POTENTIAL OF STANDARDLESS X-RAY FLUORESCENCE ANALYSIS OF ENDODONTIC REPAIR MATERIALS USING A PORTABLE SPECTROMETER IOANA SUCIU 1 , ELENA S. PREOTEASA 2 , BOGDAN DIMITRIU 1 , OANA AMZA 1 , PAULA PERLEA 1 , ANCA RADUCANU 1 , MIHAELA TANASE 1 , BOGDAN CONSTANTINESCU 3 , DANIELA STAN 3 , EUGEN A. PREOTEASA 3 1 “Carol Davila” Medical University, Faculty of Dentistry, Bucharest, Romania 2 Helident Ltd., Bucharest, Romania 3 Horia Hulubei Institute for Physics and Nuclear Engineering, Bucharest, Romania Received July 2, 2015 Using a portable spectrometer, we performed a preliminary standardless X-ray fluorescence (XRF) analysis of four endodontic repair materials. The potential of this simple and versatile method was evaluated in comparison with other more powerful techniques used previously. Thick target analysis of endodontic cements provided relative concentrations with an accuracy better than orders of magnitude. In addition to Ca and Fe, the spectra evidenced Zr and Bi as major elements and La and Au as minor elements. Zr, Bi, La and Au were embeded in the materials in order to make them more opaque to X-rays than the tooth. Probably, La and Au were sintered with ceramo-metallic glass microparticles. Zr was accompanied by its chemical analogue Hf. While XRF proved to be complementary to other methods, further studies of endodontic repair materials will be needed to follow the fate of Bi and La due to their significant chemical reactivity and low to moderate level of toxicity. Key words: XRF, portable spectrometer, standardless analysis, thick target, endodontic repair materials, MTA-based cements, dentistry. 1. INTRODUCTION Recently we evaluated the potential of X-ray fluorescence (XRF) with a portable spectrometer for the analysis of endodontic sealers [1] and orthodontic cements, including three glass-ionomer cements and a zinc-phosphate cement. The simple analytical technique used proved to be valuable and fruitful by unexpectedly evidencing W and Bi in the endodontic sealers [1] as well as Sr, La and Au in the substituted glass-ionomer cements together with the more common elements Ca and Fe in almost all analyzed materials. Rom. Journ. Phys., Vol. 60, Nos. 9–10, P. 1490–1500, Bucharest, 2015