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A fully automatic navigation assistant for root canal therapy? What may initially sound like robo-doc treatment or treatment by remote control will take endodontics a significant step forward on the way to sustainable, reliable preparation. Cases presented in this article illustrate how digital endodontic assistance systems will revolutionise everyday treatment in the future.
Strictly speaking, an intelligent lane assistant of the type we are familiar with from road safety was a long overdue, logical progression in technical advancement of apex locators and so on. Whereas clinicians nowadays often assist machines in high-tech surgery, it is only logical that the digital co-pilot should be able to support the endodontic expert on his or her route to the apex, when the field of vision is limited and the anatomy is unclear.
While treating a strongly curved S-shaped root canal some time ago, Italian endodontic specialist Prof. Eugenio Pedullà came up with an idea that was as simple as it was captivating: the vision of autonomous driving could also make root canal preparation far safer and more efficient in dental practice as well. Lane departure warning, traffic jam alerts or cruise control, all useful features of modern mobility development, could just as easily be put to use for endodontic treatment. In collaboration with international dental specialist COLTENE, he then developed the appropriate prototype. Prof. Pedullà was so proud of the device, which has been available since 2020, that he even bestowed his nickname on the new endodontic motor, the “enchanting Jeni”, which finds its way independently through the root canal and adapts filing motion to the conditions prevailing in the respective root section within milliseconds (Fig. 1).
Moving steadily from the coronal to apical aspect
Using this innovative work aid for the first time requires a little bit of getting used to in the beginning. Traditionally, flexible nickel–titanium (NiTi) files are inserted gradually into the root canal in dabbing up and down motions. Up to now, tactile feedback has enabled the dentist to sense the course of the curvature and thus avoid misalignments or blockages that could lead to file breakage. With the innovative CanalPro Jeni endodontic motor, the user works continuously forwards, applying only slight pressure, while the digital co-pilot decides independently on the progress of motion. Complex algorithms control the variable filing motions. The computer’s reaction time is in the millisecond range and thus significantly faster than that of humans. Rotary motion, speed and torque have already been adjusted before the user even notices that he or she may have been applying too much pressure.
The experienced endodontic expert, in particular, may wonder whether the assistance of the endodontic motor can be trusted when used in the dental practice. However, a fully automatic endodontic motor is more precise than the conventional contra-angle handpiece alone. In the beginning, it takes a bit of courage to constantly push forwards and rely on the co-pilot to reduce the rotation speed or to let the file rotate backwards if the system detects resistance before noticing anything oneself. Furthermore, the new types of endodontic motors, such as CanalPro Jeni, also fully respect the classic rinsing protocol: an acoustic signal indicates when and how often rinsing should be performed between file changes. This consistent forward motion can ultimately save considerable time during preparation, especially in the case of complex anatomies. In such complicated root canal profiles, endodontic specialists can save between 10 and 30 minutes with Jeni, time that is important for extensive rinsing and disinfection.
Shaping according to the original anatomy
The benefits of modern endodontic assistance systems quickly become apparent, especially with regard to highly curved root canals, as illustrated by the following two patient cases.
In Case 1, periapical periodontitis was diagnosed in tooth #37 after CBCT imaging in a patient aged approximately 50 years (Fig. 2). The mesial root canal entrances were difficult to identify because they contained welladapted, tooth-coloured composite. The treating endodontic specialist, Dr Thomas Rieger from Memmingen in Germany, selected the appropriate sequence of flexible NiTi files on Jeni’s touch screen. The HyFlex CM or EDM and the MicroMega One Curve or 2Shape from COLTENE are already pre-installed in the software. In the latest update, the 30/.07 HyFlex and MicroMega Remover files were added, making a significant difference to an endodontic revision treatment. The new Remover files fit perfectly with the established file systems and quickly and reliably remove inadequate gutta-percha fillings as well as similar endodontic restorations that have become outdated. In the Doctor’s Choice program, users can also store up to eight additional filing systems of their choice if they are familiar with the respective motion protocol.
In Case 1, the appropriate access was achieved with an orifice opener. The extreme curvature in the apical third presented a particular challenge during preparation. The following sequence was therefore used: the 10/.05 HyFlex EDM file was followed by the 20/.05, and the universal file 25/~ HyFlex EDM OneFile then performed most of the work in the mesial and distal root canals. The final sequence involved the 40/.05, 50/.03 and 60/.02 files in the distal root canals for final shaping. In this process, Jeni enabled rapid preparation despite the highly curved profile of the root canals. Each file virtually worked itself to its working length. The natural shaping of the root canals is clearly shown in the postoperative radiographic image (Fig. 3).
Frequent rinsing with efficient material removal
A revision treatment by Dr Silviu Bondari from Beuzeville in France also demonstrates that retreatment can be performed quickly and easily with the new endodontic motor. In a 30-year-old patient, removal of the insufficient gutta- percha filling also proved necessary owing to periapical periodontitis in tooth #36 (Fig. 4). At a speed of 1,000 rpm with continuous rotation, a delicate MicroMega Remover file was inserted to over two-thirds of the distal root canal length. The remainder of the root was then treated with a HyFlex EDM OneFile in the contra-angle handpiece at 500 rpm. HyFlex EDM files of size 20/.05 were used in the mesial root canals. The speed was also set at 500 rpm. The HyFlex EDM OneFile was then used in the mesial canals for final shaping of the root canal. A 40/.04 EDM file was used in the distal root canal. The result on the radiograph promised a more durable obturation than the initial treatment five years earlier (Figs. 5 & 6).
Thorough rinsing is recommended in endodontics, especially for the efficient removal of material, be it dentine or old filling material from a revision treatment. If too much material remains in the root canal, the file may block and, in the worst case, even break. At the working speeds of modern NiTi files, even endodontic experts often underestimate how much debris has already accumulated in the root canal. Here too, an acoustic signal helps, automatically sounding when rinsing would prove advisable.
For dentists who prefer using cordless motors because of their reduced weight, Jeni ticks all the boxes. It can be conveniently placed chairside on a small rolling table and, thanks to its long battery life, no cumbersome power cable is required, so the instrument of the future can be easily integrated into one’s practice. Interested dentists will probably be able to conduct the first trials with the new endodontic motor no later than at the 2021 International Dental Show in the autumn.
Digital endodontic assistance systems speed up preparation by controlling the rotary motion fully automatically, making preparation considerably safer and more reliable. This is especially true in the case of irregular root canal anatomies, where the co-pilot will in future help to shape root canals naturally while being a reliable reminder of the appropriate rinsing protocol.
Editorial note: A list of references available from the publisher. This article was published in roots―international magazine of endodontics No. 2/2021.