Atomic force microscopy and energy dispersive X‐ray spectrophotometry analysis of reciprocating and continuous rotary nickel‐titanium instruments following root canal retreatment

The aim was to examine the effect of retreatment process on the surface roughness and nickel titanium (NiTi) composition of ProTaper Universal Retreatment (PTUR; consists of 3 files; D1, D2, D3) and WaveOne Gold (WOG) (primary) instruments. Twenty extracted mandibular molar teeth with severe curved (30–40°) mesial roots were selected and divided into two groups (n = 10) based on the instrument used for the removal of the root canal filling. Before and after using the instruments in two canals, they were subjected to atomic force microscopy (AFM) and energy dispersive X‐ray spectrophotometry (EDX) analysis. The EDX analysis data and roughness average (Ra) and root mean square (RMS) values were analyzed statistically using a one‐way analysis of variance and post hoc Tukey's test at the 5% significant level. There was no significant difference between the new and used D1 and D2 PTUR and WOG instruments in terms of the Ni composition (p > .05). The Ti contents of the used D2 and D3 PTUR instruments were lower those of the new instruments (p < .05). In both new and used instruments, PTUR and WOG have no difference in terms of Ra and RMS values. (p > .05). The Ra and RMS values of the PTUR and WOG systems significantly increased after removal of the root canal filling (p < .05). The use of PTUR and WOG instruments for removal of root canal filling in severely curved root canals affected the surface topography of the files. The NiTi composition of the WOG instruments was unaffected by the retreatment process.     

Micro‐Computed Tomography and Scanning Electron Microscopy Comparisons of Two Nickel–Titanium Rotary Root Canal Instruments Used With Reciprocating Motion

The single‐file root canal instrumentation technique using reciprocating motion has been gaining concern. Therefore, the purpose of this study was to compare the shaping ability of single ProTaper F2 file and WaveOne Primary file when they were used in the curved root canal with reciprocation motion and to investigate the durability of the file after use with a scanning electron microscopy (SEM). Changes in structure model index (SMI), root canal volume, curvature, surface area, and degree of transportation were measured from the cross‐sectional images of the prepared canals using the micro‐CT system with an isotropic resolution of 16 μm. Results showed that there were no differences in the changes of root canal volume, surface area, and SMI between the two file groups after the preparation (p > 0.05). The ProTaper group showed a curvature straightening value of 25.45 ± 12.51%, while the WaveOne group showed 27.30 ± 10.91%, and there was no statistically significant difference (p > 0.05). The transportation values between the two groups showed no significant differences (p > 0.05). SEM revealed that 60% of ProTaper files showed initiation of microcracks on the surface while those were detected on the only one WaveOne file. The single‐file technique using either WaveOne Primary or ProTaper F2 can be safely used under each reciprocating motion without creating an increased apical transportation in curved canals. However, the metallurgic property resists cyclic fatigue was more favorable with WaveOne under the scanning evaluation. SCANNING 35: 112‐118, 2013. © 2012 Wiley Periodicals, Inc.     

Evaluation of surface alterations in different retreatment nickel‐titanium files: AFM and SEM study

The aim of this study was to evaluate the surface changes of nickel titanium (Ni‐Ti) rotary retreatment files after three and five uses. Furthermore, the effects of 2% sodium hypochlorite and chloroform solutions and sterilization procedures on the NiTi rotary retreatment surfaces were investigated. ProTaper Retreatment files, R‐endo files, and Mtwo retreatment files were used for this study. The palatinal roots of maxillary molar teeth were obturated with gutta percha and Ah26. Retreatment procedures were performed with these retreatment file systems. The surface changes of untreated NiTi rotary files that were used three and five times, immersed in NaOCl and chloroform and subjected to sterilization procedures were investigated with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The RMS values, three dimensional images and SEM images at various magnifications were obtained. RMS values showed that all three NiTi rotary retreatment file systems showed significant deteriorations after three and five uses. Cracks, damages and spiral construction deteriorations were detected in the SEM images after three and five uses. Furthermore, the Mtwo 15 file was broken off after five uses. AFM data indicated that 2% NaOCl caused significant surface deteriorations on NiTi rotary files and both AFM and SEM evaluation showed that chloroform solution and sterilization procedures did not cause significant surface deteriorations. In conclusion, ProTaper retreatment, R‐endo, and Mtwo retreatment files showed surface damages depending on retreatment procedures. Clinicians have to consider that retreatment files always have a tendency to break off after the third time they have been used. Microsc. Res. Tech. 78:356–362, 2015. © 2015 Wiley Periodicals, Inc.     

Effects of irrigation solutions on the surface of protaper instruments: A microscopy study

The aim of this study was to evaluate the effects of sodium hypochlorite (NaOCl), chlorhexidine digluconate (CHX), and mixture of tetracycline, citric acid, and detergent (MTAD) solutions on the surfaces of nickel titanium (NiTi) rotary files with scanning electron microscopy (SEM) and atomic force microscopy (AFM). Irrigation solutions including 2.5% NaOCl, 5% NaOCl, 2% CHX, and MTAD were used. Four new ProTaper rotary NiTi files (F3) were immersed in each four irrigation solutions for 10 min, separately. One untreated NiTi file was used as a control specimen. The surface analysis was performed with SEM and AFM. The surface analysis in AFM was performed on 12 different regions located between first and second millimeters from the tip. SEM images were taken with different magnifications. No surface alteration was recorded under SEM evaluation. AFM revealed that the root mean square (RMS) values of all treated specimens were statistically higher than the control sample (P < 0.05). The sample which was treated with CHX showed lowest RMS values in test groups. All tested solutions caused surface alterations. CHX demonstrated limited surface alterations when compared to the other tested solutions. Microsc. Res. Tech. © 2012 Wiley Periodicals, Inc.     

Topographic characterization of unworn contact lenses assessed by atomic force microscopy and wavelet transform

This paper analyses the three‐dimensional (3‐D) surface morphology of optic surface of unworn contact lenses (CLs) using atomic force microscopy (AFM) and wavelet transform. Refractive powers of all lens samples were 2.50 diopters. Topographic images were acquired in contact mode in air‐conditioned medium (35% RH, 23°C). Topographic measurements were taken over a 5 µm × 5 µm area with 512 pixel resolution. Resonance frequency of the tip was 65 kHz. The 3‐D surface morphology of CL unworn samples revealed (3‐D) micro‐textured surfaces that can be analyzed using (AFM) and wavelet transform. AFM and wavelet transform are accurate and sensitive tools that may assist CL manufacturers in developing CLs with optimal surface characteristics. Microsc. Res. Tech. 78:1026–1031, 2015. © 2015 Wiley Periodicals, Inc.     

Cyclic fatigue resistance and energy dispersive X‐ray spectroscopy analysis of novel heat‐treated nickel–titanium instruments at body temperature

The aim of this study was to evaluate the cyclic fatigue resistance of Dia‐X, WaveOne Gold and One Curve files in a water bath at intracanal temperature (35°C). Thirty‐nine instruments Dia‐X, WaveOne Gold, and One Curve systems (n = 13) were tested in an artificial canal with a curvature angle of 60° and a radius of 3 mm. A water bath setup at a temperature of 35°C was used to simulate the intracanal temperature and time to fracture (TTF) as seconds was recorded. The mean data were analyzed statistically using one‐way ANOVA, and post hoc Tukey test (p = .05). The fractured surface of the instruments was examined with scanning electron microscopy (SEM) and chemical composition of the instruments were investigated with energy dispersive X‐ray spectroscopy (EDS). Statistically significant differences were detected in TTF values of all the systems as follows: One Curve > WaveOne Gold > Dia‐X (p < .05). One Curve instruments demonstrated the highest TTF values in all the tested instruments. The EDS microanalysis revealed similar NiTi composition of on the surface of One Curve, WaveOne Gold, and Dia‐X instruments. The novel manufacturing process, including C‐wire heat treatment and the variable cross‐section of the One Curve files, could be the main factors affecting the fatigue life of the instruments.     

A Novel Atomic Force Microscope with High Stability and Scan Speed

Abstract

A novel atomic force microscope (AFM) has been developed. Unlike conventional AFM systems, its cantilever and tip were set up in the X direction with respect to the sample. It can practically eliminate the crawling effect of the probe itself. Meanwhile, using a beam splitter, we devised a unique path optical beam deflection method for the measurement of the cantilever's displacement with its minimized structure and an optimal light‐amplifying ratio; the position of the sensitive detector (PSD) is just in front of the visual sight of operator. This makes observation and operation easier. Furthermore, the PSD attached to the translation stage can be adjusted and, thus, adapts the setpoint of imaging force to different samples. In this way, our new AFM provides high stability and scan speed. The highest scan rate is about 40 lines/s or 10s for a 400×400‐pixel, 3 µm×3 µm image.     

Surface roughness and filler particles characterization of resin‐based composites

The purpose of this study was to evaluate the surface roughness (Ra), and the morphology and composition of filler particles of different composites submitted to toothbrushing and water storage. Disc‐shaped specimens (15 mm × 2 mm) were made from five composites: two conventional (Z100?, and Filtek? Supreme Ultra Universal, 3M), one “quick‐cure” (Estelite ∑ Quick, Tokuyama), one fluoride‐releasing (Beautiful II, Shofu), and one self‐adhering (Vertise Flow, Kerr) composite. Samples were finished/polished using aluminum oxide discs (Sof‐Lex, 3M), and their surfaces were analyzed by profilometry (n = 5) and scanning electron microscopy (SEM; n = 3) at 1 week and after 30,000 toothbrushing cycles and 6‐month water storage. Ra data were analyzed by two‐way analysis of variance and Tukey's test (α = 0.05). Filler particles morphology and composition were analyzed by SEM and X‐ray dispersive energy spectroscopy, respectively. Finishing/polishing resulted in similar Ra for all the composites, while toothbrushing and water storage increased the Ra of all the tested materials, also changing their surface morphology. Beautifil II and Vertise Flow presented the highest Ra after toothbrushing and water storage. Filler particles were mainly composed of silicon, zirconium, aluminum, barium, and ytterbium. Size and morphology of fillers, and composition of the tested composites influenced their Ra when samples were submitted to toothbrushing and water storage.     

Micromorphological characterization of zinc/silver particle composite coatings

The aim of this study was to evaluate the three‐dimensional (3D) surface micromorphology of zinc/silver particles (Zn/AgPs) composite coatings with antibacterial activity prepared using an electrodeposition technique. These 3D nanostructures were investigated over square areas of 5 μm × 5 μm by atomic force microscopy (AFM), fractal, and wavelet analysis. The fractal analysis of 3D surface roughness revealed that (Zn/AgPs) composite coatings have fractal geometry. Triangulation method, based on the linear interpolation type, applied for AFM data was employed in order to characterise the surfaces topographically (in amplitude, spatial distribution and pattern of surface characteristics). The surface fractal dimension D_f, as well as height values distribution have been determined for the 3D nanostructure surfaces. Microsc. Res. Tech. 78:1082–1089, 2015. © 2015 The Authors published by Wiley Periodicals, Inc.     

Microtensile strength of resin cement bond to indirect composite treated by different output powers of Er:YAG laser

The study aimed to evaluate the effect of different output powers of Er:YAG laser on microtensile bonding strength of indirect composite to resin cements.36 indirect composite blocks (GC Gradia DA2, Japan) size 15 × 10 × 10 mm³ were constructed, and divided into 12 groups, as follows:G1: control group (no treatment); Groups G2 to G6: treated with Er:YAG laser (2,940 nm) in noncontact mode, frequency 20 Hz, pulse duration 470 µs, with output power ranging from 2W to 6W; Groups G7 sandblasting, Groups 8 to G12: as Groups G2 to G 6 with preparatory sandblasting. One specimen from each group was analyzed by SEM; each specimen was fixed to a specialized metal jig using cyanoacrylate (Mitreapel, Beta Kimya San. Ve TIC, Iran) and debonded under tension with a universal testing machine (Zwick, Germany) at a crosshead speed of 0.5 mm min^?1. Sandblasting and laser can improve bond strength above an energy level of 150 mJ. SEM evaluation of laser‐treated specimens showed irregularities and deep undercuts. T test analysis showed no significant difference between sandblasted and non‐sandblasted group, with laser output power of 0, 100, or 150 mJ (P = 0.666, P = 0.875, and P = 0.069); in the specimens irradiated with energy output of 200, 250, or 300 mJ, sandblasted specimens showed higher bond strength than non‐sandblasted ones. The results demonstrate that, in composite resin irradiated with laser at energy output of 200–300 mJ, sandblasting might be a suitable procedure to enhance bond strength of resin cement. Microsc. Res. Tech. 79:328–333, 2016. © 2016 Wiley Periodicals, Inc.     

Effects of Galla chinensis on the surface topography of initial enamel carious lesion: an atomic force microscopy study

To investigate the effect of Galla chinensis on the surface topography of initial enamel carious lesion, atomic force microscope (AFM) was used, and it was a new AFM application in enamel de‐/remineralization research. Bovine sound enamel slabs were demineralized to produce initial carious lesion in vitro. Then, the lesions were exposed to a pH‐cycling regime for 12 days. Each daily cycle included 4×1 min applications with one of three treatments: negative control group: deionized water; positive control group: 1 g/L aqueous solutions of NaF; experimental group: 4 g/L aqueous solutions of G. chinensis extract (GCE). The surface topography and roughness were investigated on the enamel slabs before and after pH‐cycling by AFM. 3D AFM images revealed the surface topographical changes of GCE‐treated enamel. Significant difference existed before and after the pH‐cycling among the groups. AFM offers a powerful tool for enamel de‐/remineralization research. The surface roughness results provide the evidences to remineralization of carious lesion, and indicate the potential of G. chinensis in promoting the remineralization. G. chinensis may become one more promising agent for caries prevention. SCANNING 31: 195–203, 2009. © 2010 Wiley Periodicals, Inc.     

Substrate influence on cell shape and cell mechanics: HepG2 cells spread on positively charged surfaces

A human hepatoma cell line (HepG2) was cultured on positively and negatively charged polyelectrolytes. Cell/surface adhesion and cell shape evolution were followed with quartz microbalance with dissipation (QCM‐D) and optical microscopy as a function of time, respectively. In particular, substrates coated with poly(ethyleneimine) (PEI) led to fast cell attachment and further spreading, with average maximum frequency Δf = 79 Hz and dissipation ΔD = 40 × 10^?6. On the contrary, no cell spreading was observed on poly(sodium‐4‐styrenesulfonate) (PSS), with Δf = 33 Hz and ΔD = 4.5 × 10^?6. Atomic force microscopy (AFM) was used to investigate the influence of cell shape on its mechanical properties. Considering the cells as an homogenous solid material, the corresponding elastic modulus was estimated using the Hertz model. The elastic modulus was calculated at the central part of the cell, and the average values obtained were 191 ± 14 Pa and 941 ± 58 Pa for cells adsorbed on PSS and PEI, respectively. Thus, different cell–substrate interaction implied different cell mechanical properties reflected in a higher elastic modulus for stronger cell/substrate interaction. The combination of QCM‐D, AFM, and optical microscopy allowed the online study of the cell adhesion process, and the mechanical properties of the adhered cells. Microsc. Res. Tech. 2009. © 2009 Wiley‐Liss, Inc.     

Two‐ and three‐dimensional profilometer assessments to determine titanium roughness

In this study, a comparative topography analysis of titanium (Ti) surfaces was performed using two‐ (2D) and three‐dimensional (3D) profilometers. Ti samples were either only sandblasted (SB) using Al₂O₃ particles or were SB and received an additional chemical treatment using a solution of 4% HF (SLA). Samples with no treatment were used as a control group (C). Therefore, three different surfaces were evaluated: SB, SLA and C. The Ti surface topographies were evaluated by scanning electron microscopy. An Ra roughness measurement was performed on each Ti sample by 2D and 3D profilometers. Surface roughness was also characterized using amplitude, spatial and hybrid 3D parameters. 2D and 3D profilometer analyses produced very close results. Mean Ra values range from 0.19 to 0.25 (C, p<0.05), 0.84 to 0.99 (SLA, p<0.05) and 0.98 to 1 µm (SB, p>0.05). The statistically different Ra values depending on the surface studied may be explained by methodological and technical differences. Also, 3D profilometer seems to be the more appropriate analytical method for measuring the roughness of Ti surfaces because it also describes surface organization. SCANNING 31: 174–179, 2009. © 2009 Wiley Periodicals, Inc.     

Ultrastructural effect of self-ligating bracket materials on stainless steel and superelastic NiTi wire surfaces

Frictional interactions between wires and brackets reduce the efficacy in orthodontic treatments. Self‐ligating brackets (SLBs) are now more often used due to lower frictional forces when compared with conventional‐ligating brackets. In this study, scanning electron microscopy and atomic force microscopy were used to examine the microstructural effects of stainless steel and ceramic SLBs on the surface roughness of stainless steel and superelastic NiTi wires both after in vivo clinical orthodontic treatment as well as in in vitro three‐point bending experiments. A combination of two wires—0.019 in. × 0.025 in. stainless steel wires and 0.016 in. superelastic NiTi wires—and two SLBs—both passive‐type stainless steel SLBs and active‐type ceramic SLBs—was applied for 4 months (bicuspid‐extraction) in an in vivo setting and for 1 month in an in vitro setting (200 g loads). After the SLB treatments, all wires exhibited severe scratches secondary to frictional interactions with the brackets. When used with the stainless steel SLBs (Damon 3MX®), the surfaces of 0.019 in. × 0.025 in. stainless steel (P < 0.0001) and 0.016 in. superelastic NiTi wires (P < 0.05) were significantly smoother than when used with the ceramic SLBs (Clippy‐C®). Such results suggest that orthodontic treatments with stainless steel SLBs are more effective than with ceramic SLBs. Microsc. Res. Tech. 75:1076–1083, 2012. © 2012 Wiley Periodicals, Inc.     

In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel

The present study aimed to evaluate in situ the effect of CO₂ laser irradiation to control the progression of enamel erosive lesions. Fifty‐six slabs of bovine incisors enamel (5 × 3 × 2.5 mm³) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO₂ laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO₂ laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2‐day lead‐in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross‐over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three‐way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO₂ laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO₂ laser irradiation was performed. There was no difference in enamel wear between specimens CO₂‐laser irradiated and non‐irradiated (P = 0.513). Under intraoral conditions, CO₂ laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. Microsc. Res. Tech. 77:586–593, 2014. © 2014 Wiley Periodicals, Inc.     

Rapid and Highly Sensitive Method for Protein Determination in Biological Samples with m‐Nitrophenylfluorone‐Mo(VI) Complex as a Spectral Probe

Abstract

A simple, rapid, highly sensitive, and selective method for detecting protein in biological samples has been developed, which is based on the interaction between protein and m‐nitrophenylfluorone‐Mo(VI) complex as a spectral probe. The optimum condition for the reaction is investigated. Bovine serum albumin (BSA) obeys Beer's law up to 10 µg · mL^?1, having a molar absorption coefficient of 8.51×10⁶ L · mol^?1 · cm^?1 at 535 nm. Many amino acids and metal ions do not interfere. The results of determination for biological samples are comparable to those obtained by the Bradford method. Meanwhile, the binding number is also determined.     

Microscopic analysis of the quality of obturation and physical properties of MTA Fillapex

This study analyzed the quality of obturation and physical properties of MTA Fillapex and AH Plus sealer. A sample of 30 human maxillary central incisors were instrumented with Protaper until a F5 (50/05) file. Both sealers were mixed with Rhodamine‐B dye to allow visualization on a confocal laser‐scanning microscope (CLSM). Next, the canals were filled using the single cone technique. After setting, all samples were sectioned at 2, 4, and 6 mm from the apex. CLSM was used to analyze the gaps and sealer penetration into the dentinal tubules. All samples were scanned 10 µm below the dentin surface and images were recorded at 100× magnification using the fluorescent mode. Additionally, the solubility, flowability and setting time of the sealers were evaluated. All the measured quantities of the examined materials were evaluated for significant differences by means of statistical analysis. The CLSM analysis of the MTA Fillapex showed the highest percentage of gaps at all sections (P = 0.0001). Physical tests revealed adequate properties for both sealers except for a higher solubility of the MTA Fillapex (P = 0.0001). The MTA Fillapex presented flowability and intratubular penetration similar to the AH Plus. Nevertheless, the MTA Fillapex sealer presented a higher solubility and considerable quantity of gaps between the sealer/dentin interface in relation to the AH Plus sealer. Clinicians must take into consideration, the quality of endodontic sealers as it is essential in the outcome of the root canal filling. Microsc. Res. Tech. 77:1031–1036, 2014. © 2014 Wiley Periodicals, Inc.     

Acute effects of splint immobilization of the forearm on in vivo microcirculation and histomorphology of the human skin

BACKGROUND: Splint immobilization of the forearm is often performed in clinical practice. Previous studies investigated the effect of immobilization on bone, cartilage, muscle, and tendon, however, the acute effects on human skin microcirculation and histomorphology remains elusive. METHODS: In 12 healthy, nonsmoking individuals (aged 29.7 ± 9.1 years) a randomly selected forearm was immobilized by splinting for 72 h, whereas the other forearm served as control. In vivo Reflectance‐Mode Confocal‐Microscopy (RMCM) was performed prior (baseline value) and postimmobilization to evaluate: quantitative blood cell flow; density of functional dermal capillaries; epidermal thickness; and granular cell size. RESULTS: At 72h forearm immobilization, quantitative blood cell flow was significantly reduced (42.86 ± 3.68 cells/min) compared to the control blood flow (53.11 ± 3.68 cells/min, P < 0.05) and dermal capillaries indicates less functional density (5.73 ± 0.63 capillaries/mm²) compared to the controls (7.04 ± 0.81 capillaries/mm², P < 0.05). Histometric assessment reveals significantly thinner epidermis following immobilization compared to the control site (40.02 ± 2.91 vs. 46.64±3.09 µm, P < 0.05). Granular cell size was significantly altered at 72 h splinting (730.1 ± 42.53 µm²) compared to the control cell size at 770.2 ± 38.21 µm². Comparison of baseline values of both forearms indicate statistically insignificance (P > 0.05) for each parameter. CONCLUSION: At 72 h splint immobilization, for the first time, significant adaptive mechanisms were evaluated on human skin microcirculation and histomorphology using in vivo RMCM. These adaptations may be considered as an incipient atrophy of the human skin. Long‐term effects of immobilization including the regenerative potential should be evaluated in further RMCM studies. Microsc. Res. Tech. 77:99–103, 2014. © 2013 Wiley Periodicals, Inc.     

Morphological investigation of various orthodontic lingual bracket slots using scanning electron microscopy and atomic force microscopy

Various labial and lingual orthodontic appliances with aesthetic materials have been developed due to an increased demand in aesthetic orthodontic treatment. However, there are few reports regarding the morphology of lingual orthodontic appliances. Therefore, this study evaluates the roughness of slot surfaces of various orthodontic lingual brackets using field emission scanning electron microscopy (FE‐SEM) and atomic force microscopy (AFM). Three types of stainless steel lingual brackets (Stealth^®, 7th Generation^®, and Clippy L^®) and one gold lingual bracket (Incognito?) with a slot size of 0.018 inches × 0.025 inches (0.457 × 0.635 mm²) were selected as representative lingual materials. Both FE‐SEM and AFM examinations showed that the Stealth^® and Clippy L^® brackets had the lowest surface roughness, while the 7th Generation^® bracket had the highest surface roughness. There was a significant difference in surface morphology between the types of lingual brackets, even when composed of the same material. The surface roughness of the bracket slot was dependent on the manufacturing process or surface polishing process rather than the fundamental properties of the bracket materials. There was no significant difference in the mean surface roughness of the slot floor between gold and stainless steel lingual brackets. These findings suggest that, although the gold lingual bracket is very expensive, it has great potential for use in patients with nickel allergy.     

Simultaneous Determination of Six Trace Elements in Plant Medicines by Derivative Adsorption Waves in Conjunction with a Microwave Technique

Abstract

Complex adsorption waves of Cu(II), Pb(II), Cd(II), Ni(II), Co(II), and Zn(II) in substrate solution (pH=9.26) of diacetyldioxime‐ammonia‐ammonium chloride‐sodium citrate‐gelatin‐sodium sulfite were studied and a new method for determination of the six trace elements in aqueous solutions was developed. The results show that there are sensitive adsorption waves of Cu(II), Pb(II), Cd(II), Ni(II), Co(II), and Zn(II) complexes at about ?0.45, ?0.61,?0.78, ?1.07, ?1.23, and ?1.38 V, respectively. The method is easy to operate and is able to determine these trace elements in aqueous solutions rapidly and simultaneously. When the signal‐to‐noise ratio equals 3, the detection limits of copper, lead, cadmium, nickel, cobalt, and zinc are 3.2×10^?4, 4.8×10^?3, 1.9×10^?3, 1.7×10^?5, 2.1×10^?6, and 1.0×10^?3 µg/cm³. Good linear relationships exist between the concentrations and the current peaks when copper, lead, cadmium, nickel, cobalt, and zinc concentrations are within 6.5×10^?4～10⁰, 9.3×10^?3～10, 4.1×10^?3～10, 3.2×10^?5～10^?1, 4.0×10^?6～10^?2, and 2.1×10^?3～10 µg/cm³, respectively. In conjunction with a microwave assimilation technique, the method has been used in the rapid and simultaneous determination of these trace elements in some plant medicines with satisfactory results.