PURPOSEThis study investigated the influence of bone quality and surgical technique on the implant stability quotient (ISQ) value. In addition, the influence of interfacial bone quality, directly surrounding the implant fixture, on the resonance frequency of the structure was also evaluated by the finite element analysis.MATERIALS AND METHODSTwo different types of bone (type 1 and type 2) were extracted and trimmed from pig rib bone. In each type of bone, the same implants were installed in three different ways: (1) Compaction, (2) Self-tapping, and (3) Tapping. The ISQ value was measured and analyzed to evaluate the influence of bone quality and surgical technique on the implant primary stability. For finite element analysis, a three dimensional implant fixture-bone structure was designed and the fundamental resonance frequency of the structure was measured with three different density of interfacial bone surrounding the implant fixture.RESULTSIn each group, the ISQ values were higher in type 1 bone than those in type 2 bone. Among three different insertion methods, the Tapping group showed the lowest ISQ value in both type 1 and type 2 bones. In both bone types, the Compaction groups showed slightly higher mean ISQ values than the Self-tapping groups, but the differences were not statistically significant. Increased interfacial bone density raised the resonance frequency value in the finite element analysis.CONCLUSIONBoth bone quality and surgical technique have influence on the implant primary stability, and resonance frequency has a positive relation with the density of implant fixture-surrounding bone.
Purpose:The purpose of present study is to compare mechanical properties and microstructural characteristics of fractured surface for cast, 3-D printing laser sintered and CAD/CAM milled cobalt-chromium (Co-Cr) alloy specimens and to investigate whether laser sintered technique is adequate for dental applications. Materials and methods: Thirty six flat disc shape Co-Cr alloy specimens were fabricated for surface hardness test and divided into three groups according to the manufacturing methods; 12 specimens for casting (n=12), 12 specimens for laser sintered technology (n=12) and 12 specimens for milled technology (n=12). Twelve dumbbell shape specimens for each group were also fabricated for a tensile test. Statistical comparisons of the mechanical properties for the alloys were performed by Kruskal-Wallis test followed by Mann-Whitney and Bonferroni test. The microstructural characteristics of fractured surfaces were examined using SEM. Results: There were significant differences in the mean Vickers hardness values between all groups and the cast specimen showed the highest (455.88 Hv) while the CAD/CAM milled specimen showed the lowest (243.40 Hv). Significant differences were found among the three groups for ultimate tensile strength, 0.2% yield stress, elongation, and elastic modulus. The highest ultimate tensile strength value (1442.94 MPa) was shown in the milled group and the highest 0.2% yield strength (1136.15 MPa) was shown in the laser sintered group. Conclusion: Different manufacturing methods influence the mechanical properties and microstructure of the fractured surfaces in Co-Cr alloys. The cast Co-Cr alloy specimens showed the highest Vickers hardness, and the CAD/CAM milled specimens revealed the highest tensile strength value. All alloys represent adequate mechanical properties satisfying the ISO standards of dental alloy. (J Korean Acad Prosthodont 2014;52:67-73)
Background: Hemodialysis patients are prone to ischemic events potentially aggravated by hypoxia. The key player in adaptation to hypoxia is hypoxia-inducible factor-1 alpha (HIF-1α). Therefore, we investigated the association of HIF-1α polymorphisms with ischemia/hypoxia-related events in hemodialysis patients. Methods: Patients on maintenance hemodialysis were enrolled from 4 training hospitals in Korea. Seven single nucleotide polymorphisms (SNP) of HIF-1α were genotyped. The association of these SNP with hypoxia-related clinical outcomes (ischemic diseases and anemia) and cancer was analyzed. Results: A total of 376 patients participated in the study. No significant difference in genotype distribution was found between subjects with and without the hypoxia-related events. Three sets of linkage disequilibrium blocks were made for haplotype analyses (rs2783778 and rs7148720 in 5′ upstream region; rs7143164 and rs10873142; rs2301113, rs11549465 and rs2057482). Of these, the CT haplotype in the first set was associated with both acute myocardial infarction and frequent intradialytic hypotension (acute myocardial infarction: adjusted odds ratio = 0.15, 95% CI: 0.03–0.69; frequent intradialytic hypotension: adjusted odds ratio = 0.29, 95% CI: 0.12–0.72). Conclusion: Genetic polymorphisms of HIF-1α were associated with acute myocardial infarction and intradialytic hypotension in hemodialysis patients.
This assignment applies to all translations of the Work as well as to preliminary display/posting of the abstract of the accepted article in electronic form before publication. If any changes in authorship (order, deletions, or additions) occur after the manuscript is submitted, agreement by all authors for such changes must be on file with the Publisher. An author's name may be removed only at his/her written request. (Note: Material prepared by employees of the US government in the course of their official duties cannot be copyrighted.
Magnetic fields under 10 mT did not influence FN adsorption on the titanium surface. However, a significant effect was found on cell attachment and proliferation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.