Determining Trace Elements And Strontium Isotope In Teeth And Its Clinical Significance

As the important and trace element enrichment organ, tooth play the indicative role that can reveal diseases and poisoning for human body. Previous scholars both at home and abroad had a lot of researches about caries and trace element, they believed that trace elements may influence the occurrence, development and prognosis of dental decay process. In recent years, with appearance and development of high precision analysis instruments, trace element analysis technology constantly has been improved, the studies about tooth trace elements and caries have been more deeply. Inductively coupled plasma mass spectrometry (ICP-MS) has become the main method of tooth trace elements determination. At present there are no domestic reports using ICP-MS for analysis of trace elements in teeth and oral diseases, so this area needs the further research and development. Meanwhile, there also have been few reports about isotope analysis of dental caries both at home and abroad.In this present vitro study, ICP-MS and Thermal Ionization Mass Spectrometry(TIMS) as the basic research techniques, determined the content for trace elements in healthy tooth enamel from the Hui and Han ethnic groups in Xi’an and Strontium concentrations, isotope ratios in enamel of teeth in southern Shaanxi. At the same time, the study also investigated the remineralization effects of Sr element on demineralization of human enamel in vitro. The aim of the present study was to detect the content of trace elements and isotopes in the teeth, discuss the influences of trace elements and isotopes for dental decay, provide experiment information for clinical prevention and treatment of caries disease.Part1Determining Trace Elements in the Tooth Enamel from two Ethnic Groups using Microwave Digestion and ICP-MSAim To determine and compare the content for the trace elements Mg, Al, Mn, Fe, Cu, Zn, Ni, Sr, Cd, and Pb in healthy tooth enamel from the Hui and Han ethnic groups in Xi’an, China.Methodology Using microwave digestion and ICP-MS, this study accurately determined the content for trace elements, such as Mg, Al, Mn, Fe, Cu, Zn, Ni, Sr, Cd, and Pb, in healthy tooth enamel from these two groups.Results The results showed a significant difference (P<0.05) in the trace element Fe as well as the trace elements Al, Mn, Cu, Zn, Ni, Sr, Cd, and Pb (P<0.01). In healthy tooth enamel, the contents of the trace elements Cd, Ni, Mn, and Pb, which may promote or accelerate caries and its development, are higher in the Han than the Hui ethnic group. However, for healthy tooth enamel, the contents of the trace elements Cu, Fe, Zn, and Sr, which may prevent caries, are lower in the Han than the Hui ethnic group.Conclusion The hereditary factor and different habits for the Hui and Han ethnic groups in Xi’an, China may be the primary basis for the distinction in trace element content and dental caries incidence. Part2Isotopic Measurement of Sr in Carious Teeth of Enamel by Thermal Ionization Mass SpectrometryAim To determine isotope composition (87Sr/86Sr) of carious teeth, discuss its influence factors and clinical significance, provide experiment information for clinical prevention and treatment of caries disease.Methodology The carious teeth were collected from the southern Shaanxi area of China and completely dissolved with HNO3-HClO4mixed acid. The Sr in carious teeth of enamel was fast separated by Sr-Spec selective specific resin, and the Sr isotope was analyzed by IsoProbe-T thermal ionization mass spectrometry.Results The87Sr/86Sr ratios vary in the small range of0.710935-0.711034, and the isotope of Sr was similar when people lived in the same geological background. The87Sr/86Sr ratios of male teeth have slight fluctuations, from0.710935to0.711031.Conclusion The isotope of Sr was similar when people lived in the same geological background. The small change about87Sr/86Sr ratios of male teeth may be attributed to living environments and eating habits. Part3Strontium concentrations and isotope ratios in enamel of healthy and carious teeth in southern Shaanxi, ChinaAim As the trace element Sr plays a significant role in dental health, it is important to determine the Sr concentration and isotope composition (87Sr/86Sr) of teeth and whether these values are related to caries formation, age and sex.Methodology A total of160permanent teeth were collected from7-to79-year-old people from the southern Shaanxi area of China, including100healthy teeth and60carious teeth (men and women each accounted for half of the samples). The concentration and isotope composition of Sr elements in the dental enamel of the teeth were measured using inductively coupled plasma mass spectrometry (ICP-MS) and thermal ionization mass spectrometry (TIMS).Results A significantly lower Sr concentration was found in the enamel of the carious teeth than in that of the healthy teeth for individuals of varying ages and sex. The Sr concentration in human carious teeth ranged between79.70μg/g and85.80μg/g; while the Sr concentration in healthy teeth ranged between128μg/g and156.77μg/g. Our results also demonstrated that the87Sr/86Sr ratio did not appear to be affected by the caries formation, age or sex. The87Sr/86Sr ratio in the enamel of the healthy and carious teeth of individuals of varying ages and genders ranged between0.710935and0.711037, which falls into the range of87Sr/86Sr ratios found in the local, naturally occurring water, soils and rocks.Conclusion Sr plays a significant role in dental health, and there is a negative correlation between Sr and the occurrence of dental caries. The87Sr/86Sr ratio of teeth reflects the87Sr/86Sr ratio of the associated environment, and there is no significant relationship with the frequency of dental caries, age or sex. Part4The effect of different strontium concentrations on dental enamel demineralization in vitroAim The purpose of this study in vitro was to evaluate the effect of different strontium concentrations combining fluoride treatments on enamel demineralization and remineralization by investigating the variety of microhardness.Methodology The artificial caries model was made with acidulous gel. The demineralized enamel specimens were randomly divided into7groups, according to the Sr2+level (mg/L):0、10、50、100、150、200, deionized water as control. The micro hardness of specimens were detected after treatment.Results The microhardness of demineralized enamel specimens increased significantly after remineralization by solutions containing strontium and fluoride. Sr2+can improve microhardness of enamel surface at a lower value (100mg/L). When the value was higher than100mg/L, the Sr2+effect was even lower.Conclusion Solutions containing strontium and fluoride can enhance remineralization and inhibit demineralization. The degree of mineralization may be related to Sr concentration.