THE DEMINERALIZATION IMPACT ON MORPHOLOGY AND COMPOSITION OF TOOTH HARD TISSUES Alexey A. Selifonov,1,2 Yulia S. Skibina,1,3 Daria K. Tuchina,1,4 Andrey M. Zakharevich,1 Valery V. Tuchin1,4,5 1, Saratov State University (National Research University of Russia), 83 Astrakhanskaya str., Saratov 410012, Russia 2, Saratov State Medical University, 112 B Kazachaya str., Saratov 410012, Russia 3, LLC SPE “Nanostructed Glass Technology”, 101 Avenue 50 let Oktyabrya (P. O. Box 2985), Saratov 410033, Russia 4,Tomsk State University (National Research University of Russia), 36 Lenin’s av., 634050 Tomsk, Russia 5, Precision Mechanics and Control Institute of the Russian Academy of Sciences, 24 Rabochaya, 410028 Saratov, Russia

X-ray fluorometer Innov X-5000 with a silicon detector GOAL ● To study microelement structure of human teeth before and after demineralization by orthophosphoric acid ●To study morphology of enamel and dentine of human teeth before and after demineralization ● To measure spectrum of diffuse reflection (SDR) of enamel and dentine of human teeth MATERIALS AND METHODS The Scanning Electronic Microscope (SEM) Tescan Mira II LMU in the detecting mode of secondary electrons (SE) at the accelerating voltage of 30 kV and pressure in the camera ≈ (5.0-6.0)10–2 Pa X-ray fluorometer Innov X-5000 with a silicon detector Spectrophotometer SHIMADZU UV-2550, 250 - 850 nm Orthophosphoric acid 85 % Ethanol 95 % (ch.p.) Ultrasonic bath Techsonic UD100 SH-45 L

Preparation of human tooth samples for SEM analysis and model demineralization The extracted human teeth were cut by a diamond disk Thin sections of human tooth (0.9  1.2 mm) were impregnated by 35%-orthophosphoric acid during 1 hour., along with the help of a brush and 95% of ethanol carried out a superficial cleaning from products of a sawing and other external pollutants; The thin sections of human tooth washed out by water jet during 30 s., placed an exemplar in an ultrasonic bathtub for 10 min. And wiped it with a lint-free napkin and washed with alcohol; Dried up exemplars at ambient condition within 24 hours. For receiving SEM images of a surface of the studied samples were fixed on an express carbon substrate (a carbon adhesive tape) and gold was spread on their surface.

The electron micrograph enamel The electron micrograph received on SEM (Uv. 5000 times) enamel human tooth

Spectrum of a diffuse reflection (SDR) of dentine human tooth received on a spectrophotometer SHIMADZU UV-2550

dentine The electron micrograph received on SEM (Uv. 5000 times) dentine human tooth

Spectrum of a diffuse reflection (SDR) of dentine human tooth received on a spectrophotometer SHIMADZU UV-2550

Composition of thin sections of human tooth before and after a model demineralization (after tooth treatment with 35% orthophosphoric acid during 1 min. exposures)

a) – without demineralization; b The electron micrograph (SEM) of thin sections of human tooth after a model demineralization on the enamel-dentine junction crystal outgrowths were formed: brushit (СаНРО4х2Н2О) which represent oblong bars various in a form and the size (at increase by 5000 times: a) – without demineralization; b) – after a demineralization during 1 hour

Conclusion The microelement structure of thin sections of human tooth after a model demineralization is defined. Images of morphology of a surface of enamel and a dentine of human tooth at increase by 5000 times are received. Ranges of a spectrum of a diffuse reflection of enamel and dentine of human tooth are received. We have plan to continue study the definition of a demineralization of enamel and a dentine of human tooth on SDR and their deformations at influence of fluid environments.