is the smallest unit of a digital image that can be displayed and represented on a digital display device, also known as a picture element (pix = picture, el = element). A pixel is represented by a dot or square on a computer display screen. Pixels are the basic building blocks of a digital image or display and are created using geometric coordinates. Depending on the graphics card and display monitor, the quantity, color combination, and size of pixels vary and are measured in terms of the display resolution. A full high‐definition (full HD) image is 1920 pixels in width and 1080 pixels in height, totaling 2.07 megapixels. Ultra HD (also known as 4 K) resolution has 3840 × 2160 pixels, totaling 8.3 megapixels.
The 3D version of a pixel is called a voxel. In general, the smaller the voxel size is, the better quality a 3D reconstructed model will have.
The quality of radiographic images depends on contrast resolution and spatial resolution. Contrast resolution is proportional to the size of the contrast scale available to produce the image. As a result, the higher the contrast resolution of an image, the easier it will be to distinguish between multiple densities. In digital imaging, contrast resolution depends on the bit‐depth of the imaging method, following a logarithmic scale. Therefore, a panoramic radiograph produced with an 8‐bit system can show 28 = 256 different gray‐scale levels distributed from black to white. A CBCT device with a 12‐bit system will offer 212 = 4096 gray‐scale values. Spatial resolution is the ability of an imaging method to identify the actual limits and differentiate two adjacent structures [2–4].
Resolutions in 3D CAD files basically depends on the size and densities of the meshes. The quality of the respective manufactured device, however, is also dependent on factors related to CAM (e.g., resolution of 3D printers or milling devices). For 3D printers, there will be factors related to the resolution such as the number of layers and layer thicknesses. For milling machines, the resolution will be dependent on the number of axes and size of burs (see Chapter 3).
1.2 History of Digital Dentistry
Science and technology are the foundations of human development. From the rudimentary creation and improvement of stone tools, accompanied by the breakthrough in learning to control fire and the Neolithic revolution, which multiplied the sustenance availability, to the significant invention of the wheel which allowed humans to travel and produce machinery, or the overcoming of physical barriers with advancements in communications, technology is what sets humanity apart.
Alongside technology, a lexicon development has always been necessary to provide a common understanding of innovations in the meaning and usage of new or existing words. The technological lexicon expansion will often plainly exhibit a novel sense in use but also a rationalization as to why a fresh sense has surfaced. This derives from the need to name new inventions, and when these ascend to a well‐known state, so does the correlated terminology. A widespread example of this lexicon expansion is the “digital” concept which, in the last century, underwent a huge increase in usage and meaning as an unswerving consequence of modern computing.
However, contrary to what is customary in technology, the term “digital” is by no means a new word. With its etymology in the Latin word digitus, meaning finger or toe, “digital” has come a long way since. In the fifteenth century, the word was used to identify Arabic numbers from 1 to 9 and 0 as digits. It was not until the twentieth century that the term became widespread and gained significance. In the 1930s and 1940s, the existing analogue computing devices which computed data with the normal decimal system were replaced by new machines which functioned with data represented as sequences of discrete digits.
In the late 1970s, electronics using the digital concept were no longer limited to research institutions and companies. As their cost dropped, the general public started to have access and myriad information sources and equipment were converted to the digital era. From a simple CD to a more complex digital sensor camera, radiovisiography or 3D scanner, the world was changed forever.
The construct of “digital” did not stop with machine development but acquired a broader meaning. It has evolved to encompass everything linked to digital or computer technology, as well as to describe any computer‐mediated equivalent of an object or entity that exists in the palpable world. Daily uses of this concept are digital shopping carts and digital books, among others. Not only ordinary objects but also professions, expertise fields, and whole organizations acquire the digital connotation when they embrace technology (either hardware or software) for their activities. Examples of this are the many references to digital dentistry or the thriving European Academy of Digital Dentistry that quickly became one of the most respected and widespread scientific societies in the dental field.
Although the twentieth century was overflowing with the word “digital” as the most significant technological innovation in human history, it is predictable that the twenty‐first century renders the word “digital,” but not the concept, obsolete. As digital becomes the norm, the need to identify it as such becomes archaic. Fields like digital dentistry will overrun the previous model as all dentistry becomes digital, thus eliminating the need for an alias. Similar to the previously named “digital computers,” so digital wax‐ups, digital photography, and many more entities will lose the superfluous prefix.
Having discussed the past, present, and future general notions of digital, it is imperative to clarify the current concept of digital dentistry, as it may not comply with the ingrained notion promoted and labeled by the industry. Although more widely marketed in oral rehabilitation and surgery fields, digital dentistry has a vast predominance in endodontics, cariology, periodontics, orthodontics, and occlusion, among others. Nowadays, it is clear that digital dentistry encompasses all areas and not only the well‐marketed misconception of “digital” as a synonym of CAD‐CAM dentistry, a common buzzword in oral healthcare. CAD‐CAM technology presents a vast sea of innovation opportunities and is undoubtedly one of the drivers of development in modern dentistry. Nonetheless, according to the concept regulated by the European Academy of Digital Dentistry, “Digital dentistry encompasses any and all scientific, clinical or laboratory techniques and/or procedures with the purpose of examining, diagnosing, treating, assisting directly or indirectly in the treatment, production of medical devices or any other techniques used by dentists and dental technicians to better pursue the goal of improving patient treatment, comfort and outcome, as well as the healthcare professional's work environment.”
Taking the aforementioned concept, it is perceivable that dentistry areas such as endodontics present an even higher digitalization than other more well‐known digital fields, as endodontists dwell in a fully digitalized workspace where all clinical procedures are performed with the aid of technology – diagnostics with 2D or 3D radiology, microscopes and cameras, apex finders, ultrasonic technology for accessing root canals, static and dynamic endodontic guides, instrumentation with highly advanced digital motors, irrigation activation techniques, and warm obturation methods.
The mandatory multidisciplinary approach in digital dentistry renders the task of defining a clear historical timeline impossible, as innumerable events, developments and clinical or laboratory fields are involved and intertwined in the modern concept.
However, focusing on oral rehabilitation and the developments in computer‐aided design and manufacturing, the first CAD‐CAM systems in dentistry date to 1971 when Dr François Duret introduced them in his DDS graduation thesis “Optical Impression,” but the technology had been used since the 1960s in the automobile and aircraft industries.
In 1984, Dr Duret patented a CAD‐CAM device, which was presented at the Chicago Dental Society Midwinter Meeting of 1989, where a dental crown was fabricated in a record time of 4 hours. In parallel, Dr Werner Mormann worked on the development of a digital scanning system to be used by the general dentist, which was branded CEREC 1 and launched in 1985. This innovative system was composed of a three‐dimensional
