The Study of the Behaviors of Zinc and Strontium in Caries-Affected Teeth by Laser-Induced Breakdown Spectroscopy(LIBS) Technique

We report on the application of Laser Induced Breakdown Spectroscopy(LIBS)technique to the study of Ca,P,Zn and Sr evolutions for adult caries-affected teeth using nanosecond laser pulses.The aim of this work is to better understand the behaviors of Zn and Sr as trace-elements in the caries eruption with respect to the behaviors of one of the main compounds of the hydroxyapatite crystal which is the calcium.The study was focused on the investigation of these elements’evolutions from three parts of the enamel surfaces of twenty two adult caries-affected teeth;the healthy part,the dental plaque part and the caries-affected part.The decrease rates of Zn,Sr and P was,also,compared to the Ca one.Comparison concerned normalized emission line intensities.For every species,normalization was done relatively to the emission line intensities of the healthy part.Results showed that abundances of these elements decrease similarly from the healthy parts to the affected-caries parts.The higher decrease rate was noticed for the calcium.The evolutions of Zn and Sr for the three parts of the teeth surfaces cannot inform about the substitution of the calcium by these trace-elements,however the comparison of their decrease rates to the calcium one can be considered as a valuable index of this substitution.     

Structural features of human tooth tissues affected by high dose of external ionizing radiation after nuclear catastrophe of Chernobyl plant

The application of micro-Raman spectroscopy is discussed for the analysis of structural features of human tooth tissues affected by high doses of external ionizing radiation (0.5–1.7 Gy) after the nuclear plant catastrophe in Chernobyl in 1986. The results have shown significant changes in the mineral matrix of dental enamel that lead to the decrease of tooth enamel hardness. Destruction of the collagen chain of the organic matrix has been observed for dentin and cementum.     

牙釉质中稀土和微量元素的ICP-MS方法检测

主要研究应用电感耦合等离子体质谱法测定牙釉质中稀土和微量元素的实验方法。实验证明牙釉质样品经硝酸-过氧化氢体系消解,样品溶解完全,可以满足ICP-MS检测方法的要求。方法的精密度用相对标准偏差表示在0.50%～6.79%之间,方法准确度以标准回收率度量在94.45%～104.78%之间,完全能满足生物样品的测试要求。本实验为口腔医学研究提出一个简便、准确和可行的研究方法的同时,也为龋齿病防治提供了有龋齿和无龋齿中样品中稀土微量元素测试数据。     

Assessment of teeth elemental content using μ‐EDXRF: effects by in‐office and at‐home bleaching products

The purpose of this in vitro study is to assess whether the elemental content of tooth enamel is altered when bleaching the teeth with bleaching gel. Because of tooth bleaching growing popularity and to match the public demands, manufacturers increased the range of bleaching products available, changing its presentation, techniques and concentration of active principles. This way, two different bleaching products were compared, one for in‐office and another for domestic use. In order to perform this evaluation, sound vestibular surfaces of anterior healthy teeth, extracted for periodontal or orthodontic reasons, were treated with the bleaching products accordingly to manufacturer instructions. Spectra were acquired using the M4 Tornado μ‐XRF setup, and quantitative calculations were performed using fundamental parameter method to determine the elemental composition of the analyzed samples before and after treatment. No significant statistical differences in the mineral content of the analyzed teeth were obtained. Copyright © 2014 John Wiley & Sons, Ltd.     

Methylmercury determination in biological samples using electrothermal atomic absorption spectrometry after acid leaching extraction

An efficient and sensitive method for the determination of methylmercury in biological samples was developed based on acid leaching extraction of methylmercury into toluene. Methylmercury in the organic phase was determined by electrothermal atomic absorption spectrometry (ETAAS). The methylmercury signal was enhanced and the reproducibility increased by formation of certain complexes and addition of Pd-DDC modifier. The complex of methylmercury with DDC produced the optimum analytical signal in terms of sensitivity and reproducibility compared to complexes with dithizone, cysteine, 1,10-phenanthroline, and diethyldithiocarbamate. Method performance was optimized by modifying parameters such as temperature of mineralization, atomization, and gas flow rate. The limit of detection for methylmercury determination was 0.015 μg g⁻¹ and the RSD of the whole procedure was 12% for human teeth samples (n=5) and 15.8% for hair samples (n=5). The method’s accuracy was investigated by using NIES-13 and by spiking the samples with different amounts of methylmercury. The results were in good agreement with the certified values and the recoveries were 88–95%.     

Potentiometric measurement of ionic, acid-labile and covalently bound fluorine

Fluoride (F⁻) is the predominant chemical form of F in serum and bone, during administration of NaF as cariostatic agent or in the treatment of osteoporosis. In the treatment with sodium monofluorophosphate (MFP), F⁻, F bound to proteins by acid-labile linkage and non-volatile covalently bound F are detected. Only F⁻ is detectable with the ion-selective electrode. This paper describes a method for the measurement of non-volatile covalently bound F with the ion-selective electrode, which has a detection limit of 0.8 ± 0.6 nmol, within-run standard deviation of 7 nmol and a between-run standard deviation of 13 nmol at 100 nmol F and has a linear behaviour above 1 nmol. This paper also reports a methodology for the potentiometric measurement of F⁻, acid-labile F and covalently bound F in biological samples.     

ICP-AES法测定猪骨、猪牙中超微量稀土元素

利用P507萃淋树脂预富集分离技术,结合ICP－AES法测定猪骨、猪牙中超微量稀土元素La、Ce、Pr、Nd、Sm、Y。本法排除了基体中Ca、P的干扰,方法检出限为2．0－4．4ng/g,回收率为80％－90％,RSD为3．1％－9．1％,适用于市售猪体内稀土水平的检测。     

电感耦合等离子体-原子发射光谱法测定龋齿中微量元素

牙齿样品经HNO3-HClO4体系消解,采用电感耦合等离子体-原子发射光谱法(ICP-AES)测定龋齿和健康齿的牙釉质与牙本质中Zn、Fe、Cu、Sr、Mg、Cr、Al和Pb等微量元素。方法相对标准偏差在1.1%—2.7%之间,标准回收率在90.0%—106.7%之间。实验测得龋齿牙釉质与牙本质中Zn、Fe、Cu和Sr含量均明显低于健康齿,而Mg、Cr、Al和Pb含量则均高于健康齿,说明牙齿中的微量元素是指示龋病的一种因子。本实验为口腔医学研究提出了一个简单、准确和可行的研究方法,也为医院口腔科预防和治疗龋齿,提供参考数据。     

Application of potentiometric stripping analysis with constant inverse current for determining soluble lead in human teeth

A method for the determination of soluble lead in human teeth by potentiometric stripping analysis with constant inverse current in the analytic step (PSA-i_R), is described. The metal ions were concentrated as their amalgams on the glassy carbon surface of a working electrode that was previously coated with a thin mercury film and then stripped by a suitable oxidant. This paper examined effect of various factors on the PSA-i_R results including the electrolysis potential, the solution stirring rate, and the constant inverse current. Quantitative analysis was carried out by both standard addition and calibration curve methods; a good linearity was obtained in the concentration range from 5 to 25 μg/dm³. A detection limit of 0.64 μg/dm³ was obtained, with a 5.21% coefficient of variation. Results obtained for teeth were not significantly different from these obtained by flameless atomic absorption spectrophotometry (FAAS).     

An improved sample preparation for an LC method used in the age estimation based on aspartic acid racemization from human dentin

The determination of age on the basis of aspartic acid (Asp) racemization in teeth is one of the most reliable and accurate methods to date. In this paper, the usefulness of HPLC coupled with fluorescence detection for determination of Asp racemization was evaluated. A modified sample preparation is proposed for better stability of o-phthaldialdehyde-N-acetyl-L-cysteine derivatives of D/L-Asp (due to the instability below pH 7). To ensure the accuracy of the method, the validation parameters' specificity, precision, linearity, and LOD were determined. Three dentin samples of premolar teeth, extracted from living individuals (bucco-lingual longitudinal sections of 1 mm thickness), were analyzed and quantitative results are discussed.