Beam time request February 2010 Eugen A. Preoteasa DFVM Necessary beamtime: 6 x 24 h

IBA studies on biomineral structures A 10 year old program of studies on: teeth, bones, dental materials and drugs. IBA methods: PIXE, PIGE, ERDA, m-PIXE on thick samples. GUPIX and LEONE analysis of spectra. Complementary methods: FTIR, AFM, optical microscopy, histochemistry, electrochemistry. A large diversity of topics, problems, approaches. Some studies require biological statistics to account for individual variability -> a large number of measurements and long time are necessary. Planning – short, medium, long term is useful. 8 articles in X-Ray Spectrom., NIM-B, Rom. Rep. Phys. 14 citations.

Long term - More remote future Reference materials – improvement of accuracy, precision, sensitivity, reproducivity in PIXE of teeth and dental composites – Different standard samples preparation and characterization by optical microscopy and AFM – H-parameter refinement for GUPIX analysis – Correlation to matrix structure. Sensitive PIGE analysis of F in teeth using a large NaI crystal  scintilation detector.

Medium-term future Influence of cumulated charge-dependent alteration of dental composites on PIXE analysed concentrations. – A simple remote-control (electric switch) of the beam blocker, operated directly by the experimentalist (instead of the technician) is needed. – An improved charge measurement system is desirable. PIXE study of Sn incorporation in enamel from SnF 2 -containing toothpaste. – Sensitive detection is needed – thick target PIXE of Sn: LDL ~325 ppm.

Short-term planning – to be continued also for longer term periods Iodine in preparations for pregnant women. PIXE of trace elements from dental cementum in periodontal disease and diabetes. PIXE of metal contamination from dental alloys (of crowns, bridges and dowels) in calculi, cementum and enamel. PIXE of dental calculi – contamination of medical, occupational and environmental origin. Dental alloys analysis. Variable angle PIXE of dental composites – preliminary measurements.

Iodine in two preparations for pregnant women Two preparations. Do they contain the nominal I level? I is hard to analyze by PIXE – LDL ~ 170 ppm in thick samples. Suggestion: Preparation of soluble extracts + thin layer PIXE. Lack of I may cause mental retardation in newborns children.

PIXE of trace elements from dental cementum in periodontal disease Periodontal disease (periodontitis) - inflammation of gums; collagen, ligaments and bone affected; teeth fall out; risk of heart, respiratory, nutritional disease and diabetes. Calcium absorption in teeth from the gut is decreased. Tooth cementum is in direct contact with gum. Are P/Ca, Zn, Fe changed in cementum?

PIXE of metal contamination from dental alloys in dental tissues Non-biological metals used in dentistry: – Amalgam fillings: Hg, Ag. – Composite fillings: Yb, Zr, Ba, Sr. – Implants: Ti. – Bridges, crowns, dowels: Au, Pt, Ir, Pd, Cu, Co, Ni, Mn. Enamel, dentin, cementum, mucosa – and dental calculi – may be contaminated with dental metals. Calculi – noninvasive, easy sampling/removal. Calculi – also possible contamination of medical, environmental, ocupational, nutritional origin.

Example of dental calculus contamination with metals Dental alloy – Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As/Pb. It is nor Palliag (no Pd and Ag), neither Pallidor (no Pdand Au) – it may be Gaudent alloy (Al , Ni 3-4, Fe , Mn , Cu %). Contaminated dental calculus – Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, As/Pb. Almost all alloy metals were found in the calculus.

Extra-dental contamination from dowels of a root-crown restoration PIXE analysis of samples around a root-crown-bridge restoration used for 35 years, which required a reattachment due to erosion of the dowel-fixing cement. Bridge - gold alloy (Au 83, Ag 6-7, Cu 9-11 %, Pb traces). Dowel - Gaudent alloy (Al , Ni 3-4, Fe , Mn , Cu %). Samples: mucosa, two calculi, a small fragment of gold. Samples on carbon disks, 3 MeV protons PIXE, Si(Li) detect.

Mucosa - Cu, Mn, Fe; traces of Ti, V, Cr, Pb. Cu, Mn, Fe complexes catalyze the production of noxious reactive oxygen radicals - toxicity risk! Both calculi – Cu, Mn, Fe. Different additional compositions: one – P, Ca, Zn, Sr traces; other – Si, S, Cl, Ca, Zn – calculi of different chemical nature (Ca phosphate vs. Ca chloro-sulfo-silicate?). No trace of Au and Ag in the mucosa and calculi – gold alloy chemically inert. Gold alloy contaminated with Mn and Fe. Dentistry-relevant conclusions: Cu, Mn, Fe dissolved by dowel corrosion diffused through the dentinal tubuli outside, and deposited partially in the oral surroundings. No contamination from gold alloy. PIXE evidenced oral contamination beyond dental root surface.