I. Denture and oral health and general health Denture can restore the patient’s chewing function, pronunciation and aesthetics, but if not properly cared for, it can affect oral health and general health. (a) Denture plaque biofilm Denture plaque biofilm is a complex aggregate of breath bacteria, fungi and other microorganisms gathered on the surface of the denture. 1 mg weight of plaque contains more than 10¹¹, more than thirty different microorganisms. Studies have shown that plaque biofilms are more likely to accumulate on rough denture surfaces than on smooth denture surfaces. If the denture is not properly cared for, it can cause scratches on the denture surface, increasing the roughness of the denture surface and causing the accumulation of plaque biofilm. (B) Denture stomatitis Denture stomatitis refers to the inflammatory damage of the oral mucosa in contact with the removable denture base. The lesion is mainly characterized by red edema of the mucosa. Denture stomatitis is an inflammatory disease of the oral mucosa caused by improper use of the denture. Candida is the main pathogenic organism of denture stomatitis. Candida can adhere to the surface of various restorations, and the rough denture base surface provides more mucosal area for Candida and an environment conducive to plaque accumulation, resulting in inflammation of the mucosal tissue under the denture. Denture stomatitis can cause dry mouth and burning pain in the oral mucosa, and often combined with orofacial stomatitis, resulting in restricted mouth opening, affecting the patient’s chewing function and quality of life. (iii) Impact on systemic health Epidemiological surveys and clinical studies have shown that oral infectious diseases are risk factors for systemic diseases such as cardiovascular diseases, diabetes, gastrointestinal diseases and respiratory diseases, as well as for the occurrence of premature birth and low birth weight babies. Denture is more likely to deposit soft scale and attach bacteria than natural teeth, making it difficult to clean. If the denture is poorly cleaned for a long time, it will affect the oral hygiene of the denture restorer, and then affect the oral health, such as the surviving natural teeth are more prone to caries, periodontitis and denture stomatitis, etc. It is also associated with other systemic diseases, and the inflammatory cytokines in the inflammatory soft tissues can enter the blood circulation and act on the whole body. Some harmful bacteria in the oral cavity are associated with bacterial endocarditis, aspiration pneumonia, chronic obstructive pulmonary disease, infections of the respiratory tract, and alternative systemic diseases. Patients with periodontitis and other oral infections should first eliminate the infection of harmful bacteria in the oral cavity and control inflammation before denture restoration, which should be based on oral health. After the denture restoration should maintain oral hygiene, daily cleaning of natural teeth and denture, and regular oral examination at the dental hospital live clinic. Second, the cleaning of the denture (a) the definition of clean denture and evaluation criteria Clean denture refers to the denture in use should keep the denture surface clean, no odor, no pigmentation and soft scale. The clinical evaluation of denture cleanliness can be done by using the denture plaque adhesion detection method, which is a comprehensive evaluation of denture cleanliness based on the denture plaque adhesion, odor and pigmentation as shown by the plaque stain. The method is to rinse the denture with running water after applying the stain and observe the area of the denture’s labial and buccal surfaces, lingual and palatal surfaces and tissue surfaces stained by the stain, and the odor and pigmentation of the denture. Grade 0: No plaque, no odor, no pigmentation. Grade 1: Small amount of plaque and pigmentation (covering 1-25% of the area), little odor. Grade 2: medium amount of plaque and pigment (covering 26%-50% of the area), medium odor. Grade 3: large amount of plaque and pigment (covering 51%-75% of the area), severe odor. Grade 4: plaque and pigment cover almost all surfaces of the denture (covering 76%-100% of the area), very serious odor. (The results of the oral health survey of denture restorers in five provinces and municipalities directly under the Central Government in Beijing, Sichuan, Hubei, Shaanxi and Fujian found that the denture cleaning condition of denture restorers was not optimistic, and denture restorers generally lacked knowledge of denture care. Among 918 middle-aged and elderly people with removable prostheses, only 26% of the prosthetics had good denture cleaning, 68% of the prosthetics had plaque build-up and pigmentation on the denture; 49% of the prosthetics chose to use toothpaste and toothbrush to clean the denture, and less than 1% used denture cleaning products; 82% of the prosthetics thought that the denture could be cleaned with ordinary toothpaste and toothbrush as well as natural teeth. After removing the denture, 75% of the prosthetics only used water to soak the denture, and 26% of the prosthetics rarely or never removed their teeth. (c) Denture cleaning guide 1, the significance of denture cleaning: because the denture is more likely to attach bacteria, deposit dirt and pigment and form plaque than natural teeth, the denture will to a certain extent affect the physiological self-cleaning effect of oral soft and hard tissues (cheek, tongue, teeth). Firstly, because the components of the denture form a retention area between the retainer and abutment teeth, abutment teeth and abutment teeth, and the connection body and tissue surface, it promotes the accumulation of plaque in the abutment teeth, and the increase of Streptococcus deformans, Lactobacillus, Gram-negative bacteria and Candida albicans, which leads to the obvious increase of caries rate in the abutment teeth and the difficulty of controlling periodontal inflammation; secondly, because of the complex shape of the denture and the uneven surface, it is not easy to clean the food residue and bacteria after attachment. At the same time, the materials of denture base and artificial teeth are composite resin, which are easy to make bacteria attach and pigmentation, such as poor cleaning of denture, long-term accumulation of plaque, increase of harmful bacteria can affect the oral microenvironment and oral health of denture restorers, reduce the flow of oral saliva, change the PH value of saliva, increase the content of salivary microorganisms, and increase the chance of denture stomatitis and halitosis; again, poorly cleaned denture is a gathering place for bacteria. The denture is a gathering place for bacteria, wearing a poorly cleaned denture is not only susceptible to oral infectious diseases, but also associated with infectious diseases of other organs, affecting the health of the whole body. Therefore, denture restorers must perform daily cleaning of the denture to maintain good oral hygiene. 2, denture cleaning methods: This guide recommends the best denture cleaning methods as follows: ① Use effective denture cleaning tablets, powders and liquids specifically designed for denture soaking, and use them according to the product instructions; ② Brush all parts of the denture with a soft-bristled toothbrush dipped in the cleaning solution, especially the hard-to-clean parts such as the rings, the cervical edges of the artificial teeth, and the tissue surface of the abutment; ③ After soaking and brushing the denture, and before taking the denture into the mouth ④The toothbrush used for denture cleaning should not only be soft, but also should not be used with excessive force, and it is best to avoid using cleaning products with rubbing agents (such as common toothpaste) to avoid abrasion of the surface of the components of the denture, especially the surface of the artificial tooth and resin base. 3, denture cleaning time: in addition to the daily morning and evening cleaning of the denture and oral cavity, after each meal should also take off the denture, and cleaning of the oral cavity and denture, especially should pay attention to the night before going to bed should be carefully cleaned natural teeth and denture. The cleaned denture should be soaked in cold water or special denture cleaning solution if it is not worn in the mouth, not in boiling water or non-denture cleaning chemical products to avoid damage and deformation of the denture. Denture care precautions: ① When the denture is first worn, there may be pain, shedding, inconvenience and other uncomfortable reactions, you should go to the hospital in time to check and adjust, in order to facilitate the normal function of the denture; ② After the denture repair should be regularly reviewed every year, in order to timely detection of the denture and oral problems, to maintain good comfort and function of the denture; ③ It is recommended not to wear the denture during sleep, in order to let the oral soft tissue get ③ It is recommended to not wear the denture during sleep to allow the oral soft tissues to rest, which is helpful to reduce the occurrence of denture stomatitis; ④ Appropriate use of denture adhesive products that increase the retention force of the denture, especially when the retention force of the denture decreases, helps to improve the comfort of the patient using the denture; ⑤ If there is alveolar ridge resorption and soft tissue changes, relining methods can be used to improve the fit between the denture tissue surface and the soft tissue surface; ⑥ If the alveolar ridge resorption is serious, the difference with the oral soft tissues is great, the artificial tooth wear has changed the denture. (6) If the alveolar ridge is severely absorbed, the soft tissues of the oral cavity are very different, or the normal occlusal relationship of the denture is changed by the wear of artificial teeth, the denture should be replaced in time, and the damage to the remaining tissues of the oral cavity will be aggravated by the reluctant use of the bad denture.