Having been in the trade as an endo-savvy dentist for the last 20 years, I have treated referred cases that were structurally compromised, produced nice white lines (also in questionable teeth) and finally decided to address these types of situations once and for all. I have spent a great deal of time teaching about less invasive approaches, on social media I have shared my knowledge about referring patients to an endodontist as soon as possible and I have organised congresses with the aim of fostering fair relationships between endodontists and general dentists. The main message has always been: if you decide to collaborate with an endodontist, make up your mind well in time and come to terms with your limitations as a general dentist. We all must be aware of our (in)abilities instead of attempting treatments on our own. The latter could lead to unnecessary and excessive loss of sound tissue or, even worse, a shorter survival. There is no reason that one should not refer the patient to an endodontist straight away.
What has changed? Almost nothing!
When I first read about guided endodontics, I intended suggesting this method to general dentists—and to endodontists with complex cases as well—as a solution to avoiding access preparation failure. The reason behind this is that the entry point, the depth of drilling and the angulation of drilling are implemented in one tool. Unnecessary tissue removal can be avoided, since there is no need for blind guessing or hollowing out the tooth with huge round burs, let alone working without magnification. To put it in a nutshell: the clinician can get exactly where he or she wants much easier. Static guides for endodontic treatment can be fabricated in laboratories, just as is done for guided implant placement. The methodology of planning and printing and the costs are similar.
Is this method really a panacea for avoiding failures?
Having gained experience with 3-D printed template guides in the last two to three years, my answer is yes. On the one hand, static guidance can be a solution for better accuracy and theoretically this method has the potential to be a general solution for most cases. On the other hand, there are some cases where, due to some limitations and disadvantages, guided endodontics is not recommended.
The use of static guidance is predictable and easy in calcified incisors. In such high-difficulty cases, where the failure rate is high, even working under an operating microscope and with a CBCT scan allows accurate access cavity preparation up to the apical third of the root. In my practice, I use it also for treating molars and premolars; however, I do it with caution.
To be able to use this kind of treatment, patients have to be able to open up their mouths really wide. But we do not usually treat lions, do we? One has to consider the common lack of interocclusal distance to accommodate the additional 10 mm drill or bur length required by the guide ring position over the tooth. To avoid this, I usually have guide burs at hand. Before planning this option, I try to insert the guide bur in the patient’s mouth. Metal restorations can also create problems while planning the treatment. Since CBCT data (DICOM data) is used for that, metal artefacts could be a source of inaccuracy. However, with superimposition of scan data (STL data gained from an intra-oral scan, impression or cast scan) and experience, the possibility of this type of mistake can be minimised.
Static guides are not suitable for high-speed handpieces either. When drilling through enamel, ceramics and cast restorations, one could encounter issues with cooling. My advice is to mark the point of entry with the help of the guide through the sleeve, then remove the enamel or restoration through freehand preparation, and finally, drill the dentine with the guide and guide bur in order to reach directed dentine conservation.
Usually, one guide is not enough when treating premolars and molars, and it is therefore necessary to have a drill guide for each root canal. This can raise the costs.
The main disadvantage is that static guidance is not suitable in acute cases. One should wait to receive printed or milled drill guides before scheduling an appointment with the patient. Considering these issues, it is clear that static guidance can help us in certain situations, but not in general. Guided endodontics will not be easier and cannot replace expertise, thinking and planning.
In conclusion, I must say that compared with operating freehand, using any type of guidance results in better accuracy, especially in borderline situations. Dynamic guidance, however, may revolutionise our daily endodontic practice in the near future. Planned on CBCT data, the avatar of the bur can be visualised on the screen in three planes and controlled in real time in 3-D to remove just as much tooth structure as is minimally necessary for access preparation in endodontic treatment, without the disadvantages of static guidance.