Evaluation of the effectiveness of various treatment procedures on dentine micro-structure in-vitro

Introduction
Investigation of dentine microstructure in-vitro using scanning electron microscopy (SEM) allows comparing effects of various treatment methods of dentine hypersensitivity (DH). The aim of this study was to investigate the microstructure of dentine in-vitro after application of fluoride varnish, low-level laser (LLL) (810 nm) irradiation, ethanolic extract of propolis (EEP) application, and joint LLL (810 nm) irradiation and EEP application using SEM.

Material and methods
32 specimens of permanent teeth were divided into four groups. Samples of the first group were treated with fluoride varnish, second group with EEP, third group with LLL (810 nm) irradiation, and fourth 4 group with joint LLL (810 nm) irradiation with EEP application. Four samples were taken from all groups and immersed in 6% citric acid. From each of the four groups, 4 other samples were placed in oral fluid for a week, and were brushed twice a day with a soft toothbrush. Then, samples were studied by the SEM.

Results
The utilization of fluoride varnish as well as EEP on the surface of the exposed dentine promotes formation of acid-resistant film. After using LLL irradiation, dentine tubules with a double structure were found. After joint use of EEP and LLL irradiation, the entrances of dentinal tubules were completely blocked, and only single-opened entrances to the dentinal tubules were identified.

Conclusions
The joint usage of EEP and LLL irradiation provides the highest permeability of components to the dentinal tubules, which was proved by the results of SEM.