THE IMPACT OF COVID-19 ON ORAL FLUID PROPERTIES: MINERAL POTENTIAL AND ANTIMICROBIAL ACTIVITY IN THE CONTEXT OF DENTAL CARIES RISK

Introduction. Numerous scientific papers have emphasised that COVID-19 should not be considered solely as an acute respiratory viral infection, as this disease can affect not only the respiratory system but also other organs and systems, exerting a complex effect on health and well-being, including the salivary glands and saliva. Considering that teeth are constantly bathed in saliva, the composition and properties of this oral fluid play a significant role in the onset and progression of dental caries, which created the prerequisites for our study. The purpose of the current study was to evaluate the impact of COVID-19 on the properties of oral fluid – particularly mineral potential and antimicrobial activity – in order to substantiate the risk of dental caries. Materials and Methods. In accordance with the aims and objectives of the study, 110 patients aged 18 to 35 years were examined and divided into two groups: patients with a history of COVID-19 confirmed by polymerase chain reaction (PCR) test (2 to 6 months prior) and conditionally healthy individuals. The first group was further divided into three subgroups according to the severity of COVID-19, classified by the WHO: mild, moderate, and severe. The objectives were to determine the mineral potential and antimicrobial activity of the oral fluid. Results. The observed changes in the concentration of calcium-phosphate compounds indicated an imbalance in the mineral metabolism of the oral fluid. The concentrations of calcium and phosphorus were directly associated with disease severity, decreasing progressively from the first to the third subgroup. The lowest values of calcium and phosphorus were recorded in patients of the third subgroup, measuring 1.08±0.034 mmol/L and 2.09±0.074 mmol/L, respectively, with a significant reduction in alkaline phosphatase activity (28.26±4.70 U/L) in this subgroup. The assessment of the antimicrobial activity of oral fluid revealed that microbial contamination of the oral cavity increased among patients with COVID-19. A pattern similar to that observed for mineral potential was noted in the third subgroup with severe disease, where urease activity was 0.148±0.013 U/mL and lysozyme activity was 77±11 µg/mL. As a result, the dysbiosis index significantly deviated from the normal value of 1, reaching 4.78±0.5, which, based on the interpretation, corresponded to a clinically subcompensated stage. Conclusions. Based on the conducted studies, it should be noted that patients with a history of COVID-19 are more susceptible to dental hard tissue caries due to a reduction in the natural protective and restorative mechanisms of enamel crystal structure.