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Living Up to the Name of an Endodontic Technology Icon

Dental Products ReportDental Products Report April 2024
Volume 58
Issue 4

Built on the same reliable, accurate technology as the original Root ZX apex locator, the new Root ZX3 from J MORITA aims to be equally innovative with the integration of high-frequency conduction therapy.

Kazunari Matoba Former General Manager of Research and Development, J MORITA MFG CORP – Pictured with (from left to right) Root ZX II, Root ZX, Root ZX3, Root ZX mini | Image Credit: © J MORITA MFG CORP

Kazunari Matoba – Former General Manager of Research and Development, J MORITA MFG CORP – Pictured with (from left to right) Root ZX II, Root ZX, Root ZX3, Root ZX mini | Image Credit: © J MORITA MFG CORP

Carrying the mantle of a standard setter is not an easy task.

This is true for the child of a hall-of-famer and it’s just as true for the next generation of an iconic dental product. So when the research and development team at J MORITA MFG CORP set out to develop what is now the Root ZX3, they knew that to live up to the legacy of the name Root ZX, the goal must be to open a new paradigm in endodontic treatment.

With the introduction of a module capable of high-frequency conduction (HFC) therapy, and the same reliable apex location technology used in every Root ZX apex locator, the Root ZX3 is designed to be just that, says Kazunari Matoba, a former general manager of research and development at J MORITA MFG CORP who oversaw the development of the Root ZX line.

“Until now, the machines that have existed in root canal treatment have been those that help the act of treatment to make the diagnosis accurate and the treatment fast and easy,” Matoba says. “The HF Module is the first product to enter a new field where by its high-frequency conduction, symptoms are expected to improve due to the natural healing process of the human body…in cases where doctors are having trouble with treatment and healing is not possible. I am excited that we have entered a new world.”

Root ZX3 Apex Locator | Image Credit: © J MORITA MFG CORP

Image Credit: © J MORITA MFG CORP

Root ZX3

Featuring a new design with a large display and a smaller footprint, the Root ZX3 apex locator features automated calibration and a high-contrast display screen. Using impedance measurement-based technology that has been evaluated to be 97.5% accurate, it can be trusted to provide accurate measurement of file depth during endodontic treatment. A versatile device, it can be used in wet or dry canals.




Getting to that world was not a straight line, but neither was the development of the Root ZX technology that functions in any canal environment and provides accuracy that’s been measured at 97.5%.1 The accuracy is the key detail that makes the Root ZX apex locator so important, and Matoba says that when looking to create a solution for dentists, it was clear that precise, accurate measurement could make endodontic treatment easier and more predictable for everyone.

“It all started when I met doctors,” he says. “You can’t do proper development without knowing clinical practice. Endodontics is a field where the best solution for treatment is completely different from person to person. If you ask 5 doctors a question, sometimes all 5 will give you completely different answers. I was also troubled at that time. I wondered who was the most correct.”

The History of Electronic Apex Locators

Launched in 1991, the original Root ZX and its successors have been shown to be highly reliable systems for accurate measurement of the location of the apical constriction to determine the working length of the canal. Still, many endodontic treatments are performed today without an electronic apex locator, with clinicians using radiographs, tactile sensation, and other methods to determine the working length.

Early generations of apex locator technology did not provide the accuracy or reliability required for clinical use due to moisture in the canal or other issues.2 Using a technology called the ratio method that takes measurements of the ratio between the impedances of 2 electronic currents, the Root ZX solved many of the problems with earlier generations of electronic apex locator solutions and lived up to the promise of a technology dreamed up more than 70 years earlier.

Levitt Ellsworth Custer, DDS, was the first to describe using electric current to measure when an endodontic file reaches the apex of the root canal in a 1918 article in The Journal of the National Dental Association. An early proponent of the use of electrical technologies in the practice of dentistry, Dr Custer did not see his apex location theories put to use in his lifetime.3 However, the concept was further tested in the 1940s and finally launched as a commercial product in 1969. Unfortunately, the first generation of apex locators used alternating current and resistance and were less accurate than radiographic measurement. A second wave of technologies based on single-frequency impedance measurements were also shown to be unreliable.2

The Root ZX was among a third generation of apex locators, and as noted above, it offered the reliability necessary for clinical use. Since that time multiple new technologies for apex location and canal length measure have been developed, but the Root ZX remains a standard bearer for apex locator accuracy today, and technology that powers the original Root ZX is a key component of all of its successors.

“We don’t intend to say that we’re completely redesigning the model,” Matoba says. “The apex locator’s bar in the Root ZX3 has been greatly improved to shift smoothly. It is very easy to use. However, even as we have made these improvements, we have not changed from the original Root ZX all the way through.”

Root ZX Evolutions

Over the years new versions of the Root ZX have found innovative ways to incorporate this foundational apex locator technology. In 1996 the Tri Auto ZX integrated apex location technology directly into an endodontic handpiece. Then in 2007, the Root ZX II added the possibility of integrating different modules into the device.

This was followed in 2009 by the Root ZX mini, which put the same apex location technology in a small and convenient form factor. In 2014 the OTR Module made it possible to connect a low speed handpiece directly to the Root ZX II. In 2017 the Tri Auto ZX2 upgraded the integrated endodontic handpiece–apex locator solution. Now the Root ZX3 is joining this legacy.

What the Root ZX3 and HFC Therapy Accomplish

While the core apex locator technology remains the same, the Root ZX3 packs everything into a smaller footprint with a larger display screen featuring 40 indicator bars providing real-time readings of the file location within the canal and an audio signal to provide warnings even when the clinician is not looking at the device.

Those upgrades improve the core function of the device, but the HF Module that attaches to the back of the Root ZX3 brings a new treatment approach to endodontics. HFC therapy can be used to cauterize and coagulate tissue, which can be used to create hemostasis during a pulpectomy. The therapy can also be applied during retreatment to cauterize infected tissue. The module can also be used for gingival procedures including gingivectomies, gingival polypectomies, and gingival retraction.

The HFC therapy treatment can be performed using HF endo files or specialized electrode tips depending on the procedure, and multiple modes and output settings can be used to customize the treatment. The technology takes advantage of the apex locator to show where the file is in the canal, and the HFC is used to heat the tip of the file to cauterize or ablate tissue.

Matoba says the work he and his team produced with the Root ZX3 is a great accomplishment. He hopes HFC can help provide treatment to situations that were previously challenging to deal with. Still, he believes even more progress can be made in endodontic technologies.

“The most important thing is to prevent endodontic treatment,” he says. “I think it is our job to prevent endodontic treatment by utilizing the comprehensive capabilities of J MORITA MFG CORP. We are probably at the forefront of this kind of prevention, so our ideal vision for the future of the endodontic field is to create preventive machines that will prevent endodontic diseases from occurring.”


  • Guise GM, Goodell GG, Imamura GM. In vitro comparison of three electronic apex locators. J Endod. 2010;36(2):279-281. doi:10.1016/j.joen.2009.09.016
  • Gordon MP, Chandler, NP. Electronic apex locators. Int Endo J. 2004;37(7):425-437. doi:10.1111/j.1365-2591.2004.00835.x
  • Gutmann JL. Origins of the electronic apex locator - achieving success with strict adherence to business. J Hist Dent. 2017;65(1):2-6.
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