Case report

 

Endodontic procedure accidents. Case report

 

Tania Abigail Terrazas Ríos,* Germán González Pérez,* Maribel Liñan Fernández,* Mónica Ortiz Villagómez*

 

* This research was conducted at the endodontics Graduate clinic of the University of Querétaro, México (Autonomous University of Querétaro).

Correspondence

 

Received: 12 march 2010.
Accepted: 26 march 2010.

 

ABSTRACT

While undertaking endodontic procedures, setback can occur. These accidents are defined as unfortunate events taking place while performing endodontic therapy. Some of these events are a result of poor attention to detail, others are totally unpredictable. Some of these unfortunate events are perforation in the chamber of the floor of the mouth, or poor obturation of the canal system, which will lead to failure of the treatment. In drilling procedures, time is of the essence. The best time to repair root perforations is immediately after the accident occurs, minimizing thus the potential of infection at the perforation site. Use of restorative materials such as Mineral Trioxide Aggregate (MTA) offer better prognosis in perforations treatments.

Key words: Root canal, drilling, mineral trioxide aggregate.

 

INTRODUCTION

Root canal treatment is associated with unforeseen and unwanted random circumstances, these are generally defined as procedure accidents.¹ Accidents which occur during endodontic therapy can be defined as unfortunate events occurring during treatment, some due to lack of attention while others are totally unforeseeable. The endodontic misadventures classification proposed by Ingle describes instrument related accidents. Part of these are perforations in the cervical section of the canal, and misadventures related to obturation, among which we find overextended or underextended obturation of root canals.² A perforation, or false connection is the artificial communication between chamber or root canal system with support tissues of the tooth or to the oral cavity. Pathological causes like root resorption and caries can lead to a perforation. Nevertheless, the source is very often iatrogenic, as a result of an excessive use of the dental burr in the pulp chamber.³

In general terms, direct perforation occurs during the canal exploration. It is rather a ''puncture'' in the bifurcation carried out with the burr. Among the causes leading to this type of perforation are the lack of dental and pulpar anatomy, and, of utmost importance for endodontists, lack of radiographic information.⁴ When a perforation occurs, time is of the essence. The best moment to repair root perforations is immediately upon occurrence, so as to reduce as much as possible infection at the perforation site. It is not always possible to properly handle the perforation because of the operator's lack of experience, or lack of proper equipment for its treatment. In these cases a proper temporal seal should be established to avoid bacterial passage.⁵

The size of the defect also plays an important role since large perforations do not respond as well as the smaller ones.⁶ Large perforations can cause problems of incomplete sealing of the defect, thus allowing continual bacterial irritation at the perforation site.⁷ Smaller perforations are usually associated to lesser tissue damage and inflammation, and are easier to repair. Healing is more predictable and has a better prognosis. Small perforations are those caused with endodontic instruments size 15 or 20.⁸

The four circumstances to consider when treating endodontic accidents mishaps are: detection, correction, prognosis and prevention. Detection of a root perforation requires a combination of symptomatic findings, clinical observation and diagnostic means. Torabinejad informs that an immediate and typical sign is an abundant hemorrhaging emanating from the perforation site. A perforation can be detected through indirect means such as paper points or the radiographic image of a file in the bone or periodontal ligament. In cases when the patient is not under anesthesia he experiences a strong periodontal pain.⁹

Another aide for perforation diagnosis is the electronic apexes localizer. Kaufmann considers it a reliable instrument and essential factor for treatment success. Readings show a working time shorter than the original work time length; this indicates a perforation.¹⁰ Authors like Gutman recommend to carry out a preoperative evaluation with two X rays for diagnosis, one in orthoradial direction, and the other with a 15 degree mesio or distoradial angulation.¹¹ Lasala points out certain criteria to avoid perforations:

1. Be cognizant with the pulpal anatomy of the tooth to be treated, proper access to be gained the chamber and guidelines for instrument use.

2. To have tridimensional, positional criterion and perfect visibility.

3. In narrow canals be careful with the passage of instruments from 25 to 30, which could foster a perforation.

4. Avoid use of rotary instruments. There are to be used only when the case warrants it and the canals are sufficiently wide.

Prognosis of a perforated tooth is unfavorable.¹² Of all variables affecting long term prognosis, the most important parameter is the location of the perforation in relation to the crest, and the sealing potential of the restoration material.¹³ Another type of accident that can occur during endodontic therapy is underobturation. Rodriguez Ponce defines it as the obturation of the root canal away from the work length determined by a previous conductometry radiograph, this will lead to an endodontic failure.

If organic residues remain in the canal the most frequent underobtuation causes are the creation of too short a stop, the lack of exact fit of the master cone, and lack of penetration of the filling material up to the predetermined work length. Correction is achieved through securing of a new determination of work length and proper obturation.¹⁴

 

CLINICAL CASE REPORT

A 30 year old woman lacking family or personal history of pathological data, arrives to the Graduate Endodontic Clinic of the Autonomous University of Queretaro, complaining of pain in the D.O. 46 area. She informs of root treatments carried out 3 months ago, she complains of nocturnal, spontaneous and localized pain when chewing. Upon inspection, a metal free restoration and an apparently healthy gingival are observed. As a response to periapical sensitivity tests, to palpation, to vertical and horizontal percussion, a positive response is elicited, with grade 1 mobility. When probing, a 9 mm periodontal pocket is detected in the vestibular middle third. Negative response was obtained to hot and cold pulpal sensitivity tests (Figure 1). Radiographic findings show non obturated mesial canals and a circumscribed periapical rarefaction. In the distal canal underobturation was found as well as guttapercha points in the furcation zone. A radiolucent area was also observed in that area. Presumptive and definitive pulpal diagnosis indicate pulpal necrosis and periapical presumptive and definitive diagnosis correspond to symptomatic chronic apical periodontitis (Figure 2). Treatment plan consisted in coronary or orthographic removal of the guttapercha present in the furcation after that, canals were retreated, the perforation was sealed with Mineral Trioxide Aggregate (MTA). Surgery can also be contemplated in cases where coronary guttapercha removal from the furcation is not possible. Prognosis is guarded. The patient is anesthetized, the restoration is isolated, then removed. Obturations are identified. Mesiolingual guttapercha (ML) is extracted exclusively through a coronary approach, with a K type file, mesial canals are located with the help of an endodontic microscope, and perforations are temporary sealed with cavit. With the help of Hedstrom files the distal canal where underobturation is present is cleared. Necessary working length for mesial canals is obtained at 17.5 mm and distal length at 18 mm (Figure 3). Use of instruments was performed manually, with coronary-apical technique and irrigation with 2.5% sodium hypochloride. The master apical file for mesial canals is # 40. For the distal canal a file # 50 was used. Retraction was undertaken and final irrigation was carried out with 2.5% sodium hypochlorite, then 17% etilendiaminotetraacetic (EDTA) acid was applied, after that, once more, 2.5% sodium hypochlorite was applied to finally neutralize with physiological serum. An chronometric X ray of the three canals is obtained, after that they are filled following cold lateral condensation technique and with epoxy resin based AHplus cement. An X ray is taken of the cone excess. A final X ray is taken to examine the mesiolingual (mL) guttapercha and the temporary seal of the perforations carried out with cavit (Figure 4). When carrying out surgery for guttapercha cone extraction and perforations sealing, the steps are as follows: first, asepsis of the operating field, to be followed by the raising of a modified Newman flap; osteotomy follows to identify the guttapercha point and then proceed to its removal. After this, curetting is carried out on the furcation zone to remove granular tissue. The site is cleansed with physiological solution. Perforations are sealed with MTA and finally, radiographic evidence identifies the perforations' sealing (Figure 5).

After three months, a control X-ray is taken. After six months the reconstruction of the stump for the crown the can be observed. After fine months the tooth is restored, with proper bone regeneration in the furcation zone. After 12 months, radiographically, the repair of the defect is almost complete. Clinically, we can observe the restored tooth with a full crown free of metal, healthy gums, and when probing the middlevestibular third, we find 4 mm. We observe a clear improvement from the moment of initial treatment, and, 15 months after surgery we encounter good regeneration of the bone defect as well as sealing of both perforations (Figure 6). Finally a comparative follow up is carried out 21 months after finishing treatment and initial radiographic study (Figure 7).

 

DISCUSSION

Prognosis for a perforated tooth depends on the location of the perforation, the time in which the perforation allows entry of contamination, the possibility of sealing it and the accessibility of the main canal.¹⁵

In recent studies, a research group in Toronto found that in re-treatment cases only two factors significantly affected success in treatment: presence of a preoperative radiolucency and presence of a preoperative perforation.¹⁶

Among accidents with worse prognosis are perforations at bone crest level, specifically in the furcation since its proximity to the gingival sulcus favors bacterial contamination.^17-19 Global index of success in the repair of these accidents, based in 55 cases, was 92%.²⁰ MTA is the most popular material to repair perforations. This material induces osteogenesis and cementogenesis. Different studies report on cement deposition on MTA.²¹

 

CONCLUSIONS

From this case we can conclude that the sooner the repair is carried out, the greater will be the possibility of success. In cases which prove to be most resistant, surgical correction will be required. In this case due to its inherent complication, endodontic surgery was performed, and through it, adequate repair was achieved. Prevention is the most important factor to avoid accidents during endodontic therapy. Benefits are always for the patient, who must receive the best possible treatment.

 

REFERENCES

 

Mailing Address:
CD Tania Abigail Terrazas Ríos
15 de Mayo 114-5, Centro, Querétaro, Qro. 76000
E-mail: abiterrazas@hotmail.com

 

Note

This article can be read in its full version in the following page: http://www.medigraphic.com/facultadodontologiaunam

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