Recently, the digitization of dentistry has progressed rapidly, and the content of treatment has changed markedly due to data processing. Regarding the production of prosthetic devices, the introduction of dental CAD/CAM technology has enabled high-precision, high-quality treatments to be implemented, and new materials can be used, providing numerous benefits for patients and dentist. The use of intraoral scanners avoids the disconfort of conventional impression-taking and promotes infection prevention, preservation, and transmission of intraoral information. On the other hand, for the milling machine and additive manufacturing machine, the selection of materials according to the type of restoration and the purpose of use is a key point, and this is especially true with the use of 3D printers. Digital dentistry has a major impact on the future dental treatment process and fusion with empirical skills that have been cultivated from the past will attract attention as dentistry that can be disseminated throughout the world.

Recently, digital technology has been rapidly introduced to the field of dental implants. The consensus is that CT is required to decide on the length and diameter of implants. Diagnostic simulation of implant placement will become a standard protocol in the near future. Moreover, surgical guides to reproduce the simulated position in the mouth will be used more frequently. Regarding impression and fabricating prostheses, traditional methods have been gradually replaced by novel techniques. The CAD/CAM system is now essential equipment to fabricate titanium abutments and zirconia superstructures such as crown and fixed partial dentures. In addition, optical impression with intraoral scanners and fabricating dental models with 3D printers can be clinically applied. Thus, digital technology is indispensable for current dental treatments, especially for implant therapy. As described above, there is a huge potential for digital dentistry to improve traditional dentistry, and it is expected to be continuously developed. However, there are some issues to be elucidated, such as accuracy and efficiency.

CAD/CAM has been used sparingly in designing removable dentures and manufacturing frameworks and denture bases. Traditional methods of denture construction using precision casting for frameworks and polymerization with mixing powder and liquid for denture bases may be replaced by CAD/CAM. Although complete dentures have reached the stage of practical application due to their simple structure, fully digital construction is still difficult, as removable partial dentures consist of many components and a structure that is more complex, including the framework in the denture base. Recently, an assembly method was tested whereby each component is separately fabricated and then jointed on the master cast. This review outlines the current status of the CAD/CAM system(milling or additive manufacturing) for the construction of removable dentures as well as the future possibilities of fully digital construction, hybrid manufacturing, and topologically optimal designing.

The fourth industrial revolution has been markedly changing our lives. This revolution can make considerable changes or rearrange existing occupations, and create new businesses and services beyond existing industry frameworks．In the dental laboratory, working procedures have been markedly changed by digital equipment such as CAD/CAM, and 3D printers. Although we often hear that dental technicians will not have a future due to mechanization, I do not think so. Surely, most simple manual work will be performed by machines. Then, what are things that machines are not able to do? What should we do? Thinking seriously, we can see what needs to be done. It seems that dental technicians will have a more attractive profession due to their handling of digital data. Also, in the digital era, communication skills will be more essential. I would like to introduce our company’s attempts, and I hope this will help when thinking about the digital dental technician’s rolle.

Through digital data output from various devices and software, dental professionals and their patients can share images, make diagnoses, and devise treatments after consideration from many perspectives.
On the other hand, because there are many digital devices that are advanced devices, we are often confused when categorizing the medical devices and devising suitable evaluation methods to ensure safety and reliability.
Expansion of the application range for each device and system, and implementing new functions requested by end-users require our continuous efforts.
In addition, we propose a new system that uses multiple digital data, a new system that utilizes a database and provides a total system by sharing digital data, and we would like to further develop our digital workflow to realize a healthy and long-lived society.

In the latter half of the 20th century, various technologies in the dental field such as metal ceramics and implants progressed rapidly; many areas of research and development toward the digitization of dental systems also rapidly advanced. However, key devices or materials were necessary for the widespread dissemination of digital devices such as CAD/CAM. One key factor was the pharmaceutical approval of zirconia ceramics in Japan in 2005. In addition, both the pharmaceutical approval of the CAD/CAM crown in Japan and additional specification of the “digital impression device” let to the spread of dental CAD/CAM systems. On the other hand, overseas manufacturers are leading the development and provision of current digital equipment. In Japanese academic societies, many researchers used those products and materials that had been developed in advance. The aim of this article is to review digital-related research based on abstracts of our society since 2005, when zirconia ceramics became approved.

The aim of this study was to compare the properties of different types of resin hybrid CAD/CAM blocks based on the volume of the inorganic filler. Experimental blocks with the same composition as that of a commercially hybrid resin block for molars but with different volumes of inorganic fillers were used. Surface hardness, flexural strength (three-point bending test), three-body abrasive wear behavior, tensile bond strength, and color differences were assessed. The data obtained were subjected to statistical analysis；correlations between the inorganic filler content and various properties of the materials were determined.
The inorganic filler content was positively correlated with surface hardness and three-point bending strength and negatively correlated with abrasive wear ( p＜0.05). The color difference decreased with an increase in the inorganic filler content. However, the tensile bond strength was not significantly correlated with the filler content. Furthermore, the rate of cohesive failure in the hybrid resin block increased with a decrease in the inorganic filler content.

The aim of this study was to evaluate the mechanical properties of different dental hard resin using indirect restorative materials. Surface hardness, three-point bending, wear, and staining tests were performed, and the inorganic filler content of the resins was measured. Additionally, a three-point bending test was performed after storage of the resins under thermal stress at 5℃ and 55℃ for 10,000 cycles. Data were analyzed using one- or two-way analysis of variance and Bonferroni post-hoc tests. Correlations between the inorganic filler content and various properties of the resins were analyzed using Pearson’s correlation coefficient. The elastic modulus and surface hardness of the resins were positively correlated with the inorganic filler content. Furthermore, significant differences in flexural strength were observed for each dental hard resin between the control and thermal stress groups. However, no significant differences in the wear loss volume were noted. It was shown that the inorganic filler content is one of the factors that influence the properties of dental hard resin.