Now an exciting technology for in-office manufacturing is following in the footsteps of CEREC: in-office 3D-printing solutions leverage some of the same technologies as CEREC, such as accurate intra-oral scanning and CAD/CAM software. The difference lies in the manufacturing process: milling high-strength materials versus depositing resins in a process known as digital light processing (DLP).

With the introduction of every new technology, a question arises: will the new method replace or complement the existing technology? Dentsply Sirona is the only company offering both in-office manufacturing technologies at scale. This gives us a unique view on which technology is most suitable for which indications to enable excellent results for both patients and practices. In a nutshell, milling is ideal for manufacturing high-quality permanent restorations made from materials with extensive clinical track records and expected survival rates of over ten years. In-office 3D printing is most suitable for temporary applications, such as temporary restorations, surgical guides, models and splints.

In-office 3D-printing deposits liquid resins in a stepwise manner, allowing for the creation of complex designs. Printer resins suitable for the fabrication of dental devices are those with a maximum filler content comparable to that of flowable dental composites and have lower strength values compared with materials utilised in milling systems. This is because the printing resin must be light-polymerised and high levels of filler diffract light and lower polymerisation efficiency.

Recently, some resin brands have launched new materials marketed as ceramic restorative materials. While these materials contain ceramic particles as fillers, they technically are still lightly filled composite materials with strengths that do not exceed 150 MPa. High-strength milling materials for CEREC, such as glass-ceramic, zirconia and highly filled composites, however, have three to six times greater strength (530–850 MPa).¹ These types of milling materials are backed by clinical evidence that demonstrates their suitability for use in definitive dental restorations. By nature of the DLP printing requirements, 3D-printing materials lack comparable long-term durability, making 3D printing most suitable for (complex) temporary applications, such as surgical guides, bite splints, models and other plastic appliances. At the current stage of technology and given the lack of solid clinical evidence, caution is warranted for the printing of permanent crowns, even if advertisements for these materials imply the production of ceramic restorations. They remain, in fact, composite resin crowns.

Milling and 3D-printing technologies can be combined to reduce labour and increase predictability in clinical procedures. For example, to restore an edentulous space with an implant, a printed surgical guide and provisional restoration can be fabricated with a 3D printer, and the definitive crown can be manufactured in the CEREC milling machine—all within one digital treatment plan.

“Both CEREC and in-office 3D printing are highly attractive for dental practices owing to the improved practice efficiency, supporting the business case for investment in this technology.”

Implementing CEREC in a practice follows a well-established workflow with a history of more than 35 years. When employing in-office 3D printing, it is important to consider the complete process, involving printing, cleaning and polymerising. Conventional 3D printing requires the use of chemicals such as isopropanol for cleaning. Safe use of isopropanol necessitates a fume hood for ventilation and personal protective equipment to protect the operator. Additionally, to ensure patient safety, special dental polymerisation units must be used in order to guarantee complete polymerisation of the printing resin. Advanced printing solutions automate printing and post-processing to ensure staff safety and save valuable staff time.

Economic factors ultimately drive the adoption of technologies in dental practices. Both CEREC and in-office 3D printing are highly attractive for dental practices owing to the improved practice efficiency, supporting the business case for investment in this technology. Both technologies serve different indications, and dentists’ decision to invest should be based on the benefits to their practice.

An important economic factor for crowns is the revenue for different types of crowns. Clinically proven permanent crowns made from glass-ceramic or zirconia command two to three times higher prices than do composite resin crowns.² Printed crowns may play a role in the value segment, but to make the same revenue, a dental practice would have to place two to three times as many composite restorations versus ceramic crowns. Using long-term proven materials such as zirconia also lowers the risk of rework that may arise from newer printed composite materials with limited clinical data.

In conclusion, in-office 3D printing is a highly attractive technology that will enrich dentistry. At its current level of development and research, it is highly suitable for intermediate, temporary restorations and temporary applications, like night guards, guides and models. This technology complements the strength of the proven CEREC technology for rapid manufacture of clinically proven permanent restorations. A dental practice using both technologies effectively can expect satisfied patients and growth in revenue and margins.

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