The application of digital technology in the production of removable partial dentures and complete dentures also needs to go through the process of impression, model, design, transfer of jaw relationship and processing and production, which is the same as the traditional technology, but the two are completely different in terms of the technology, materials and equipment used.

Digital impression technology

Digital impression is an important feature of the digital fabrication of denture, through the scanner will be transformed into the oral cavity into digital information stored in the system, which will become the basis of the subsequent design and fabrication. The scanner is the key equipment for this step. Since the development of the first hand-held intraoral scanner by Professor Mõrmann in Switzerland in 1982, a large number of powerful and highly accurate oral digital impression systems have emerged on the market.

Currently, oral digital impression systems mainly include two types of scanning methods: extraoral (bin) scanning and intraoral scanning. Among them, extraoral scanning is mainly used to scan an impression or plaster model to obtain a digital model, in which scanning an impression is mostly used to obtain a digital model of edentulous jaws. The latest extra-oral scanners are usually equipped with multiple high-resolution cameras inside, allowing efficient scanning of the surrogate or impression inside the model, thus saving time for individual scanning, or even scanning the impression without having to create a plaster model or being able to combine the impression and surrogate at the same time.

Intraoral scanning is the use of a scanner to scan hard and soft tissue information directly into the mouth. According to its use of different light sources can be divided into two main categories: one is based on laser technology, intraoral scanning system, the application of the technical principles of parallel confocal imaging technology and laser triangulation and other technologies, intraoral scanning from different angles and positions to capture images of oral tissues; the second is based on visible light technology, intraoral scanning system, the principle of the technology is to capture images through the still image acquisition, video capture and real-time image capture and other technical methods to capture images. The second type is the visible light-based intraoral scanning system, which is based on the technical principle of capturing images through static image acquisition, video capture and real-time image capture. Since there is no need to take the mould, it gets rid of the influence of the impression material on the quality of the impression, avoids the influence of pharyngeal reflexes of some patients on the accuracy of the impression when taking the mould, and provides a better consultation experience; and the storage of the digital file takes up less space than the traditional plaster model, and is more convenient to store. Currently, the common clinical intraoral scanners are Sirona, 3Shape, iTero, Carestream Dental (Now called Dexis), Medit, Shining 3D, Alliedstar.