsule or giant cells were present. Fibroblasts infiltrated BC, which was well integrated into the host tissue, and did not elicit any chronic inflammatory reactions. The biocompatibility of BC is good and the material has potential to be used as a scaffold in tissue engineering. PMID:16278860

Helenius, Gisela; Bäckdahl, Henrik; Bodin, Aase; Nannmark, Ulf; Gatenholm, Paul; Risberg, Bo

2006-02-01

242

Phosphate based oil well cements  

Microsoft Academic Search

The main application of the cement in an oil well is to stabilize the steel casing in the borehole and protect it from corrosion. The cement is pumped through the borehole and is pushed upwards through the annulus between the casing and the formation. The cement will be exposed to temperature and pressure gradients of the borehole. Modified Portland cement

Ramkumar Natarajan

2005-01-01

243

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.

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

244

Preparation, physical-chemical characterization, and cytocompatibility of polymeric calcium phosphate cements.  

PubMed

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

245

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. Laboratory testing during the eleventh quarter focused on evaluation of the alkali-silica reaction of eight different cement compositions, four of which contain ULHS. This report provides a progress summary of ASR testing. The original laboratory procedure for measuring set cement expansion resulted in unacceptable erosion of the test specimens. In subsequent tests, a different expansion procedure was implemented and an alternate curing method for cements formulated with TXI Lightweight cement was employed to prevent sample failure caused by thermal shock. The results obtained with the modified procedure showed improvement over data obtained with the original procedure, but data for some compositions were still questionable. Additional modification of test procedures for compositions containing TXI Lightweight cement were implemented and testing is ongoing.

Fred Sabins

2003-07-31

246

Cytotoxicity Comparison of Harvard Zinc Phosphate Cement Versus Panavia F2 and Rely X Plus Resin Cements on Rat L929-fibroblasts  

PubMed Central

Objective: Resin cements, regardless of their biocompatibility, have been widely used in restorative dentistry during the recent years. These cements contain hydroxy ethyl methacrylate (HEMA) molecules which are claimed to penetrate into dentinal tubules and may affect dental pulp. Since tooth preparation for metal ceramic restorations involves a large surface of the tooth, cytotoxicity of these cements would be more important in fixed prosthodontic treatments. The purpose of this study was to compare the cytotoxicity of two resin cements (Panavia F2 and Rely X Plus) versus zinc phosphate cement (Harvard) using rat L929-fibroblasts in vitro. Materials and Methods: In this experimental study, ninety hollow glass cylinders (internal diameter 5-mm, height 2-mm) were made and divided into three groups. Each group was filled with one of three experimental cements; Harvard Zinc Phosphate cement, Panavia F2 resin cement and Rely X Plus resin cement. L929- Fibroblast were passaged and subsequently cultured in 6-well plates of 5×105 cells each. The culture medium was RPMI_ 1640. All samples were incubated in CO2. Using enzyme-linked immune-sorbent assay (ELISA) and (3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) (MTT) assay, the cytotoxicity of the cements was investigated at 1 hour, 24 hours and one week post exposure. Statistical analyses were performed via two-way ANOVA and honestly significant difference (HSD) Tukey tests. Results: This study revealed significant differences between the three cements at the different time intervals. Harvard cement displayed the greatest cytotoxicity at all three intervals. After 1 hour Panavia F2 showed the next greatest cytotoxicity, but after 24-hours and oneweek intervals Rely X Plus showed the next greatest cytotoxicity. The results further showed that cytotoxicity decreased significantly in the Panavia F2 group with time (p<0.005), cytotoxicity increased significantly in the Rely X Plus group with time (p<0.001), and the Harvard cement group failed to showed no noticeable change in cytotoxicity with time. Conclusion: Although this study has limitations, it provides evidence that Harvard zinc phosphate cement is the most cytotoxic product and Panavia F2 appears to be the least cytotoxic cement over time.

Mahasti, Sahabi; Sattari, Mandana; Romoozi, Elham; Akbar-zadeh Baghban, Alireza

2011-01-01

247

Cement composite delivery system.  

PubMed

Several new and innovative techniques have recently been introduced that purport to increase the strength of polymethyl methacrylate bone cement. One of these concepts is the use of carbon and polymer fibers to form a cement composite. Bone cement composites usually 1% fiber, are very difficult to use clinically. The composite is very sticky and viscous, which precludes effective hand packing or the use of conventional delivery systems. A new delivery system for very viscous materials is presented and examples of in vitro application are shown. PMID:3453485

Convery, F R; Devine, S D; Hollis, J M; Woo, S L

1986-09-01

248

Cement and concrete  

NASA Astrophysics Data System (ADS)

To produce lunar cement, high-temperature processing will be required. It may be possible to make calcium-rich silicate and aluminate for cement by solar heating of lunar pyroxene and feldspar, or chemical treatment may be required to enrich the calcium and aluminum in lunar soil. The effects of magnesium and ferrous iron present in the starting materials and products would need to be evaluated. So would the problems of grinding to produce cement, mixing, forming in vacuo and low gravity, and minimizing water loss.

Corley, Gene; Haskin, Larry A.

249

Cement and concrete  

NASA Technical Reports Server (NTRS)

To produce lunar cement, high-temperature processing will be required. It may be possible to make calcium-rich silicate and aluminate for cement by solar heating of lunar pyroxene and feldspar, or chemical treatment may be required to enrich the calcium and aluminum in lunar soil. The effects of magnesium and ferrous iron present in the starting materials and products would need to be evaluated. So would the problems of grinding to produce cement, mixing, forming in vacuo and low gravity, and minimizing water loss.

Corley, Gene; Haskin, Larry A.

1992-01-01

250

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

PubMed

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

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

2011-09-01

251

Soil-Cement Study.  

National Technical Information Service (NTIS)

This study consisted of an examination of the compressive strengths of soil-cement mixtures on 15 construction projects from the standpoint of design and actual achievement. The laboratory design test was examined closely along with the present field meth...

J. L. Melancon S. C. Shah

1973-01-01

252

[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

253

Development, characterization, and validation of porous carbonated hydroxyapatite bone cement.  

PubMed

Carbonated hydroxyapatite (CHA) bone cement is capable of self-setting and forming structures similar to mineralized bone. Conventional CHA leaves little room for new bone formation and delays remodeling. The purposes of this study were to develop porous CHA (PCHA) bone cement and to investigate its physicochemical properties, biocompatibility, biodegradation, and in vivo bone repair potential. Vesicants were added to modify CHA, and the solidification time, porosity, and pore size of the PCHA cements were examined. The cytotoxicity and bone repair potential of PCHA were tested in a rabbit bone defect model and assessed by x-ray, histological examination, and mechanical testing. The porosity of the modified PCHA was 36%; 90.23% of the pores were greater than 70 mum, with a calcium/phosphate ratio of 1.64 and a solidification time of 15 minutes. The PCHA did not affect bone cell growth in vitro, and the degrading time of the PCHA was two and four times faster in vitro and in vivo when compared to CHA. In the bone defect model, the amount of new bone formation in the PCHA-treated group was eight times greater than that of the CHA group; the compressive strength of the PCHA setting was relatively weak in the first weeks but increased significantly at 8 to 16 weeks compared to the CHA group. The PCHA has stable physicochemical properties and excellent biocompatibility; it degrades faster than CHA, provides more porous spaces for new bone ingrowths, and may be a new form of bone cement for the management of bone defects. PMID:19353574

Tang, Pei-Fu; Li, Gang; Wang, Ji-Fang; Zheng, Qiu-Jian; Wang, Yan

2009-08-01

254

In vivo evaluation of the biocompatibility of three current bonding agents.  

PubMed

The aim of this in vivo study was to evaluate the biocompatibility of three current bonding agents and calcium hydroxide cement. Sixty polyethylene tubes filled with the following materials: Group 1: Prime & Bond NT (PB-Dentsply, US; Group 2: Bond 1 (BO-Jeneric/Pentron, US); Group 3: Optibond Solo (OP-Kerr, US); and Group 4 (control): calcium hydroxide cement - Dycal (CH-Dentsply, US) were implanted into the connective tissue of 30 rats. After 15, 30 and 60 days, the implants were excised and the animals sacrificed. The biopsies were immersed in Karnovsky (pH, 7.2) fixative solution for 48 hours, and processed using routine histological technique. Six-micron-thick sections were cut and stained with hematoxilin and eosin and Masson's trichome technique. Microscopic evaluation was used to compare the connective tissue reactions caused by the experimental and control materials adjacent to the tube opening. At 15 days, the experimental and control materials triggered a moderate to intense inflammatory response which gave rise to a thick capsule adjacent to the tube opening. With time, the inflammatory reaction decreased. At 60 days, the connective tissue adjacent to the bonding agents exhibited a persistent inflammatory response mediated by macrophages and giant cells which were engulfing displaced resin components. On the other hand, for the control group (calcium hydroxide) no inflammatory response associated with a thin capsule adjacent to the material was observed even at the 30-day period. The hard-setting calcium hydroxide cement allowed complete healing and was considered more biocompatible than the bonding agents. PMID:16774514

Teixeira, H M; Do Nascimento, A B L; Hebling, J; De Souza Costa, C A

2006-07-01

255

In vitro biocompatibility of fluorinated polyurethanes  

Microsoft Academic Search

The in vitro biocompatibility of fluorinated polyurethanes (FPUs), labelled as FPU 42, 52, 58, and 60, was evaluated by means of thrombogenicity, cytoxicity and cytocompatibility tests. Cardiothane® was taken as control material. The thrombogenicity was tested on thin material films by measuring the activation of prekallikrein (PKK) to kallikrein (KK). Level I cytoxicity tests of the bulk materials, i.e. Neutral

R. SBARBATI DEL GUERRA; L. Lelli; C. Tonelli; T. Trombetta; M. G. Cascone; M. Taveri; P. Narducci; P. Giusti

1994-01-01

256

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

257

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

258

Linker-based bio-compatible microemulsions.  

PubMed

In this work we have studied the formulation of biocompatible microemulsions using lecithin as the main surfactant and bio-compatible linker molecules (hexyl polyglucoside asthe hydrophilic linker and sorbitan monoleate as the lipophilic linker). These bio-compatible systems are discussed as potential substitutes for chlorinated solvents in dry-cleaning applications and as solvent delivery systems for pharmaceutical applications. Formulation parameters and conditions were evaluated using isopropyl myristate (IPM) as the model oil. It was found that the proposed linker-based formulations were able to form alcohol-free microemulsions while achieving higher solubilization capacity than similar systems reported in the literature. In addition, these lecithin/linker formulations were able to form microemulsions with a wide range of oils, from polar chlorinated hydrocarbons to hydrophobic oils such as squalene. These microemulsions were achieved under isotonic conditions (0.9% NaCl) by only varying the relative proportions of the linkers. The "solvency" power of these bio-compatible formulations was tested for the removal of hexadecane (used as model oil) from cotton fabrics and compared to the solvency power of a typical dry cleaning solvent tetrachloroethylene (PCE). While PCE and the linker-based lecithin formulation removed the same amount of hexadecane at low loading ratios (less than 1% oil volume fraction), at higher loading ratios the linker-based lecithin formulation retained its oil removal capacity while the efficiency of the PCE system declined rapidly. These initial results thus demonstrate the remarkable oil solubilization capacity of these bio-compatible linker-based lecithin formulations and illustrate their potential as environmentally friendly replacements for organic solvents. PMID:15787367

Acosta, Edgar J; Nguyen, Thu; Witthayapanyanon, Anuradee; Harwell, Jeffrey H; Sabatini, David A

2005-03-01

259

Foamed cement: A second generation. [Foamed cement slurries  

Microsoft Academic Search

Advanced technology in design and implementation of stable foamed cement systems now offers new solutions to critical oil-field cementing problems well beyond the original utility of lightweight slurries in reducing hydrostatic pressure across fracture-sensitive zones. Implications of new high-performance foamed cement capabilities are discussed for specialized applications such as thermal recovery, deep cementing in a narrow annular gap, lost-circulation control

Loeffler

1984-01-01

260

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 tasks performed in the fourth quarter as well as the other three quarters of the past year. The subjects that were covered in previous reports and that are also discussed in this report include: Analysis of field laboratory data of active cement applications from three oil-well service companies; 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; and Comparison of compressive strengths of ULHS systems using ultrasonic and crush methods Results reported from the fourth quarter include laboratory testing of ULHS systems along with other lightweight cement systems--foamed and sodium silicate slurries. These comparison studies were completed for two different densities (10.0 and 11.5 lb/gal) and three different field application scenarios. Additional testing included the mechanical properties of ULHS systems and other lightweight systems. Studies were also performed to examine the effect that circulation by centrifugal pump during mixing has on breakage of ULHS.

Fred Sabins

2001-10-23

261

Expansive Cements and Their Use.  

National Technical Information Service (NTIS)

The primary purpose of shrinkage-compensating expansive cement concrete is to minimize cracking in concrete pavements and structures caused by drying shrinkage. The paper reviews the various types of expansive cements and their properties. The expansive m...

G. C. Hoff

1972-01-01

262

Reducing cement's CO2 footprint  

USGS Publications Warehouse

The manufacturing process for Portland cement causes high levels of greenhouse gas emissions. However, environmental impacts can be reduced by using more energy-efficient kilns and replacing fossil energy with alternative fuels. Although carbon capture and new cements with less CO2 emission are still in the experimental phase, all these innovations can help develop a cleaner cement industry.

van Oss, Hendrik G.

2011-01-01

263

High temperature lightweight foamed cements  

DOEpatents

Cement slurries are disclosed which are suitable for use in geothermal wells since they can withstand high temperatures and high pressures. The formulation consists of cement, silica flour, water, a retarder, a foaming agent, a foam stabilizer, and a reinforcing agent. A process for producing these cements is also disclosed.

Sugama, Toshifumi (Mastic Beach, NY)

1989-01-01

264

High temperature lightweight foamed cements  

DOEpatents

Cement slurries are disclosed which are suitable for use in geothermal wells since they can withstand high temperatures and high pressures. The formulation consists of cement, silica flour, water, a retarder, a foaming agent, a foam stabilizer, and a reinforcing agent. A process for producing these cements is also disclosed. 3 figs.

Sugama, Toshifumi.

1989-10-03

265

Biocompatible Hydrogels by Oxime Click Chemistry  

PubMed Central

Oxime Click chemistry was used to form hydrogels that support cell adhesion. Eight-armed aminooxy poly(ethylene glycol) (PEG) was mixed with glutaraldehyde to form oxime-linked hydrogels. The mechanical properties, gelation kinetics, and water swelling ratios were studied and found to be tunable. It was also shown that gels containing the integrin ligand arginine-glycine-aspartic acid (RGD) supported mesenchymal stem cell (MSC) incorporation. High cell viability and proliferation of the encapsulated cells demonstrated biocompatibility of the material.

Grover, Gregory N.; Lam, Jonathan; Nguyen, Thi H.; Segura, Tatiana; Maynard, Heather D.

2012-01-01

266

Biocompatible magnetic core\\/shell nanoparticles  

Microsoft Academic Search

Biocompatible magnetic fluids composed of modified nano-sized magnetic iron oxide particles have been prepared. The magnetic particles have been obtained (diameter in the order 2–30nm) by variations of the concentration of reactants, temperature, operation time and pH conditions as well as the electrolyte concentration. Besides one- or two-step coating processes were used successfully. The adsorption process of the modified dextran

T. Goetze; C. Gansau; N. Buske; M. Roeder; P. Görnert; M. Bahr

2002-01-01

267

Biocompatibility of implants: lymphocyte\\/macrophage interactions  

Microsoft Academic Search

The monocyte-derived macrophage is recognized as a critical determinant in biocompatibility, but its appearance in the chronic\\u000a inflammatory phase is accompanied by the presence of lymphocytes, which have been much less studied in this regard. Here,\\u000a we first present an overview of the physiologic continuum comprising host reactions to the surgical implantation of biomaterial.\\u000a Secondly, we describe our collective research

James M. Anderson; Amy K. McNally

2011-01-01

268

Biocompatibility of engineered nanoparticles for drug delivery.  

PubMed

The rapid advancement of nanotechnology has raised the possibility of using engineered nanoparticles that interact within biological environments for treatment of diseases. Nanoparticles interacting with cells and the extracellular environment can trigger a sequence of biological effects. These effects largely depend on the dynamic physicochemical characteristics of nanoparticles, which determine the biocompatibility and efficacy of the intended outcomes. Understanding the mechanisms behind these different outcomes will allow prediction of the relationship between nanostructures and their interactions with the biological milieu. At present, almost no standard biocompatibility evaluation criteria have been established, in particular for nanoparticles used in drug delivery systems. Therefore, an appropriate safety guideline of nanoparticles on human health with assessable endpoints is needed. In this review, we discuss the data existing in the literature regarding biocompatibility of nanoparticles for drug delivery applications. We also review the various types of nanoparticles used in drug delivery systems while addressing new challenges and research directions. Presenting the aforementioned information will aid in getting one step closer to formulating compatibility criteria for biological systems under exposure to different nanoparticles. PMID:23262199

Naahidi, Sheva; Jafari, Mousa; Edalat, Faramarz; Raymond, Kevin; Khademhosseini, Ali; Chen, P

2013-03-10

269

External sleeve cementing tool  

SciTech Connect

This patent describes a cementing tool apparatus. It comprises a tubular housing having an inner passage defined longitudinally therethrough and having a radially outer surface, the housing also having a cementing port and a longitudinal slot both disposed through a wall thereof; an outer closure sleeve slidably received about the outer surface of the housing and movable relative to the housing between an open position wherein the cementing port is uncovered by the closure sleeve and a closed position wherein the cementing port is closed by the closure sleeve; an inner operating sleeve slidably received in the housing and slidable between first and second positions relative to the housing; and mechanical interlocking means, extending through the slot and operably associated with both the operating sleeve and the closure sleeve, for mechanically transferring a closing force from the operating sleeve to the closure sleeve and thereby moving the closure sleeve to its closed position as the operating sleeve moves from its first position to its second position.

Giroux, R.L.; Brandell, J.T.

1991-08-13

270

Bone regeneration with glass ceramic implants and calcium phosphate cements in a rabbit cranial defect model.  

PubMed

Hydroxyapatite cement (BoneSource®) and brushite calcium phosphate cement (chronOS™ Inject) were tested for fixation of glass ceramic implants (Bioverit®) in experimentally created cranial defects in 24 adult New Zealand White rabbits. Aim of the in vivo study was to assess and compare the biocompatibility and osseointegration of the implanted materials. Macroscopic and histological evaluations were performed 1 month, 3 months, and 6 months postoperatively. All implanted materials were well tolerated by the surrounding tissue. Both bone cements exhibited osteoconductive properties. Differences could be detected regarding to the rates of cement resorption and new bone formation. The brushite cement was resorbed faster than the hydroxyapatite cement. The chronOS™ Inject samples exhibited a higher rate of connective tissue formation and an insufficient osseointegration. BoneSource® was replaced by bone with minimal invasion of connective tissue. New bone formation occurred faster compared to the chronOS™ Inject group. Bioverit® implants fixed with BoneSource® were successfully osseointegrated. PMID:20859655

Schneider, Gerlind; Blechschmidt, Karin; Linde, Dirk; Litschko, Peter; Körbs, Thomas; Beleites, Eggert

2010-10-01

271

Biological responses of brushite-forming Zn- and ZnSr- substituted beta-tricalcium phosphate bone cements.  

PubMed

The core aim of this study was to investigate zinc (Zn)- and zinc and strontium (ZnSr)-containing brushite-forming beta-tricalcium phosphate (TCP) cements for their effects on proliferation and differentiation of osteoblastic-like cells (MC3T3-E1 cell line) as well as for their in vivo behaviour in trabecular bone cylindrical defects in a pilot study. In vitro proliferation and maturation responses of MC3T3-E1 osteoblastic-like cells to bone cements were studied at the cellular and molecular levels. The Zn- and Sr-containing brushite cements were found to stimulate pre-osteoblastic proliferation and osteoblastic maturation. Indeed, MC3T3-E1 cells exposed to the powdered cements had increased proliferative rates and higher adhesiveness capacity, in comparison to control cells. Furthermore, they exhibited higher alkaline phosphatase (ALP) activity and increased Type-I collagen secretion and fibre deposition into the extracellular matrix. Proliferative and collagen deposition properties were more evident for cells grown in cements doped with Sr. The in vivo osteoconductive propertiesof the ZnCPC and ZnSrCPC cements were also pursued. Histological and histomorphometric analyses were performed at 1 and 2 months after implantation, using carbonated apatite cement (Norian SRS) as control. There was no evidence of cement-induced adverse foreign body reactions, and furthermore ZnCPC and ZnSrCPC cements revealed better in vivo performance in comparison to the control apatite cement. Additionally, the presence of both zinc and strontium resulted in the highest rate of new bone formation. These novel results indicate that the investigated ZnCPC and ZnSrCPC cements are both biocompatible and osteoconductive, being good candidate materials to use as bone substitutes. PMID:20821372

Pina, S; Vieira, S I; Rego, P; Torres, P M C; da Cruz e Silva, O A B; da Cruz e Silva, E F; Ferreira, J M F

2010-01-01

272

In vivo disintegration of four different luting agents.  

PubMed

The purpose of this study was to evaluate the disintegration of luting agents. An intraoral sample holder was made having four holes of 1.4?mm diameter and 2?mm depth. The holder was soldered onto the buccal surface of an orthodontic band, which was cemented to the first upper molar in 12 patients, average age 26 years. The holes were filled with a zinc phosphate (Phosphate Kulzer), a glass ionomer (Ketac Cem), a resin-modified-glass ionomer (Fuji Plus), and a resin cement (Calibra). Impressions were made at baseline, and 6, 12, and 18 months from which epoxy replicas were made, which were scanned with an optical scanner. Total volume loss was calculated. The rank order of mean volume loss was as follows: Phosphate cement > Ketac Cem = Fuji Plus = Calibra. Cement type and time had statistically significant effects on volume loss of cements (P < 0.001). Under in vivo conditions, zinc phosphate cement disintegrated the most, whereas no significant difference was observed for glass ionomer and resin-based cements. As intraoral conditions are considerably less aggressive than experimental laboratory conditions, the erosion behavior of glass ionomer cement was found to be similar to the resin-based cements in contradiction to previous laboratory results. PMID:22007219

Gemalmaz, Deniz; Pameijer, Cornelis H; Latta, Mark; Kuybulu, Ferah; Alcan, Toros

2012-01-01

273

In Vivo Disintegration of Four Different Luting Agents  

PubMed Central

The purpose of this study was to evaluate the disintegration of luting agents. An intraoral sample holder was made having four holes of 1.4?mm diameter and 2?mm depth. The holder was soldered onto the buccal surface of an orthodontic band, which was cemented to the first upper molar in 12 patients, average age 26 years. The holes were filled with a zinc phosphate (Phosphate Kulzer), a glass ionomer (Ketac Cem), a resin-modified-glass ionomer (Fuji Plus), and a resin cement (Calibra). Impressions were made at baseline, and 6, 12, and 18 months from which epoxy replicas were made, which were scanned with an optical scanner. Total volume loss was calculated. The rank order of mean volume loss was as follows: Phosphate cement > Ketac Cem = Fuji Plus = Calibra. Cement type and time had statistically significant effects on volume loss of cements (P < 0.001). Under in vivo conditions, zinc phosphate cement disintegrated the most, whereas no significant difference was observed for glass ionomer and resin-based cements. As intraoral conditions are considerably less aggressive than experimental laboratory conditions, the erosion behavior of glass ionomer cement was found to be similar to the resin-based cements in contradiction to previous laboratory results.

Gemalmaz, Deniz; Pameijer, Cornelis H.; Latta, Mark; Kuybulu, Ferah; Alcan, Toros

2012-01-01

274

Mineral resource of the month: hydraulic cement  

USGS Publications Warehouse

Hydraulic cements are the binders in concrete and most mortars and stuccos. Concrete, particularly the reinforced variety, is the most versatile of all construction materials, and most of the hydraulic cement produced worldwide is portland cement or similar cements that have portland cement as a basis, such as blended cements and masonry cements. Cement typically makes up less than 15 percent of the concrete mix; most of the rest is aggregates. Not counting the weight of reinforcing media, 1 ton of cement will typically yield about 8 tons of concrete.

van Oss, Hendrik G.

2012-01-01

275

Biofilm formation of salivary microbiota on dental restorative materials analyzed by denaturing gradient gel electrophoresis and sequencing.  

PubMed

The microbial diversity of biofilms formed on the surfaces of amalgam, glass-ionomer cement, and resin composite was analyzed by denaturing gradient gel electrophoresis (DGGE). The V2-V3 region of salivary microbial 16S rDNA gene sequences of planktonic and biofilm bacteria, after 1 day and 1 week of incubation, was amplified by polymerase chain reaction (PCR) and analyzed by DGGE. The amounts of strongly adherent phylotypes after 1 day and 1 week on the three dental restorative materials were more than those on hydroxyapatite. Streptococcus salivarius was detected in both loosely adherent and strong adherent groups of all 1-day samples. At 1 week, the amounts of loosely adherent and strongly adherent phylotypes present on the three restorative materials ranked in this ascending order: glass-ionomer cement < resin composite < amalgam. Results of DGGE analysis suggested that glass-ionomer cement was the best material of choice in terms of suppressing bacterial phylotypes in biofilms. PMID:24598237

Wang, Shuai; Guo, Lihong; Seneviratne, Chaminda Jayampath; Huang, Bo; Han, Jianmin; Peng, Lei; Liu, Xiaodi; Zhang, Chengfei

2014-05-31

276

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

277

Cement evaluation tool: a new approach to cement evaluation  

SciTech Connect

Cement bond logging achieves its greatest utility when it provides the production engineer with precise indications of cement strength and distribution around the casing. Zone isolation is of critical importance in production. Previous logging systems have yielded measures of cement bond that were circumferential averages of cement quality. These were difficult to interpret. Additionally, they were sensitive to the degree of shear coupling between pipe, cement, and formation and thus were affected by microannulus. The cement evaluation tool (CET) described here overcomes these difficulties. It provides a measurement of cement presence and strength, which is largely insensitive to microannulus. Its log output is interpreted easily. Tool design allows examination of the casing circumferentially at each depth. Impedance behind casing is measured. Laboratory calibration measurements allow this to be presented in terms of cement compressive strength. Cement channels are distinguished easily, and a zone isolation indicator can be presented. Additionally, casing internal diameter and distortion are displayed. European and North American field tests have been completed, and performance for a variety of well conditions is discussed. The ability of the tool to identify channels is confirmed. Sequential runs with and without excess pressure demonstrate immunity to microannulus in cases where CBL is affected but where microannulus is small enough to prohibit hydraulic communication. Geometrical measurements have been good indicators of casing deformation and have identified casing corrosion and wear.

Froelich, B.; Dumont, A.; Pittman, D.; Seeman, B.

1982-08-01

278

CAD\\/CAM Zirconia vs. slip-cast glass-infiltrated Alumina\\/Zirconia all-ceramic crowns: 2-year results of a randomized controlled clinical trial  

Microsoft Academic Search

Zirconia crowns were fabricated and cemented with a glass ionomer cement in 20 patients. At baseline, 6-month, 1-year, and 2-year recall appointments, Californian Dental Association (CDA) quality evaluation system was used to evaluate the prosthetic replacements, and plaque and gingival index scores were used to explore the periodontal outcome of the treatments. No clinical sign of marginal discoloration, persistent pain

Murat Cavit Çehreli; Ali Murat Kökat; Kivanç Akça

2009-01-01

279

Fluoride release from orthodontic bonding agents  

Microsoft Academic Search

The aim of this in vitro study was to compare fluoride release from two cement disc models (partially varnished and unvarnished) of three orthodontic bonding materials with fluoride release from the same materials when used to bond an orthodontic bracket onto a tooth surface.A resin-modified glass ionomer cement (Vitremer) and a compomer material (Dyract Ortho) were compared with a conventional

V. L Monteith; D. T Millett; S. L Creanor; W. H Gilmour

1999-01-01

280

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

281

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

282

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

283

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.

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

284

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.

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

2012-01-01

285

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

286

[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

287

An in vitro biocompatibility evaluation of double-J stents  

Microsoft Academic Search

Objectives. For several years, studies performed to estimate in vitro biocompatibility of urinary catheters have been carried out using permanent cell lines. However, for a rational design of the testing procedure, the cell culture model should depend on the material application. We assess the biocompatibility of 13 double-J stents using an in vitro model of normal human urothelial cells (HUC).

J. L Pariente; L Bordenave; N Valli; R Bareille; Ch Baquey; M. Le Guillou

1998-01-01

288

The quantification of biocompatibility: toward a new definition  

Microsoft Academic Search

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''

Buddy Ratner

2008-01-01

289

Olive Oil as a Biocompatible Solvent for Pristine C60  

Microsoft Academic Search

Olive oil is suggested a new solvent for C60 which offers the possibility to deliver in a biocompatible from this compound to biosystems and living organisms. This allows investigating for the first time the true biocompatibility and toxicity of C60.

Tibor Braun; László Márk; Róbert Ohmacht; Uma Sharma

2007-01-01

290

Glass ionomer-silver cermet Class II tunnel-restorations for primary molars.  

PubMed

Tunnel preparations preserve the anatomical marginal ridge and minimize the loss of healthy tooth structure adjacent to the carious lesion. When the practitioner has developed proficiency in restoring class II carious lesions with tunnel restorations, less treatment time is required than with traditional class II preparations. The technique for restoring a primary first molar with a class II carious lesion, using a tunnel preparation and Ketac-Silver restorative material is described. PMID:2968382

Croll, T P

1988-01-01

291

Phosphate based oil well cements  

NASA Astrophysics Data System (ADS)

The main application of the cement in an oil well is to stabilize the steel casing in the borehole and protect it from corrosion. The cement is pumped through the borehole and is pushed upwards through the annulus between the casing and the formation. The cement will be exposed to temperature and pressure gradients of the borehole. Modified Portland cement that is being used presently has several shortcomings for borehole sealant. The setting of the Portland cement in permafrost regions is poor because the water in it will freeze even before the cement sets and because of high porosity and calcium oxide, a major ingredient it gets easily affected by the down hole gases such as carbon dioxide. The concept of phosphate bonded cements was born out of considerable work at Argonne National Laboratory (ANL) on their use in stabilization of radioactive and hazardous wastes. Novel cements were synthesized by an acid base reaction between a metal oxide and acid phosphate solution. The major objective of this research is to develop phosphate based oil well cements. We have used thermodynamics along with solution chemistry principles to select calcined magnesium oxide as candidate metal oxide for temperatures up to 200°F (93.3°C) and alumina for temperatures greater than 200°F (93.3°C). Solution chemistry helped us in selecting mono potassium phosphate as the acid component for temperatures less than 200°F (93.3°C) and phosphoric acid solution greater than 200°F (93.3°C). These phosphate cements have performance superior to common Portland well cements in providing suitable thickening time, better mechanical and physical properties.

Natarajan, Ramkumar

292

Cytotoxicity of calcium enriched mixture cement compared with mineral trioxide aggregate and intermediate restorative material.  

PubMed

Calcium enriched mixture (CEM) cement has been recently invented by the last author. It is composed of calcium oxide, calcium phosphate, calcium silicate and calcium sulphate; however, it has a different chemical composition to mineral trioxide aggregate (MTA). The purpose of this ex vivo study was to investigate the cytotoxicity of CEM cement, and compare it with intermediate restorative material (IRM) and MTA. The materials were tested in fresh and set states on L929 fibroblasts to assess their cytotoxicity. The cell viability responses were evaluated with methyl-tetrazolium bromide assay and Elisa reader at 1, 24 and 168 h (7 days). The tested materials were eluted with L929 culture medium according to international standard organisation 109935 standard. Distilled water and culture medium served as positive and negative controls, respectively. Differences in cytotoxicity were evaluated by one-way anova and t-tests. The cytotoxicity of the materials was statistically different at the three time intervals (P < 0.01). The lowest cytotoxic values recorded were expressed by MTA subgroups followed by CEM cement; IRM subgroups were the most cytotoxic root-end/dental material (P < 0.001). CEM cement and MTA are reasonable alternatives to IRM because of lower cytotoxicity. CEM cement also has good biocompatibility as well as lower estimated cost to MTA and seems to be a promising dental material. PMID:22827819

Mozayeni, Mohammad A; Milani, Amin S; Marvasti, Laleh A; Asgary, Saeed

2012-08-01

293

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

PubMed

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

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

2014-06-01

294

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.

Perez, Roman A; Kim, Hae-Won

2012-01-01

295

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

296

Electrospun fullerenol-cellulose biocompatible actuators.  

PubMed

Though there are many stimuli-responsive polymer actuators based on synthetic polymers, electroactive natural biopolymer actuators are very rare. We developed an electrospun fullernol-cellulose biocompatible actuator with much lower power consumption and larger electromechanical displacement in comparison with a pure cellulose acetate actuator. Morphology of the electrospun membranes resembles the nanoporous structure of extracellular matrix in natural muscles. Presence of minute concentrations of fullerenol leads to sharp increase in the degree of crystallinity and substantial increase in tensile strength of membranes. Chemical interactions between cellulose acetate and fullerenols are confirmed by three shifts in carboxylate, carboxy, and carbonyl linkages from the Fourier-transform infrared spectrometry. Much larger tip displacement, nearly 3-fold even at 0.5 wt % fullerenol content, was observed with much lower power consumption under both alternating and direct current conditions. PMID:21517072

Li, Jia; Vadahanambi, Sridhar; Kee, Chang-Doo; Oh, Il-Kwon

2011-06-13

297

Accelerating set of retarded cement  

SciTech Connect

This patent describes improvement in a method of setting a volume of cement in a well completed in a subterranean formation in which a cement is or may become retarded and is pumped into the well and allowed to set to form a hard cementitious material there within. The improvement comprises contacting the cement with a solution of a compatible organic accelerator comprising a material that will produce formate ions in the cement slurry and selected from the group consisting of the first four carbon esters of formic acid, the esters including methyl formate, ethyl formate, normal-propyl formate, iso-propyl formate, normal-butyl formate, iso-butyl formate, and t-butyl formate. The patent also describes improvement in a method of setting a volume of cement in a well completed in subterranean formation, in which a cement is or may become retarded and is pumped into the well and allowed to set to form hard cementitious material therewithin at liner tops and in wellbore plugs. The improvement comprises contacting downhole the cement with a solution of a compatible organic accelerator comprising a material that will produce formate ions in the cement slurry and selected from the group consisting of formamide, and esters of formic acid, the esters including methyl formate, ethyl formate, normal propyl formate, isopropyl formate, normal butyl formate, iso-butyl formate and t-butyl formate.

Bloys, J.B.; Carpenter, R.B.; Wilson, W.N.

1991-04-09

298

Biostability and biocompatibility of modified polyurethane elastomers  

NASA Astrophysics Data System (ADS)

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

Christenson, Elizabeth Marie

299

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. Copyright © 2012 John Wiley & Sons, Ltd. PMID:22700366

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

2014-05-01

300

Dual setting ?-tricalcium phosphate cements.  

PubMed

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

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

2013-03-01

301

Natural cement as the precursor of Portland cement: Methodology for its identification  

Microsoft Academic Search

When cements appeared in the 19th century, they took the place of traditional binding materials (lime, gypsum, and hydraulic lime) which had been used until that time. Early cements can be divided into two groups, natural and artificial (Portland) cements. Natural cements were introduced first, but their widespread usage was short-lived as they were quickly replaced by artificial cements (Portland),

M. J.. Varas; M. Alvarez de Buergo; R. Fort

2005-01-01

302

New Cement Composite of Carbon Fiber,  

National Technical Information Service (NTIS)

Continuous carbon fiber cement composites are developed to have high fire resistance and high strength by using PAN type carbon fiber and fine cement as matrix. To improve the bond strength between carbon fiber and cement matrix, fine cement is used to fi...

K. Suzuki T. Nishigaki T. Matsuhashi H. Sasaki

1987-01-01

303

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.

Gulve, Meenal Nitin; Gulve, Nitin Dilip

2013-01-01

304

Carbon nanotube biocompatibility with cardiac muscle cells  

NASA Astrophysics Data System (ADS)

Purified carbon nanotubes are new carbon allotropes, sharing similarities with graphite, that have recently been proposed for their potential use with biological systems as probes for in vitro research and for diagnostic and clinical purposes. However the biocompatibility of carbon nanotubes with cells represents an important problem that, so far, remains largely uninvestigated. The objective of this in vitro study is to explore the cytocompatibility properties of purified carbon nanofibres with cardiomyocytes. Cardiac muscle cells from a rat heart cell line H9c2 (2-1) have been used. Highly purified single-walled nanotubes (SWNTs) were suspended at the concentration of 0.2 mg ml-1 by ultrasound in complete Dulbecco's modified Eagle's medium, and administered to cells to evaluate cell proliferation and shape changes by light microscopy, cell viability by trypan blue exclusion, and apoptosis, determined flow cytometrically by annexin/PI staining. Microscopic observation evidenced that carbon nanotubes bind to the cell membrane, causing a slight modification in cell shape and in cell count only after three days of treatment. Cell viability was not affected by carbon nanotubes in the first three days of culture, while after this time, cell death was slightly higher in nanotube-treated cells (p = ns). Accordingly, nanotube treatment induced little and non-significant change in the apoptotic cell number at day 1 and 3. The effect of nanotubes bound to cells was tested by reseeding treated cardiomyocytes. Cells from a trypsinized nanotube-treated sample showed a limited ability to proliferate, and a definite difference in shape, with a high degree of cell death: compared to reseeded untreated ones, in SWNT-treated samples the annexin-positive/PI-negative cells increased from 2.9% to 9.3% in SWNT (p<0.05, where p<0.05 defines a statistically significant difference with a probability above 95%), and the annexin-positive/PI-positive cells increased from 5.2% to 18.7% (p<0.05). However, overtime cells from a trypsinized nanotube-treated sample continued to grow, and partially recovered the original shape. In conclusion our results demonstrate that highly purified carbon nanotubes possess no evident short-term toxicity and can be considered biocompatible with cardiomyocytes in culture, while the long-term negative effects, that are evidenced after reseeding, are probably due to physical rather than chemical interactions.

Garibaldi, Silvano; Brunelli, Claudio; Bavastrello, Valter; Ghigliotti, Giorgio; Nicolini, Claudio

2006-01-01

305

Well cementing valve  

SciTech Connect

A well cementing valve is described for a well tubing string, comprising: a tubular mandrel having at least one mandrel port communicating the interior of the mandrel with the exterior thereof, the mandrel being adapted to be made-up in the well tubing string; an axially movable sleeve valve initially covering the mandrel port on the mandrel exterior, the sleeve valve having a pressure responsive seal area subject to fluid pressure in the mandrel for moving the sleeve valve; an axially slidable protective sleeve initially surrounding the mandrel and the sleeve valve; and shear means connecting the protective sleeve to the sleeve valve to restrain the sleeve valve against axial displacement, the pressure responsive seal area on the sleeve valve being operable to apply a shearing load on the shear means, permitting an axial displacement of the protective sleeve and an opposite axial displacement of the sleeve valve to open the port.

VanWormer, R.A.; Baugh, J.L.

1986-07-29

306

Intramedullary plugs in cemented hip arthroplasty.  

PubMed

The use of intramedullary plugs in cemented total joint arthroplasty is currently considered standard practice by most surgeons. In this in vitro study, the authors evaluated the holding power, migration, and leakage of four commonly used plug types--bone, acrylic bone cement, and two polymeric plugs from different manufacturers. Only acrylic bone cement plugs prevented distal leakage of cement and did not migrate under the influences of pressurized cement injection. PMID:2746246

Beim, G M; Lavernia, C; Convery, F R

1989-01-01

307

Holocene cemented beach deposits in Belize  

Microsoft Academic Search

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

Eberhard Gischler; Anthony J. Lomando

1997-01-01

308

Molecular mechanisms of crystallization impacting calcium phosphate cements  

PubMed Central

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

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

2010-01-01

309

Short-Term Analysis of Human Dental Pulps After Direct Capping with Portland Cement  

PubMed Central

This study evaluated the short-term response of human pulp tissue when directly capped with Portland cement. In this series of cases, twenty human third molars that were scheduled for extraction were used. After cavity preparation, pulp exposure was achieved and Portland cement pulp capping was performed. Teeth were extracted after 1, 7, 14 and 21 days following treatment and prepared for histological examination and bacterial detection. Each group had 5 teeth. The results were descriptively analysed. Dentin bridge formation was seen in two teeth with some distance from the material interface (14 and 21 days). Soft inflammatory responses were observed in most of the cases. Bacteria were not disclosed in any specimen. PC exhibited some features of biocompatibility and capability of inducing mineral pulp response in short-term evaluation. The results suggested that PC has a potential to be used as a less expensive pulp capping material in comparison to other pulp capping materials.

Barbosa, Antonio Vinicius Holanda; Sampaio, Gerhilde Callou; Gomes, Fabio Almeida; de Oliveira, Daniel Pinto; de Albuquerque, Diana Santana; Sobral, Ana Paula Veras

2009-01-01

310

Ocular Biocompatibility of Nitinol Intraocular Clips  

PubMed Central

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

Velez-Montoya, Raul; Erlanger, Michael

2012-01-01

311

Nanoscale contact mechanics of biocompatible polyzwitterionic brushes.  

PubMed

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

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

2013-08-27

312

Bacterial Cellulose: Long-Term Biocompatibility Studies.  

PubMed

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

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

2011-06-28

313

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.

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

2011-01-01

314

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.

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

2013-01-01

315

Graphite-reinforced bone cement  

NASA Technical Reports Server (NTRS)

Chopped graphite fibers added to surgical bone cement form bonding agent with mechanical properties closely matched to those of bone. Curing reaction produces less heat, resulting in reduced traumatization of body tissues. Stiffness is increased without affecting flexural strength.

Knoell, A. C.

1976-01-01

316

Synthesis and characterization of hydroxyapatite cement  

NASA Astrophysics Data System (ADS)

This study deals with synthesizing hydroxyapatite bone cement as a bone substitute for clinical applications. The powder part of the cement is using ?-tricalcium phosphate, calcium carbonate, dicalcium phosphate and the liquid part contains NaH 2PO 4·2H 2O solution with different concentrations. The effects of liquid concentration on the setting times of the cement have been investigated. XRD analysis and FT-IR spectroscopy were used to study the phase composition of calcium phosphate cement. Morphology and chemical analysis of the synthesized cement was performed using a scanning electron microscope equipped with an energy dispersive X-ray analyser. In addition, the effect of soaking time of synthesized bone cement in simulated body fluid (SBF) on the final phase and strength has been studied. Soaking prepared cement in SBF solution for appropriate time resulted in transformation of the composition of the cement into hydroxyapatite and hence the strength of the cement has been increased.

Rabiee, S. M.; Moztarzadeh, F.; Solati-Hashjin, M.

2010-04-01

317

Effects of added mannitol on the setting reaction and mechanical strength of apatite cement.  

PubMed

Apatite cement containing porogen can be a useful material for the fabrication of biporous (macro- and microporous) apatite, which has gained much attention as a bone substitute material because of its large surface area and that it improves cell penetration. In the present study, the effects of added mannitol on the setting reaction and mechanical strength of apatite cement were evaluated. Apatite cements containing 0-40 wt% of mannitol were prepared and allowed to set in 0.9% saline kept at 37 degrees C for 1-7 days. Although the diametral tensile strength (DTS) value increased with time, it decreased with the amount of added mannitol. SEM observation and XRD analysis revealed that mannitol had no inhibitory effect on the transformation reaction of apatite cement to apatite. It was thus concluded that mannitol was a good candidate for the fabrication of biporous apatite because it is biocompatible, exhibits satisfactory dissolution behavior, and that it caused no inhibitory effects on the compositional transformation to apatitic material. PMID:19822995

Shimogoryo, Ryoji; Eguro, Toru; Kimura, Eiichiro; Maruta, Michito; Matsuya, Shigeki; Ishikawa, Kunio

2009-09-01

318

Pegylation increases platelet biocompatibility of gold nanoparticles.  

PubMed

The increasing use of gold nanoparticles in medical diagnosis and treatment has raised the concern over their blood compatibility. The interactions of nanoparticles with blood components may lead to platelet aggregation and endothelial dysfunction. Therefore, medical applications of gold nanoparticles call for increased nanoparticle stability and biocompatibility. Functionalisation of nanoparticles with polythelene glycol (PEGylation) is known to modulate cell-particle interactions. Therefore, the aim of the current study was to investigate the effects of PEGylated-gold nanoparticles on human platelet function and endothelial cells in vitro. Gold nanoparticles, 15 nm in diameter, were synthesised in water using sodium citrate as a reducing and stabilising agent. Functionalised polyethylene glycol-based thiol polymers were used to coat and stabilise pre-synthesised gold nanoparticles. The interaction of gold nanoparticles-citrate and PEGylated-gold nanoparticles with human platelets was measured by Quartz Crystal Microbalance with Dissipation. Platelet-nanoparticles interaction was imaged using phase-contrast, scanning and transmission electron microscopy. The inflammatory effects of gold nanoparticles-citrate and PEGylated-gold nanoparticles in endothelial cells were measured by quantitative real time polymerase chain reaction. PEGylated-gold nanoparticles were stable under physiological conditions and PEGylated-gold nanoparticles-5400 and PEGylated-gold nanoparticles-10800 did not affect platelet aggregation as measured by Quartz Crystal Microbalance with Dissipation. In addition, PEGylated-gold nanoparticles did not induce an inflammatory response when incubated with endothelial cells. Therefore, this study shows that PEGylated-gold nanoparticles with a higher molecular weight of the polymer chain are both platelet- and endothelium-compatible making them attractive candidates for biomedical applications. PMID:24749395

Santos-Martinez, Maria Jose; Rahme, Kamil; Corbalan, J Jose; Faulkner, Colm; Holmes, Justin D; Tajber, Lidia; Medina, Carlos; Radomski, Marek Witold

2014-06-01

319

The water jet as a new tool for endoprosthesis revision surgery--an in vitro study on human bone and bone cement.  

PubMed

In revision surgeries of endoprostheses, the interface between implant and bone cement or bone must be loosened. Conventional tools have many disadvantages because of their size and limited range. Taking advantage of the selective and athermic cutting process, a plain water jet is already used in order to cut soft tissues. This study investigates the possibilities of both a plain and an abrasive water jet as cutting tools for revision surgery. Samples of the mid-diaphysis of human femora and bone cement (CMW3) were cut with a plain water jet (PWJ) and an abrasive water jet (AWJ) at two different jet-to-surface angles (30 degrees,90 degrees ) and at five different pressure levels (30, 40, 50, 60, 70 MPa). For a PWJ a selective pressure range was identified, where only bone cement was cut. Injecting a bio-compatible abrasive (lactose) to the jet stream resulted in significantly higher cut depths in both materials. Material removal in bone was significantly less at the smaller jet-to-surface angle for both techniques. No clear selectivity between bone and bone cement was observed for application of the AWJ. However, the material removal rate was significantly higher for bone cement than for bone at all pressure levels. The results indicate that an AWJ might be an alternative tool for cement removal. The possibility for localised cutting at interfaces could be an advantage for revision of a non-cemented prosthesis. PMID:14646047

Honl, Matthias; Rentzsch, Reemt; Schwieger, Karsten; Carrero, Volker; Dierk, Oliver; Dries, Sebastian; Louis, Hartmut; Pude, Frank; Bishop, Nick; Hille, Ekkehard; Morlock, Michael

2003-01-01

320

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.

Bajwa, Navroop Kaur; Pathak, Anuradha

2014-01-01

321

Stage cementing valve  

SciTech Connect

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

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

1989-11-14

322

Oilwell/gaswell cement-sheath evaluation  

SciTech Connect

Cement is placed in the casing/openhole annulus for two primary purposes: to isolate producible formation horizons and to support the casing. When one evaluates a cement in an oilwell/gaswell annulus, all one really needs to know is whether cement exists in the annulus (regardless of its strength) and whether the cement occupies 100% of the annulus. If 10-psi cement exists in 100% of the annulus, no portion of it can be removed for replacement by a 1,000-psi cement. If the annulus is packed with settled barite (from the drilling mud) or formation particles, no portion of the particulate matter can be removed and replaced by cement. Only liquids can be removed from the annulus for replacement by squeeze cementing. Acceptance of this basic premise can both simplify evaluation of a cement sheath in a casing/openhole annulus significantly and complicate measurement methods significantly. This leaves one with trying to identify solids or liquids behind the casing, not the difference between 250- and 5,000-psi cement. The paper discusses cement-sheath complications, cement-bond logs, annular segmentation for analysis, cement-evaluation recommendations, and interpretation guidelines.

Goodwin, K.J. [Mobil Technology Co., Dallas, TX (United States). Producing Technical Center

1997-12-01

323

Bridging the gap--biocompatibility of microelectronic materials.  

PubMed

There is an increasing interest in cell-based microelectronic biosensors for high-throughput screening of new products from the biotech pipeline. This requires fundamental knowledge of the biocompatibility of the materials used as the growing support for the cells. Using monolayer-forming Caco-2 cells of human origin, the biocompatibility of silicon wafers coated with various metals, dielectrics and semiconductors was assessed. Besides microscopic inspection, proliferation of cells indicating viability as well as brush border enzyme activity indicating differentiation of adherent growing cells were chosen as parameters to estimate biocompatibility. The type of wafer used for deposition of the coating initially influences the biocompatibility of the final product. Whereas p-doped silicon was fully biocompatible, n-doped silicon reduced the proliferation of cells. Among the different coatings, Al and Ti even increased the cell growth as compared to glass. Culturing the cells for 6 days on coated wafers demonstrated that the differentiation of adhering cells on Ti- and ZrO2-coated wafers was comparable to glass, whereas coatings with Si3N4, Au, Al, and ITO reduced differentiation to 15-35%. In the cases of Au and Si3N4 this effect equilibrated with prolonged culturing. These results demonstrate the importance of a careful selection of the materials used for the production of cell-based biosensors. PMID:16701882

Bogner, E; Dominizi, K; Hagl, P; Bertagnolli, E; Wirth, M; Gabor, F; Brezna, W; Wanzenboeck, H D

2006-03-01

324

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

325

Nanospearing - Biomolecule Delivery and Its Biocompatibility  

NASA Astrophysics Data System (ADS)

Introduction of exogenous DNA into mammalian cells represents a powerful approach for manipulating signal transduction. However, the currently available techniques have serious limits in terms of either low transduction efficiency or low cell viability. It is found that carbon nanotubes (CNTs) can mediate molecule transportations via various mechanisms. We have reported a highly efficient molecular delivery technique, called nanotube spearing, based on the penetration of Ni-particle-embedded nanotubes into cell membranes by magnetic field driving. DNA was immobilized onto the nanotubes and subsequently speared into targeted cells. We have achieved a high transduction efficiency in Bal 17 B-lymphoma cell line, ex vivo B cells, and primary neurons with high viability. This technique may provide a powerful tool for highly efficient gene transfer in a variety of cells, especially, in the hard-to-transfect cells. However, CNTs have been associated with environmental and public health concerns which arose in the course of research on possible biomedical applications. The disturbances CNTs cause in the immune system have been met with particular interest because any ideal in vivo application of CNTs should not trigger any undesirable bodily responses. It is imperative to unravel the effects of CNTs on B cells, which represent the humoral component of acquired immunity, so that the potential risk of CNTs to public health can be thoroughly understood and advanced strategies can be employed to develop safe applications. We investigated the compatibility of the PECVD nanotubes and the nanospearing procedure in terms of cell viability, growth, and intracellular signal pathways by means of flow cytometry and biochemical analysis. No additional cell death was observed after the spearing treatment, nor had B cell activation been indicated by changes in cell size, growth, CD69 expression, and kinase phosphorylation. The post-spearing cells preserve the ability to respond to stimulation in as robust a manner as cells left untreated. Our study suggests the biocompatibility of the nanospearing procedure and PECVD nanotubes under the proposed spearing conditions with regard to the humoral component of the immune system, therefore, reducing concerns that surround in vivo applications of CNTs.

Cai, Dong; Kempa, Krzysztof; Ren, Zhifeng; Carnahan, David; Chiles, Thomas C.

326

[Study on biocompatibility of titanium alloys].  

PubMed

The biocompatibility of two different titanium alloys, Ti-6Al-4V ELI and Ti-5Al-2, 5Fe, and pure titanium were evaluated. The results were as follows: 1) Titanium alloys were implanted into the dorsal subcutaneous tissues of the Hartley guinea-pig for 12 weeks, immersed in calf serum or in Ringer's solution for 8 weeks. The surface changes of the titanium alloys were observed by SEM and the chemical composition was analyzed by XMA. No evident surface changes were found. 2) Three hundred mg, 200 mg and 100 mg of the powders of the tested materials were immersed in 2ml of Eagle's MEM, incubated for 1-7 days, 8-21 days and 22-70 days at 37 C degrees. The amount of metallic elements dissolved in the solutions was measured by ICP and AAS. The detected corrosion rates of V and Al contained in the solution, in which Ti-6Al-4V ELI 100 mg was immersed for 1-7 days, were 194.3 +/- 17.6 and 73.0 +/- 28, 1 pg/mg alloy/day, respectively. V was released more than Al. The amount of Ti was below the detectable limit. The solution Ti-5Al-2.5 Fe 100 mg immersed for 1-7 days contained 31.9 +/- 34.4 pg/mg alloy/day Fe and 25.7 +/- 6.3 pg/mg alloy/day Al. Only in the solution 300 mg immersed for 1-7 days was Ti detected at 1.4 pg/mg alloy/day. 3) By the bacterial mutation assay of Salmonella typhimurium TA 98, Salmonella typhimurium TA 100 and Escherichia coli WP2 uvrA, the solutions, in which the tested materials were immersed, were not found to be mutagenic. 4) By the UDS assay, the grain counts on autoradiography with the solutions, in which the tested materials were immersed, were not greater than the negative control. The results suggest an excellent corrosion resistance of the titanium alloys. Mutagenicity was negative by these mutation assays, indicating that the tested alloys and pure titanium are safe for humans and animals. PMID:2794696

Kodama, T

1989-06-01

327

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.

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

2008-01-01

328

FTIR investigation of monomer polymerisation and polyacid neutralisation kinetics and mechanisms in various aesthetic dental restorative materials  

Microsoft Academic Search

Diamond ATR FTIR has been used to quantify light catalysed polymerisation and polyacid neutralisation rates in various glass ionomer cements (GIC), resin-modified GICs (RMGIC) and compomers. At 150s after the start of light exposure, levels of methacrylate polymerisation on the lower surfaces of 1mm thick specimens were 97% and 98% for the RMGIC, Vitremer and Fuji II LC and 47%

A. M. Young; S. A. Rafeeka; J. A. Howlett

2004-01-01

329

Time required to remove totally bonded tooth-colored posterior restorations and related tooth substance loss  

Microsoft Academic Search

Objectives. The study was conducted to measure the time required to remove large totally bonded tooth-colored posterior restorations and related tooth substance loss. This information was collected to determine if there were differences between bonded restorations and conventional restorations. Methods. Molars were restored with the following materials: amalgam, composite, glass ionomer cement or glass ceramic cusp coverages. After submitting them

Ivo Krejci; Claudia M. Lieber; Felix Lutz

1995-01-01

330

Biocompatibility of adhesive complex coacervates modeled after the sandcastle glue of Phragmatopoma californica for craniofacial reconstruction.  

PubMed

Craniofacial reconstruction would benefit from a degradable adhesive capable of holding bone fragments in three-dimensional alignment and gradually being replaced by new bone without loss of alignment or volume changes. Modeled after a natural adhesive secreted by the sandcastle worm, we studied the biocompatibility of adhesive complex coacervates in vitro and in vivo with two different rat calvarial models. We found that the adhesive was non-cytotoxic and supported the attachment, spreading, and migration of a commonly used osteoblastic cell line over the course of several days. In animal studies we found that the adhesive was capable of maintaining three-dimensional bone alignment in freely moving rats over a 12 week indwelling period. Histological evidence indicated that the adhesive was gradually resorbed and replaced by new bone that became lamellar across the defect without loss of alignment, changes in volume, or changes in the adjacent uninjured bone. The presence of inflammatory cells was consistent with what has been reported with other craniofacial fixation methods including metal plates, screws, tacks, calcium phosphate cements and cyanoacrylate adhesives. Collectively, the results suggest that the new bioadhesive formulation is degradable, osteoconductive and appears suitable for use in the reconstruction of craniofacial fractures. PMID:20950851

Winslow, Brent D; Shao, Hui; Stewart, Russell J; Tresco, Patrick A

2010-12-01

331

Biocompatibility of adhesive complex coacervates modeled after the Sandcastle glue of P. californica for craniofacial reconstruction  

PubMed Central

Craniofacial reconstruction would benefit from a degradable adhesive capable of holding bone fragments in three-dimensional alignment and gradually being replaced by new bone without loss of alignment or volume changes. Modeled after a natural adhesive secreted by the sandcastle worm, we studied the biocompatibility of adhesive complex coacervates in vitro and in vivo with two different rat calvarial models. We found that the adhesive was non-cytotoxic and supported the attachment, spreading, and migration of a commonly used osteoblastic cell line over the course of several days. In animal studies we found that the adhesive was capable of maintaining three-dimensional bone alignment in freely moving rats over a 12 week indwelling period. Histological evidence indicated that the adhesive was gradually resorbed and replaced by new bone that became lamellar across the defect without loss of alignment, changes in volume, or changes in the adjacent uninjured bone. The presence of inflammatory cells was consistent with what has been reported with other craniofacial fixation methods including metal plates, screws, tacks, calcium phosphate cements and cyanoacrylate adhesives. Collectively, the results suggest that the new bioadhesive formulation is degradable, osteoconductive and appears suitable for use in the reconstruction of craniofacial fractures.

Winslow, Brent D.; Shao, Hui; Stewart, Russell J.; Tresco, Patrick A.

2011-01-01

332

Immobilization of chromium in cement matrices  

Microsoft Academic Search

Portland cement and blended cements containing blast furnace slag afford both physical and chemical immobilization of chromium. To separate physical and chemical effects, the pore fluid contained in set, hydrated cements has been expressed and analyzed. In Portland cement spiked with 5,000 ppm Cr(III), pore fluid levels are 0.1--1 ppm, whereas in well-cured slag blends, they decrease to <0.01 ppm.

A. Kindness; A. Macias; F. P. Glasser

1994-01-01

333

Cementing oil and gas wells  

SciTech Connect

This patent describes a cement composition for cementing in a well penetrating subterranean formations and having an aqueous drilling fluid containing at least one cement retarder. It comprises a major proportion of the drilling fluid from the well as it was drilled the fluid having a density in the range of about 9.0 - 18.0 ppg; water; a lesser proportion of dry cementitious material; about 0.5 to about 10.0 ppb of a dispersant selected from the group consisting of sulfonated styrene maleic anhydride, sulfonated styrene imide, and sulfonate styrene itaconic acid; and a compatible accelerator selected from the group consisting of acetic acid; the first 4 carbon esters thereof; acetamide; monoethanolamine; and diethanolamine.

Bloys, J.B.; Wilson, W.N.; Bradshaw, R.D.

1991-12-31

334

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.

335

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

336

Biocompatibility correlation of polymeric materials using human osteosarcoma cells.  

PubMed

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 degrees and 20 degrees for advancing and receding probes, respectively. PMID:11013886

Geckeler, K E; Wacker, R; Aicher, W K

2000-08-01

337

Blended cement using volcanic ash and pumice  

Microsoft Academic Search

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

Khandaker M. Anwar Hossain

2003-01-01

338

Plastic compaction of cemented granular materials  

Microsoft Academic Search

We analytically relate hydrostatic stress to strain in a random dense pack of identical spheres cemented at their contacts. The spheres are elastic and the cement is perfectly plastic. This solution for the sphere pack is based on a solution for the normal interaction of two cemented spheres. Initially, the two spheres touch each other at a point. We show

J. Dvorkin; D. Yale

1997-01-01

339

Behavior of cemented sands - I. Testing  

Microsoft Academic Search

This paper is accompanied by a study on constitutive modelling issues of cemented sands. The concentration here is on experimental issues related to the triaxial testing of cemented sands. A preliminary investigation is performed aiming to identify potential effects of specimen size and slenderness on the stress-strain-strength characteristics of cemented sands. A comprehensive experimental study follows where clean sand specimens,

Ali A. Abdulla; Panos D. Kiousis

1997-01-01

340

Elastic moduli of cemented sphere packs  

Microsoft Academic Search

We present a method for estimating the effective elastic moduli of a dense random pack of identical elastic spheres with elastic binder (cement). The cement concentration in the pore space varies from a few percent (where it fills the space at grain contacts) to 100%. To construct the solution we start at a small cement concentration value where the effective

Jack Dvorkin; Jim Berryman; Amos Nur

1999-01-01

341

Biocompatibility of Ti-alloys for long-term implantation.  

PubMed

The design of new low-cost Ti-alloys with high biocompatibility for implant applications, using ubiquitous alloying elements in order to establish the strategic method for suppressing utilization of rare metals, is a challenge. To meet the demands of longer human life and implantation in younger patients, the development of novel metallic alloys for biomedical applications is aiming at providing structural materials with excellent chemical, mechanical and biological biocompatibility. It is, therefore, likely that the next generation of structural materials for replacing hard human tissue would be of those Ti-alloys that do not contain any of the cytotoxic elements, elements suspected of causing neurological disorders or elements that have allergic effect. Among the other mechanical properties, the low Young's modulus alloys have been given a special attention recently, in order to avoid the occurrence of stress shielding after implantation. Therefore, many Ti-alloys were developed consisting of biocompatible elements such as Ti, Zr, Nb, Mo, and Ta, and showed excellent mechanical properties including low Young's modulus. However, a recent attention was directed towards the development of low cost-alloys that have a minimum amount of the high melting point and high cost rare-earth elements such as Ta, Nb, Mo, and W. This comes with substituting these metals with the common low cost, low melting point and biocompatible metals such as Fe, Mn, Sn, and Si, while keeping excellent mechanical properties without deterioration. Therefore, the investigation of mechanical and biological biocompatibility of those low-cost Ti-alloys is highly recommended now lead towards commercial alloys with excellent biocompatibility for long-term implantation. PMID:23507261

Abdel-Hady Gepreel, Mohamed; Niinomi, Mitsuo

2013-04-01

342

Effects of biocompatible versus standard fluid on peritoneal dialysis outcomes.  

PubMed

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 m(2) 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 m(2) 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

Johnson, David W; 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

2012-06-01

343

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

344

Skin ulceration due to cement.  

PubMed

Despite legislation that requires manufacturers to inform the public about the dangers of contact with cement, severe ulceration from cement contact still occurs. We present a retrospective study of seven patients presenting to this department over a 2-year period. All were male and employed in the building trade, their injuries being sustained whilst at work. The injuries were to the lower limb, often multiple and required a median of seven visits before healing was complete. One required hospital admission and skin grafting. PMID:1449582

Robinson, S M; Tachakra, S S

1992-09-01

345

Properties of cement waste composites  

SciTech Connect

Many nominally inert waste materials can be activated by alkaline substances, including Ca(OH){sub 2} and Portland cement, to form valuable supplementary cementitious materials. Waste materials are inherently more variable in composition than well specified, manufactured materials. Nevertheless, sufficient characterization techniques are available to permit the specification of materials such as fly ash and blast furnace slags with confidence. Applications for other processed waste materials, e.g. metakaolin, are being developed. Properly applied, these wastes can actually improve the performance of cement materials. The leach testing of products containing potentially hazardous waste materials, suited only for disposal, is described.

Glasser, F.P. [Univ. of Aberdeen (United Kingdom). Dept. of Chemistry] [Univ. of Aberdeen (United Kingdom). Dept. of Chemistry

1996-12-31

346

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

347

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

348

In vitro evaluation of biocompatibility of different wound dressing materials  

Microsoft Academic Search

The in vitro biocompatibility of newly developed wound dressings consisting of different chitosan salts (chitosan lactate, glutamate and chloride) and a chitosan derivative (methylpyroolidinone chitosan) was compared with three commercially available wound dressings made of collagen, calciumalginate, and gelatin, by evaluation in a fibroblast cell culture system. Three experimental models which reflect relevant stages of wound healing were used, and

P. C. Berscht; B. Nies; A. Liebendörfer; J. Kreuter

1995-01-01

349

Biocompatibility of phosphorylcholine coated stents in normal porcine coronary arteries  

Microsoft Academic Search

OBJECTIVETo improve the biocompatibility of stents using a phosphorylcholine coated stent as a form of biomimicry.INTERVENTIONSImplantation of phosphorylcholine coated (n = 20) and non-coated (n = 21) stents was performed in the coronary arteries of 25 pigs. The animals were killed after five days (n = 6), four weeks (n = 7), and 12 weeks (n = 8), and the

D. M. Whelan; W J van der Giessen; S C Krabbendam; E A van Vliet; P D Verdouw; P W Serruys; H M M van Beusekom

2000-01-01

350

Functionalization of iron oxide nanoparticles with biosurfactants and biocompatibility studies.  

PubMed

We present methodologies to functionalize iron oxide (Fe3O4) nanoparticles with biosurfactants and biocompatibility results. Positively charged Fe3O4 nanoparticles of average hydrodynamic size -26 nm is functionalized with four different molecules of interest, viz., surfactin, rhamnolipid, polyethylene glycol (PEG) and dextran. The functionalization results in dramatic alterations in surface potential and hydrodynamic size due to the presence of coated moieties on the nanoparticle interface. The Fourier transform infrared spectroscopy and thermogravimetric analysis confirm the presence of adsorbed moieties on nanoparticles. The phase contrast microscopy studies show the formation of reversible chains of functionalized nanoparticles under an external magnetic field. Cell viability studies using L929 mouse fibroblast cell line show that pure surfactin, rhamnolipid and dextran exhibit cytotoxicity with increase in concentration, whereas, pure PEG exhibit biocompatibility at different concentrations. Accordingly, surfactin and rhamnolipid coated nanoparticles are found to be cytotoxic with increase in concentration and PEG coated nanoparticles are found to be biocompatible. Dextran coated nanoparticles do not exhibit significant increase in biocompatibility. PMID:23802405

Sangeetha, J; Thomas, Susha; Arutchelvi, J; Doble, Mukesh; Philip, John

2013-05-01

351

Self-Assembled Antimicrobial and biocompatible copolymer films on Titanium  

PubMed Central

Biofilm formation on biomedical devices such as dental implants can result in serious infections and finally in device failure. Polymer coatings which provide antimicrobial action to surfaces without compromising the compatibility with human tissue are of great interest. Copolymers of 4-vinyl-N-hexylpyridinium bromide and dimethyl(2-methacryloyloxyethyl) phosphonate are interesting candidates in this respect. These copolymers form ultrathin polycationic layers on titanium surfaces. As the copolymerization reaction is almost ideal statistical, copolymers with varying compositions can be synthesized and immobilized onto titanium surfaces for comprehensive screening concerning antimicrobial activity and biocompatibility. Copolymer films on titanium were characterized by contact angle measurements, ellipsometry and X-ray photoelectron spectroscopy. Antibacterial properties were assessed by investigation of adherence of S. mutans which represents a strain found in the human oral cavity. Biocompatibility was rated based on human gingival fibroblast adhesion, proliferation and cell morphology. Depending on polymer composition the coatings displayed a behavior ranging from biocompatibility equal to titanium but no antibacterial action to highly antimicrobial activity but poor biocompatibility. By balancing these two opposing effects by tailoring chemical composition, copolymer coatings were fabricated, which were able to inhibit the growth of S. mutans on the surface significantly but still show a sufficient attachment of gingival fibroblasts.

Pfaffenroth, Cornelia; Winkel, Andreas; Dempwolf, Wibke; Gamble, Lara J.; Castner, David G.; Stiesch, Meike; Menzel, Henning

2013-01-01

352

Chemical design of biocompatible iron oxide nanoparticles for medical applications.  

PubMed

Iron oxide nanoparticles are one of the most versatile and safe nanomaterials used in medicine. Recent progress in nanochemistry enables fine control of the size, crystallinity, uniformity, and surface properties of iron oxide nanoparticles. In this review, the synthesis of chemically designed biocompatible iron oxide nanoparticles with improved quality and reduced toxicity is discussed for use in diverse biomedical applications. PMID:23233377

Ling, Daishun; Hyeon, Taeghwan

2013-05-27

353

Dynamic In Vivo Biocompatibility of Angiogenic Peptide Amphiphile Nanofibers  

PubMed Central

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

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

2009-01-01

354

The biocompatibility of crosslinkable copolymer coatings containing sulfobetaines and phosphobetaines  

Microsoft Academic Search

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

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

2004-01-01

355

Enhanced biocompatibility of GPC by ion implantation and deposition  

Microsoft Academic Search

Biocompatible Glassy Polymeric Carbon (GPC) is used for artificial heart valves and in other biomedical applications. Although it is ideally suited for implants in the blood stream, tissue that normally forms around the moving parts of a GPC heart valve sometimes loses adhesion and creates embolisms downstream. We have previously shown that oxygen ion implantation slightly enhances cell adhesion to

R. Zimmerman; I. Gürhan; C. Muntele; D. Ila; M. Rodrigues; F. Özdal-Kurt; B. H. Sen

2007-01-01

356

[Nickelid titanium implants biocompatibility evaluation in animal experiment].  

PubMed

In experiment on 15 rabbits it was shown that the highest biocompatibility in living organism was demonstrated by implants with modified by molybdenum-ions surface. The least corrosion stable there were the implants from alloy VT-8. Surface modification by silver-ions exerted depressive action upon red bone marrow producing its fatty degeneration. PMID:19156098

Razdorski?, V V

2008-01-01

357

Evaluation of Biocompatibility and Cytotoxicity Using Keratinocyte and Fibroblast Cultures  

Microsoft Academic Search

Determination of biocompatibility and cytotoxicity is part of the initial evaluation of medical devices stipulated by ISO standards on biological evaluation of medical devices. Cell culture systems for testing biological reactions to drugs, biomaterials or treatment techniques used in various disciplines have been gaining importance. A wide variety of cell lines are commonly used: cultured fibroblasts from human skin, buccal

C. Wiegand; U.-C. Hipler

2009-01-01

358

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

PubMed

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

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

2006-09-01

359

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

360

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

361

Dependence of curing time, peak temperature, and mechanical properties on the composition of bone cement.  

PubMed

Commercial bone cements usually contain hydroquinone as the polymerization inhibitor and N,N-dimethyl-p-toluidine as the accelerator in the benzoyl peroxide-initiated redox polymerization. The former compounds have certain shortcomings in their biocompatibility profile. Measurements of the setting times, polymerization exotherms, and postpolymerization strengths of the cured monomer-polymer compositions show that the hydroquinone can be replaced by food grade di-tert-butyl-p-cresol (BHT). The more reactive 4-N,N-(dimethylamino)phenethanol can replace 4-N,N-dimethyl-p-toluidine, yielding cements with shorter setting times and increased strengths. Excessive heat liberated on polymerization can be reduced by partial substitution of higher-molecular-weight methacrylates, e.g., dicyclopentenyloxyethyl methacrylate for methyl methacrylate, but there is a decrease in strength of the resulting polymer. More successful has been the addition to the monomer of 1% or 2% of the chain transfer agent pentaerythritol tetra(3-mercaptopropionate), which lowers the peak temperature without changing the physical properties of the cement. Compositions with short curing times, lower exotherms, and mechanical properties that exceed those of a commercial material have been formulated. PMID:3722218

Brauer, G M; Steinberger, D R; Stansbury, J W

1986-01-01

362

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

PubMed Central

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

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

2005-01-01

363

About Calcium Phosphate Cements (CPC)  

NASA Astrophysics Data System (ADS)

Calcium phosphate cements (CPC) are used in orthopaedic surgery as bone substitution and fixation of metallic implants, showing advantages with respect to other materials like polymeric cements or ceramic blocks also used for bone repair. For example, they are easy to shape and fill bone defects, react at low temperature and their setting product is hydroxyapatite, mineral from it's composed the inorganic part of the bone, resulting a bioabsorbable material that can be replaced by new bone. Nevertheless there are still some complications like their low absorption rate, inyectability, setting times and their low strength that limits their use to only non load bearing applications. In this work we present a brief resume of some investigations that has been proposed to solve some of these problems, like the addition of phosphates solutions or seeds to increase the reaction rate, or fibers and hard particles to produce a composite material.

Piñera, Silvia; Piña, Cristina

2006-09-01

364

Toxic elements in silicate cements.  

PubMed

Six brands of silicate cements have been characterized by means of optical emission spectrography with respect to the contents of elements in minor or trace quantities in a search for presence of possible toxic elements. Beryllium was observed in two powders at levels of 1.3 and 1.6% Cadmium was found in two powders at levels of 0.02 and 0.03%. Lead was measured in three powders at levels of 0.001-0.003%. Bismuth, boron, copper, gallium, iron, manganese, titanium, tin and zirconium were found in various brands in either powder or liquid at levels of 0.001-0.1%. Upper limits of the amounts of the various elements that might be transferred to the gastrointestinal tract after dissolution of the cement matrix in the oral cavity have been calculated. PMID:296570

Brune, D

1979-12-01

365

Lunar cement and lunar concrete  

NASA Astrophysics Data System (ADS)

Results of a study to investigate methods of producing cements from lunar materials are presented. A chemical process and a differential volatilization process to enrich lime content in selected lunar materials were identified. One new cement made from lime and anorthite developed compressive strengths of 39 Mpa (5500 psi) for 1 inch paste cubes. The second, a hypothetical composition based on differential volatilization of basalt, formed a mineral glass which was activated with an alkaline additive. The 1 inch paste cubes, cured at 100C and 100 percent humidity, developed compressive strengths in excess of 49 Mpa (7100 psi). Also discussed are tests made with Apollo 16 lunar soil and an ongoing investigation of a proposed dry mix/steam injection procedure for casting concrete on the Moon.

Lin, T. D.

366

Lunar cement and lunar concrete  

NASA Technical Reports Server (NTRS)

Results of a study to investigate methods of producing cements from lunar materials are presented. A chemical process and a differential volatilization process to enrich lime content in selected lunar materials were identified. One new cement made from lime and anorthite developed compressive strengths of 39 Mpa (5500 psi) for 1 inch paste cubes. The second, a hypothetical composition based on differential volatilization of basalt, formed a mineral glass which was activated with an alkaline additive. The 1 inch paste cubes, cured at 100C and 100 percent humidity, developed compressive strengths in excess of 49 Mpa (7100 psi). Also discussed are tests made with Apollo 16 lunar soil and an ongoing investigation of a proposed dry mix/steam injection procedure for casting concrete on the Moon.

Lin, T. D.

1991-01-01

367

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

368

Natural cement as the precursor of Portland cement: Methodology for its identification  

SciTech Connect

When cements appeared in the 19th century, they took the place of traditional binding materials (lime, gypsum, and hydraulic lime) which had been used until that time. Early cements can be divided into two groups, natural and artificial (Portland) cements. Natural cements were introduced first, but their widespread usage was short-lived as they were quickly replaced by artificial cements (Portland), still the most important and predominant today. The main differences between natural and artificial cements arise during the manufacturing process. The final properties of the cements are greatly influenced by differences in the raw materials and burning temperatures employed. The aim of this paper is to assess the efficiency of traditional analytical techniques (petrographic microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR)) used to differentiate natural and artificial cements.

Varas, M.J. [Institute of Economic Geology, Spanish Council for Scientific Research-Complutense University, Madrid (Spain)]. E-mail: mjvaras@geo.ucm.es; Alvarez de Buergo, M. [Institute of Economic Geology, Spanish Council for Scientific Research-Complutense University, Madrid (Spain); Fort, R. [Institute of Economic Geology, Spanish Council for Scientific Research-Complutense University, Madrid (Spain)

2005-11-15

369

Evaluation of Hazardous Waste Incineration in Cement Kilns at San Juan Cement Company.  

National Technical Information Service (NTIS)

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 ...

J. A. Peters T. W. Hughes J. R. McKendree L. A. Cox B. M. Hughes

1984-01-01

370

Industrial Hygiene Survey of Marquette Cement Co., Rockmart, Georgia. Cement Workers Morbidity Study.  

National Technical Information Service (NTIS)

As part of the Cement Workers Morbidity Study, an industrial hygiene survey was conducted at the Marquette Cement Company in Rockmart, Georgia. Environmental sampling was conducted to determined respirable and total dust concentrations of various contamin...

C. Davidson W. T. Sanderson

1982-01-01

371

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.

2014-01-01

372

Porous calcium phosphate cement for alveolar bone regeneration.  

PubMed

The present study aimed to provide information on material degradation and subsequent alveolar bone formation, using composites consisting of calcium phosphate cement (CPC) and poly(lactic-co-glycolic) acid (PLGA) with different microsphere morphology (hollow vs dense). In addition to the plain CPC-PLGA composites, loading the microspheres with the growth factors platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF) was investigated. A total of four different CPC composites were applied into one-wall mandible bone defects in beagle dogs in order to evaluate them as candidates for alveolar bone regeneration. These composites consisted of CPC and hollow or dense PLGA microspheres, with or without the addition of PDGF-IGF growth factor combination (CPC-hPLGA, CPC-dPLGA, CPC-hPLGAGF , CPC-dPLGAGF ). Histological evaluation revealed significantly more bone formation in CPC-dPLGA than in CPC-hPLGA composites. The combination PDGF-IGF enhanced bone formation in CPC-hPLGA materials, but significantly more bone formation occurred when CPC-dPLGA was used, with or without the addition of growth factors. The findings demonstrated that CPC-dPLGA composite was the biologically superior material for use as an off-the-shelf material, due to its good biocompatibility, enhanced degradability and superior bone formation. Copyright © 2012 John Wiley & Sons, Ltd. PMID:22777771

Félix Lanao, R P; Hoekstra, J W M; Wolke, J G C; Leeuwenburgh, S C G; Plachokova, A S; Boerman, O C; van den Beucken, J J J P; Jansen, J A

2014-06-01

373

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

374

HYDRAULIC CEMENT PREPARATION FROM LURGI SPENT SHALE  

SciTech Connect

Low cost material is needed for grouting abandoned retorts. Experimental work has shown that a hydraulic cement can be produced from Lurgi spent shale by mixing it in a 1:1 weight ratio with limestone and heating one hour at 1000°C. With 5% added gypsum, strengths up to 25.8 MPa are obtained. This cement could make an economical addition up to about 10% to spent shale grout mixes, or be used in ordinary cement applications.

Mehta, P.K.; Persoff, P.; Fox, J.P.

1980-06-01

375

Nanofunctionalized zirconia and barium sulfate particles as bone cement additives  

PubMed Central

Zirconia (ZrO2) and barium sulfate (BaSO4) particles were introduced into a methyl methacrylate monomer (MMA) solution with polymethyl methacrylate (PMMA) beads during polymerization to develop the following novel bone cements: bone cements with unfunctionalized ZrO2 micron particles, bone cements with unfunctionalized ZrO2 nanoparticles, bone cements with ZrO2 nanoparticles functionalized with 3-(trimethoxysilyl)propyl methacrylate (TMS), bone cements with unfunctionalized BaSO4 micron particles, bone cements with unfunctionalized BaSO4 nanoparticles, and bone cements with BaSO4 nanoparticles functionalized with TMS. Results demonstrated that in vitro osteoblast (bone-forming cell) densities were greater on bone cements containing BaSO4 ceramic particles after four hours compared to control unmodified bone cements. Osteoblast densities were also greater on bone cements containing all of the ceramic particles after 24 hours compared to unmodified bone cements, particularly those bone cements containing nanofunctionalized ceramic particles. Bone cements containing ceramic particles demonstrated significantly altered mechanical properties; specifically, under tensile loading, plain bone cements and bone cements containing unfunctionalized ceramic particles exhibited brittle failure modes whereas bone cements containing nanofunctionalized ceramic particles exhibited plastic failure modes. Finally, all bone cements containing ceramic particles possessed greater radio-opacity than unmodified bone cements. In summary, the results of this study demonstrated a positive impact on the properties of traditional bone cements for orthopedic applications with the addition of unfunctionalized and TMS functionalized ceramic nanoparticles.

Gillani, Riaz; Ercan, Batur; Qiao, Alex; Webster, Thomas J

2010-01-01

376

Nanofunctionalized zirconia and barium sulfate particles as bone cement additives.  

PubMed

Zirconia (ZrO(2)) and barium sulfate (BaSO(4)) particles were introduced into a methyl methacrylate monomer (MMA) solution with polymethyl methacrylate (PMMA) beads during polymerization to develop the following novel bone cements: bone cements with unfunctionalized ZrO(2) micron particles, bone cements with unfunctionalized ZrO(2) nanoparticles, bone cements with ZrO(2) nanoparticles functionalized with 3-(trimethoxysilyl)propyl methacrylate (TMS), bone cements with unfunctionalized BaSO(4) micron particles, bone cements with unfunctionalized BaSO(4) nanoparticles, and bone cements with BaSO(4) nanoparticles functionalized with TMS. Results demonstrated that in vitro osteoblast (bone-forming cell) densities were greater on bone cements containing BaSO(4) ceramic particles after four hours compared to control unmodified bone cements. Osteoblast densities were also greater on bone cements containing all of the ceramic particles after 24 hours compared to unmodified bone cements, particularly those bone cements containing nanofunctionalized ceramic particles. Bone cements containing ceramic particles demonstrated significantly altered mechanical properties; specifically, under tensile loading, plain bone cements and bone cements containing unfunctionalized ceramic particles exhibited brittle failure modes whereas bone cements containing nanofunctionalized ceramic particles exhibited plastic failure modes. Finally, all bone cements containing ceramic particles possessed greater radio-opacity than unmodified bone cements. In summary, the results of this study demonstrated a positive impact on the properties of traditional bone cements for orthopedic applications with the addition of unfunctionalized and TMS functionalized ceramic nanoparticles. PMID:20161983

Gillani, Riaz; Ercan, Batur; Qiao, Alex; Webster, Thomas J

2010-01-01

377

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

378

Comparison of modified sulfur cement and hydraulic cement for encapsulation of radioactive and mixed wastes  

Microsoft Academic Search

The majority of solidification\\/stabilization systems for low-level radioactive waste (LLW) and mixed waste, both in the commercial sector and at Department of Energy (DOE) facilities, utilize hydraulic cement (such as portland cement) to encapsulate waste materials and yield a monolithic solid waste form for disposal. A new and innovative process utilizing modified sulfur cement developed by the US Bureau of

P. D. Kalb; J. H. Heiser; P. Colombo

1990-01-01

379

Characteristics of Portland blast-furnace slag cement containing cement kiln dust and active silica  

Microsoft Academic Search

This investigation dealt with the effect of active silica, silica fume (SF) or rice husk ash (RHA), on the mechanical and physico-chemical characteristics of the hardened blended cement pastes made of Portland blast-furnace slag cement (PSC) containing cement kiln dust (CKD) cured under normal conditions. Two blends made of PSC and CKD, improved by SF and two blends made of

A. Abdel Rahman; S. A. Abo-El-Enein; M. Aboul-Fetouh; Kh. Shehata

380

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

Microsoft Academic Search

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

Dale P. Bentz; Gaurav Sant; Jason Weiss

2008-01-01

381

Influence of key cement chemical parameters on the properties of metakaolin blended cements  

Microsoft Academic Search

The use of metakaolin (MK) as a mineral admixture for cement and concrete is a well-documented practice. The properties of cement pastes and mortars containing MK have been investigated as a function of key cement chemical parameters recognized as potential activators of the MK. Rheological behavior, initial setting time and compressive strength development have been compared by varying the total

E Moulin; P Blanc; D Sorrentino

2001-01-01

382

Physicochemical Properties and Biocompatibility of Polymer/Carbon Nanotubes Composites  

NASA Astrophysics Data System (ADS)

Due to the unique structure and combination of extremely high durability, electrical and calorific conductivities, carbon nanotubes (CNTs) are prospective fillers for polymer materials. The reinforcement of polymer by developed set-like form of CNT provides an increase in mechanical, electrical, and thermophysical properties, chemical stability, and biocompatibility of nanocomposites. The manufacture of CNT and polymers (polypropylene, Teflon-4, and elastomers on the base of butadiene-nitrile and fluorinated rubbers) filled with nanotubes and nanofibers of various contents is described. The CNT and the nanocomposites are characterized in detail by structural and physicochemical methods. It is shown that not only bulk characteristics but also surface properties of filled polymers are changed and this explains better the biocompatibility of nanocomposites, which is observed in in vivo experiments.

Sementsov, Yu. I.; Prikhod'Ko, G. P.; Melezhik, A. V.; Aleksyeyeva, T. A.; Kartel, M. T.

383

Magnesium-based composites with improved in vitro surface biocompatibility  

PubMed Central

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

Huan, Zhiguang; Duszczyk, Jurek

2010-01-01

384

Structure-property relationships and biocompatibility of carbohydrate crosslinked polyurethanes.  

PubMed

Biocompatible and biodegradable polyurethanes (PUs) based on castor oil and polypropylene glycols (PPGs) were prepared using various carbohydrate crosslinkers: monosaccharide (glucose), disaccharide (sucrose) and polysaccharides (starch and cellulose). The mechanical and thermal properties were investigated and interpreted on the basis of SEM study. The advantage of incorporating various carbohydrates is to have tunable mechanical properties and biodegradability due to variety in their structure. The glass transition temperature and sorption behavior were dominated by the type of polyol than by the type of crosslinker. All the PUs were observed to be biodegradable as well as non-cytotoxic as revealed by MTT assay in normal lung cell line L132. The study supports the suitability of carbohydrates as important components of biocompatible PUs for development of biomedical devices. PMID:24906764

Solanki, Archana; Mehta, Jayen; Thakore, Sonal

2014-09-22

385

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

386

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

387

Biocompatible photolithographic process for the patterning of biomolecules.  

PubMed

A new approach for the patterning of biomolecule layers is introduced based on the design of a new photoresist material with biocompatible lithographic processing requirements. The photoresist is based on poly(t-butyl acrylate), which allows positive imaging with very dilute basic solutions, tolerable by selected biomolecules used in immunoanalysis. Sensitivity at lambda>300 nm is obtained using a suitable sulfonium salt photoacid generator. Thermal steps also take place under conditions tolerable by biomolecules. Lithographic results on Si wafer substrates show resolution capabilities for equal lines/spaces, down to the range of 5-10 microm under biocompatible conditions. The process is also used on substrates of different geometries, including inner capillary surfaces. The patterning of the inner surface of a polystyrene capillary with mouse IgG is reported to demonstrate the principles of the above approach. PMID:11849922

Douvas, Antonios; Argitis, Panagiotis; Misiakos, Konstantinos; Dimotikali, Dimitra; Petrou, Panagiota S; Kakabakos, Sotirios E

2002-04-01

388

Biocompatibility studies of polyacrylonitrile membranes modified with carboxylated polyetherimide.  

PubMed

Poly (ether-imide) (PEI) was carboxylated and used as the hydrophilic modification agent for the preparation of polyacrylonitrile (PAN) membranes. Membranes were prepared with different blend compositions of PAN and CPEI by diffusion induced precipitation. The modified membranes were characterized by thermo gravimetric analysis (TGA), mechanical analysis, scanning electron microscopy (SEM) and contact angle measurement to understand the influence of CPEI on the properties of the membranes. The biocompatibility studies exhibited reduced plasma protein adsorption, platelet adhesion and thrombus formation on the modified membrane surface. The complete blood count (CBC) results of CPEI incorporated membranes showed stable CBC values and significant decrease in the complement activation were also observed. In addition to good cytocompatibility, monocytes cultured on these modified membranes exhibited improved functional profiles in 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. Thus it could be concluded that PAN/CPEI membranes with excellent biocompatibility can be useful for hemodialysis. PMID:23910257

Senthilkumar, S; Rajesh, S; Jayalakshmi, A; Mohan, D

2013-10-01

389

Evaluation of Sulfate Resisting Cements by a New Test Method.  

National Technical Information Service (NTIS)

Five ASTM Type V portland cements, two portland blast-furnace slag cements, and two portland pozzolan cements are evaluated for sulfate resistance by a new laboratory method which is reliable, quick and reproducible. It is concluded that significant diffe...

P. K. Mehta

1974-01-01

390

21 CFR 888.3027 - Polymethylmethacrylate (PMMA) bone cement.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Polymethylmethacrylate (PMMA) bone cement. 888.3027 Section...888.3027 Polymethylmethacrylate (PMMA) bone cement. (a) Identification. Polymethylmethacrylate (PMMA) bone cement is a device...

2010-04-01

391

21 CFR 888.3027 - Polymethylmethacrylate (PMMA) bone cement.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Polymethylmethacrylate (PMMA) bone cement. 888.3027 Section...888.3027 Polymethylmethacrylate (PMMA) bone cement. (a) Identification. Polymethylmethacrylate (PMMA) bone cement is a device...

2009-04-01

392

Engineering Biomaterials to Integrate and Heal: The Biocompatibility Paradigm Shifts  

PubMed Central

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

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

2012-01-01

393

Macrokinetic aspects of the biocompatibility and biodegradation of polymers  

NASA Astrophysics Data System (ADS)

We review the quantitative relationships between the degradation kinetics of the main classes of polymers (polyolefins, polyesters, polyamides, elastomers) used as implants. Their biocompatibility criteria and the reactions of the organism on the implants are considered, and the catalytic activity of biological media (water, salts, enzymes) are discussed together with problems in the metabolism and conjugation of the degradation products. The bibliography includes 127 references.

Gumargalieva, K. Z.; Zaikov, Gennadii E.; Moiseev, Yu V.

1994-10-01

394

A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys  

Microsoft Academic Search

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

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

2009-01-01

395

Biocompatible polymer alloy membrane for implantable artificial pancreas  

Microsoft Academic Search

The preparation of a novel polymer alloy membrane with both biocompatibility and permeability for fabrication of an implantable artificial pancreas was carried out. The polymer alloy was composed of a segmented polyurethane (SPU) and phospholipid polymer with 2-methacryloyloxyethyl phosphorylcholine (MPC) units. The MPC polymer was poly(MPC-co-2-ethylhexyl methacrylate) (PMEH), which can be dissolved in the same solvent for SPU. The SPU\\/PMEH

Tomoaki Uchiyama; Junji Watanabe; Kazuhiko Ishihara

2002-01-01

396

Biocompatibility study for PVP wound dressing obtained in different conditions  

NASA Astrophysics Data System (ADS)

Hydrogels composed of PVP, PEG and agar, produced by simultaneous crosslinking and package sterilization by ionizing radiation, are used mainly as wound dressing. In this study, membranes prepared in different conditions were tested for their properties including in vitro biocompatibility. The results showed that the mechanical properties were in an acceptable range of values and that the membranes can be considered as non toxic and non hemolytic to the cells.

Higa, O. Z.; Rogero, S. O.; Machado, L. D. B.; Mathor, M. B.; Lugão, A. B.

1999-08-01

397

Development of novel biocompatible hydrogel coatings for implantable glucose sensors  

Microsoft Academic Search

Due to sensor -tissue interactions, currently none of the commercially available glucose sensors are capable of continuous, reliable monitoring of glucose levels during long-term implantation. In order to improve the lifetime of implanted glucose sensors, two series of biocompatible novel hydrogel coatings were designed, synthesized and the physical properties were measured. Different hydrogels with various 2,3-dihydroxypropyl methacrylate (DHPMA) compositions were

Chunyan Wang

2008-01-01

398

Biocompatibility of injectable chitosan–phospholipid implant systems  

Microsoft Academic Search

Injectable biomaterials are desirable therapeutic platforms due to minimal invasiveness and improved patient compliance, and are applicable in such areas as compound delivery and tissue engineering. The present work examined the biocompatibility of injectable blends composed of chitosan, phospholipid and lauric aldehyde (PoLigel-LA) or lauric chloride (PoLigel-LCl). In vitro cytotoxicity was evaluated in L929 and HeLa cell lines. Both blends

Raquel De Souza; Payam Zahedi; Christine J. Allen; Micheline Piquette-Miller

2009-01-01

399

Biocompatibility and degradability of sepiolite-collagen complex.  

PubMed

Sepiolite, a magnesium silicate, binds collagen resulting in a complex which has a gel-like structure when hydrated. The binding of the protein to the clay decreases its degradability by collagenase, and no degradation was observed after treatment of the complex with glutaraldehyde. Extracts of both the untreated and the glutaraldehyde-treated complex are biocompatible for fibroblast growth. Based on its properties, this material should be considered in the design of biomaterials. PMID:3030456

Olmo, N; Lizarbe, M A; Gavilanes, J G

1987-01-01

400

Permeability and Biocompatibility of Novel Medicated Hydrogel Wound Dressings  

Microsoft Academic Search

Hydrogel dressings are being popularized for wound care management because of their softness, tissue compatibility, and ability to enhance wound healing process. PVP-CMC and PVP-CMC-BA hydrogels were prepared using polyvinylpyrrolidone (PVP), sodium-carboxymethylcellulose (CMC), polyethyleneglycol (PEG), agar, glycerine and without\\/with boric acid (BA). Permeability: water vapor transmission and microbe penetration and biocompatibility: cytotoxicity, skin irritation, and skin sensitization tests of hydrogels

Niladri Roy; Nabanita Saha; Petr Humpolicek; Petr Saha

2010-01-01

401

Evaluation of biocompatible products for managing cucurbit powdery mildew  

Microsoft Academic Search

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

M. T McGrath; N Shishkoff

1999-01-01

402

Evaluation of Biocompatible Photopolymers II: Further Reactive Diluents  

Microsoft Academic Search

Summary.  Within these investigations a new monomer formulation – consisting of a biodegradable basis monomer, reactive diluents, fillers,\\u000a and an appropriate photoinitiator – was developed for the stereolithographic fabrication of bone replacement materials. In\\u000a the current paper we describe the testing of several acrylate based reactive diluents – having different functional groups\\u000a – concerning reactivity, biocompatibility, and mechanical properties. Polymers from

Monika Schuster; Claudia Turecek; Alexander Mateos; Jürgen Stampfl; Robert Liska; Franz Varga

2007-01-01

403

Highly flexible and biocompatible Carbon Nanotube thin film transistors  

Microsoft Academic Search

We demonstrate a highly flexible and biocompatible Single-Walled Carbon Nanotube (SWNT) based thin film transistor (TFT). These devices were fabricated on a parylene-C substrate (10¿m) and encapsulated from the environment with a 1¿m thick parylene-C layer. Carbon nanotube (CNT) TFT was realized by field assisted (dielectrophoretic) assembly followed by electrical breakdown of SWNTs at room temperature. These SWNT TFTs exhibited

S. Selvarasah; K. Anstey; S. Somu; A. Busnaina; M. R. Dokmeci

2009-01-01

404

Super-resolution fluorescence imaging of biocompatible carbon dots.  

PubMed

Carbon Dots (CDs) are a new promising type of small (5 nm), biocompatible and multicolor luminescent nanoparticle. Here, we demonstrate super-resolution imaging of CDs at the nanoscale through STimulated Emission Depletion (STED) microscopy. In addition, we report the application of STED for detection of CD localization in both fixed and living cells, achieving a spatial resolution down to 30 nm, far below the diffraction limit, showing great promise for high resolution visualization of cellular dynamics. PMID:24983856

Leménager, Godefroy; De Luca, Elisa; Sun, Ya-Ping; Pompa, Pier Paolo

2014-07-10

405

Biocompatibility Parameters of Different Dialysis Membranes Assessed during Systemic Inflammation  

Microsoft Academic Search

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

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

2005-01-01

406

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.

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

2009-01-01

407

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.

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

2012-01-01

408

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-ins