金属对金属新假体临床使用体会

目的:探讨金属对金属大头(ASRTMXL)全髋关节置换术的早期疗效和临床体会,以及该技术的安全性和有效性。方法:2007年1月至2008年3月,采用金属对金属大头全髋关节置换术治疗37例(39髋)髋关节疾患,男24例,女13例;年龄43～75岁,平均58.5岁。其中股骨头坏死14例、骨性关节炎2例、新鲜股骨颈骨折18例、先天性髋关节发育不良3例。结合手术前后患者髋关节功能检查、Harris评分及X线分析,对金属大头全髋的临床应用特点进行分析。结果:术后患者伤口均Ⅰ期临床愈合,无早期并发症发生。37例(39髋)均获随访,随访时间12～19个月,平均16.5个月。术后X线片显示关节假体位置良好,肢体长度及股骨偏心距基本恢复正常。髋关节活动度得到大幅改善,前屈由(20.1±8.2)°增加到(85.7±9.8)°(t=32.86,P0.01),外展由(10.2±4.4)°增加到(41.5±9.1)°(t=19.34,P0.01),内收由(16.3±8.8)°增加到(40.3±10.4)°(t=11.00,P0.01),外旋由(12.3±5.2)°增加到(42.0±7.7)°(t=19.96,P0.01),内旋由(3.4±1.1)°增加到(23.0±9.8)°(t=12.41,P0.01)。Harris髋关节评分从术前(39.3±5.6)分提高到最后随访的(91.4±10.3)分(t=27.75,P0.01)。结论:金属对金属大头全髋假体设计具有臼杯变形小、磨损率低、活动范围大、脱位发生率低等特点。其为治疗术后活动量要求较高的髋关节疾病如股骨头缺血性坏死、骨关节炎、股骨颈骨折、髋发育不良患者提供了一种新的有价值的手术方式。     

不同金属材料义齿基托对口腔感染的影响

目的探讨不同金属材料义齿基托对口腔感染的影响。方法选取2018年1月-2019年2月在我院进行义齿修复的患者80例,采用随机数字表法的分组方式,分为对照组和观察组,每组各40例。对照组患者采用钴铬合金铸造义齿基托,观察组患者采用纯钛铸造义齿基托,观察分析两组患者的临床指标(口腔异味、真菌感染、退苔例数)、牙周健康状况及口炎发生率。结果佩戴后,观察组患者出现口腔异味及真菌感染状况显著低于对照组,出现退苔状况显著高于对照组,差异有统计学意义(P<0.05);佩戴后,观察组患者的菌斑指数及牙龈指数显著低于对照组,差异有统计学意义(P<0.05);佩戴1及2个月时,观察组患者产生口炎状况显著低于对照组,差异有统计学意义(P<0.05)。结论金属材料义齿基托均有一定的口腔感染风险,但纯钛铸造义齿基托可减少真菌感染,改善患者菌斑及牙龈情况,降低口炎发生率。     

Consequences of exposure to peri-articular injections of micro- and nano-particulate cobalt–chromium alloy

Metal hip replacements generate both metal particles and ions. The biological effects of peri-articular exposure to nanometre and micron sized cobalt chrome (CoCr) wear particles were investigated in a mouse model. Mice received injections of two clinically relevant doses of nanoparticles (32 nm), one of micron sized (2.9 μm) CoCr particles or vehicle alone into the right knee joint at 0, 6, 12 and 18 weeks. Mice were analysed for genotoxic and immunological effects 1, 4 and 40 weeks post exposure. Nanoparticles but not micron particles progressively corroded at the injection site. Micron sized particles were physically removed. No increase of Co or Cr was seen in peripheral blood between 1 and 40 weeks post exposure to particles. No significant inflammatory changes were observed in the knee tissues including ALVAL or necrosis. DNA damage was increased in bone marrow at one and forty weeks and in cells isolated from frontal cortex at 40 weeks after injection with nanoparticles. Mice exposed to the micron sized, but not nanoparticles became immunologically sensitized to Cr(III), Cr (VI) and Ni(II) over the 40 week period as determined by lymphocyte transformation and ELISpot (IFN-γ and IL-2) assays. The data indicated that the response to the micron sized particles was Th1 driven, indicative of type IV hypersensitivity. This study adds to understanding of the potential adverse biological reactions to metal wear products.     

金属烤瓷冠修复体对牙龈健康的影响分析

目的：探讨如何减少金属烤瓷冠修复体对牙龈组织的炎症及牙龈缘着色的影响。方法随机选取口腔门诊做金属烤瓷冠修复体3年的患者80例,270颗修复体,对修复后牙龈炎症、牙龈缘着色的情况进行分析。结果17颗修复体出现牙龈炎症,占6．2％,20颗修复体出现牙龈缘着色,占7．4％。结论合理的设计、规范的牙体预备及基底冠金属材质的选择,能减少牙龈炎症和牙龈缘着色的发生。     

Physiological features of Halomonas lionensis sp. nov., a novel bacterium isolated from a Mediterranean Sea sediment

A novel halophilic bacterium, strain RHS90^T, was isolated from marine sediments from the Gulf of Lions, in the Mediterranean Sea. Its metabolic and physiological characteristics were examined under various cultural conditions, including exposure to stressful ones (oligotrophy, high pressure and high concentrations of metals). Based on phylogenetic analysis of the 16S rRNA gene, the strain was found to belong to the genus Halomonas in the class Gammaproteobacteria. Its closest relatives are Halomonas axialensis and Halomonas meridiana (98% similarity). DNA–DNA hybridizations indicated that the novel isolate is genotypically distinct from these species. The DNA G + C content of the strain is 54.4 mol%. The main fatty acids (C_18:1 ω7c, 2-OH iso-C_15:0, C_16:0 and/or C_19:0 cyclo ω8c), main polar lipids (diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and an unidentified phosphoglycolipid) and major respiratory quinone (ubiquinone Q9) were determined. The novel isolate is heterotrophic, mesophilic, euryhaline (growth optimum ranging from 2 to 8% w/v NaCl) and is able to grow under stressful conditions. The strain accumulates poly-β-hydroxyalkanoates granules and compatible solutes. Based on genotypic, chemotaxonomic and phenotypic distinctiveness, this isolate is likely to represent a novel species, for which the name Halomonas lionensis is proposed. The type strain of H. lionensis is RHS90^T (DSM 25632^T = CIP 110370^T = UBOCC 3186^T).     

Analysis of thermal distributions in veneered zirconia and metal restorations during firing

Objective

The present work evaluated the thermal behavior of porcelain–metal and porcelain–zirconia restorations during fast and slow firing and cooling.

Methods

All-ceramic (porcelain on zirconia) and porcelain-fused-to-metal (PFM) molar crowns were fabricated with 1 or 2 mm porcelain thickness. Thermocouples were attached to the cementation (T1) and occlusal (T4) surfaces of the restoration and embedded at the framework–porcelain interface (T2) and inside the porcelain (T3) to acquire temperature readings by time. Slow heating was set as 45 °C/min and fast heating as 140 °C/min. For fast cooling, the furnace was opened immediately after the holding time. Slow cooling was effected by opening the furnace when it reached 50 °C below the T_g. Porcelains T_g were calculated for each cooling rate.

Results

Slow heating rate was measured at T4 as being 30 °C/min while fast heating at T4 was 100 °C/min. The measured cooling rates within the porcelain (T2) around the T_g range were 20 °C/min and 900 °C/min for slow and fast cooling, respectively. During slow cooling, similar temperatures were found for both zirconia and metal crowns. Remarkable temperature gradients were observed for the fast cooled all-ceramic crown (T1–T4 = 100 °C) and, of lower magnitude for PFM (T1–T4 = 30 °C). T_g of porcelains increase with faster cooling rates.

Significance

Slow cooling appears to be especially important for all-ceramic crowns to prevent high magnitude thermal gradients, which could influence cracking and fracture of the porcelain.     

Direct Metal Laser Sintering: A Digitised Metal Casting Technology

Dental technology is undergoing advancements at a fast pace and technology is being imported from various other fields. One such imported technology is direct metal laser sintering technology for casting metal crowns. This article will discuss the process of laser sintering for making metal crowns and fixed partial dentures with a understanding of their pros and cons.