investigating the relationship between salivary nitric oxide concentration and tooth decay index in different age groups of children

Background: nitric oxide (no) is a highly active radical that prevents the growth of oral bacteria by inhibiting their growth and increasing the cytotoxicity of salivary macrophages as a non-specific defense mechanism. the aim of this study was to investigate the salivary no concentration and its relationship with the dfs caries index and salivary ph in children.materials and methods: in a cross-sectional study, 177 children aged 4-12 years with different levels of dfs were selected. 2 ml of unstimulated saliva was collected from each child, and the ph and no concentration of the collected saliva were measured using a ph meter and the enzyme-linked immunosorbent assay (elisa) method, respectively. statistical analyzes were done with the help of one-way analysis of variance and pairwise comparisons.results: the mean concentration of salivary no in children with severe caries (dfs>8) was significantly lower than in children with mild caries (dfs≤2) (p=0.008). the ph of saliva in children with severe caries (dfs>8) was significantly higher than in children with moderate caries (2 ≥dfs>8) (p=0.027), and in children aged 4-6, it was higher than in children aged 6-9(p=0.039).conclusion: increasing the amount of no in saliva  can decrease decay, as the production of nitrous oxide is actually the body’s defense mechanism to neutralize the acids produced by decay-causing bacteria. salivary ph decreases first and then increases with increasing caries.