In the present study, rutile phase titanium dioxide nanoparticles (R-TiO2 NPs) were prepared by hydrolysis of titanium tetrachloride in an aqueous solution followed by calcination at 900℃. The composition of R-TiO2 NPs was determined by the analysis of X-ray diffraction data, and the characteristic features of R-TiO2 NPs such as the surface functional group, particle size, shape, surface topography, and morphological behavior were analyzed by Fourier-transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, transmission electron microscopy, dynamic light scattering, and zeta potential measurements. The average size of the prepared R-TiO2 NPs was 76 nm, the surface area was 19 m2/g, zeta potential was −20.8 mV, and average hydrodynamic diameter in dimethyl sulfoxide (DMSO)–H2O solution was 550 nm. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and morphological observations revealed that R-TiO2 NPs were cytocompatible with oral cancer cells, with no inhibition of cell growth and proliferation. This suggests the efficacy of R-TiO2 NPs for the aesthetic white pigmentation of teeth.

Introduction
Materials and Methods
    1. Preparation of rutile phase titanium dioxide nanoparticles
    2. Fourier transform infrared spectroscopy
    3. X-ray diffraction
    4. Scanning electron microscopy and energy dispersive X-ray spectroscopy
    5. Transmission electron microscopy and selected area electron diffraction
    6. Dynamic light scattering and zeta potential
    7. Cell culture
    8. Cytotoxicity assay
Results
    1. Preparation of rutile phase titanium dioxide nanoparticles
    2. Phase composition analysis of rutile phase titanium dioxide nanoparticles
    3. Surface function analysis of R-TiO2 NPs
    4. Morpholoical feature, element analysis and crystallinity of rutile phase titanium dioxide nanoparticles
    5. Particle size and zeta potential rutile phase titanium dioxide nanoparticles
    6. Cytotoxicity of rutile phase titanium dioxide nanoparticles
Discussion
References

• Vu Phuong Dong(Department of Pharmacology and Dental Therapeutics, College of Dentistry, Chosun University)
• Nguyen Thi Kieu Trang(Department of Pharmacology and Dental Therapeutics, College of Dentistry, Chosun University)
• Hoon Yoo(Department of Pharmacology and Dental Therapeutics, College of Dentistry, Chosun University) Correspondence to