bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of bleaching agents on the fluoride release and microhardness of dental materials4
Authors: Lee J. H. , Kim H. I. , Kim K. H. , Kwon Y. H. 
Published: September 2002

AbstractThe use of bleaching agents has become a popular procedure for whitening teeth. Recently introduced polyacid‐modified composite resins (compomers) have several favorable features, such as improved physical properties and fluoride release. Because these two materials have many possibilities to interact in the oral cavity during dental treatment, it is necessary to understand such interaction. To evaluate the effect of a bleaching agent on dental restoratives, three compomers were photopolymerized and then bleached for 1, 2, 3 and 5 days with the use of 30% hydrogen peroxide. Fluoride release, surface microhardness, and surface modifications were evaluated. It was found that the cumulative fluoride release was found to be linearly correlated to the tested periods of bleaching in all compomers. Among the tested compomers, F2000 showed the highest cumulative fluoride release. Bleached compomers became soft because of surface degradation, so the surface microhardness decreased. F2000 showed an apparent crack formation that was not observed in other compomers. The nearly linear correlation between the filler content and microhardness was found in the control samples. However, the same correlation was not observed after the compomers were stored in a bleaching agent or distilled water. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 535–541, 2002
Fabrication and surface modification of macroporous poly(L‐lactic acid) and poly(L‐lactic‐co‐glycolic acid) (70/30) cell scaffolds for human skin fibroblast cell culture
Authors: Yang Jian , Shi Guixin , Bei Jianzhong , Wang Shenguo , Cao Yilin , Shang Qingxin , Yang Guanghui , Wang Wenjing 
Published: September 2002

AbstractThe fabrication and surface modification of a porous cell scaffold are very important in tissue engineering. Of most concern are high‐density cell seeding, nutrient and oxygen supply, and cell affinity. In the present study, poly(L‐lactic acid) and poly(L‐lactic‐co‐glycolic acid) (70/30) cell scaffolds with different pore structures were fabricated. An improved method based on Archimedes' Principle for measuring the porosity of scaffolds, using a density bottle, was developed. Anhydrous ammonia plasma treatment was used to modify surface properties to improve the cell affinity of the scaffolds. The results show that hydrophilicity and surface energy were improved. The polar N‐containing groups and positive charged groups also were incorporated into the sample surface. A low‐temperature treatment was used to maintain the plasma‐modified surface properties effectively. It would do help to the further application of plasma treatment technique. Cell culture results showed that pores smaller than 160 μm are suitable for human skin fibroblast cell growth. Cell seeding efficiency was maintained at above 99%, which is better than the efficiency achieved with the common method of prewetting by ethanol. The plasma‐treatment method also helped to resolve the problem of cell loss during cell seeding, and the negative effects of the ethanol trace on cell culture were avoided. The results suggest that anhydrous ammonia plasma treatment enhances the cell affinity of porous scaffolds. Mass transport issues also have been considered. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 438–446, 2002
Theoretical investigation of elastic flexural properties for multistranded orthodontic archwires
Authors: Rucker Brian K. , Kusy Robert P. 
Published: September 2002

AbstractThe bending and torsional stresses during flexure were detailed and simplified for a single twisted strand, which emulates a spring. General expressions were derived to evaluate the elastic properties (i.e., strength, stiffness, and range) of multistranded wires by combining the effects of a number of outer twisted strands, with or without an inner strand. Specific expressions were solved for single‐stranded, twisted, and coaxial wires. Initially, we considered the following multistranded wire configurations: two‐ (twin), three‐ (triple), four‐strand (quad) twisted, and coaxial wires. The elastic properties of the twin and quad wires were essentially subsets of the triple wire. For a given overall wire diameter (D) and helix angle (α), the ranges of multistranded wires were independent of wire configurations. By varying the α from 45 to 85°, the D from 0.394 to 0.546 mm (15.5 to 21.5 mil), and the stress at the proportional limit from 1.03 to 3.28 GPa (150 to 475 ksi), the theoretical elastic properties of triple and coaxial stainless steel wires matched many of the properties of conventional nickel titanium leveling wires. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 338–349, 2002
Evaluation of feasibility of hydroxyapatite putty as a local hemostatic agent for bone
Authors: Momota Yukihiro , Miyamoto Youji , Ishikawa Kunio , Takechi Masaaki , Yuasa Tetsuya , Tatehara Seiko , Nagayama Masaru , Suzuki Kazuomi 
Published: September 2002

AbstractAlthough bone wax is known to cause an inflammatory reaction in soft tissue and a delay of bone healing, it is usually the first choice to arrest bleeding from bone. Hydroxyapatite (HAP) putty is proposed here. This study evaluated the feasibility of HAP putty with respect to whether or not it has potential value as a hemostatic agent for bone. First, the adhesive strength of HAP putty to bone was evaluated. The adhesive strength of HAP putty to wet bone was much higher when compared with that of bone wax, even though the adhesive strengths of HAP putty and bone wax to dry bone were equivalent. Next, to evaluate the hemostatic ability of HAP putty, bony defects were made in rabbits. HAP putty could arrest bleeding from bone within 3 min. However, when the hemostasis was performed with bone wax, bleeding was arrested within 8 min. Thus, HAP putty showed better hemostatic ability than bone wax. Finally, the tissue response to HAP putty in rabbit subcutaneous tissue was evaluated. Histological observation revealed a slight inflammatory response around HAP putty, whereas bone wax was surrounded by moderate inflammatory tissue. In conclusion, HAP putty has good potential value to be a hemostatic agent for bone because it has strong adhesion, good hemostatic ability, and biocompatibility. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 542–547, 2002
Theoretical prediction and experimental determination of the effect of mold characteristics on temperature and monomer conversion fraction profiles during polymerization of a PMMA‐based bone cement
Authors: Vallo Claudia I. 
Published: September 2002

AbstractThe present work is concerned with applications of a kinetic model for free‐radical polymerization of a polymethylmethacrylate‐based bone cement. Autocatalytic behavior at the first part of the reaction as well as a diffusion control phenomenon near vitrification are described by the model. Comparison of theoretical computations with experimental measurements for the temperature evolution during batch casting demonstrated the capacity of the proposed model to represent the kinetic behavior of the polymerization reaction. Temperature evolution and monomer conversion were simulated for the cure of the cement in molds made of different materials. The maximum monomer conversion fraction was markedly influenced by the physical properties of the mold material. The unreacted monomer acts as a plasticizer that influences the mechanical behavior of the cement. Hence, the same cement formulation cured in molds of different materials may result in different mechanical response because of the differences in the amounts of residual monomer. Standardization of the mold type to prepare specimens for the mechanical characterization of bone cements is recommended. Theoretical prediction of temperature evolution during hip replacement indicated that for cement thickness lower than 6 mm the peak temperature at the bone–cement interface was below the limit stated for thermal injury (50 °C for more than 1 min). The use of thin cement layers is recommended to diminish the risk of thermal injury; however, it is accompanied by an increase in the amount of unreacted monomer present in the cured material. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 627–642, 2002
A jet impingement investigation of osteoblastic cell adhesion
Authors: Giliberti Danielle C. , Anderson Kimberly A. , Dee Kay C 
Published: September 2002

AbstractWhen designing dental and orthopedic implants, it is important to consider phenomena occurring at the microscopic level, particularly at the bone‐implant interface. The presence of hard tissue at this interface is essential to implant viability. The integrity of this tissue‐biomaterial interface is dependent on appropriate osteoblast functions (adhesion, matrix deposition, etc.) in the immediate area. Researchers have modified various materials with cell‐adhesive peptides with the ultimate goal of controlling osteoblast functions. This study used microjet impingement to compare the strength of adhesion of osteoblastic cells (at varying populations) and fibroblasts to peptide‐modified substrates in the presence and absence of fetal bovine serum. In the presence of the serum, there was no significant difference in cellular adhesion strength between substrates. In the absence of serum, all cells tested adhered more strongly to underlying substrates, and the strength of cellular adhesion was greater on modified surfaces than on plain glass surfaces. In the absence of serum, second‐passage osteoblastic cells generally adhered to substrates more strongly than first‐passage osteoblastic cells; fibroblasts adhered similarly to second‐passage osteoblastic cells. Fundamental studies such as the present increase the understanding of cell adhesion to various substrates—knowledge that may be ultimately useful in creating an optimal bone‐implant interface. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 422–429, 2002
Tissue responses against immunoisolating alginate‐PLL capsules in the immediate posttransplant period
Authors: de Vos Paul , van Hoogmoed Chris G. , de Haan Bart J. , Busscher Henk J. 
Published: September 2002

AbstractAlginate‐polylysine (PLL) capsules are commonly applied for immunoisolation of living cells for the treatment of a wide variety of diseases. Large‐scale application of the technique, however, is hampered by insufficient biocompatibility of the capsules with failure of the grafts as a consequence. Most studies addressing biocompatibility issues of alginate‐PLL capsules have focused on the degree of overgrowth on the capsules after graft failure and not on the reaction against the capsules in the immediate posttransplant period. Therefore, capsules were implanted in the peritoneal cavity of rats and retrieved 1, 5, and 7 days later for histological examination and X‐ray photoelectron spectroscopy analysis for evaluation of chemical changes at the capsule surface. After implantation, the nitrogen signal increased from 5% on day 0, to 8.6% on day 7, illustrating protein adsorption on the capsule's surface. This increase in protein content of the membrane was accompanied by an increase in the percentage of overgrown capsules from 0.5 ± 0.3% on day 1 to 3.3 ± 1.6% on day 7. The cellular overgrowth was composed of monocytes/macrophages, granulocytes, fibroblasts, erythrocytes, multinucleated giant cells, and basophils. This overgrowth was not statical as generally assumed but rather dynamic as illustrated by our observation that at day 1 after implantation we mainly found monocytes/macrophages and granulocytes that on later time points were substituted by fibroblasts. As the inflammatory reaction predictably interfere with survival of encapsulated cells, efforts should be made to suppress activities or recruitment of inflammatory cells. These efforts may be temporary rather than permanent because most inflammatory cells have disappeared after 2 weeks of implantation. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 62: 430–437, 2002
Extracellular matrix of human amnion manufactured into tubes as conduits for peripheral nerve regeneration
Authors: Mligiliche Nurru , Endo Katsuaki , Okamoto Keiko , Fujimoto Etsuko , Ide Chizuka 
Published: September 2002

AbstractThe human amnion consists of the epithelial cell layer and underlying connective tissue. After removing the epithelial cells, the resulting acellular connective tissue matrix was manufactured into thin dry sheets called amnion matrix sheets. The sheets were further processed into tubes, amnion matrix tubes (AMTs), of varying diameters, with the walls of varying numbers of amnion matrix sheets with or without a gelatin coating. The AMTs were implanted into rat sciatic nerves. Regenerating nerves extended in bundles through tubes of 1–2 mm in diameter and further elongated into host distal nerves 1–3 weeks after implantation. Morphometrical analysis of the regenerated nerve cable at the middle of each amnion matrix tube 3 weeks after implantation was performed. The average numbers of myelinated axons were almost the same (ca. 80–112/104 μm2) in AMTs of 1–2 mm in diameter, as in the normal sciatic nerve (ca. 95/104 μm2). No myelinated fibers were found in AMTs composed of multiple thin tubes of 0.2 mm in diameter. The myelinated axons were thinner in implanted tubes than those in the normal sciatic nerve. The rate of occurrences of myelinated axons less than 4 μm in diameter was significantly higher in the AMTs, whereas axons in the normal sciatic nerve were diverse in distribution, with the highest population at 8–12 μm in diameter. Reinnervation to the gastrocnemius muscle was demonstrated electrophysiologically 9 months after implantation. It was concluded that the extracellular matrix sheet from the human amnion is an effective conduit material for peripheral nerve regeneration. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 591–600, 2002
Effect of ball milling on the processing of bone substitutes with calcium phosphate powders
Authors: Bignon Aurélien , Chevalier Jérôme , Fantozzi Gilbert 
Published: September 2002

AbstractDecreasing the microscale morphology of synthetic bone substitutes is of primary importance in order to enhance the morphology of the surface of the material, which is directly in contact with osteoconductive cells when it is implanted in bone. The aim of this study was to investigate the influence of ball milling of slurries on the microscale morphology of hydroxyapatite and tricalcium phosphate bone substitutes and the influence on their processing. Ball milling appeared to be a successful method in order to raise the sintering reactivity of the powders, that is, to decrease the sintering temperature and microstructural morphology of the material. However, it was demonstrated that ball milling had a great influence on dispersion, which became very difficult under long milling times because of dissolution of the calcium phosphate powders. Due to dissolution, ionic species were generated in the slurry and interfered with the dispersing agent. Moreover a reprecipitation process occurred simultaneously, and large particles of the most stable phase (HAP) formed. The presence of such large particles generated stress gradients and cracks in the material during the sintering stage. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 619–626, 2002
Effect of surface conditions on the color of dental resin composites
Authors: Lee Yong‐Keun , Lim Bum‐Soon , Kim Cheol‐We 
Published: September 2002

AbstractThe objectives of this study were to evaluate the effect of surface conditions of dental resin composites on the measured color depending on the measuring geometry (SCE, SCI), and to determine the color difference (ΔE*) caused by varied surface conditions. Color and surface roughness (Ra) of five brands of resin composites of A2 shade were measured after polymerization and polishing with 600‐, 1000‐, or 1500‐grit SiC paper. Color was measured according to the CIE L*a*b* color scale. ΔE* between different surface conditions was calculated by the equation ΔE* = [(ΔL*)2 + (Δa*)2 + (Δb*)2]1/2. Before polishing, CIE L* values with the SCE were significantly lower than those measured with the SCI. Before polishing, ΔE* values depending on the measuring geometry were very high (3.78–5.93). However, those after polishing were lower than 1.61. CIE L* values increased after polishing (p < 0.05) with the SCE; however, they were not changed with the SCI. ΔE* values between Mylar‐covered and 600‐grit polished specimens were 4.20–5.99 with the SCE and 0.27–1.46 with the SCI. Measurement with the SCE geometry may result in accurate color determination, which reflects the surface conditions of dental restorative materials. ΔE* values measured with the SCE between the specimens of different surface conditions were significantly higher than those with the SCI (p < 0.05). © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 657–663, 2002
A field‐focusing device to increase power output of ThermoRod™ implants for thermal ablation of tissue
Authors: Berthusen Andrew H. , Tucker Robert D. , Park Joon B. 
Published: September 2002

AbstractInduction heating of small, cylindrical ferromagnetic implants (1.4 cm long and 1 mm in diameter) is a method for treating deep‐seated tumors. These implants, or ThermoRods™, are placed within a lesion in 1‐cm2 arrays and are exposed to an alternating magnetic field. The implants absorb energy from that field and transfer it as heat to the surrounding tissue. Each ThermoRod™ offers approximately 400 mW of power, and to kill cells, the target temperature must be greater than 42 °C. In this work, a magnetic field‐focusing device is employed to concentrate the induced magnetic flux toward a local region near the base of the prostate to increase the power output of proximal ThermoRods™. This, in turn, allows for more complete thermal ablation of lesions near the base of the prostate where the heat‐sink characteristics of the bladder can cause significant power losses. Boundary element analysis and in vitro testing have shown that the use of a ferrofluid‐based field‐focusing device can lead to a significant increase in power output of approximately 25% and 13%, respectively, of proximal ThermoRods™. These preliminary results indicate that the incorporation of such a ferrofluid‐based focusing device into ThermoRod™ treatments is promising for the avoidance of significant power loss and for assuring complete thermal ablation of prostatic lesions. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 650–656, 2002
Glucose‐dependent regulation of osteoclast H+‐ATPase expression: Potential role of p38 MAP‐kinase
Authors: Larsen Kirsten I. , Falany Marina L. , Ponomareva Larissa V. , Wang Wei , Williams John P. 
Published: September 2002

AbstractBone resorption is glucose concentration dependent. Mechanisms regulating glucose‐dependent increases in bone resorption have not been identified. Glucose activates p38 MAP‐kinase in other cells and since MAP kinases activate transcription factors, we hypothesized that glucose‐stimulated bone resorption may be modulated by increased expression of the vacuolar H+‐ATPase. Glucose activates osteoclast p38 MAP‐kinase in a time and concentration‐dependent manner as determined by Western analysis with phospho‐specific p38 antibody while total p38 levels are unchanged. The K0.5 for glucose‐dependent activation of p38 MAP‐kinase is ∼7 mM, activation is maximal at 30 min and is elevated but returning to basal levels by 60 min. The concentration‐dependent increase in H+‐ATPase expression was confirmed by Northern analysis. The specific inhibitor of p38 MAP‐kinase, SB203580, inhibited glucose transport in osteoclasts, as well as glucose concentration‐dependent increases in bone resorption and expression of H+‐ATPase A and B subunits. Glucose had no effect on calmodulin expression levels that are regulated in response to other environmental changes. The glucose‐stimulated increase in H+‐ATPase mRNA expression is a specific response to glucose since glucose has little effect on G3PDH mRNA levels. We conclude that glucose regulates osteoclast H+‐ATPase expression by a mechanism likely to involve p38 MAP‐kinase. J. Cell. Biochem. 87: 75–84, 2002. © 2002 Wiley‐Liss, Inc.
Further characterization of human fetal osteoblastic hFOB 1.19 and hFOB/ERα cells: Bone formation in vivo and karyotype analysis using multicolor fluorescent in situ hybridization
Authors: Subramaniam M. , Jalal Syed M. , Rickard David J. , Harris Steven A. , Bolander Mark E. , Spelsberg Thomas C. 
Published: September 2002

AbstractWe have previously generated an immortalized human fetal osteoblastic cell line (hFOB) using stably transfected temperature sensitive SV40 T‐antigen (Harris et al. [1995a] J. Bone. Miner. Res. 10:178–1860). To characterize these cells for phenotypic/genotypic attributes desired for a good cell model system, we performed karyotype analysis by multicolor fluorescent in situ hybridization (M‐FISH), their ability to form bone in vivo without developing cell transformation, and finally their ability to form extracellular matrix formation in vitro. The karyotype analysis of hFOB cells revealed structural or numeric anomalies involving 1–2 chromosomes. In contrast, the human osteosarcoma MG63 cells displayed multiple, and often complex, numeric, and structural abnormalities. Subcutaneous injection of hFOB cells in the presence of Matrigel into nude mice resulted in bone formation after 2–3 weeks. Electron microscopic analysis of the extracellular matrix deposited by hFOB cells in culture revealed a parallel array of lightly banded fibrils typical of the fibrillar collagens such as type I and III. These results demonstrate that the hFOB cell line has minimal chromosome abnormalities, exhibit the matrix synthetic properties of differentiated osteoblasts, and are immortalized but non‐transformed cell line. These hFOB cells thus appear to be an excellent model system for the study of osteoblast biology in vitro. J. Cell. Biochem. 87: 9–15, 2002. © 2002 Wiley‐Liss, Inc.
Identification of cultured progenitor cells from human marrow stroma
Authors: Shur I. , Marom R. , Lokiec F. , Socher R. , Benayahu D. 
Published: September 2002

AbstractThe marrow stromal cells (MSC) are essential for regulation of bone remodeling and hematopoiesis. It is of prime importance to isolate MSC and to expand the proliferating cells ex vivo. In this study, we analyzed cultured MSC for various cellular parameters, including cell morphology, cell cycle, and expression of cell surface antigens by flow cytometry. MSC were divided based on cell size to small (S‐cells) and large (L‐cells) and were visualized by light and electron microscope. The S‐cells were proliferating cells correlated with G0/G1 phase of cell cycle, and expressed cFOS. The expression of surface markers CD‐34, ‐44, ‐51, ‐61, ‐62E, ‐62P, ‐62L was quantified using flow cytometry. CD‐44 was ubiquitously expressed by S and L cells, CD‐51 and ‐61 were expressed by 30%–38% of S‐cells. CD‐34 and ‐62 expressed 20% positive of the analyzed cells that were of the proliferating progenitors (S‐cells). This study enables the identification of subpopulations from MSC with special attention paid to the proliferating cells from ex vivo cultures of marrow stroma. J. Cell. Biochem. 87: 51–57, 2002. © 2002 Wiley‐Liss, Inc.