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111.
Cutting efficiency of diamond burs operated with electric high‐speed dental handpiece on zirconia 下载免费PDF全文
Keisuke Nakamura Yusuke Katsuda Shuhei Ankyu Akio Harada Taichi Tenkumo Taro Kanno Yoshimi Niwano Hiroshi Egusa Percy Milleding Ulf Örtengren 《European journal of oral sciences》2015,123(5):375-380
Zirconia‐based dental restorations are becoming used more commonly. However, limited attention has been given to the difficulties experienced, concerning cutting, in removing the restorations when needed. The aim of the present study was to compare the cutting efficiency of diamond burs, operated using an electric high‐speed dental handpiece, on zirconia (Zir) with those on lithium disilicate glass–ceramic (LD) and leucite glass–ceramic (L). In addition, evaluation of the cutting efficiency of diamond burs on Zir of different thicknesses was performed. Specimens of Zir were prepared with thicknesses of 0.5, 1.0, 2.0, and 4.0 mm, and specimens of LD and L were prepared with a thickness of 1.0 mm. Cutting tests were performed using diamond burs with super coarse (SC) and coarse (C) grains. The handpiece was operated at 150,000 rpm with a cutting force of 0.9 N. The results demonstrated that cutting of Zir took about 1.5‐ and 7‐fold longer than cutting of LD and L, respectively. The SC grains showed significantly higher cutting efficiency on Zir than the C grains. However, when the thickness of Zir increased, the cutting depth was significantly decreased. As it is suggested that cutting of zirconia is time consuming, this should be taken into consideration in advance when working with zirconia restorations. 相似文献
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Hironori Tsujimoto Hiroyuki Horiguchi Risa Takahata Satoshi Ono Yoshihisa Yaguchi Shinsuke Nomura Nozomi Ito Manabu Harada Hiromi Nagata Yusuke Ishibashi Keita Kouzu Satoshi Tsuchiya Yujiro Itazaki Seiichiro Fujishima Yoji Kishi Hideki Ueno 《Journal of gastroenterology and hepatology》2020,35(5):788-794
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Environmental stress is a major factor that affects courtship behavior and evolutionary fitness. Although mature virgin females of Drosophila melanogaster usually accept a courting male to mate, they may not mate under stressful conditions. Above the temperature optimal for mating (20–25?°C), copulation success of D. melanogaster declines with increasing temperature although we observed vigorous courtship attempts by males, and no copulation takes place at temperatures over 36?°C. We attempted to identify the sensory pathway for detecting heat threat that drives a female to escape rather than to engage in mating that detects hot temperature and suppresses courtship behavior. We found that the artificial activation of warmth-sensitive neurons (‘hot cells’) in the antennal arista of females completely abrogates female copulation success even at permissive temperatures below 32?°C. Moreover, mutational loss of the GR28b.d thermoreceptor protein caused females to copulate even at 36?°C. These results indicate that antennal hot cells provide the input channel for detecting the high ambient temperature in the control of virgin female mating under stressful conditions. 相似文献
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Masayuki Kaga Shinichi Kakuda Yusuke Ida Hirokazu Toshima Masanori Hashimoto Kazuhiko Endo Hidehiko Sano 《European journal of oral sciences》2014,122(1):78-83
The buffering capacity and inhibitory effects on enamel demineralization of two commercially available dental sealants were evaluated in this study. The effects of filler particles were also examined. Disks of enamel and cured sealant materials of BeautiSealant (silica or S‐PRG filler) or Teethmate F‐1 were incubated in lactic acid solutions (pH 4.0) for 1–6 d. The pH changes and amounts of ions released in the solutions were assessed, and enamel surfaces were observed using a scanning electron microscope. The pH of the solution with BeautiSealant (S‐PRG filler) was neutralized from pH 4.0 to pH 6.1 (after incubation for 1 d) and from pH 4.0 to pH 6.7 (after incubation for 6 d). In addition, no release of calcium ions was detected and the enamel surface was morphologically intact in scanning electron microscopy images. However, the pH of the solution with Teethmate F‐1 remained below pH 4.0 during incubation from days 1 to 6. Calcium release was increased in solutions up to and after 6 d of incubation. Scanning electron microscopy images showed that the structures of hydroxyapatite rods were exposed at the specimen surfaces as a result of demineralization. Ions released from S‐PRG filler‐containing dental sealant rapidly buffered the lactic acid solution and inhibited enamel demineralization. 相似文献
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