When dentists do prosthetic treatment for patients, they are often asked, “How many years will my dentures last?” But such a question will not have a uniform answer, said Meng Xiangfeng, deputy director of the Department of Prosthodontics at Nanjing Stomatological Hospital, because there are many types of dentures (denture) and the materials used to make them vary, so their service life is also different. In addition, the health of the soft and hard tissues in the patient’s mouth, the use and maintenance of the denture after wearing it, and other factors will also affect the life of the denture. The life span of fixed dentures is directly related to the health of the abutment teeth and periodontal tissues, and if well maintained, the life span is usually more than ten years, or even a lifetime. A removable partial denture is a type of denture that can be removed by the patient to restore one or more missing teeth by using the natural teeth and the mucosa and bone tissue covered by the denture for support and retention. For example, the denture should be placed in the correct position when it is put in place, rather than using the teeth to bite into position to prevent deformation due to improper force. After 3-5 years of denture use, changes in the mucosa, alveolar bone and other hard and soft tissues in the oral cavity that support the denture may cause discomfort such as lack of fit and pressure pain between the denture and the mouth. If these changes in the patient’s mouth are not significant, the denture can be repaired, but when the changes are significant and not suitable for repair, it will need to be rebuilt. Complete dentures rely entirely on the adsorptive force and atmospheric pressure generated by the close fitting edge closure of the denture base to the mucosal tissue, thus attaching to the alveolar ridge and obtaining retention. Therefore, after 3-5 years of use, complete dentures can also face the problem of needing relining or remaking. There are some criteria in the opinion of dentists when dentures need to be replaced. The first thing to look at is the straight line distance between the upper and lower teeth, or in layman’s terms, the distance from the bottom of the nose to the chin. After several years of denture use, especially with full dentures, resorption of the alveolar bone and wear of the tooth surfaces can cause changes in the vertical distance, and when these occur, complete dentures that once fit accurately become loose and unstable. Since this is a slow, gradual process, patients may have gradually adapted to their changing conditions. But one sign that patients can notice is a change (increase) in the skin folds around the mouth. In addition, although the materials used in the fabrication of modern dentures are very durable, it is inevitable that changes in shape or misused components will occur over time and eventually the denture will not fit well and will need to be replaced. Particularly in the case of front teeth, the aging color loses its natural appearance, and the cleaning adds texture and has textured coloring, making the denture appear artificial. The deterioration of the denture plastic also has the potential to create excessive microbial contamination. It may cause irritation to the mouth and produce an odor that is unacceptable to others.