RCW'12, Poster

TIO2 AND ZNO NANOPARTICLES AS DISINFECTION COMPOUNDS

Natalia A. Trunina, Research-Educational Institute of Optics and Biophotonics, Saratov State University;
Alexey P. Popov,Optoelectronics and Measurement Techniques Laboratory, Faculty of Technology, Department of Electrical Engineering, University of Oulu, Finland;
Jürgen Lademann, 3Center of Experimental and Applied Cutaneous Physiology (CCP), Department of Dermatology, Charité – Universitätsmedizin Berlin, Germany;
Valery V. Tuchin, Research-Educational Institute of Optics and Biophotonics, Saratov State University
Optoelectronics and Measurement Techniques Laboratory, Faculty of Technology, Department of Electrical Engineering, University of Oulu, Finland;
Risto Myllylä, Optoelectronics and Measurement Techniques Laboratory, Faculty of Technology, Department of Electrical Engineering, University of Oulu, Finland;
Maxim E. Darvin, Center of Experimental and Applied Cutaneous Physiology (CCP), Department of Dermatology, Charité – Universitätsmedizin Berlin, Germany

ABSTRACT

Penetration of nanoparticles into tooth tissues is of significant interest in solving the problems related to the reduction of tooth sensitivity, enamel strengthening and restoration and cosmetic bleaching. Particles of TiO2 and ZnO are known for their photoactive properties and can be used as bacteria inhibitors 1,2. Monitoring of particles penetration into tooth is, however, a challenging task.
Keeping in mind the potential application of nanoparticles as an antibacterial agent and a free-radical producer when embedded into the tooth dentine tissue, in the present paper we dwell on two key issues relevant to the problem. The first aim is to study the process of nanoparticle penetration into tooth dentine samples by using a nonlinear optical technique. The second is to investigate the influence of the same nanoparticles on the generation of free radicals using the EPR technique.
To visualize the penetration of TiO2 and ZnO nanoparticles into tooth tissues we used two-photon autofluorescent (AF) and second-harmonic generation (SHG) microscopy3. Tooth tissue slices containing dentin and enamel sections were used as samples. The samples merged in a suspension of nanoparticles were placed in an ultrasonic bath to enhance the penetration before imaging. Evidence of TiO2 and ZnO nanoparticles penetration into dentin and enamel of human tooth was observed using multiphoton tomography (MPM) operating in the superficial tissue area down to 200 μm. In this study, AF and SHG images of the enamel and dentin were obtained.
We have found that the enamel produces a strong AF signal, clearly revealing the structure of the enamel rods. Dentin produces both AF and SHG signals. The collagen of the dentin tubules produces a strong SHG signal, while the peritubular dentin response contains both the SHG and AF signals.
It was found that ZnO nanoparticles penetrated up to a depth of 12 μm and 45 μm in human tooth enamel and dentine correspondingly, while the maximum detectable penetration depth of TiO2 nanoparticles was 5 μm in tooth dentine. The size and shape of nanoparticles as well as their aggregation ability play a significant role in the penetration process. ZnO nanoparticles in contrast to TiO2 produce strong SHG signal, because they possess considerable second-order nonlinear optical coefficients (d333 and d311) due to their crystalline symmetry.
Our results demonstrate the efficiency of using MPM for imaging the tooth structure and nanoparticles penetration.

Representing author

photo

Ms. Natalia Andreevna Trunina

Saratov State University, PhD student
Saratov, Russia

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