Intraoral Scanners: The Key to Dentistry’s Digital Revolution

While CAD/CAM has surged into the mainstream dental industry relatively recently, its history dates back to 1973, when Dr. François Duret proposed the idea of optical impressions for application in dentistry. A decade later, in 1984, he demonstrated the first dental crown produced using a patented electro-optical scanner to take a digital impression and CAD/CAM system for the fabrication of a crown.²

By 1985, the first chairside CEREC 1 CAD/CAM system (Sirona Dental Systems GmbH) capable of producing a restoration was unveiled.^3,4 The system did not have complete CAD software; rather, it simply copied the cavity preparation and required the occlusion to be refined in the mouth. CEREC, which is an abbreviation for CEramic REConstruction, was developed with ceramic crowns in mind, and the focus on ceramic crowns and same-day dentistry remains a selling point to this day.

Since their inception, IOSs have always been optical in nature, utilizing laser or structured light technology. This light reflects off the soft and hard tissues into a sensor in the IOS device and is then converted into a digital impression by software. As opposed to laboratory scanners, IOSs are designed to obtain digital impressions directly in a patient's mouth. Therefore, the overall size and shape of these scanners have been limited by the oral cavity, and their general appearance from one model to the next does not vary significantly.

For instance, scanner heads are small enough to fit in the mouth and long enough to capture the distal aspect of the last molar, and the device is light enough to allow for operation with one hand. For these reasons, it is not surprising that many modern scanners still resemble the first-ever IOS developed by Dr. Duret.

The benefits of intraoral scanning when compared with conventional impressions are plentiful and well-established both in literature and by the multitude of anecdotes provided by clinicians around the globe. These benefits include increased speed, better clinical efficiency, greater comfort for patients, and ease of use for clinicians.^5,6 Furthermore, with multiple studies having compared the accuracy of conventional impressions with digital impressions, it can be confidently concluded that digital scans have comparable or even superior accuracy to physical impressions.^7,8 It is important to note, however, that not all scanners are made equal, as some devices struggle to maintain accuracy when used to scan more complicated structures such as edentulous arches or for scanning full-arch implant prosthetics.⁹

Over the past decade, the IOS market has grown increasingly competitive. Ten years ago, only two main intraoral scanner options were available: CEREC^® (Dentsply Sirona) and E4D (now known as Planmeca). Today, there are more than 15 different IOS manufacturers, not including the many white-labeled products.

With this increase in competition and market pressure, scanner prices have seen an unprecedented reduction, which benefits clinicians globally. It is well-known that the biggest barrier to adopting IOS is cost.¹⁰ The decrease in prices is driving adoption rates of IOS devices. While 10 years ago the entry price for an intraoral scanner was around US $60,000, today the most economical scanner on the market is less than US $10,000. These prices are likely to keep falling, a trend largely driven by the development of Korean and Chinese products.

Since the early days, intraoral scanners have gone through multiple evolutions and improvements. IOSs originally were corded devices that captured a single image at a time. The operator then had to manually stitch these images together, a time-consuming chore that was prone to inaccuracies. Today, modern IOSs are capable of continuous capturing of hundreds of images per minute, with the software stitching them together in real-time. The process is much easier, faster, and more accurate than ever before.

The market trend in IOS seems to be moving toward wireless, battery-powered scanners with removable scanning heads rather than traditional wired models with fixed scanning heads that require cold disinfection. This is evident in several of the latest notable releases in the market, such as the Medit i700 Wireless (Medit) and the TRIOS 5 (3Shape). Additionally, the first wireless intraoral scanner from a Chinese company, the AS 200E from AlliedStar, has become available. It seems likely that all major manufacturers will eventually release a wireless IOS device.

Scanner hardware also has improved significantly over the years, with scanners having shrunk significantly in size and increased in speed. Presently, experienced users are able to easily complete a full-arch scan in 30 seconds with almost any modern scanner on the market. Some features, such as caries detection in scanners, have struggled to catch on in the market and are available in only a few products.

For dental providers who are considering investing in an IOS, it is important to understand that proper training is essential. Following the recommended scanning protocols and/or strategies set out by the manufacturer is crucial. Doing so gives users a methodology to ensure the most efficient way to scan and minimizes the risk of incorrect stitching of images, which results in inaccuracies.¹¹ Scanning is now easier than ever before with most devices having powerful artificial intelligence (AI) that effectively guides the user and can identify and remove soft-tissue artefacts and filter scan data to capture only what is important. Scanning protocols also have improved, with IOS companies introducing features like "smart stitching" (Medit) and "scan assist" (TRIOS) that use AI to stitch together data regardless of whether the right scanning strategy was used.

Another advancement in IOS development is that coating the oral cavity in scanning powder is no longer necessary with modern scanners. However, due to the optical nature of an IOS, wet and very shiny surfaces can still pose a challenge to scan, although this is easily managed inside the mouth with, for example, the use of adequate moisture control or changing the angle of the scanner to prevent light reflection back into the sensor.

Almost all modern IOSs have some sort of mechanism to prevent condensation on the scanner tip while scanning, such as an external or in-built heater or an in-built fan. There has also been a strong focus on the hygiene aspect of IOS devices since the emergence of COVID-19. For cross-infection control, scanning tips are either wiped and disinfected or covered with a removable single-use scanning head/sleeve, or clinicians may use a removable scanning head capable of withstanding multiple autoclave cycles. The market seems to be moving in the direction of removable scanning tips that can be autoclaved rather than cold sterilization.

A major market trend occurring is related to software improvements, with companies making significant efforts to enhance their software as a point of differentiation among the multitude of available devices. IOSs are moving away from being just impression replacement tools, to being viewed as a means of developing a valuable treatment plan and a communication tool to be included in the patient examination. Leading manufacturers are now including various so-called "software apps" in IOS software. These apps include but are not limited to orthodontic simulators, smile design simulators, and patient monitoring over time. With the rise of 3D printing in dentistry, companies are now including a "model builder" app in their software, which enables scans to be made into printable models easily and efficiently.

Moving forward, most of the advancements in the IOS market will likely continue to be in the software space, especially in the realm of AI and better workflows with other devices that are being adopted in dental clinics, such as 3D printers. While milling machines have never been widely adopted in dental offices (mainly due to cost), 3D printers are much more affordable and allow clinicians an opportunity to move production in-house at a fraction of the cost of a milling machine. This appears to be a dynamic development in dentistry, and scanner companies are taking notice, with many making integrations with popular 3D printers.

With considerable advancement having occurred in dentistry over the past decade, this is an exciting time for the profession. Dentistry is dramatically changing, and with the advent of AI diagnostics, intraoral scanning data, 3D printing, and CAD/CAM software, it is highly conceivable that diagnostic methods, treatment planning, and treatment execution will continue to rapidly change over the course of the next 5 to 10 years. For practitioners still without a scanner, it is time to accept the inevitable and make the investment. It is indeed an interesting time to be a dentist.

Ahmad Al-Hassiny, BDS (Hons)
Director, Institute of Digital Dentistry,
Wellington, New Zealand; Private Practice,
Wellington, New Zealand