Objective: To observe the effect of infiltration resin combined with cold light whitening in the treatment of dental fluorosis. Methods: According to the distance between teeth and the long axis of each tooth, 18 anterior teeth were divided equally and randomly between group A and B. Samples in group A underwent cold light whitening, while samples in group B were treated with infiltration resin combined with cold light whitening. The color was measured before and after the treatment. Then, 6 teeth (the first subgroup) were randomly selected from the 18 anterior teeth after measurement for scanning electron microscopy (SEM) to observe the surface microstructure of the teeth. Then, another 6 teeth (the second subgroup) were selected from the remaining 12 teeth for the measurement of the color level and ΔE after being dyed with tea. Results: After treatment, the color level changed significantly in group A and B (P < 0.05), ΔE in group A and B was 13.75, 14.98. There was no significant difference in the color level change between group B and group A, there was a significant difference in the ΔE between the two groups (t = -3.58, P < 0.05). SEM showed that the enamel surface was intact and that the enamel space was filled in group B. In group A, the enamel surface was reduced and uneven, and the characteristic badminton racquet shape of the enamel was not obvious. The color level was lower in both groups after staining, and these differences were significant (P < 0.05), ΔE in group A and B was 19.69, 18.95. There was no significant difference in the color level (t = 1.00, P > 0.05) and ΔE (t = 0.02, P > 0.05) between two groups. Conclusion Cold light whitening combined with infiltration resin is better for treating dental fluorosis than cold light whitening alone.

Exosomes are vesicles with a double globular membrane of lipids that can be secreted by a variety of cells, including stem cells. Exosomes have unique biological characteristics and irreplaceable powerful functions which play an important role in intercellular communication. The various cytokines, signal proteins, lipids and regulatory nucleic acids contained in stem cell exosomes can play a protective role against the injury of kidney, liver, heart, blood vessels and nerves. Stem cell exosomes delay the process of intervertebral disc degeneration by inhibiting the apoptosis of nucleus pulposus cells and increasing the synthesis of extracellular matrix, etc. The mechanism of its role is mainly through miRNA and related signaling pathways. Exosomes contain complex components. Although the mechanism of action of exosomes in intervertebral discs has been preliminarily explored, the components contained in exosomes are complex and the specific situation has not been fully understood, which still needs further study. In this review, the characteristics and functions of stem cell exosomes, extraction, identification and storage methods, the impacttovarious other tissues, as well as the effects on intervertebral discs and their mechanisms were elaborated in order to provide a basis for the study of intervertebral disc degenerative diseases.