Dental implants are a restorative technique in which a specially designed and treated titanium artificial root is placed in the alveolar bone of the missing tooth. Since its introduction in the 1960s, dental implants have progressed rapidly in terms of basic, material, clinical and related technologies, and have become a fairly mature discipline for the treatment of missing teeth. The main advantages are: the denture contains crowns and roots, and the overall structure is similar to that of natural teeth, so there is no need to harm the neighboring teeth to obtain retention; the shape and function of the denture are close to that of natural teeth, so the patient feels comfortable after using it, with little foreign body sensation and high chewing efficiency, which can achieve more than 90% of the function of natural teeth; if the denture is broken after use, the whole tooth does not need to be removed, but only the upper structure needs to be screwed out, and it can be replaced again; on the basis of normal use and good maintenance On the basis of normal use and good maintenance, dental implants can be used for life. According to statistics, the success rate of mainstream implant systems is over 98% in 5 years and over 95% in 10 years. The disadvantages are the long treatment period (may take several months), the high cost and the need for bone grafting for patients with insufficient alveolar bone. Prosthodontics Prosthodontics is a traditional technique for restoring missing teeth, containing a base to support the denture and a metal ring fixed to the abutment around the missing tooth, which is called removable denture because it can be freely removed and worn. The main advantages of the removable denture are: relatively inexpensive, relatively little abrasion of dental tissue, and suitable for all types of missing teeth. However, the disadvantages of the removable denture are also obvious: there is micro-mobility when using, chewing efficiency is low, about 30% of the function of natural teeth can only be restored; the denture is large, the use of foreign body feeling is strong, some patients are prone to nausea and increased saliva and other discomfort; when eating, food embedding, after meals need to be removed and cleaned, if not cleaned in time, it is easy to cause decay of adjacent teeth; removable denture in use 3 The removable denture needs to be replaced after 3 -5 years of use. Fixed denture Fixed denture is also a traditional restoration technology, its technical essence is to first grind down the adjacent teeth on both sides of the missing teeth, through a one-piece cast bridge, metal or porcelain braces to restore the missing teeth, and fixed in the patient population with a special adhesive. The advantages of fixed denture are: no need to remove, chewing efficiency is more than 80% of natural teeth, the shape is also closer to natural teeth, feel comfortable. The disadvantage is that more adjacent tooth tissues need to be removed, some patients may hurt the pulp nerve and need root canal treatment before restoration; the price is higher if precious metal porcelain or all-porcelain is used, and the lack of effective chewing force stimulation of the alveolar bone below the missing tooth area may lead to ageing atrophy, and the fixed denture may develop food embedding and adjacent tooth decay after 8-10 years of use. Therefore, it should be decided whether to replace it after expiration by regular review.