SARS-CoV-2-associated gut microbiome alteration; A new contributor to colorectal cancer pathogenesis.

The emergence of a novel coronavirus, COVID-19, in December 2019 led to a global pandemic with more than 170 million confirmed infections and more than 6 million deaths (by July 2022). Studies have shown that infection with SARS-CoV-2 in cancer patients has a higher mortality rate than in people without cancer. Here, we have reviewed the evidence showing that gut microbiota plays an important role in health and is linked to colorectal cancer development. Studies have shown that SARS-CoV-2 infection leads to a change in gut microbiota, which modify intestinal inflammation and barrier permeability and affects tumor-suppressor or oncogene genes, proposing SARS-CoV-2 as a potential contributor to CRC pathogenesis.

Effect of photodynamic therapy on microleakage of class V composite restorations in primary teeth.

BACKGROUND: Photodynamic therapy (PDT) is a treatment by which, light sensitive chemicals are activated at a specific wavelength, generating reactive oxygen species which can be antimicrobial and assist in disinfection. However, the oxygen radicals may interfere with the bonding process. The purpose of this study was to assess the effect of PDT with different photosensitizers on microleakage of composite restorations. METHODS: Seventhy-two primary teeth with sound labial/buccal and lingual surfaces were collected for this study. The teeth were randomly divided into four groups of control, PDT with indocyanine green, PDT with methylene blue, and PDT with toluidine blue. Next, the cavities were restored with composite resin. The specimens were stained with 0.5 % Fuchsine and sectioned. The specimens were observed under a microscope to determine the microleakage score. The microleakage was compared between the groups and between the occlusal and cervical walls in each group. Data were analyzed using SPSS version 25. RESULTS: According to the kruskal-wallis test, no significant difference was observed in microleakage between the groups in the occlusal wall (p = 0.859). However, there was a significant difference in the cervical wall between the control and toluidine blue (p = 0.019), and the control and methylene blue (p = 0.008) groups. The Wilcoxon test showed a significant difference in microleakage (p < 0.05) between the occlusal and cervical walls within each group. CONCLUSIONS: PDT may be used in cavities with enamel margins to decrease the microbial load and prevent secondary caries. PDT is not recommended for cavities with cementum margins. Alternatively, it can be performed with indocyanine green as photosensitizer in such cases.