06 May 2022

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How to manage broken endodontic instruments - Interview with Dott. Castellucci

Author: Arianna Bianchi

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The fracture of endodontic instruments during root canal treatment is an event that often worries clinicians, who risk finding themselves faced with an obstacle that is difficult to overcome, with the additional burden of having to communicate "the inconvenience" to the patient.

Dr. Arnaldo Castellucci  then clarifies the main aspects regarding the fracture of endodontic instruments. Aspects that will then be further explored on 6 and 7 May in Florence together with Dr. Yoshi Terauchi. Dr. Castellucci, author of the box set with the three volumes (Edra editions) of the work "Endodontics" and of the book "Microsurgical endodontics".

"First of all - underlines Castellucci - since nickel-titanium tools appeared on the market, their fracture is seen much more frequently than when there was only steel".

For Castellucci, in fact, the fracture of steel instruments is linked to their incorrect use, “that is, pushing them in an apical direction until they get stuck and break. Steel tools must never work with an inward thrusting motion, but rotating outward and so they will never break. Another reason why they can fracture is due to an excessive number of their use. Especially small-caliber instruments must even be considered "single-use".

"Small caliber steel instruments, in particular, especially the very first files that are used to 'explore' the anatomy of a canal, must be pre-curved and used with delicacy, as would the blind man who, using his cane, can find the exit of a room. Thus the endodontist is able to find the apical foramen ".

Castellucci then continues underlining how the discourse is slightly different for rotating instruments made of nickel-titanium. “We know that these should also be considered single-use, but due to their high cost this is rarely achieved. However, it must be emphasized that, although visually the tools appear perfect, during their use they accumulate stress and therefore their duration obviously has a limit. In particular, rotary instruments undergo two types of stress: bending stress, since they rotate in the curved section of the canal, and torsional stress, due to the shear action exerted on the dentin ".

It is precisely torsional stress, he explains, that is most involved in the fracture of instruments, an event that occurs when the rotating instrument is inserted into a canal that has not been previously widened so that its tip (the most fragile part of the instrument) find the channel of its own size. In this regard, Dr. Castellucci underlines how "numerous manufacturers have developed thin and resistant nickel-titanium tools, to be used for the" preliminary enlargement ", a procedure that considerably reduces the risk of fracture and then allows you to work in total safety ".

But how to remove any fractured instruments?

"The techniques - he explains - are numerous and first of all involve the use of the operating microscope and Cone Beam Computed Tomography (CBCT)".

Dr. Castellucci advises against trying to remove a fractured instrument if you don't have a microscope. This is because it would risk creating further damage and also complicating the work of the colleague to whom one usually turns to solve this kind of problem. "Several times - he says - I have seen that in the vain attempt to solve the case, next to the fractured instrument the colleague had fractured another and also made a perforation".

"Once the metal fragment has been visualized with the aid of the microscope, there are various tools that allow it to be extracted: some are specially designed to 'fit' the fragment, while others are based on the use of a glue that blocks the fragment inside a small metal tube and then remove it ".

"The simplest method - he indicates - is represented by the use of specific ultrasound tips, with which vibrations are transmitted capable of making the fractured instrument" jump "out of the canal. The tips are extremely thin, they must be worn alongside the fragment and if this is fractured within a curved portion of the canal, it must be positioned on the "inner" side of the curve ... and here lies the great difficulty ".

“It is also possible to bypass fractural instruments and indeed - for Castellucci - this should be the first choice”.

“In these cases - continues Dr. Castellucci- it is necessary to inform the patient that the damage he receives is linked not so much to the presence of the metal fragment inside the canal as to the fact that the presence of the fractured instrument blocks the way to disinfectants for disinfection (first) and to the materials and instruments for the obturation (then) of the portion of the canal located apical to the fragment. The patient must understand that although it is an unpleasant accident, it is not comparable to the forgetfulness of the surgeon who leaves a surgical forceps in the abdomen. The patient will live 100 years in peace, having the obturation of that canal consisting of gutta-percha and a metal portion in the middle of the canal ".

Given that in the vast majority of cases the instruments fracture in the mesial root of the lower molars and in the mesio-buccal of the upper molars, Dr. Castellucci makes another consideration, given that we are talking about roots with two channels inside.

“In a fair percentage of cases, the two canals of the same root converge in a single foramen and to notice this particular anatomy the systems described in the literature are many and today CBCT in axial projection is extremely helpful. Therefore, if I am sure of the confluence of the two canals, once the canal free from the problem has been properly cleaned and shaped, I do not make the slightest effort to remove the fragment, since the part of the canal in common to the two has already been prepared by passing through other channel. Fortunately, this happens often and in fact it is the confluence (not diagnosed in time ...) that is the cause of the unpleasant accident. Where there is a confluence, in fact, the canal makes a counter-curve that the instrument cannot bear and breaks… ".

But the orthograde approach is not the only one possible.
“There are cases - underlines Castellucci - that require an exclusively surgical solution. This is the case with large-caliber instruments, firmly embedded at the level of the apical foramen and beyond a curvature of a long root. The same is true for instruments broken in the foramen and protruding in the periapical tissues. "In these situations, Dr. Castellucci suggests proceeding directly with a surgical approach. An approach that must be carried out by the endodontist himself, without involving oral surgeons. or maxillofacial, which often do not even have the experience and skills necessary to solve such complex cases that are purely the responsibility of the endodontist.

To conclude, Dr. Castellucci returns to the need for the clinician to communicate the fracture of an endodontic instrument during a treatment.
"Patients are often not duly informed about what happened or are only partially informed. On the other hand, it would be ethically correct for the clinician to make the patient aware of the situation and possibly address him to more experienced colleagues who are therefore able to solve the problem, also taking charge of the fee ".

Dr. Castellucci then ends with a final reflection: "In Italy there are no post-graduate specialization schools and there are few degree courses in which endodontics is taught 'seriously', thus churning out new graduates in Dentistry who often never have performed endodontic treatments ".