Optical clearing and molecular diffusivity of hard and soft oral tissues

Abstract

The measured diffuse reflectance and full transmission spectra can provide important information about the main biophysical properties of biological tissue under study: scattering and absorption coefficients, as well as concentrations of endogenous chromophores. The chapter presents the main optical parameters of human gums and dentin obtained using the inverse adding-doubling (IAD) method. However, significant scattering and partial absorption of radiation by tissues, such as gingival mucosa and the dentin of human teeth, limit the transport of probe radiation to a sufficient depth in the tissue. To reduce the scattering of tissues, the optical clearing (OC) method has been successfully used, which ensures an increase in the efficiency of optical methods in diagnostics and therapy. Diffusion processes play a significant role in the life process when carrying out therapeutic procedures or diagnostics with various agents. Knowledge of the kinetic parameters of diffusion processes (the diffusion and permeability coefficients of the agent) is an important stage in the design of correct clinical protocols. The chapter presents data on the effective diffusion coefficients of various agents in human gingival and dentin tissues. Reflection spectroscopy, a modified version of Fick's second law, and the free diffusion model are used.