HIGH-SPEED DETECTION METHOD OF METALLIC ELEMENTS OF DENTAL RESTORATION FROM ALLERGY SUSPECTED PATIENTS BY X-RAY FLUORESCENCE ANALYSIS

为了诊断和治疗金属过敏，了解疑似患者修复体中的金属元素是至关重要的。本研究旨在证实一个假设，即尽管从患者口腔中采集的样本非常少，但微观x射线荧光分析可以快速提供有关金属元素的有效信息。样品是通过用折叠的研磨膜的尖角摩擦修复体来收集的。用显微镜x射线荧光设备（XGT-2700，堀场，日本）分析了角状斑点样样品，该设备产生直径0.1 mm的x射线束。常规分析最多需要8分钟，包括从患者口腔中采集样本，对样本进行充电，检测特征x射线，最后显示结果。根据对标准金薄膜x射线强度的测量得到的校准线，估计薄膜上的金样品量为几十纳克。在这种微弱的样品中，由于缺乏足够的信息深度，每个元素的灵敏度随着其特征x射线能量的增加而降低。为了纠正这种强度异常，在测量前用塑料薄膜覆盖研磨膜。对于典型的牙科合金，主要成分的评估值与制造值的偏差在几个百分点以内。此外，0.5%或更多的添加元素，如锌，可以检测到高可靠性。结果表明，牙体修复体金属元素高速检测方法对金属过敏诊断具有重要意义。

For diagnosis and treatment of metal allergy, it is essential to know the metallic elements composing the restorations in a suspected patient. This research aimed to confirm the hypothesis that microscopic X-ray fluorescence analysis can quickly provide effective information on the metallic elements, in spite of a very small amount of sample collected from the patient's mouth. The sample was collected by rubbing the restorations with the sharp corner of a folded lapping film. The sample like a spot at the corner was analyzed by a microscopic X-ray fluorescence equipment (XGT-2700, Horiba, Japan), which generates X-ray beam of 0.1 mm in diameter. Routine analysis took 8 minutes at most, including collection of the sample from the patient's mouth, charge of the sample, detection of the characteristic X-rays, and final display of the result. Based on the calibration line that was obtained by measuring X-ray intensity from standard gold films, the amount of gold sample on the film was estimated to be several tens nanogram. In the case of such a faint sample, the sensitivity for each element decreases with the increase of its characteristic X-ray energy because of the lack of sufficient information depth. To correct this intensity abnormality, the lapping film was covered with a plastic film before measurement. For typical dental alloys, main components were evaluated within a few percents deviation from the values indicated by manufacture. Furthermore, additive elements of 0.5 % or more, such as zinc, could be detected in high reliability. From these results, it is concluded that the high-speed detection method of metallic elements of dental restoration is very useful for diagnosis metal allergy.