SummaryHuman tissues contain many kinds of minerals and trace essential elements that act as catalytic or structural components of large biochemical molecules. In addition, various metallic and inorganic materials are used in dental and medical materials and devices. In the dental and medical fields, specimens that are wet and/or have low heat resistance are often requested for elemental analysis. Therefore, a rapid and non-destructive method of elemental analysis is required. X-ray fluorescence analysis (XRF) provides useful elemental information about specimens without causing specimen damage or requiring extra specimen preparations.In this paper, an outline of the XRF apparatus and applications of XRF to hard and soft dental and medical specimen tissues are presented, and dental materials are reviewed

Teeth clenching during exercise is important for sports performance and health. Recently, several mouth guard (MG)-type wearable devices for exercise were studied because they do not disrupt the exercise. In this study, we developed a wearable MG device with force sensors on both sides of the maxillary first molars to monitor teeth clenching. The force sensor output increased linearly up to 70 N. In four simple occlusion tests, the trends exhibited by the outputs of the MG sensor were consistent with those of an electromyogram (EMG), and the MG device featured sufficient temporal resolution to measure the timing of teeth clenching. When the jaw moved, the MG sensor outputs depended on the sensor position. The MG sensor output from the teeth-grinding test agreed with the video-motion analysis results. It was comparatively difficult to use the EMG because it contained a significant noise level. Finally, the usefulness of the MG sensor was confirmed through an exercise tolerance test. This study indicated that the developed wearable MG device is useful for monitoring clenching timing and duration, and the degree of clenching during exercise, which can contribute to explaining the relationship between teeth clenching and sports performance.

Na-incorporated Cu(In1−xGax)3Se5(Cu(In1−xGax)3Se5:Na) films were prepared by the deposition of Cu(In1−xGax)3Se5 layers on Na2S-coated substrates. Electrical properties of the Cu(In1−xGax)3Se5:Na films were evaluated by I–V and spectral response measurements of devices with an ITO/ZnO/CdS/Cu(In1−xGax)3Se5:Na/Mo/glass structure. The Cu(In1−xGax)3Se5:Na films with x>0 showed p-type conduction, whereas for Cu(In1−xGax)3Se5 without the addition of Na2S, films with x<0.3 showed n-type conduction. The addition of Na was found to have a strong influence on the electrical properties of Cu(In1−xGax)3Se5 films as well as Cu(In1−xGax)Se2 films.

Oral lichen planus (OLP) and oral lichenoid contact lesions (OLCL) are chronic inflammatory mucocutaneous reactions with a risk of malignant transformation that alter the epithelium. OLP and OLCL have similar clinical and histopathological features and it is difficult to distinguish one from the other. Metallic restorations are suspected to generate OLCLs. Trace metal analysis of OLCL specimens may facilitate the discrimination of symptoms and identification of causative metallic restorations. The purpose of this study was to assess OLCL tissue samples for the prevalence of metallic elements derived from dental restorations, and to discriminate OLCL from OLP by using synchrotron radiation-excited X-ray fluorescence analysis (SR-XRF), particle-induced X-ray emission (PIXE), and X-ray absorption fine structure (XAFS). Typical elements of dental materials were detected in the OLCL, whereas no obvious element accumulation was detected in OLP and negative control specimens. The origin of the detected metallic elements was presumed to be dental alloys through erosion. Therefore, our findings support the feasibility of providing supporting information to distinguish OLCL from OLP by using elemental analysis.

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