The TEA CO2 Laser as a Promising tool for Elemental Analysis of Restored Teeth and Evaluation of Restoration Constituent Penetration into Dental Tissues

The purpose of this study is to evaluate the feasibility of using the originally developed Laser Induced Breakdown Spectroscopy (LIBS) laboratory setup for the qualitative analysis of human tooth tissues and tooth restorations. Plasma was induced by the infrared TEA (Transversally Excited Atmospheric) CO2 laser in the air under atmospheric pressure. Optical emission spectra with sharp and well-resolved spectral lines and a negligibly low background were obtained. The results of the qualitative analysis showed the presence of various elements in the tooth tissues (P, Ca, and Mg), as well as trace elements within restorations such as Zn, Sn, Cu, Ag, and Hg. The estimated temperatures of plasma for composite, dentin, and amalgam were 21,000 K, 16,200 K, and 13,300 K respectively. The electron density deduced from the Stark-broadening line profiles varies from 8.5 x 10(17) cm(- 3) for amalgam, 2 x 10(18) cm(- 3) for composite, and 1.9 x 10(18) cm(- 3) for dentin. The surface of the tooth tissue was imaged with a scanning electron microscope (SEM), showing that dentin contains pores, cavities and bubbles. The results indicated that the alternative and cost-effective LIBS system can be used as a useful tool for further research on laser-induced plasma in dentistry. These insights are useful in the field of laser dentistry, where lasers are commonly utilized to treat teeth.