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Clinical Oral Investigations Jun 2003The microfill veneering of hybrid composite restorations has been indicated to improve esthetics. Also, polyethylene fiber reinforcement has been proposed for use in...
MAIN PROBLEM
The microfill veneering of hybrid composite restorations has been indicated to improve esthetics. Also, polyethylene fiber reinforcement has been proposed for use in composite restorations in high-stress clinical situations. However, minimal information in the literature addresses the influence of such combinations on the resistance to fracture. The purpose of this study was to investigate the flexural strength of two composites, a microfill and a hybrid, the effect of their combination, and the influence of polyethylene fiber reinforcement.
MATERIALS AND METHODS
Twenty-eight specimens were prepared using a standard metallic mold (20x2x2 mm) and divided into groups of seven each: Filtek Z-250 (3M ESPE, St. Paul, Minn., USA) (group I), Filtek A-110 (3M ESPE) (group II), Filtek Z-250 combined with Filtek A-110 (group III), and Filtek Z-250 combined with polyethylene fiber (Ribbond, Seattle, Wash., USA) (group IV). The specimens were stress-loaded to fracture in a three-point bending device according to International Standardization Organization (ISO) 4049.
RESULTS
Data were analyzed using analysis of variance and Tukey's test at a 0.05 level of significance. No statistically significant differences were observed between groups I and IV. Group II, however, exhibited statistically lower resistance to fracture than the other groups. Group III presented intermediate results, showing statistically higher fracture resistance than group II but lower than group I.
CONCLUSIONS
With the methodology employed, microfill composite presented the lowest flexural strength, but its association with hybrid composite increased the resistance to fracture. The combination of polyethylene fiber and hybrid composite did not present higher flexural strength than hybrid composite alone.
Topics: Analysis of Variance; Composite Resins; Dental Materials; Humans; Materials Testing; Pliability; Polyethylene; Polyethylenes; Resin Cements; Stress, Mechanical; Surface Properties
PubMed: 12690535
DOI: 10.1007/s00784-003-0198-3 -
A.M.A. Archives of Surgery Jan 1955
Topics: Aneurysm; Aortic Aneurysm; Humans; Polyethylene; Polyethylenes
PubMed: 13217604
DOI: 10.1001/archsurg.1955.01270070067012 -
Water Research Sep 2002A study of the diffusion of organic additives from four polyethylene (PE) materials into drinking water was conducted. Various structures of organic chemicals were...
A study of the diffusion of organic additives from four polyethylene (PE) materials into drinking water was conducted. Various structures of organic chemicals were identified in the water extracts by means of gas chromatography-mass spectrometry analysis. Most of them presented a basic common structure characterised by a phenolic ring typically substituted with hindered alkyl groups in positions 2 and 6 on the aromatic ring. The structures attributed to some of the chemicals have been confirmed using commercial or purposely synthesised standards. Unprocessed granules of raw PE were also analysed, in order to investigate the origin of the chemicals detected in the water samples. Consequently, the presence of some of the compounds was attributed to impurities or by-products of typical phenolic additives used as antioxidants in pipeline production. Finally, the occurrence of the identified chemicals was tested under field conditions, i.e. in water samples from newly installed pipelines in a distribution system. Here, the presence of three of the compounds identified in vitro was detected.
Topics: Environmental Monitoring; Gas Chromatography-Mass Spectrometry; Manufactured Materials; Polyethylene; Water Pollutants, Chemical; Water Supply
PubMed: 12369514
DOI: 10.1016/s0043-1354(02)00084-2 -
Journal of Materials Science. Materials... Jun 2014Wear of polyethylene causes loosening of joint prostheses because of the particle mediated activity of the host tissue. It was hypothesized that conventional and... (Comparative Study)
Comparative Study
Wear of polyethylene causes loosening of joint prostheses because of the particle mediated activity of the host tissue. It was hypothesized that conventional and crosslinked polyethylene particles lead to similar biological effects around the knee joint in vivo as well as to a similar particle distribution in the surrounding tissues. To verify these hypotheses, particle suspensions of six different polyethylene materials were injected into knee joints of Balb/C mice and intravital microscopic, histological and immunohistochemical evaluations were done after 1 week. Whereas the biological effects on the synovial layer and the subchondral bone of femur and tibia were similar for all the polyethylenes, two crosslinked materials showed an elevated cytokine expression in the articular cartilage. Furthermore, the distribution of particles around the joint was dependent on the injected polyethylene material. Those crosslinked particles, which remained mainly in the joint space, showed an increased expression of TNF-alpha in articular cartilage. The data of this study support the use of crosslinked polyethylene in total knee arthroplasty. In contrast, the presence of certain crosslinked wear particles in the joint space can lead to an elevated inflammatory reaction in the remaining cartilage, which challenges the potential use of those crosslinked polyethylenes for unicondylar knee prostheses.
Topics: Animals; Biocompatible Materials; Equipment Failure Analysis; Female; Foreign-Body Migration; Knee Joint; Knee Prosthesis; Materials Testing; Mice; Mice, Inbred BALB C; Particle Size; Polyethylene; Prosthesis Design
PubMed: 24562818
DOI: 10.1007/s10856-014-5176-6 -
American Journal of Ophthalmology Apr 1964
Topics: Dacryocystorhinostomy; Humans; Lacrimal Apparatus; Lacrimal Duct Obstruction; Nose; Polyethylene; Polyethylenes; Surgical Equipment; Surgical Procedures, Operative; Trephining
PubMed: 14139311
DOI: No ID Found -
Macromolecular Rapid Communications Jun 2012Allene groups are first employed as the reactive moiety in the simple and efficient synthesis of well-defined functional polyethylene. By copolymerization of ethylene...
Allene groups are first employed as the reactive moiety in the simple and efficient synthesis of well-defined functional polyethylene. By copolymerization of ethylene with allene group substituted norbornene, the allene group is successfully introduced into the polyethylene with a high content. The retained allene groups are demonstrated to be highly reactive in following photoinduced functionalized reactions and can be efficiently converted into the functional groups without the multi-step, time consuming processes that have generally been required in previous reports, providing the side group-functionalized polyethylene with a wide range of functional group content.
Topics: Alkadienes; Photochemistry; Polyethylene
PubMed: 22411771
DOI: 10.1002/marc.201100855 -
Acta Oto-laryngologica. Supplementum 1953
Topics: Humans; Nose; Polyethylene; Polyethylenes
PubMed: 13138144
DOI: 10.3109/00016485309132504 -
A.M.A. Archives of Surgery May 1953
Topics: Humans; Infusions, Parenteral; Patients; Polyethylene; Polyethylenes
PubMed: 13039740
DOI: 10.1001/archsurg.1953.01260030692017 -
Stain Technology Jan 1955
Topics: Coloring Agents; Histological Techniques; Histology; Polyethylene; Polyethylenes; Staining and Labeling
PubMed: 13225983
DOI: No ID Found -
The Journal of Pediatrics Jul 1952
Topics: Enteral Nutrition; Humans; Infant; Infant, Newborn; Infant, Premature; Polyethylene; Polyethylenes
PubMed: 14939122
DOI: 10.1016/s0022-3476(52)80030-7