The relationship between the teeth and the kidneys is both close and complex. It is close because many patients with chronic kidney disease are comorbid with varying degrees of chronic periodontal or root disease. One study found that non-dialysis adolescent patients with CKD (chronic kidney disease) commonly have comorbid periodontal support tissue damage, and in 2005, Kshirsagar et al. conducted a cross-sectional study of 5537 whites as well as blacks to demonstrate that patients with comorbid renal impairment had twice as much comorbid periodontal disease as those with non-periodontitis. Not only is the prevalence of periodontal disease significantly higher when entering dialysis treatment, but the extent of the lesions also progressively increases. A large number of studies have found that plaque microorganisms are the initiating factors of periodontitis, and the pathogenic bacteria include Porphyromonas gingivalis, dense scale spirochetes, and Haemophilus with Actinomyces. In addition to causing local inflammation, these pathogens also trigger and amplify the immune and inflammatory response of the body, leading to the deposition of a large number of immune complexes in the kidney, inducing nephropathy (e.g., IgA nephropathy) and aggravating renal damage. In my clinical study of IGA nephropathy, I found that a significant number of patients have a combination of chronic inflammation of the gingiva or pulp. The main pathological change of chronic inflammation of these periodontal supporting tissues is alveolar bone resorption, and there is evidence that inflammatory mediators such as IL-6 play an important role in the process of alveolar bone resorption, and the concentration of IL-6 is closely related to the development of chronic periodontitis and its degree of destruction. Such chronic inflammation is prolonged or recurrent, often resulting in a constant state of chronic inflammation in the body, a process that will induce chronic kidney damage or accelerate the progression of chronic kidney disease. At the same time, the disorder of calcium and phosphorus metabolism (bone decalcification) caused by chronic kidney disease will further aggravate dental disease. I say it is complicated because the impact of chronic dental disease on kidney disease has not yet received sufficient clinical attention, and there is a lack of large-scale in-depth studies. I found in the clinic that many patients with chronic kidney disease, especially those with proteinuria and microscopic hematuria that have not been cured for a long time, after intensive oral hygiene treatment (scaling, treatment of periodontitis and dental caries), a considerable number of patients with urinary protein and microscopic hematuria were significantly controlled. In fact, the relationship between chronic dental disease and kidney is just like the relationship between “upstream and downstream pollutants”, if the upstream pollutant (teeth) is not removed, the downstream pollution and damage (proteinuria and hematuria) can not be completely controlled. Therefore, for patients with chronic kidney disease that is not cured for a long time, it is necessary to carefully check the teeth and completely remove the upstream “source of pollution”. The main manifestations of periodontal disease are: 1. Gum swelling and periodontal pocket formation. Due to the expansion of inflammation, the periodontal membrane is destroyed, the alveolar bone is gradually resorbed, the gums are separated from the roots, so that the gingival sulcus is deepened and periodontal pockets are formed. 2, periodontal pus overflow. With the prolongation of the disease, periodontal pockets wall ulcers and inflammatory granulation tissue formation, pockets with purulent secretions remain, so lightly press the gums, visible pus overflow and bad breath. 3, loose or lost teeth due to the destruction of periodontal tissue, especially when the alveolar bone resorption aggravated, support teeth strength is insufficient, appear teeth loose, displacement and other phenomena. This is often accompanied by toothache, chronic bleeding of the gums and increased bad breath.