Waterproof Abrasive Paper Research Articles

Effects of Different Chemical Disinfectants on Physical Properties of Denture Base Acrylic Resin Material

Statement of the problem: There is still a lack of data regarding the effects of exposure to different chemical disinfectants on the color stability, light translucency, and surface roughness of dentures is limited. Objective: This study aims to investigate the impact of six different chemical disinfectants on the color change, translucency, and surface roughness properties of heat-polymerized denture base acrylic resin. Material & Methods: Totally 70 rectangular blocks (10×10×2 mm) were polymerized from the heat-polymerized acrylic denture base resin material. The surfaces of the specimens polished with 600- and 1200-grit waterproof abrasive paper. Each specimen were immersed in six denture cleansers. The total immersion time of a specimen in selected chemical disinfectant was 36 hours. Color changes, translucency and, surface roughness were measured after immersion process. The results were statistically analyzed with 1-way ANOVA and the Tukey honestly significant difference (HSD) test (α=.05). Results: According to the results of the 1-way ANOVA test, significant differences were observed in the ∆E00, TP00 and Ra properties among the acrylic resin groups following immersion in chemical disinfectants (P<0.05). ΔE00 value of the CG group was significantly higher than that of the NS, SH, G, and E groups (P<0.05). The TP00 values of the NS and G groups were demonstrated significant differences compared with C group (P<0.05). The Ra values of the SH, SP, G, CG and, E groups were significantly increased after immersion process, in comparison with C and NS groups (P<0.05). Conclusions: Color stability, translucency and surface roughness of the denture base heat polymerized acrylic resin is influenced by chemical disinfectants.

Optimisation of testing parameters on two-body abrasive wear behaviour of nano-oMMT filled carbon-epoxy composites based on the Taguchi method

Two-body abrasive wear behaviour of carbon fabric reinforced epoxy (C-E) composites and nanosized organo modified montmorillonite (oMMT) particles dispersed C-E hybrid composites was investigated. Abrasive wear tests were carried out using a pin-on-disc machine under multi-pass condition. Silicon carbide (SiC) waterproof abrasive papers of different particle sizes were used under dry abrasion conditions. The influence of tribological parameters like applied normal load, abrading distance, filler loading and particle size of the SiC abrasives on the wear volume was investigated. Routine experimental results indicate that the wear volume depends on wt % of oMMT loading and the specific wear rate decreases with increase of abrading distance and increases with increasing load for all the composites. The scanning electron microscopy pictures indicate the reasons for failure of composites and influencing parameters. The orthogonal array, signal-to-noise ratio and analysis of variance were employed to study the optimal testing parameters on oMMT filled carbon-epoxy composites with 20 µm and 40 µm SiC particle sizes. The experimental results demonstrate that the abrading distance was the major parameter on abrasive wear, followed by filler loading and applied normal load. The particle size of SiC, however, was found to have a neglecting effect. Moreover, the optimal combination of the testing parameters could be predicted. Regression analysis was used to arrive at a mathematical model to predict the wear volume in terms of tribological parameters. The predicted wear volume of the composites was found to lie close to the experimental values.

Effect of surface roughness on plasticity of Zr52.5Cu17.9Ni14.6Al10Ti5 bulk metallic glass

Zr52.5Cu17.9Ni14.6Al10Ti5 (Vit105) bulk metallic glass (BMG) rods were abraded to different surface roughnesses using different types of waterproof abrasive papers and sometimes polishing pastes, and the compressive deformation behavior was examined. The results show that the yield strength of the BMG is hardly affected while the compressive plasticity increases from 2.3% to 4.5% with decreasing the surface roughness. Observation of the fractured samples under a scanning electron microscope indicates that the rise in plasticity is accompanied with an increase in shear band density. The results suggest that it is necessary to reduce the surface roughness of BMGs for achieving a large plasticity.

損耗したEr:YAGレーザー用石英ファイバーチップの再利用の試み

The output energy of quartz-fiber tips for an Er:YAG laser reduces with repeated or inappropriate handling during cavity preparation. The aim of this study was to find the best way to reuse a damaged tip for an Er:YAG laser. An amputated surface of a tip was produced by using the following: group 1 (G1): diamond disk; group 2 (G2): carborundum point; group 3 (G3): waterproof abrasive paper; group 4 (G4): ceramic scissors. An unused new tip was used as a control. The amputated tip surface was observed under a scanning microscope. G3 showed a relatively flat surface compared to G1, 2, and 4, which showed a rough and irregular surface. By analysis using a power meter, although G1 and 2 showed a large reduction of the output energy, G3 and 4 showed slightly lower energy than the control. In addition, the ablated cavity of a bovine dentine plate irradiated for 10 s with each tip was evaluated using a laser microscope. G1, 2, and 4 showed significant reduction of the ablation rate, whereas G3 showed no significant difference. These results suggest that among these four methods, waterproof abrasive paper might recover, to some extent, the tip surface morphology, output energy, and ablation rate.

メタケイ酸ナトリウム‐ｏ‐クレゾール‐４‐スルホン酸水溶液におけるマグネシウムの陽極酸化

Anodizing of magnesium was studied in sodium metasilicate with ortho-Cresol-4-sulfonic acid aqueous solution. A gray-colored anodic oxide film was obtained in 3.0mol·dm−3 sodium metasilicate-0.25mol·dm−3 o-Cresol-4-sulfonic acid aqueous solution at constant current density of 1000A·m−2 for 6.0×105C·m−2 at 278K. This film mainly consisted of magnesium, silicon, and oxygen and contained small amounts of carbon and sulfur. In the wear test using #800 SiC waterproof abrasive paper, this anodic oxide film showed almost the same wear resistance as that obtained in 2.0mol·dm−3 sodium metasilicate aqueous solution. However, in 0.86mol·dm−3 NaCl solution at 308K, the former without sealing showed higher corrosion resistance than the latter with sealing. Moreover, its corrosion resistance was further improved by the sealing treatment in boiling distilled water.

Titanium Surface Roughness Accelerates RANKL-dependent Differentiation in the Osteoclast Precursor Cell Line, RAW264.7

The present study was a molecular analysis of the initial differentiation of osteoclast precursor RAW264.7 cells on titanium specimens. RAW264.7 cell line was cultured on titanium specimens of which the surfaces were finished by wet grinding with 2000-, 1200-, 600-, or 180-grit waterproof abrasive paper. Total RNA was extracted from cells cultured in the presence or absence of Receptor Activator of NF-kappaB Ligand (RANKL), prior to cDNA synthesis for real-time quantitative reverse transcriptase-polymerase chain reaction analysis. Titanium surfaces initially enhanced the expression of osteoclast differentiation markers including tartrate-resistant acid phosphatase and cathepsin K in RAW264.7 cells cultured with RANKL stimulation, in a roughness-dependent manner. The mRNA expressions of both RANKL receptor, RANK, and its adapter protein TNF receptor-associated factor 6 (TRAF6) increased when RAW264.7 cells were cultured on titanium specimens with roughened surfaces, as compared with that of control specimen with a polished surface. These results, taken together, suggested that titanium surface roughness facilitated osteoclast differentiation through the activation of the RANK-TRAF6 signaling network.

コバルトクロム合金鋳造床のバレル研磨―研磨材と研磨時間に関する基礎的研究―

This study was designed to establish the optimum grinding condition of barrel finishing for cobalt-chromium alloy. Smoothing of the mucosal surface, reduction of labor, and improvement of the working environment were estimated by the application of barrel finishing to cobalt-chromium alloy. Tabular test pieces cast in cobalt-chromium alloy whose surface was standardized by waterproof abrasive papers were used in this study with a centrifugal flow barrel finishing machine. The abrasive that was most suitable for the primary polishing was selected, and proper polishing time was then decided by measuring the surface roughness of the test pieces. The abrasive and polishing time for the secondary polishing were decided in the same manner. Finally, the surface texture of the test pieces, which were finished in this condition by the manufacturer's instruction or by the electrolytic polishing method, were compared. Statistic analysis was performed by one-way analysis of variance and the multiple comparison test. A triangular prism-shape abrasive made of Al(2)O(3) and SiO(2) whose one side or height was 6 mm was selected for the primary polishing, and the same kind of abrasive with one side or height of 4 mm was chosen for the secondary one. The optimum polishing time for the primary polishing and the secondary polishing were 60 minutes and 40 minutes, respectively. The surface roughness of the test pieces that were finished in this condition was significantly smaller than that finished following the manufacturer's indication or that finished by the electrolytic polishing method. The optimum polishing condition of barrel finishing for cobalt-chromium alloy was established in this study. For the polished surface of cast dentures, polishing by a rotary cutting instrument after barrel finishing in this condition would be needed, as no luster was observed on the finished surface.

Experimental Relationships between Surface Roughness, Glossiness and Color of Chromatic Colored Metals

This paper describes the establishment of an evaluation method for metal surface texture. The evaluation parameters used for surface texture were roughness, glossiness and color. Seven sample materials were studied: aluminum alloys (A2017, A5052), stainless steel (SUS304) and copper alloys (tough pitch copper C 1100, brass C2801, phosphor bronze C5191 and nickel silver C7541). The surfaces of all specimens were polished using waterproof abrasive papers. The correlation of the surface texture parameters for all specimens was investigated experimentally. The surface roughness of specimens was evaluated using the arithmetical mean roughness Ra. The method for evaluating surface color was assessed by using CIELAB color space. The CIELAB color space is one of a uniform color space defined by CIE (Commission Internationale de l'Eclairage) in 1976. The results indicated that as surface roughness value Ra decreased, as the glossiness value Gs(60°) increased exponentially. The lightness value L* of the CIELAB color space decreased, as surface roughness value Ra decreased. Thus, the relationship between the lightness value L* and surface roughness value Ra showed an inverse correlation with the glossiness value Gs(60°) and surface roughness value Ra. Moreover, the surface color showed that the blue hue increased, as the surface roughness value Ra decreased for all seven types of materials.

アルミニウム合金の表面色によるテクスチャ評価方法

In this paper, we carried out an experimental research for establishing the evaluation of metal's surface texture by analysis of surface color. The materials of samples used in the experiment were aluminum alloys (A2017, A5052), stainless steel (SUS304) and copper alloy (nickel silver C7541). The surfaces of samples were burnished by use of waterproof abrasive papers. The surface roughness of samples evaluated by arithmetical mean Ra, root mean square slope RΔq and mean width of the profile elements RSm. The experimental results showed strong correlation for three different roughness parameters. Consequently, “Ra” was used as roughness parameter. As Ra decreased, the glossiness exponentially increased. The evaluation method of surface color was applied to CIELAB. The lightness L* in CIELAB decreased as Ra decreased. Thus, it showed that relationship between L* and Ra inverse correlation between glossiness and Ra. Moreover, surface color of four different materials showed that the chromaticness of blue increased as Ra decreased.

Scanning Tunneling Microscopic Observation of the Surface Topography of Metallographic Specimens

In this paper, surface topographies of metallographic specimens after having been ground by 1000# waterproof abrasive paper, polished mechanically, and polished electrochemically, were investigated by scanning tunneling microscopy. The undulations were compared with those caused by the surface relief effects associated with martensite in a Cu-28.3Zn-3.3A1 alloy and Widmanstätten ferrite in an Fe-0.37C (wt.%) alloy. The results indicate that the height of the surface reliefs is one order larger than that of specimen after having been polished mechanically and is two orders larger than that of specimen after having been polished electrochemically. Therefore, a scanning tunneling microscopic quantitative study on the surface relief effects is feasible and believable, if metallographic specimens are carefully prepared.

ポ−セリンの光沢度と色調に及ぼす表面仕上げの影響

An experiment using a gloss meter and a spectrophotometer was performed to elucidate the effects of surface texture on the glossiness and color stability of porcelains. Opaque porcelain (opaque), body porcelain (body), incisal porcelain (incisal) were used, and the effects of surface texture obtained by finishing with #150, #600, #2000 waterproof abrasive paper and by puff polishing with colloidalsilica having a particle size of 0.06 μm on glossiness and color stability were determined. The following conclusions were reached.1. The golssiness of the porcelain varied among opaque, body, and incisal, and increased as the surface texture became finer.2. As to the color stability of porcelains with surface texture obtained by various methods, L* and b* were the highest in opaque, followed by body, and then incisal, but no significant differences were noted for a*.3. As for the color stability of porcelain, L* decreased and b* increasedas the surface texture became finer in opaque, body, and incisal, but no significant differences were observed for a*.

Evaluation of a resin-reinforced glass ionomer cement for use as an orthodontic bonding agent.

A resin-reinforced glass ionomer cement, distributed commercially as "Fuji Ortho" (FO), has recently been developed for orthodontic bracket bonding procedures. The purposes of this study were to determine the tensile and shear bond strength of FO, to measure the amount of cement remaining on the enamel after bracket removal, and to evaluate the effects of experimental strain on the enamel surface. SEM evaluation demonstrated that polishing with 2400-grit waterproof abrasive paper followed by treatment with polyacrylic acid produced a smooth enamel surface without debris. No significant differences were seen in bond strengths between 24 hours and thermal cycling. Tensile and shear strengths of FO were significantly higher after thermal cycling than with conventional glass ionomer cement, at 3.4 +/- 0.7 MPa and 17.9 +/- 4.5 MPa, respectively. The adhesive Remant Index (ARI) indicated that FO adhered firmly to the unetched enamel surface and its scores showed 2 to 3 after thermal cycling. Results of this investigation suggest that FO may serve as an advantageous alternative to composite resin for the bonding of orthodontic brackets.

４‐ＭＥＴＡ／ＭＭＡ‐ＴＢＢ系接着剤の接着強さに及ぼす架橋剤の影響

A cross-linking agent was added to increase the bonding strength of Superbond C & B by improving its cohesiveness. PMMA powder, which was copolymerized with 0.5% (w/w) neopentylglycol dimethacrylate as a cross-linking agent, was used for the preparation of Superbond C & B. The bonding of Superbond C & B to which the cross-linking agent had been added was then examined by the pull-out test using an alloy with different levels of surface roughness prepared by two surface-processing methods (polishing with #600 waterproof abrasive paper or 50 microns sandblast processing). The results were as follows: 1. Superbond C & B had a bonding strength of 205 kgf/cm2 after polish processing of the alloy with #600 waterproof abrasive paper and 199 kgf/cm2 after 50 microns sandblast processing. The t-test showed no significant difference between the two types of processing. 2. Superbond C & B to which the cross-linking agent had been added showed a bonding strength of 285 kgf/cm2 in the material processed with #600 waterproof abrasive paper and 347 kgf/cm2 in that processed with 50 microns sandblast processing. 3. Among various combinations of bonding agents and surface processing methods, the combination of Superbond C & B with the cross-linking agent and 50 microns sandblast processing showed the highest values under all conditions.

Interpretation of Tests for Resistance to Abrasion of Textiles

The resistance to abrasion of sixteen cotton fabrics, which varied systematically in warp and filling yarn number and in ends and picks, was determined with the Schiefer abrasion testing machine, using No. 600A silicon carbide waterproof abrasive paper as the abradant and a total load of 2 lbs. on the specimen in one testing procedure, and a blade abradant and a total load of 20 lbs. on the specimen in a second testing procedure. The rate of abrasion in the first testing procedure was over ten times as great as that in the second. The results for the testing proce dures could be represented very well by the following equations: where R is the number of rotations of the abradant, W is the warp yarn number, F is the filling yarn number, E is the ends per inch, P is the picks per inch, and the other quantities are con stants. It was found that the rankings of the sixteen fabrics were different for the two testing procedures. This difference is due mainly to the fact that a given change in any one construc tion factor does not always result in quantitatively comparable changes in the resistance to abrasion obtained by the two procedures. This sort of difference is obtained, and should be expected, when comparing results of highly accelerated laboratory abrasion tests with results of comparatively slow rates of wear in service or performance tests. The resistance to abrasion of eight other fabrics of intermediate constructions obtained with each abradant agreed very well with the values computed by using the above two equations.